f4i engine mods

[jonnycowboy]

hey,
I was wondering if anybody had found a supplier for an f4/f4i stroker kit? ie rods, pistons, crank and sleeve to keep the displacement at <610cc?
thanks

[Bowtie Man]

Hey,
i've never heard of such a kit, however couldn't you bore the cylinder out say .060" and get oversized pistons and rings from like Wiseco or another aftermarket company? And I was wondering what benefits do you see in this modifacation?

[DaveC]

Youre not talking much difference between 599 to 610 ccs. Wiseco's 1mm os piston kit makes it 618 cc. The only way I'd figure you could stroke it little enough would be to offset grind the crank, get undersized rod bearings, and have custom pistons made to fit youre new stroke. Lots of $$$, not much benefit. Wiseco makes a std. size piston that ups the cr to 12.7 or 12.8, then you can use a thinner head gasket or mill the heads to up the cr a little more. Boring the block will cost a lot due to having to nikisil plate the piston bores, and I know of no off the shelf piston that will bring it in under 610 ccs. Stroking also changes connecting rod clearances, which could also be an issue. It changes rod ratio too, which wouldnt be significant here.

I'm thinking of using stock sized Wisecos, thinner head gasket, and possibly camshaft changes, polishing the chambers and exhaust ports, using internal ceramic and piston skirt coatings, a valve job and cleaning and balancing the stock injectors. That should be fairly inexpensive compared to a complete rebuild, but a motor thats already in good shape is needed. All thats if we have enough $ for it.

[Bowtie Man]

As far as I'm aware there are no aftermarket cams that would do any good for FSAE. They all make it flow better at higher rpms where we're already choked due to the restrictor. Unless of course you're going to develope cams that will bring the power lower in the rev range what's the point? I guess if you're power hungry which is a lot less important than being reliable in this competition you might be wasting your time with all the bells and whistles.

[DaveC]

Unless of course you're going to develope cams that will bring the power lower in the rev range what's the point?

Yes, thats the point. I was considering having the intake cam reground to suit the lower rpm range we are operating in compared to stock. I also believe these mods will not effect reliability at all. Actually, it gives you a chance to make sure your used motor is in good shape while also doing some upgrades.

Really the point is that its there to do, its not relatively expensive, its not very difficult or time consuming, so why wouldnt you do it? Take a couple dozen things on the whole car that dont make a huge difference, add it all up, and theres something to be gained. Why do some teams run a turbo, or do anything different? If you want to just do the bare minimum, thats fine, I'd like to improve my teams standing. It is a competition.

[Bowtie Man]

I wouldn't shrug off designing new cams as something relatively easy, and cheap for that matter. Granted if you're capable the gains of new cams can be worth the effort, but this is going off topic of the original post so I'll let it rest.

[DaveC]

Yes, youre correct designing THE optimal cam configuration for the motor isnt the easiest thing ever. I have a price of $525 for regrinding both cams, and the business owner is considering further discounts for our team. Other places may have lower prices, I have not researched further. I was considering just modifying the intake cam because I believe that will be the best cost / benefit option (just based on general theory, no concrete data yet). I plan on using our engine sim program to show what the benefits will be, for cams as well as compression ratio, then we will decide if its going to happen. I know its a little off topic, but I believe jonnycowboy is interested in what can be done to the f4i, so it may be relevant.

I did read up on others experience with cam mods on this board, and nobody has really said how much gain they realized from it. Anyone that changed cams have anything to say? http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Andycostin]

We have been running intake cam mods for the past two years - designed on our engine sim software, and then verified on the dyno. We decreased the duration and changed timing slightly, which reduced the overall overlap. This was done to target cylinder charging efficiency across the targeted rev-range of 4500-10000rpm. This cam timing was optimised with all intake and exhaust variables, and the final cam was chosen with the best torque spread, not the best peak - aim of drivability.

Hope this helps

[jonnycowboy]

wow thanks for all the replies!! I see that getting a 610cc stroker kit would probably be way too expensive, I'll look for the wiseco pistons and then shave the head 20-30 thou. As for cams, I'd like to regrind them as well, to 7.2 for intake, 6 for exhaust. Timing via adjustable sprockets, and reduce the duration about 15%.
Has anybody modified the combustion chamber?

[DaveC]

You'll need to check your piston to valve clearances before doing any head shaving. Theres not too much room in those chambers. I believe you can get a thinner head gasket to up the cr a little more. I'd look into what adjustable cam timing might do for you, especially if you get new cam(s). The timing you want can be ground into the new cam design. Adjustable sprockets can slip, which can be a PITA. I am planning on just polishing the chambers and rounding off the edges a TINY bit, removing as little material as possible, ccing the chambers, and a good valve job. The valve seats have quite a bit of contact area, which can be slightly reduced for a little better flow. This will reduce heat transfer from the valves into the head, so you need to think about that. I plan on having the valve faces (chamber, piston domes and exhaust ports too) tbc coated to reduce heat transfer into into the valves, heads and pistons.

I would use a engine sim package to figure out what any changes will accomplish, decide if you think its worthwhile, then test what you did on a dyno and a track before and after to justify your efforts. Its a little more effort than you'd typically put into the BBC in your pickup, but its an engineering exercise as well as a performance competition.

[UQ Turbo]

Hey Guys,

I think this topic is great! I'm glad to see people are playing around inside their engines as well as outside.

We all know that peak torque will be much lower in the restricted engines, which necessitates smaller I.D. inlet runners. I'm currently developing an F4i for next year's car and am planning to bore into the inlet ports on the head, fit a sleeve of the correct I.D. and hand blend the sleeve into the rest of the head with a porting tool.

Just wondering if anyone has tried this or come up with other ideas to blend a smaller than stock I.D. inlet runner into the head sucessfully. I've had a look at the head and there seems to be enough metal to be able to bore in. Let me know if any of that was unclear...

Cheers

[DaveC]

http://www.mototuneusa.com/

I ran into this site some years ago. The guy presents his material in an especially dumbed-down way which is also fairly annoying, but some of what he says has merit. He has a whole article on his "port shrink" method in his site, in which he uses JB Weld to fill up a portion of the intake ports after he prepares the aluminum in a certain way to help the epoxy "grab" the aluminum better. It seems quick and easy, but I'd be too worried about getting a chunk of epoxy in the chamber. Your sleeve idea is better, however I believe for it to be most effective, you'd need to fill in past the point where the port splits into a "Y", and be able blend the sleeve into the junction somehow. I've thought about welding, but I'm absolutely sure I don't have the skills to weld inside the port reliably. If you have any more details on how you plan on doing this, I'm interested in hearing about it. About the first thing I said when I first saw FSAE cars was why the intake and exhaust primary tubes were so big on a car making so little torque. I just got Wave for our team and am working on getting it up and running, so hopefully I can answer some of my own questions here shortly...

[Jon Weir]

If someone from Waterloo wants to pipe up, I know that a couple years ago they got Jim from Cycle Improvements to stuff the ports on an F4i. Apparenly with reasonable success, but maybe not worth all the time and effort.

[jonnycowboy]

ya if you're running lower down in teh rpm range and want to increase air velocity a good way to do it is to add epoxy smoothly in the inlet passages. Any respectable head porter can do this (montreal: TK Race Heads, down in the US, Hines from the exhaust company 'vance and hines' can port heads as well, tho it's a bit expensive. I think here in montreal the going rate to report a head completely (with epoxy) is about 3 grand CDN (2500$US).
Basically i think the reason people run such large diameter intake runners is for simplicity, they don't want to have to weld up a new adapter to where the throttle bodies use to attach. The best performance can be had from a tapered runner all the way from the plenum to the valve (quasi-impossible cost-wise).

[sticks]

I would be cautious about raising the CR on a motorcycle engine as there isn't much to play with there. Having built and subsequently seen drivers destroy R1 motors in DSR cars, it becomes apparent you have to be much more careful when engine braking due to the greater traction at the rear end (rod stretchers as C. Smith said). In fact in one drivers motor we went to getting pistons with lower deck heights to help. Just a thought though, Cheers!

[UQ Turbo]

Thanks guys,

I think I'll proceed with the bore and sleeve and let you know how it goes. Thank god we've got a bloke in the uni workshop that can port heads, would be a shame to have to spend $2500!

UQTurbo

[Garlic]

Originally posted by UQ Turbo:
Thanks guys,

I think I'll proceed with the bore and sleeve and let you know how it goes. Thank god we've got a bloke in the uni workshop that can port heads, would be a shame to have to spend $2500!

UQTurbo

While in theory a smaller port might be better, if you really think you can improve the efficiency of an OEM designed port like the f4i by making it smaller and hand-porting, I'd be very skeptical, and so would a judge.

If you do this you'd better have back-to-back proof it works better, with no other changes. Power and flowbench numbers. If you can improve on it more 'power' to you though. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[DaveC]

flowbench numbers.

I couldnt care less about flowbench numbers on a car like this. Drag racing, yes, autocross, no... I'd agree stuffing the ports wouldnt be worthwhile if there was no restrictor, or if you are running a turbo, though. I have done a good bit of porting work, and I also agree the overall shape of the ports is good. However, having smaller ports, which would enable you to use smaller primary tube on the intake manifold, will make better low end torque. I also believe the steady flow numbers will go down, but this will most likely be offset by the desired low rpm torque increases. As far as improving on OEM designs, hotrodders have been doing it forever http://fsae.com/groupee_common/emoticons/icon_wink.gif. I wouldnt look at this as an imporovement, though, more as compensation for the restrictor being there...

[UQ Turbo]

I see exactly where you are coming from Garlic; Honda know how to build engines and make ports the right shape! Though I'm more concerned about allowing the smaller diameter inlet runners to slot nicely into the head than changing the port shape.

As far as I understand, optimum velocity in the inlet runners is 240 ft/s (73.15 m/s). Larger than this and air velocity is too slow to pack the cylinders effectively while the inlet valves are open and smaller than this I'd assume Moody frictional losses begin to come into play. Honda have sized their inlet runners for 12,000 RPM (36mm ID and 80% assumed vol. eff.) and the dyno results for the stock engine support this (I will send some pictures and excel files if anyone wants them). I'm chasing peak torque at 8000 RPM and want to size the inlet runners accordingly. If this were naturally aspirated, the runner I.D would be 23.6mm which is tiny! In this case, trying to modify the ports would be pretty much impossible. However, I hope to have about 90% of choked conditions with a turbo, giving me an inlet runner ID of 27.2mm - this is still small, but workable without changing the port shape too much- I hope!

So I'm not out to re-design Honda's magic, just find a suitable compromise. Unfortunately, we don't have the resources to test dozens of intakes so we have to use our best judgement and try to get it right the first time round. I agree with DaveC too- more airflow on a flowbench is not so relevant for a restricted engine, unless we are talking about the restrictor itself...

Cheers
UQTurbo

[DaveC]

UQT, I'd definately like to see what you've got. I guess I was wrong about it not being something to consider on a turbo, although it might make a bigger difference N/A. My email is David dot Cahoon at Colorado dot edu . My work is all theoretical so far, but you've got to start somewhere... When I started working on the motor, I was given absolutely nothing, and its going to take a while to learn Wave, collect data, and get it up and running. I'd love to ask for f4i Wave models on this board, but it doesnt seem like something people would be willing to share, (but pm me if thats not the case http://fsae.com/groupee_common/emoticons/icon_wink.gif ). Good luck with the sleeve job, post up some pics when you do it!

[Garlic]

I didn't mean more flow was better, just that you need some data. Plug it into your sim, or just use some thoery to get what velocities you want at what lifts, etc.

It's a big mistake (IMO) that FSAEers (and rookie engineers alike) make. Make a ton of changes based on theory, don't isolate them and test them, and end up with a final product that might be good, but you don't know why! Maybe some changes helped, maybe some hurt. Engineers spend the time to find out what works and only use that stuff. Not just think of every unverified 'improvement' they can make and just assume they are all good.

It doesn't take a lot of resources to test a lot of intakes! No more than it takes to do one, really. Test intake don't have to be pretty. They can be cobbled togetther with just about anything. They can be as heavy as you like!

If you don't test multiple configurations, you don't learn if your thoeries have any merit, and as a result don't really learn much.

Testing things leads to measurable improvements, and that's one of the most fun things to see in engineering.

[DaveC]

It's a big mistake (IMO) that FSAEers (and rookie engineers alike) make. Make a ton of changes based on theory, don't isolate them and test them, and end up with a final product that might be good, but you don't know why!

Very true. I do plan on using Wave to figure out what will produce the biggest benefits. Unfortunately, our team doesnt have unlimited resources, so we really need to figure out what the best "bang for the buck" will be as far as modifying the motor. I'd like to do a lot, but we will have to settle on a couple of changes that will make the most difference. The first things I plan on looking at are the cams, and cylinder pressures (dynamic and static compression), because they are so closely related. Also, I'd like to figure out how to model the effects of TBC coatings on the piston domes, chambers, valve faces and exhaust ports. Related to that, I'm thinking running the motor "hot" (higher temp t-stat) might be an advantage for a restricted motor as to attempt to further improve thermal effeciency. I'd also like to look into the "port stuffing" and intake runer size as discussed before, but we'll have to see what there will be time for...

[UQ Turbo]

Hey all,

I recently measured the compression ratio on the F4i with a pippette and kerosene.

Swept volume: (bore^2/4 x pi x stroke) = 6.7^2/4 x pi x 4.25 = 149.84 cc = SV
Measured volume of combustion chamber in head (with both valves closed): = 8.500 cc
Volume of head gasket: thickness x bore^2/4 x pi = 0.0775(?) x 35.2565 = 2.73238 cc

Volume of a cylinder 10mm down = 35.25652 cc = A
Measured actual volume of piston 10mm down bore = 36.00 cc = B
So contribution to combustion chamber volume on top of piston is: B-A = 0.74348 cc

Combustion chamber volume: 8.5 + 2.73238 + 0.74348 = 11.97586 cc = CCV

Compression Ratio = (SV + CCV) / CCV = (149.84 + 11.97586) / 11.97586 = 13.5118

Honda says its compression ratio is 12:1!!!!

Has anyone else tried this? Perhaps I have measured incorrectly or made an error somewhere?

I'm going to turbo this engine and am lowering the compression ratio, hence just want to make sure that I've got my numbers right before grinding away at pistons, head and ordering lowered con-rods.

Cheers,
UQTurbo

[Garlic]

Don't forget the difference between the actual bore size and the piston bore size. This is a factor all the way to the top ring. Use the actual measured bore size in your other calcs as well. It's a bit bigger than 67mm.

[UQ Turbo]

Hmm,

Bore size is 67.03 - makes CR calc even worse: 13.58.

You are quite correct about the volume between the piston and bore until the top ring, but the Kero has taken care of that! Unless it is too viscous to get in between the piston and the bore -this seems unlikely.

Deck height is also zero and just clearing things up: the pistons look domed, but the valve cutouts and the pistone-bore gap actually has more volume in them than the domed bit in the middle, hence adding to the combustion chamber volume.

Thanks for the ideas.

UQTurbo

[DaveC]

That is interesting. I can't find an issue, unless something was measured incorrectly. I find it hard to believe Honda cant do cr calculations, though http://fsae.com/groupee_common/emoticons/icon_confused.gif Anything is possible....

Did you measure all 4 chambers? I'm curious how close the chamber volumes are. If youre lowering cr for turbo, you could polish the chambers and pistons (if youre keeping the stock ones) and remeasure before you do calculations to achieve the cr you want. Balancing all 4 cylinders is good too. It seems it might be cheaper to get custom pistons rather than connecting rods? It would also keep you from having to polish the stock pistons, and trying to keep material removal the same for all 4 pistons.

[Bowtie Man]

with all this talk about cr's, have any of you increased the cr when using E85? I've been thinking about it, and wondered if any claying of the piston or an equivalent method have been done to see what the clearance between the piston and valves is. Just wondering if a simple planing of the head would do, or will material have to be removed from the pistons. If someone has in fact done this can you give me some hints as far as what to look for, or some clearances would be great

[UQ Turbo]

Ahhhhh....

Ok, I know what I've done wrong. I didn't use a glass plate with a hole in it to know exactly when the meniscus reaches the top of the bore / head. Will get back to everyone once I've re-done the test... which may not be very soon - thesis is due in 12 days...

UQTurbo

[Frank]

and so ends the "quest to turbo" UQ's 05 engine

[DaveC]

Use plexi, easier to drill thru http://fsae.com/groupee_common/emoticons/icon_wink.gif

Also, seal the edges with a little bit of white lithium grease, so none of your fluid escapes.

[Mustang Mac]

I clayed a piston a few years ago and can't remember where I put the data. I have to look for it but there was some room for decking, not much, but there was room.

[DaveC]

I believe I saw a spec of about .04" piston/valve clearance someone posted here. With something like this, consider it a mandatory "check-it-yourself" operation. You need to know exactly what this dimension is if your going to alter it. There is also some disagreement about what is safe. I also read here about thinner head gaskets being available, that might be worth looking into. It's easier to switch to the thicker gasket than un-mill your cylinder head.

Also, since I'm trying to find a new intake cam profile, and raise static cr, I assume the new cam will decrease overlap and intake duration, which will, I'm guessing, increase cylinder pressure. Has anyone found a maximum cylinder pressure limit for the f4i? I'm thinking it may be impossible to achieve max pressure due to the restrictor, but it would be nice to know.

[Frank]

UQ Turbo update for 11 November 2005

http://www.uq.edu.au/fsae/turbo/hole_1.jpg

http://www.uq.edu.au/fsae/turbo/hole_2.jpg

http://www.uq.edu.au/fsae/turbo/hole_3.jpg

[Chris Boyden]

Bummer, not as much wall thickness as you thought? What are you guys boring the entrance ports to?

[UQ Turbo]

Just a clarification:

We knew we would break through, it's not a problem though; any material removed will be replaced with inserts that will be attached with cylinder head epoxy. Will send photos once the sleeves are made.

UQTurbo

[John Bucknell]

Another good topic, too bad I've been away.

The optimum inlet port velocity (at the 'window', ie the interface to the cylinder head) using Ricardo methods is 100 m/s at peak power, but that is using 100% volumetric efficiency. So yes, the ports are huge for FSAE....

An easy way to make the epoxy stick to the port wall is to drill some small divots in the floor (taking care to avoid the water jacket) after you've roughed up the aluminum with a tootsie roll (rough grit sandpaper on a stick, using a rotary tool). We use an A/B putty-like epoxy - very easy to smooth.

Good luck with your porting - you'll be pleased with the results based on what I'm seeing you do...

[DaveC]

John, Do you think most of the benefit will come from doing the sleeve, as UQ is doing, so as to fit smaller diameter intake runners, or would an epoxy port job be better to restrict the passages further into the intake port. How close to the valve seat would you apply the epoxy, and what brand of epoxy would you use? I have been considering this from day one, but I dont want to be the guy that got a piece of epoxy in the cylinder. That would be bad. If it were my own vehicle, I'd do it, but having 20 guys hate me for ruining our motor would be tough to live down.

[John Bucknell]

Dave,

There are several ups and downs to cylinder porting. Obviously, getting a piece of epoxy in the cylinder is a REALLY BAD THING. The measures you take to avoid such an occurence can take several forms:

1) Make sure the epoxy fill is of sufficient thickness to have structural capacity to support itself - even if it detaches from the port wall, it can't get in the cylinder. I have had no problems with thicknesses down as far as ~3mm for short-term (less than 200 engine hours) use.
2) I mentioned the methods of improving adhesion - usually a few divots in the port wall are sufficient so the epoxy can get a grip on the wall. Sometimes there is sufficient access to drill through from the outside and use a small sheet-metal screw to pull the epoxy up against the port wall.

As for which is better (sleeving or epoxy), I would say either would work. Sleeving makes it easy to transition back to a round tube for your runner - but if you're skilled with epoxy shaping there is no reason you couldn't achieve the same. The flow bench will dictate how far to fill your runner (ie how close to the valve), but generally there is no point in filling the 'throat' immediately upstream of the valveseat as that should be the minimum cross-section anyhow. One thing to keep in mind is that runners don't have to be round....

Search the internet for 2-part epoxy putty, as I don't have a brand name in front of me. I would argue that you are interested in one that is fuel-resistant.

[UQ Turbo]

I have been told that Z-spar is the best epoxy for cylinder heads currently, though there is none in Australia so I can't tell you anymore than that!

Sleeves are fitted- will post up pics as soon as I work out how to put them on the team web-site.

UQTurbo

[magicweed]

What kind of velcities are you guys shooting for in the intake ports. I've been reading up on this and high performance race engines shoot for somewhere around .55 - .6 times the speed of sound for intake velocity, which would imply we need to almost double the intake velocity in our engines.

[UQ Turbo]

Correct me if I'm wrong here, but race engines NEED to have such high velocities (M = 0.6 etc) to pump a lot of air through a set capacity engine (and create plenty of power). Engineers would probably have less velocity if they could, but are limited to how much valve area they can have in the combustion chamber. FSAE is different because the restrictor prevents us from pumping a whole lot of air. The following reference recommends 70-75 m/s in the inlet runners for peak torque. (Actual port speed I'd imagine would be similar or a bit faster - does anyone want to chip in on this?)

Taylor, CF 1985, Internal Combustion Engine in Theory and Practice, 2nd edn, The MIT Press, USA.

This speed is difficult to achieve!

UQTurbo

[magicweed]

I was under the impression that increasing the velocities of the intake charge would allow it to more efficiently fill the cylinder after the piston reached bottom dead center. Given a low intake charge velocity, cylinder filling would stop shortly after bottom dead center as the piston cancels out the low inertia of the intake charge. If the intake charge velocity is higher, the cylinder can fill much longer after the piston has reached bottom dead center due to its higher inertia, effectively increasing the amount of charge in the cylinder and maximizing the profile of the intake camshaft. I may be wrong here, but the article I read that presented these ideas is pretty clear in the fact that higher intake charge velocity equals more power, regardless of any other configuration.

[DaveC]

Its been a while since I looked it up... (so this might not be precise), but in "Theory of Engine Manifold Design" (Winterbone, Pearson), They give a "Mean Inlet Mach Number" of .6 Mach as being ideal, after this the VE curve fell off fairly sharply, and there was more gradual ramp up to the maximum value at .6 Mach. So, it looked to me like some improvements in VE were to be found on our fsae car by increasing the charge velocity in the intake port. I believe Magicweed's explanation of why this is so is good.


The optimum inlet port velocity (at the 'window', ie the interface to the cylinder head) using Ricardo methods is 100 m/s at peak power, but that is using 100% volumetric efficiency. So yes, the ports are huge for FSAE....


Does this mean when VE is %100, the optimum inlet velocity is 100 m/s, but that the optimum velocity changes depending on VE? I'm a bit unclear on this statement...

[magicweed]

I believe the article I was referencing had some different numbers based on the engine type it was dealing with. A V-twin has many different characterisitcs compared to our inline fours, but the principal should be sound. Using the 100m/s reference, proper port cross sectional area should easily be solved for.

[UQ Turbo]

I did some moody frictional losses calculations for two pipes, both 330mm long. Remember pressure drop is proportional to velocity squared...

pipe 1:
v = 73.15 m/s
d = 27.2mm
roughness value: 0.002 mm (fairly smooth pipe)
pressure loss: 660 Pa

pipe 2:
v = 208 m/s (Mach 0.6)
d = 16.13 mm (good luck blending this one into a port!)
roughness value: 0.002 mm
pressure loss: 8.56 kPa!!!

Perhaps volumetric efficiency is at its peak when inlet Mech number is 0.6, but if your engine has to overcome this pressure loss in each runner (quite a chunk of an atmosphere) then peak power will suffer! If you have 700 HP or so in an F1 engine, then you can afford to (and must) have enormous velocities as mentioned earlier.

Can I ask what the difference in VE's was for Mach 0.2 and 0.6? I can't imagine it would be that much of an improvement.

UQTurbo

[John Bucknell]

Those calculations aren't too far off - usually in-cylinder traces near peak power show pressures half of local ambient mid-intake stroke. That is to say the engine is sucking against a 50 kPa pressure drop with baro in the intake manifold....

[DaveC]

The Book that had that chart was "Design Techniques..." by the same authors, Someone else has that book right now, so I'll have to get back to you on that. Maybe I'm not remembering correctly, but I thought the book stated .55 or .6 Mach was optimal in the experiment they wrote about. Thats far off from 100 m/s http://fsae.com/groupee_common/emoticons/icon_confused.gif

[magicweed]

Ok, so we've discussed the value of the mach calculations, but have we even discussed where these values of charge velocity chould occur?? Shouldn't you assign a specific rpm for this to occur at which will dictate port size?

[John Bucknell]

Originally posted by John Bucknell:
The optimum inlet port velocity (at the 'window', ie the interface to the cylinder head) using Ricardo methods is 100 m/s at peak power, but that is using 100% volumetric efficiency. So yes, the ports are huge for FSAE....


See above...

[magicweed]

So you essentially decide where you want peak power, assign the mach number to that rpm and calculate accordingly, regardless of whether its benficial or detrimental to the rest of the rpm range. Assuming 100m/s at peak power, which I would say should be around 8000 rpm, the port size dictated in order to achieve that goal is much smaller than stock. Where is the point where the size of valves become detrimental to charge velocity and need to be changed? When do we say, "Ok, we want to make power much lower than the engine was designed for, so lets just make a whole new head" Given what I've read online, in books and on these forums, that would be the most efficient way. Creating a head in the image of a manufactuers stock example, with ports, valves, cams, and combustion chambers set to our spec. For the teams with good CNC capabilities, manufactuer wouldn't be as much of a nightmare. Since this competition is about innovation and development, this seems like a good course of action. Maybe my enthusiasm for this competition and learning as much as I can has layed waste to my sensibility, but I'd like to see my team put our own head on a CBR or R6 in the next 2 or 3 years that makes 15% more power than the stock bike. Given what we are saying here, that might not be too far off.

[DaveC]

Ouch, that sounds like too much work. Megacycle in California charges about $500 for two redone cams.As far as the ports/valves, maybe the stock head could be altered by carefully welding around the valve seat area, then machining in new valve seats for smaller valves. The rest of the port could be filled with an epoxy to finish it off. I wouldnt be too surprised if the work UQ Turbo is doing (maybe combined with some epoxy) wont get you most of the way there, though. Valve size may not be an issue, I dont know. I also believe it would be really tough to make a new head that could outperform the stock heads basic design.

Another thing I'm thinking for a restricted motor is running the coolant at higher temperatures, and using thermal barrier coatings on the pistons and head to maximize thermal efficiency. If you can only suck so much air thru the restrictor, improvements in the engines efficiency as far as heat transfer (or friction...) losses is an area that could be improved upon.

[magicweed]

The thermal barrier coatings you're mentioning will hopefully be making their way onto our 2006 engine as well. Once the (hopefully) 2 motors arrive, one gets setup on the dyno while the other will be disassembled and sent out for various coatings, including the thermal barrier coatings on the pistons, valve faces and exhaust ports. Again, hopefully. It's tough enough to get one engine donated let alone 2.

And I'm all for using epoxy versus machining a brand new head, but it seems like a logical stepping stone. If the deporting system can be proven efficient and beneficial, why notgo the next step and redesign the head. Smaller intake ports, smaller exhaust ports, an interchangable valve system so that you can swap different valve sizes depending on where power needs to be developed. I mean, its just an idea, for now anyway.

[UQ Turbo]

Well it's been a while...my port and combustion chambers are FINALLY finished - here are some pics to show that it can be done. Just a quick refresher, the discussion above was about reducing the diameter of the inlet runners and modifying the ports to accept them by boring into the head, inserting a sleeve, then grinding the sleeve out to match the original ports. This should give the right velocity for peak torque...blah blah blah.

The ports still flow enough air for 130HP, but the whole thing still needs to be tested on the dyno.

http://img61.imageshack.us/img61/2296/portmoddone0012uu.jpg

http://img61.imageshack.us/img61/3373/portmoddone0024qn.jpg

http://img153.imageshack.us/img153/3855/portmoddone0035ah.jpg

http://img224.imageshack.us/img224/2186/portmoddone0052uk.jpg

http://img224.imageshack.us/img224/9055/portmoddone0069be.jpg

Keep in mind that this is a turbo head- we went nuts taking material out of the combustion chamber to lower compression ratio. We managed to get 2cc's out of the pistons too. Soo shiny...mmm

UQTurbo

[VFR750R]

UQturbo,
I'm very impressed, they look really good. This is a big step foward for FSAE engine development!

[Jersey Tom]

I'm considering modding an F4i and adding a 5th cylinder. Any suggestions?

[Erich Ohlde]

Here's a suggestion: Don't be a tool

[Garlic]

I thought it was funny! All this talk about custom cylinder heads, that's a bit over the top. That is the most complex part of an engine. Much easier to build a custom bottom end (like WWU) than a cylinder head. And that's no easy task either!

[Jersey Tom]

Originally posted by jayhawk_electrical:
Here's a suggestion: Don't be a tool

Thanks man. Awesome.

[KU_Racing]

It is possible I am missing something here, becuase I havent completely read all 3 pages of this post. While the resleeving pics above are pretty incredible (congrats for your tenacity and your ingenuity) it seems to me that a lot of the people in this post are of the mindset that the absolute velocity of the ports is the most improtant aspect of head design. This is very far from the truth- if anything, the profile of the intake cam is probably the most important factor, followed by combustion chamber shape and valve interaction with the pistons at or near TDC. There is definately some good discussion going on here, but I am curious as to how you guys have considered other aspects of head design, and if you plan on any other head modifications (custom cams, etc.)

[Charlie]

Where did you get your ranking of the importance of engine parameters from? Very curious, since you seem so sure of it.

[jonnycowboy]

A good reference for modifying engines for racing is "Four-stroke Performance Tuning" and its brother, "Two-Stroke Performance Tuning".. written by A. Graham Bell. Basically in one of the first chapters he lists cylinders heads as being the biggest area for improvement.. Combustion chamber design and cam profiles are the biggest contributors to engine performance.. you can have all the volumetric efficiency you want, but if the air:fuel mix isn't burning properly, you might as well be running an air pump. Squish is also pretty important. However with our budjets, etc etc the easiest things to do are probably: shave the head, and drop down from 3 head gaskets to 2... all to increase compression ratio.

I wouldn't recommend anybody to try modifying cylinder heads on their own, especially on a tight budget since the risk is quite high that you will flow worse than before, especially since we are at the point where we want to shrink the ports, not enlarge them.

If you have the money, you can send your head to Hines (of Vance and Hines fame) with your specifications and they'll do an excellent job.

In addition what you can do is buy a few sets of cams off ebay (f4i cam sets (in, ex)) go for about 100$ a set, and armed with a few simulation runs do one set with reduced lift, one with reduced duration/overlap and one with both... pick the one with the best engine performance that you're looking for (power but at what RPM?) and maybe take the last stock set and go further in whatever direction the good cam was and see if further improvements can be made.

I'll dig that book up again later if I'm awake and list some info from there on valve sizing, cam profiles and airspeed.

As far as the bottom end goes, the biggest advantages can probably be found in sanding down the bearings (be careful!) to reduce friction.

[UQ Turbo]

cheers for the support and opinions guys. Obvioulsy I've done an inlet cam grind (would be a waste not to!) reducing the lift and duration. Yes, I've got Graham Bell's book and it's good. I've kept the squish area as much as possible but we do need to get compression ratio down to the right level. I get the feeling that ignition timing and avoiding detonation is more important than keeping all the original squish area in this case.

I make no claims that this is trhe way to go because it hasn't been on the dyno yet, but i'll let you know when that happens!

UQTurbo

[jonnycowboy]

I think if you're running turbo, you'd go for zero valve overlap, correct? I don't know much about modifying squish, anybody have any info on that and how it affects engine performance, other than of course if you reduce squish volume you increase CR. Have you tried any low-compression pistons? I haven't seen any low-comp ones for the F4i but perhaps they can be custom made. I think the goal for a turboed f4i would be low-pressure turbo spinning as soon as possible (low lag) just to make sure that the engine is running choked (due to restrictor) throughout the powerband and not just at the peak.

[UQ Turbo]

Zero valve overlap, as far as I understand it, was an idea given away in the early thirties! But you're correct in reasoning, valve overlap has been reduced a few degrees.

New or custom made pistons would have been more expensive than machining costs. That's it as far as that. I'm going to see if I don't burn a hole in the modified ones...then perhaps decide on custom pistons.

As for everything else, it matches my reasoning & goals- though most of the low-rev boost levels will be decided on the dyno.

UQTurbo

[KU_Racing]

Charlie:
My opinion of engine part importance is based on my own experience, and from seeing the results of parts changes applied on an engine dyno where I work.

[Charlie]

I just asked because I would tend to disagree. I think that it is impossible to rank items like that because they are highly system dependent. It's good to bring them into the discussion but I think for you to say it is 'very far from the truth' that one important aspect is more sensitive than others is quite bold, unless you've undertaken a study on this particular engine.

The ports, valves, and chamber interactions are all dependent on each other. The most important item, is the one that needs the most improvement. And this will vary with the system.

I would say that the camshafts are not quite optimal but you can adjust the timing of them easily (and perhaps more importantly, indpendent of each other) and that will help that effort a decent amount.

The combustion chamber is likely quite good, at least for NA application.

That leaves the ports... which are not right for revised cam timing or overall flow.

Of course, I am NOT saying sleeving is the correct direction to go. In fact I am highly skeptical, because I have a feeling that the OEM ports are designed to work well through a variety of flow ranges and there is quite a bit of R&D on them.

But I wouldn't be bold enough to tell someone how another parameter is more important because I just don't have the data on this unique setup (I am assuming your work does not involve restricted motorcycle-style engines).

[VFR750R]

I'd have to agree with Charlie here. The most important part is the weakest point. I will tell you that you design a cam to work with your ports, you don't design ports around a cam. If you don't have good port velocity, no amount of cam changes will speed it up. Changing the cam profile for less lift is not going to be optimum. You can change duration, and that will be helpful. You don't want to restrict flow with the cam if your ports are too big. It won't increase port velocity, but it will increase pumping losses. Since we turn less peak rpm, I suspect you could get away with increased lift(small amount, don't coil bind), and you'd be better especailly if you combine it with less duration.

[KU_Racing]

Im sorry if I came across as trying to tell everybody exactly what is right and what isnt- I thinky you guys misunderstood me. What I was trying to get across is that it is my opinion, as charlie kindof said, that no FSAE team is going to beat a Honda port design with a few weeks of research. It is also my opinion that the cam profiles, port designs, valve angles, chamber shapes, etc. are designed by Honda to produce power a certain way. My thinking is that if you are going to do such extensive modifications to the head, you will have to modify everything else to see the gains you want with your new engine design philosophy.

[fart can]

[QUOTE]Originally posted by DaveC:I plan on using our engine sim program to show what the benefits will be, for cams as well as compression ratio, then we will decide if its going to happen. QUOTE]

So what engine software do you use, and how are you going to compute the proper grind or degree for the new cams? Thanks
Will

[VFR750R]

On page two of this topic there was question on the compression ratio. I think the problem is that the piston doesn't go exactly to the top of the cylinder. Just .020 reduced the comp ratio by a considerable margin.

I also wanted to ask UQ turbo how the head turned out on the dyno if it's not top secret.

[UQ Turbo]

Hey VFR,

I definitely plan to release dyno results when I've put the engine on...even if it performs poorly (I don't want others to go through the same pain). We've got a few things to finish off first - inlet manifold, turbine-outlet to muffler exhaust, wiring loom, dry sump...and I need to get some suitable sensors to get some intercooler data. Sigh...why do things always take 400% longer than anticipated?

UQTurbo

[BStoney]

...I like to use the rule of Pi. Anyone else?

[Dr Claw]

oh my god, i thought i was the only one aware that things take just a little over 3 times as long as they should! I've been saying that for like 4 years now http://fsae.com/groupee_common/emoticons/icon_smile.gif

a 1 week job takes almost 22 days..
a 1 month job takes 12 1/2 weeks.

also, expected drive time in the spring is divided by Pi too.

[Krautsalat]

Hello,

this is not from an f4i but it shows what can be expected from reducing lift and duration on the intake of an 600cc i4 for FSAE use. According to 1D calculations the ve will raise in lower rpm's without loosing on top.
http://img185.imageshack.us/img185/3025/steuerzeitenliefergraddt7.jpg

And here the cam profiles.
http://img375.imageshack.us/img375/4776/ventilerhebungskurvenmodifiziertmb7.jpg


Krautsalat

[UQ Turbo]

Krautsalat, that's awesome! Very impressed with those results! My inlet cam has a similar profile:

http://img284.imageshack.us/my.php?image=camtiming3km5.png

UQTurbo

[formula_wally]

Originally posted by Jon Weir:
If someone from Waterloo wants to pipe up, I know that a couple years ago they got Jim from Cycle Improvements to stuff the ports on an F4i. Apparenly with reasonable success, but maybe not worth all the time and effort.

Yeap Jim helped us out with that, but there is a reason why we dont stuff anymore.....

[Schumi_Jr]

We did a fair bit of internal modifications to our 2000 engine (stuffed ports, modified valve seats, planed cylinder head, cam timing) with the goal of increasing bottom end VE. This was one of our best powertrain packages though a lotof this came from excellent tuning of the spark and fuel maps.

In 2001 we took the same goal and with a bit of stupidity managed to take a Ricardo winning powertrain and produce 65 hp. They spent too much time tinkering with the internals and didn't even properly tune the motor.

I know next to nothing about engines but I do know that 600-4 bike motors are designed to produce torque at as high an RPM as possible. It seems stupid to sacrifice hp for low-end torque unless you have quantified the effects of this compromise. Also consider where on the track you need rear-wheel torque. At low RPM you are in a corner where you are traction limited. Why invest in torque you can't use at the expense of high end which will get you a few extra kph down a straightaway.

just my $0.02...

[VFR750R]

Agreed Aaron...at Martinsville, but corner off torque is probably the most important part of the powerband, and with a restricted engine top end is often not hurt as much as you would gain in torque giving you an higher avg torque value in your operating range.

I also agree that building torque without a specfic goal in mind, is not proper engineering. You must decide on the rpm band you will be using, and if a certain shape powerband will reduce number of shifts, ect.

[Bradford]

on some of the topic covered here in my experiences

good cylinder heads with a weak cam will out perform bad cylinder heads with an excellent cam.

On the topic of cylinder heads, I have been porting for about 5 years now, all with increased flow numbers but not always increased performance. I have found that the motor has to create sufficient velocity in the port after the porting to take advantage of the new flow numbers. I seemed to run into problems on large plenum 4 cylinder engines with the porting done(2 liter -- 2.5 litre).

I am all for filling the ports to increase the velocity but the idea would be to flow before modification. Take those numbers and fill the ports while not or just slightly affecting the origional numbers.
the same flow through a smaller port = increased velocity which == better VE at ALL speeds. as long as you dont hit choked flow.
If the motor is restricted why would you try to make power at 12000 at a lower VE when you could use port and intake velocity to make more power ( and torque) at a lower rpm with a higher VE
Especially with a heavier car ( 400 - 500 lbs) torque moves you down the track not hp. If we had a lighter car I would be more interested in hp.

As for higher VE creating a burn problem as stated above, i trust that the squish and combustion of the honda designed comb chamber at 14000rpm will have no problem buring a high VE at 6000rpm.

and one question for waterloo(formula_wally). What is the reason that you no longer stuff the ports??

email me at tire_fryer@hotmail.com if you dont want to let everyone know. thank you

just my opinion on what i have seen

Bradford

[golfer17]

krautsalat, those graphs look great. what software did you use for that?

i am currently undertaking learning ricardo wave and refining our engine model, and my expectations were to decrease duration of the intake camshaft mainly, but either keep the lift the same or increase it slightly for a better powerband. i am very curious to know what differences your engine simulation provided with higher lift instead of decreased lift (although i will be finding out soon enough for myself).

[Charlie]

Well golfer, unless the F4i is in some kind of 'performance trough' where you can get more performance by going in any direction, (I'd say it's unlikely), then it seems pretty clear that with more lift, you'd lose performance in the low revs and higher revs would stay close to the same.

[drivetrainUW-Platt]

get a big ol turbo and a 100 shot of nawwwwz for that puppy, that and an open exhaust

Seriously thou... I wonder how many teams run bone stock engines vs modified ones and how many of the modifides make it through endurance

Its a heck of a lot cheaper to run a stock engine, and if you blow one you just bolt in another one.

[golfer17]

yeah, for the last couple of years our team has had great success by keeping the engine internals stock (and reliable) and spending most of the time optimizing the intake and exhaust systems and cutting weight wherever we can. however, i was thinking a reground intake camshaft along with adjusted timing shouldnt be too expensive and shouldn't impact the reliability at all.

[Krautsalat]

The software I used is AVL Boost, it's similar to wave. I think there is no need for more valve lift, because in the rpm regions where more inlet area would make a difference the restrictor limits the breathing capabilities of the engine.

Krautsalat

[Krautsalat]

I did another run with short intake duration but 10% more lift. This gives me exactly the same results for ve as in the low lift case. Beyond 9000rpm the restrictor makes it's job pretty good, so you won't gain anything here. More lift probably just would increase the loads on the valvetrain without any other benefit.

Krautsalat
http://img214.imageshack.us/img214/418/steuerzeiteneinlassyb7.jpg

http://img85.imageshack.us/img85/9812/veintakezj4.png

[VimxTech]

At the risk of blowing our own horn - one of the easiest and least expensive modifications (in time and money) would be to integrate a VXI-440 Programmable Ignition Module to ensure complete combustion.

It works well with all cam designs, even aggressive high-overlap designs, and can be easily reprogrammed to work with turbos, superchargers, and E85.

Its simply connects in series between your existing ECU and the coils.

Here's a simple photo comparing an x10Spark(tm) with a well-known CD ignition.

http://www.vimxignition.com/images/x10spark-vs-cdi.png

[drivetrainUW-Platt]

nice! you have a pm VIMX


Originally posted by VimxTech:
At the risk of blowing our own horn - one of the easiest and least expensive modifications (in time and money) would be to integrate a VXI-440 Programmable Ignition Module to ensure complete combustion.

It works well with all cam designs, even aggressive high-overlap designs, and can be easily reprogrammed to work with turbos, superchargers, and E85.

Its simply connects in series between your existing ECU and the coils.

Here's a simple photo comparing an x10Spark(tm) with a well-known CD ignition.

http://www.vimxignition.com/images/x10spark-vs-cdi.png

[Alfonso Tan]

Just curious.. figured this was the right place for this:

-Has anyone tried porting the cylinder head with a removable material? Our team was thinking about making some intake port inserts that could be swapped between heads and reusable just in case one head got trashed; it'd suck to permanently alter one head for the better, then lose it in some freak accident.
-What type of gains have people seen from porting? Have they been worth the effort? ...not asking for dimensions, just want to know if the results have proven to be worth it so far.

[JuicedH22]

just to give an answer to the original question...

in the 06 season, we used a JE custom high compression piston (on our F4i) which is oversized and takes the displacement up to 609cc and a 'rated' CR of 14.3:1. The block was bored, recoated, and honed, both maps were fully tuned (tuning for TQ),and the testing began. We found that when comparing a stock motor, with a given intake and exhaust, the High Comp. engine gave 1.5 more ft*lb of tq at peak, and very little to none elsewhere.... and IMO, that is not worth the price

[chavez]

I thought the JE piston took displacement up to 636cc or did you have them make a one-off piston. What was the cause of the failure of that motor in the 06 enduro?

[JuicedH22]

custom, one-off pistons from JE However if you are interested (though i personally don't see the gains) I can give you the serial number to the order if you would like to order a set.

failure was due to a rodcap nut backing off and eventual failure of the bolt. The team member who built that particular motor assured me he tq'd the bolts/nuts to spec (using molylube) however it was found the bolts/nuts used to assemble the engine were from a motor that had been ran with no motor oil in it(that motor had been torn down)

The failure also made us do extensive research into our oil pan to see if we were starving oil in swept turns where we pull high lateral g's for an extended amount of time, and much to my displeasure it was found we are indeed starving above 1.3 g's in turns, so we are now in process of solving that problem.

[Mike Flitcraft]

Originally posted by JuicedH22:
custom, one-off pistons from JE However if you are interested (though i personally don't see the gains) I can give you the serial number to the order if you would like to order a set.

failure was due to a rodcap nut backing off and eventual failure of the bolt. The team member who built that particular motor assured me he tq'd the bolts/nuts to spec (using molylube) however it was found the bolts/nuts used to assemble the engine were from a motor that had been ran with no motor oil in it(that motor had been torn down)

The failure also made us do extensive research into our oil pan to see if we were starving oil in swept turns where we pull high lateral g's for an extended amount of time, and much to my displeasure it was found we are indeed starving above 1.3 g's in turns, so we are now in process of solving that problem.

Nah, that's too much work! :-P BJ settle on a trap door for now, or are we pursuing a dry sump yet?

[golfer17]

Originally posted by Charlie:
Well golfer, unless the F4i is in some kind of 'performance trough' where you can get more performance by going in any direction, (I'd say it's unlikely), then it seems pretty clear that with more lift, you'd lose performance in the low revs and higher revs would stay close to the same.

yep, thats about what happened when i finally got everything setup and ran my cases. also, i got to talking with one of the more experienced members of our team and found that it might be a bad idea to try and increase lift while decreasing duration (or even just keep the lift the same) anyways since that would change how fast the valvetrain is accelerated by the camshaft and could potentially have an affect on reliability someday. for this reason, whenever i decreased the duration, i also decreased the lift by the same percentage to keep the same basic shape of the cam.

[Bradford]

quoted earlier

that no FSAE team is going to beat a Honda port design with a few weeks of research. It is also my opinion that the cam profiles, port designs, valve angles, chamber shapes, etc. are designed by Honda to produce power a certain way. My thinking is that if you are going to do such extensive modifications to the head, you will have to modify everything else to see the gains you want with your new engine design philosophy.


Just because an OEM designed something does not mean it is correct. You have to remember that most of us are only months away from being someone who could release something from an OEM manufacturer, It is still a person designing it, meaning that mistakes are possible.

There is always room for improvement, and I believe I can do anything that I want to, which includes changing honda's port design,

I beat the stock honda ports in 11 days. All it took was a superflow flow bench, plasticene and some time. With the port you see below I beat flow numbers through out the lift of the cam, mind you it is just static testing but it still has to behave by the rules of fluid dynamics.

I could run any cam (within reason) and it would be a better performing engine because the VE will increase at every point, including higher rpm, from the higher velocity in the port.

http://www.fsae.uwindsor.ca/images/apr_22_gallery/pages/DSC00549.htm

My team mates and I did the cam as well, along with an intake manifold and exhaust tuned to the power band that we wanted, but that is what this is all about -- multi system integration to create an efficient package.

Our engine design was based around VE, we did not worry about HP numbers, just usable driving torque and a large flat curve in our best power band.(sub 11000rpm)

If you want to see my flow numbers send me an email
Tire_fryer@hotmail.com

Bradford

[KU_Racing]

My stance, as stated in my post, is that port changes alone will not show gains without significant sacrifice unless the other factors are modified for the new design goal. It is true that people make mistakes, but one person didnt design the honda intake ports- there was probably a hundred engineers working on that head design for a year. I am not trying to imply that anyone on this forum does not have a great deal of knowlege- the knowledge base here is huge. What I am saying is that when you look at an engine as many systems aimed at achieving one goal, no one is going to be better at that than a company like honda who can throw engineers and currency at the problem.

It is not necessarily true that performance will increase everywhere just because your static flow numbers have increased. Anybody with a die grinder can get a head to flow more than a stock head. In my opinion, static flow numbers do not mean a whole lot in the grand sceme of port performance- they are good for comparison between heads, and not much else. I could supply you with a completely different head with different port designs that has almost the exact same flow curve as an F4i head, but would not support nearly as much horsepower.

VE does not necessarily increase everywhere. VE is not just a function of simple static flow. I can almost guarantee that the larger ports will show lower VE at low and midrange RPM where the velocities dropped due to the port changes.


My thinking is that if you are going to do such extensive modifications to the head, you will have to modify everything else to see the gains you want with your new engine design philosophy.

That was posted in response to people that seemed to want to modify the ports and leave the rest of the systems untouched. Doing what you are doing, custom intake/exhaust, and MUCH more importantly a custom cam, is a horse of a different color than what i was responding to in that post. Even still, I would estimate that by porting the head you would lose velocity at low RPM, which will sacrifice cylinder filling and thus sacrifice torque on the stock cam setup. since you are running a different cam, and I know nothing about it, I cant really make a prediction as to what changes you will see. Im not trying to be a dick, but I dont really care about static flow numbers. I would be much much more interested to see how much more torque you made in your target area.

[Bradford]

I was not attacking you, just your statement because too many people believe that an OEM piece is gold, or had special engineering aspects to it, there is not much beyond fluent that honda could have, and i would guarantee the head was designed in some software and then actually tested on a flow bench.

I do not believe that I stated I had filled the ports with epoxy and then modified to increase flow.
I did not actually remove material, it was only added, my fault for not saying that.

But based on fluid dynamics, If i flow more air through a smaller volume I will have to have a higher velocity, which will lead to better cylinder filling at almost every rpm point. we could get into mach number and piston speed and all that stuff but it is almost guaranteeded that the restrictor will create more of a problem than the smaller ports.

I do not know how you can discount actual flow numbers, being static or not an increase in flow velocity would be more evident in a dynamic situation than it would in a static anyway.

Maybe it is just different views on fluid dynamics, I would like to know what you base you opinion on about static flow numbers being useless? How else would you measure the performance of a cylinder head?? I compared stock mass flow rate at a stock port volume to the modified port flow numbers and the modified port volume.

As far as the honda situation, I doubt that they have 100 engineers working on a cylinder head for a motorcycle, maybe the entire engine but hey, i dont work there so i dont really know you would have to ask them about it. The money situation?? just because they have lots doesnt mean they know what to do with it.
If you could explain that if the port is so well designed why it was so easy for me to fill the ports with epoxy and generate more flow at almost every lift figure? I could see the port filling being a restriction at 12000 plus rpm but we do not operate there.

[Matt N]

(butting into a conversation that I'm not really part of)

Bradford's port filled head will undoubtedly make more power, more area under the curve, and should have better throttle response than a stock head. (Though, stock F4i throttle response isn't bad at all). All of these qualities come from higher velocity ports. If he slightly increased flow over stock, and reduced port volume by ~10% then the port velocity has to be higher. I don't know of any IC engine which complains about having higher velocity ports.

I know that people don't like listening to comparisons to automotive applications which are drastically different than FSAE but here goes: have you looked at the power levels some domestic V8 builders are getting out of 350-420ci V8s these days? Guys in this field have had access to commercially available heads with high flow capabilities for ~20 years now. However, until relatively recently there weren't commercially available heads with small runner cross sections and high flow capabilities.

I know some of the rest of the gains are in friction reduction and valvetrain design but still the predominant factor in IC engine cylinder pressure, and power, is the amount of air in and air out. There's nothing bad about higher velocity ports given that you have enough mass flow through the port, and you aren't reaching mach 1ish choke velocities (which I'm not sure you could really do anyways).

Matt

[VFR750R]

I can vouch for the stock ports not being 'VE gold'. Manufacturers don't spend that much time on them (certainetly not 100 engineers, probably closer to 3, the reason why being below) and they are certainly improvable. Have you ever looked at stock ports? First, what the designers designed isn't what they look like cause their cast. Castings are +-.010 at best and usually closer to +-.030. You can tell on some heads cause the port doesn't match the valve seat.


Myself, I'm torn on what porting means to FSAE. Because after choke it won't be doing a damn thing. Additionally, the more screwed up a port starts out the bigger the gains will be (duh), but 23 degree chevy motors suck stock. They're terrible. You can imagine the best port on the planet getting a value of 100. Stock 23deg heads are like a 35, Nascar heads are like a 65. Nascar heads could NEVER be 100 because they have a significant short turn. Stock CBR600 heads are like an 80. They're relatively straight with a nice gradual short turn of a small included angle and 4 valves. From there with mods you could maybe get to a 90, so the benefit won't be huge. Probably 2-3 hp a few hundred rpm before choke and not much after choke. You can definitly have more inpact with intake and exhaust runners but if it works why not. That's 2-3 more then the other guy that doesn't do it, right?

Here's a crazy idea that would be a bigger difference good or bad is converting a CBR600 to a 3 valve head. Fill in one intake port and take out the valve. You could weld in the chamber right down to the crown of the piston and get huge compression and by having a 3 valve engine get much more swirl and possibly big torque below choke. You might have to get aggressive with the one lobe you got left but maybe not. I would keep the two exhaust valves though I think.

[KU_Racing]

I didnt know that you were ADDING material to the ports. That basically reverses all my opinions on what you are doing. I assumed that you were removing port material, thus increasing area and reducing velocity. I argee 100% with what everyone has said as far as higher velocity being beneficial. Im sorry for the misunderstanding- I should have read your post more clearly.

[Bradford]

its cool, i dont usually explain myself too good at 1 in the morning, If you are at michigan comp, come and find me or i will find you.

I'm from univeristy of windsor, ontario

Let me know where you are from and i'll see if i can find you

Bradford