After pondering what kind of ideal autocross car I would like to own, I considered a single cylinder FSAE-type car. Most likely I would drive it a maximum of once per month and tow it on a trailer behind a Honda Civic. I would shy away from a 4-cylinder 600cc engine because working on it by myself would be difficult and expensive. It would weigh nearly 500 pounds and have an engine that weighs 140 pounds. I don't think I'd want an autocross-only vehicle that weighs more than 400 lb.

That's great Dave, if the car weighed 400 or 500lbs, you still can't lift it by yourself, but the 500lb car would then make crap loads more power cause for autocrossing...no restrictor. Hmmm....500lbs, and 140hp. Goodby go-kart.

Either would be fun...but I'm an engine guy, i NEED it.

quote:

Originally posted by Dave @ L.U.:
After pondering what kind of ideal autocross car I would like to own, I considered a single cylinder FSAE-type car. Most likely I would drive it a maximum of once per month and tow it on a trailer behind a Honda Civic. I would shy away from a 4-cylinder 600cc engine because working on it by myself would be difficult and expensive. It would weigh nearly 500 pounds and have an engine that weighs 140 pounds. I don't think I'd want an autocross-only vehicle that weighs more than 400 lb.

Maintenance on a single vs four banger:

Both need oil changes at similar intevals
Both never need timing set
Both have one cam chain
Singles with roller bearing cranks are harder to strip down to the cases. Well perhaps not harder just different. Everything gets pressed/pulled in and out with special tools that you can make on a lathe and mill.
If you need new rings odds are the bearings, cam chain + tensioners are going too... its almost cheaper to buy a whole 'newer' engine off ebay. A low mileage F4i just went for 400 bucks last week.

The only difference would be valve setting... 16 vs 4. Yeah the singe wins there - But your driving once a month? So your valves should be set hmmm.... like once every three years then? Honda valves dont seem to move around vary much (depends on how much you love your rev limiter too). I've run honda motorcycles as far as 40,000km with track days and then finally one valve needed to be set 'cause it was out 1 thou. However sometime they move around more on the CBR. Someone else want to comment on their CBR valve adjustments?

Singles only barely surpass the CBR on service time unless your talking about valve clearance. I still find the CBR friendlier to work on but thats just me. I like the horizontally split case. Its more forgiving than using a press for the super tight fits on the roller bearing cased singles.

I dont want to even go into taking singles vs fours for engine removal. Thats a can of worms and has no "right answer".

Bruce

Totally forgot. CRF450 valve maintainance schedule...5hrs
YZF600.....20,000miles

My high school Technological design class has been attempting to enter the FSAE competition for the past three years. I have always felt this competition is great and have incorporated the challenge into my course. Our goal is to become the first high school team entered. So far no luck. Our current car uses a Yamaha Raptor 660R single motor ( from the atv)mounted longitudinally. The motor has great torque and is bulletproof. ( we hope). I am curious as to why this motor has not appeared in any FSAE car. Check out the tech specs on the motor. seems like a good choice to me. As well we have designed and built all the usual stuff such as independent suspension, limited slip rear differential,etc.We are located in Aurora, Ontario Canada and would love to get a chance to drive with some of the FSAE teams. I know that we have a 660 engine but if we were accepted to the competition we would be glad to de stroke the motor. I would also be happy to post some photos to show what high school students can do.

You wonder why nobody uses the engine? How about it's not legal!!! Destroking or sleeving an engine isn't out of the realm of possibility, but it's not simple or cheap either.

Anyway good luck on your team's quest, wish I did that in HS.

quote:

Originally posted by BryanP:
My high school Technological design class has been attempting to enter the FSAE competition for the past three years. I have always felt this competition is great and have incorporated the challenge into my course. Our goal is to become the first high school team entered. So far no luck. Our current car uses a Yamaha Raptor 660R single motor ( from the atv)mounted longitudinally. The motor has great torque and is bulletproof. ( we hope). I am curious as to why this motor has not appeared in any FSAE car. Check out the tech specs on the motor. seems like a good choice to me. As well we have designed and built all the usual stuff such as independent suspension, limited slip rear differential,etc.We are located in Aurora, Ontario Canada and would love to get a chance to drive with some of the FSAE teams. I know that we have a 660 engine but if we were accepted to the competition we would be glad to de stroke the motor. I would also be happy to post some photos to show what high school students can do.

You wouldn't be the first pre-universitary school to compete though, I was captain of the École nationale d'aérotechnique team that competed last year. It's a technical school, we call it CEGEP here in Quebec...

Anyways, good luck, but you should look into your engine, the limit is 610cc...

Actually there is a sleeve and piston from the sister engine (Grizzly) that will fit in quite nicely. It gives a displacement of 595 cc.I have an estimate from a reputable engine builder of $500 cdn. if we disassemble the engine. That is expensive but not the price of the turbo systems that some of the teams run. We wanted to use a single to keep the car small and light.( 60 inch wheelbase) The problem that we anticipated with some of the 400 or 450 dirt bike or quad engines is they are highly stressed and blow up too often for our budget. The Raptor is very reliable. .You can see from the attached photo that we were able to mount it to a Honda 450 Es differential by turning a hub and wire edm ing it to fit the output spline on the engine. Oops. I am having problems attaching the photo. I will repost it as soon as I get it sorted out
Thaks for the interest

quote:

Originally posted by Garlic:
You wonder why nobody uses the engine? How about it's not legal!!! Destroking or sleeving an engine isn't out of the realm of possibility, but it's not simple or cheap either.

Anyway good luck on your team's quest, wish I did that in HS.

This message has been edited. Last edited by: BryanP,

I have just posted three photos of the car on the forum. I will add more soon. I checked out the École nationale d'aérotechnique website. That is an awesome school. I wish we had facilities like that.
Bryan

quote:

Originally posted by Didier Beaudoin:

quote:

Originally posted by BryanP:
My high school Technological design class has been attempting to enter the FSAE competition for the past three years. I have always felt this competition is great and have incorporated the challenge into my course. Our goal is to become the first high school team entered. So far no luck. Our current car uses a Yamaha Raptor 660R single motor ( from the atv)mounted longitudinally. The motor has great torque and is bulletproof. ( we hope). I am curious as to why this motor has not appeared in any FSAE car. Check out the tech specs on the motor. seems like a good choice to me. As well we have designed and built all the usual stuff such as independent suspension, limited slip rear differential,etc.We are located in Aurora, Ontario Canada and would love to get a chance to drive with some of the FSAE teams. I know that we have a 660 engine but if we were accepted to the competition we would be glad to de stroke the motor. I would also be happy to post some photos to show what high school students can do.

You wouldn't be the first pre-universitary school to compete though, I was captain of the École nationale d'aérotechnique team that competed last year. It's a technical school, we call it CEGEP here in Quebec...

Anyways, good luck, but you should look into your engine, the limit is 610cc...

Bryan,

I think the Yamaha Raptor/Grizzly engines, or similar ~600cc singles, are very good choices for FSAE. I too wonder why no one uses them???

Z

Because it is an atv engine and god forbid any of snooty people(majority) around here would use anything but the latest and greatest thing honda puts out regardless if it is better suited for the competiton. I think smaller engines in smaller cars is the wave of fsae future. Cornell has shown about the upper limit the cbr is gunna go in this competition. Unless they start masterbating with carbon fiber to lighten up the heavy cbr cars that exist, they will eventually go that route I bet. The bar is getting rasised every year and team s like rmit have shown the concept is very viable and very competetive. Now what will be really scary is a sub 300 pound 50hp single that is reliable. Delft,gelph,shmelt? team is getting real close to that. On

quote:

Originally posted by Rob Woods:
Now what will be really scary is a sub 300 pound 50hp single that is reliable. Delft,gelph,shmelt? team is getting real close to that. On

Yes they had a very light car, thanks to a TON of that 'carbon fiber' shit you seem to hate so much.

Rob you call FSAE people 'snooty' yet you seem to claim you are smarter than all of them with every post you make. I'm sure once you finally remember to register you'll blow us all away....

"Cornell has shown about the upper limit the cbr is gunna go in this competition"

Cornell doesn't use a Honda, genius. Are you drunk?

quote:

Originally posted by BryanP:
Actually there is a sleeve and piston from the sister engine (Grizzly) that will fit in quite nicely. It gives a displacement of 595 cc.

Sounds like a pretty good plan. I wouldn't have expected there would be such a simple solution. Good luck!

Mike,

I am an idiot. I meant to say 600cc 4 bangers. Cbr is on my lips cause the old one we have we are training ourselves on how to program and debug motec. Giving us alot of problems too but it is our fault, not motec.

Garlic,

Dont hate carbon fiber. Just think its use in this competition doesnt meet the intent of this kind of comp. Old post argument. Not worth talking about. Thats all. Never said i was smarter than anyone. Maybe more practical but definitly not smarter. If you cant look at formula kids in that joking light then you have serious tunnel vision. I was just trying to say that many people formula wouldnt even look in that direction because of a prevailing attitude of "gotta be techy or it sucks" Kinda like Honda kids about vtech in the early 90's. Oh boy. Shouldnt have opened that can of worms. Hahhahaha.

Bryan,

That motor is probably the best choice of single cylinder to use because of the incredible amount of availible stock and aftermarket parts for it along with its durability. Torquey son of bitch. Rode one once. Maybe it is just a baja rule but you might wanna check about jackshaft braking. Dont have my rules with me.

The 600 singles are too "lumpy", well that was the excuse I heard. sure they'd produce more torque though. You'd need a beefed up drivetrain though as all that torque arrives in one hit as was explained to me earlier on this thread.

quote:

The problem that we anticipated with some of the 400 or 450 dirt bike or quad engines is they are highly stressed and blow up too often for our budget

This is something i am worried about with our wr450.

It seems there may be a misconception of torque. Torque is almost solely dependent on displacement. Almost all 600cc engines have the same potential for torque. A highly tuned single and a R6 for example I bet are within 5% peak torque. And if all else is the same, the R6 will be able to use it's multicylinder format to increase volumetric efficiency with correct tuning. Torque also goes up with intake density, which is what turbos and superchargers do.
Example: a stock CRF450 and CBR600 make the same torque per displacment, although at different rpm so thier hp/l are very different.

I realize I'm being picky here, but it bugs me when people refer to engines as torquey, cause what they are really saying is they don't make any horespower, cause they're going to make the same torque as a high hp engine just at a lower rpm.

Now a turbo FSAE can be refered to as torquey cause it makes the same power as a good NA car but actually has more torque.

Quote by VFR750R;
-----------------------------------------------
"It seems there may be a misconception of torque. Torque is almost soley dependent on displacement."
---------------------------------------------

I agree. Looking at the specifications of the past fifty years of racing and production car engines shows almost all have a peak torque of 80 to 120Nm per litre.

The claim that long stroke engines give more torque than short stroke engines (of equal capacity) because of the longer "lever arm" is nonsense (the short stroke engine has a bigger push on its shorter lever arm). Those same 50 year specs show that peak piston speeds are around 20m/s, with some racing engines getting slightly past 25m/s. For a given maximum piston speed a short stroke engine can rev higher. With the same potential torque at higher revs it can make more power. With a larger bore it can have more valve area. So it is tuned to breath better at high revs so that it makes close to its "standard" torque there, and hence high power. So it has short intake pipes and large overlap cams. So at low revs it doesn't breath well and has a hole in its torque curve.

A long stroke engine is never going to rev high (because of the piston speed limit) so it is fitted with long intake pipes, appropriate cam timing, and it gets a slight "harmonic" boost to its torque curve at medium revs. Fit long intake pipes and appropriate cam to a short stroke engine and it makes plenty of torque down low.

Of course, chasing higher revs, and hence higher power, is futile with a "resricted" engine. The restrictor limits the maximum amount of air the engine can breath, and hence the maximum power. A 20mm FSAE restrictor, with standard fuel and "average" CR, gives maximum power of about 60kw (80hp). This can be increased slightly by higher CR (and appropriate anti-knock measures), reduced internal friction, and possibly some other efficiency improvements. BUT NOT BY MUCH!

A turbo or supercharged engine makes more torque because its CR is lowered, giving it a larger "true" capacity - ie. the volume of its combustion chamber. The type of fuel dictates the maximum true CR and trying to cram more fuel/air in the small combustion chamber of an already high CR engine doesn't work. Well, not at low revs because you get detonation, although at high revs the short valve open time means you don't get all the extra air/fuel in there anyway so you're back to an exceptable CR. Anyway, T/S/C engines behave like larger capacity (ie. larger combustion chamber) engines that have early exhaust valve opening. Most of the torque is generated at the top half of the power stroke so these engines have more torque than the equivalent N/A engine.

Well, that's part of the story, as I see it...


Z

PS. (Edit note) The above refers to 4-stroke, spark-ignition engines running "normal" fuel. So it doesn't apply to 2-stroke diesels, or oxygenated fuels (nitrous), or pouring powdered Semtex into the intake...

This message has been edited. Last edited by: Z,

Nice work Z. I was considering writing a little rant to complain about but mostly clarify everyone's simplistic descriptions of 'torquey' motors and otherwise. An air pump otherwise known as an IC engine behaves best while within its designed powerband. The whole airflow package which includes intake and exhaust flow, intake volume and tuned length, exhaust volume and tuned length, camshaft lift and duration, and compression ratio of CBR's and other such motors are set up to have a powerband from about 10K to 15K. The CBR hits the restrictor at about 12K (maybe slightly more, but not much) so many teams move their powerband down because it seems pointless to wind the motor out on the restrictor with power falling off. When you decide that your car is geared to have a usable powerband from 7K to 12K, it is easy to say that other motors which have powerbands designed to work from perhaps 5-10K seem 'torquey' in comparison.

The bottom line is the sensation of a 'torquey' or 'soggy' motor is more a case of how well matched ALL the airflow components are to the desired powerband. And additionally, the proper selection of this desired powerband figures into the scenario too. ie. If you have the choice of two engine configurations, one works from 5-10K and one works from 7-12K, and they make the same integral of power from the bottom to the top, (equal power over the usable range, though they might have different peak numbers) the lower rev engine will see less stress due to revs, experience less frictional losses, and if properly designed exhibit quicker transient throttle response... that's just a few of the benefits.

Z, you were right on the money until you started talking about forced induction. A good part of what you wrote there was accurate, but another reason that higher boost works at higher revs is because of the change in combustion dynamics. I know research is currently going into this (I haven't seen a super clear article yet), but it seems that as revs rise past certain levels (depends on the motor, bore size, chamber and piston dome geometry) and with combustion pressures within a reasonable range, detonation seemingly cannot catch up at high revs. At least that's how I understand it. I know some super high (16:1+) compression N/A motors work successfully under this principle, and have read of some high (13:1) forced induction motors that do too.

Matthew

Matt,

Yeah, this is a big subject - hard to fit into these little post boxes.

The other big advantage of forced induction is that it allows intercooling. The detonation happens because the air/fuel gets too hot. An intercooler cools the charge part way through its compression "stroke", so for a given CR you've got a cooler charge. Or for the same temperature limit you can have a higher CR, and hence higher thermal efficiency and higher power.

And with direct injection, maybe the fuel doesn't have time to get hot enough to detonate??? But here I am past the limits of my knowledge...

Anyway, Matt, any more on that "even worse (more radical) idea" ... huh...???

Z