throttle bodies...

[Mugenhonda]

hey, just wondering what throttle bodies you guys recommend. This is my first year doing this and i've been given the wonderful task of looking for a 34 mm throttle body. Any information would be greatly appreciated.

cheers

[Sam]

build one yourself mate.. you are going to have a hard time pulling a 34mm throttle body off a car or a bike. very messy if you do.

we built our own 34mm throttle body from billet ally. butterfly type. our SLS nylon / carbon restrictor screws on. some teams build the throttle body/restrictor in one peice. some have roller type.. some are carbon fibre etc...

you get the idea. look around. design - build.

Sam Graham
Engine Group Leader 2003
UQ Racing

[vinHonda]

Slider type. SOOO easy to make. SOOO light. SOOO reliable. amazing throttle response.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Chris Boyden]

try Jenvey Performance Induction out of England
www.jenvey.co.uk (http://www.jenvey.co.uk)
They make really nice throttle bodies in about 100 sizes, trumpets, etc...and if you're nice they might give a discount.

[A Reinke]

http://aod.no-ip.com/images/fsae/img%20039.jpg

we actually decided to kinda mod one of the existing bodies from the GSXR throttle bodies.

we sleeved it down to 1 inch, made our own throttle plate, and fit a TPS bracket on it. quite cool in my opinion. http://fsae.com/groupee_common/emoticons/icon_smile.gif

~Adam

[Ben Beacock]

I've been looking at 3 different possibilities for the throttle:
barrel
slider
butterfly

I see an advantage to using a slider or barrel because at full throttle there is no restriction. Vinh mentions good throttle response with a slider as well. Is there any advantage to using a butterfly? I can see a bit of a problem connecting a TPS to a slider which is why I'm leaning towards a barrel valve.

Ben Beacock
Co-Manager
2004 Gryphon Racing - University of Guelph (http://www.soe.uoguelph.ca/uogracing)

[B Lewis @ PE Engine Management]

Hi Ben,

In my opinion, the butterfly is by far the easiest to manufacture and get to seal correctly. The only challenging part about the whole thing is getting the correct angle on the edge of the valve itself. This is also vey easy if you know the trick.

Brian Lewis
Performance Electronics, Ltd.
www.pe-ltd.com (http://www.pe-ltd.com)
"Complete Engine Management Systems for $798"

[Denny Trimble]

We had a slider in '99. We had a rotary cam on it that turned the cable 90deg and allowed for a TPS to be mounted. Watch out for sticking though. Towards the end of the season, our throttle was a little dirty, because we drive in a lot of wet, grimy weather. When the driver would let off the gas at the end of the straight, the high vacuum would suck the slider against its mating surface hard enough for it to stick at partial (but disturbing) throttle positions in the braking zone.

University of Washington Formula SAE ('98, '99, '03, '04)

[Bob Gliege]

In 2001 I made a single barrel throttle body and in 2002 I made a double barrel throttle body. The double barrel throttle body concept was pretty cool and MIGHT have given us a couple points in design. On the down side, both were very hard to maintain due to dirt and wear. Similar to the '99 car Denny spoke of, these throttles had a tendancy to stick over time. Needless to say, the concept was cool, but in '03 we went to a simple butterfly throttle that we designed. Throttle response was actually best with the butterfly, reliability was improved greatly, and manufacturing was greatly simplified. Based on my three years exprience, flow bench results of all three designs, driver input on throttle response, ease of manufacturability, durability, simplicity, cost, and risk (you only get one shot at comp), I highly recommend a butterfly over a barrel-style throttle. Keep it simple and robust, I don't think time spent on this is worth the risk and any minimal gains you might see. There are other factors that have bigger effects on dyno results.... focus on them first. I don't have any experience with slide-throttles though, so maybe Vinh has hit on something. Throttle response, as seen by the driver, can be altered with linkage design (cams, etc) to get the response you want (linear, or whatever else) with a butterfly. Just some advice, best of luck!

Bob
UW FSAE '01-'03

[vinHonda]

You should see our slider. It's absolutely tiny and we mounted the TPS on the pedal. The response is clean and soooo easily modulated.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[A Reinke]

an interesting topic regarding throttle bodies would be whether to use a cam profile on the plate or slider. we felt the cam profile for opening the plate would beneficial, so we recycled the parts from the GSXR linkage. its pretty cool. http://fsae.com/groupee_common/emoticons/icon_cool.gif

[Charlie]

Of course everyone is partial to thier designs http://fsae.com/groupee_common/emoticons/icon_wink.gif

I made a barrel valve in 2001, in 2002 we ran a 45mm butterfly, and this year a 50mm butterfly. They have all been custom units re-using blades and shafts from production throttle bodies.

Throttle response depends on a lot of things. I think your throttle body is a little ways down the list. Of all our cars, our 2003 has, by far, the best throttle response. Theoretically a smaller throttle body will give better response, but as long as you are within a certain range, I think other factors contribute more.

Yes, the butterfly does obstruct airflow even at WOT. Turbulence is bad as the air enters the restrictor. However, turbulence is a problem with barrell valves and sliders too, because while they don't obstruct the center of flow, it is difficult to make the sides of the walls perfectly smooth, and in transients (which we see so much of), a 90% throttle opening on a slider or barrell is causing a lot of turbulence too.

No answers to my points here, but the butterflys are easy to make, very light, and pretty hard to screw up. http://fsae.com/groupee_common/emoticons/icon_wink.gif If you do something else, it's got to be done very well to even come close to an advantage, IMO.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

you have a 20 mm restrictor,

so the "blockage" of a butterfly valve at WOT on a 34 mm throttle does absolutely nothing.

can i suggest that even 34 mm diameter is BIG

45-50 mm is ridiculously big ( i know from previous mistakes), you'll have nearly no throttle response, which makes a car that's difficult to drive, especially if it is close "neutral balance".

a tps on the pedal sounds like something that COULD ruin your tuning (if your primary load method is TP), but perhaps you have a very robust way of doing it Vihn?

you may ask how do i know that a 34 mm throttle offers no resistance? flow bench testing, and a dyno run with no throttle (yes it is possible with EFI.. but dodgy)

to be honest I'd probably go for 32 mm diameter if i did it again

Frank

[A Reinke]

here's something we thought about...the restrictor is the limiting part of the intake system. does it really matter what size throttle body you use in relation to power the engine makes?

we felt that having a bigger throttle body would allow a large change in air coming into the engine when opened. we went with the plan that a smaller throttle body would give us better throttle response. has anyone tested different sizes of throttle bodies on one engine and compared the results?

~Adam

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Frank:
45-50 mm is ridiculously big ( i know from previous mistakes), you'll have nearly no throttle response, <HR></BLOCKQUOTE>

I believe you're wrong about that Frank, I wish you could drive our car, it is very responsive.

Like I said, there are a lot more variables than TB size in the throttle response function http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[schumafer]

i agree with you charlie.. thats not only the size of the throttle body that matters in throttle response...

Fernando
Universidad Simon Bolivar
FSAE

[Frank]

ok charlie, maybe

perhaps for clarity, i should replace the words "throttle response" with "throttle control"

my experience comes from 3 uni race cars we've had so far.. and my own cars (3 modified street car inductions so far)

and i was seriously disappointed with the throttle control when we had a 46 mm throttle.

for example, warm your car up

in neutral grab the throttle by hand, and try and move the engine through a series of rpm's.. much like trying to play a scale on a musical instrument..

with the 46 we had absolutely no chance of doing that

the way i see it is that a throttle causes pressure drop, that limits VE, mass flow rate power etc etc

the pressure drop is prop. to v^2

which is prop. to d^4

i usually find a way to size throttles is..

at max power velocity across butterfly =

90 ms-1 street car
55 ms-1 race car

i also distinctly remember Caroll Smith sledging the teams in AUS that were using 45mm throttles

but anyhows, personal differences perhaps, perhaps more variables

another thing that's great if you want to use a big throttle is a progressive rate linkage.. don't underestimate these things guys

[Kevin Hall]

The progressive rate linkage, or a cam on the shaft of your butterfly will give you the best throttle control along with the capability of having that wide open lack of restriction that a 50mm can only give.

Kevin Hall
University of Saskatchewan
'03-'04 Team Director

[djbrodie]

Guys,

Last year we ran a 34mm butterfly approximately 15cm above the restrictor. It displayed very good throttle response.

This year the team opted for a single barrle acting as the restrictor. The throttle response is unbelievable.

Engine Team leader 03
Full Boar Racing
Swinburne

[Alfonso Ochoa]

I tottally agree with you in this topic Frank. Thanks for that changing of throttle response to throttle control, that's is what is all about...besides learning, so thank you for exposing your reasons to your coomment and let us know learnig a little bit from your experiences.
50 mm also seems ridiculously to me (a guy from the venezuelan team that ran a 56 mm one in 2002). Since that experience we changed to 38 mm butterfly type one in 2003 and were really happy about it.
I also would like to know all those factor that you say come into play Charlie and Schumafer. As far as I know you have to control the air going into your engine that directly dependes on the area the air is passing by, less TB diameter less area increase respect to the angle moved....Please explain me all those factors you talk about.
Another thing. We have never try our engines y dynos so may only experiece in all power things carying intake and exhauts stuffs comes from reading and simulations ion Virtuakl engine. From that, I can say a bigger throttle gives you more power, 38 much more than 32, and 56 a very little more than 38, since the 20 mm restrictor became the limitting facot...
All I can help you guys...
Alfonso Ochoa.

Alfonso Ochoa Vega
cabezota311@hotmail.com
F-SAE USB Team, Venezuela

[Marc Jaxa-Rozen]

What about a stock F4i TB? Apparently they're 38mm each, which would make it a good fit, but I don't think I've seen anyone using one...what's the catch?

Marc
École Nationale d'Aérotechnique

[Ryan Schoffer]

they are all (4) jammed together in one assembly - you would need to adapt the springs and TPS sensor to one that you ahd cut out off the group

Vehicle electronics leader

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Charlie]

Well gosh, just because I know there are more variables, doesn't mean I understand them all. http://fsae.com/groupee_common/emoticons/icon_wink.gif However, I can go of practical experience and say that your engine mapping is probably one of if not the most important aspect of throttle control, or whatever you'd like to call it.

Remember the simple thought process, calcs, etc that say a smaller throttle body will give better throttle response are all at steady state. This is almost a non-issue in autocross and endurance.

That same thought process would tell you to eliminate that pesky plenum, all it does is cause a delay in throttle response. http://fsae.com/groupee_common/emoticons/icon_wink.gif

All I can say is, I've seen a range of throttle designs, and our latest car has by far the best throttle control and modulate-ability of any others. It also happens to have a 50mm throttle body. Short of letting everyone on the forum drive our car and see (you'd like that wouldn't you http://fsae.com/groupee_common/emoticons/icon_wink.gif ) I can't prove much.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Brent Howard]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> posted November 01, 2003 06:17 PM
What about a stock F4i TB? Apparently they're 38mm each, which would make it a good fit, but I don't think I've seen anyone using one...what's the catch?


<HR></BLOCKQUOTE>

The f4 i has 4 throttle bodies that attach within the runners and all actuate the same. The big problem here is that the rules state that you cannot have any throttling devices after teh restrictor...only on/off controls. Something to remember if you feel like trying a variable intake runner design.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Alfonso Ochoa]

OK Charlie..I imagined you were talking about engine mapping, my whole point was to just say it here, i thinks that is what is this for...sharing and learning

About the plenum...I've read that like 100 times, it will give you a delay in the throttle response, I see that very clear when you are talking on the fluid dinamics and all that thing (if you see electronically is just a capacitor, stores some energy and has a slower response time)...but how much that thing affect when you are mapping with the TPS in higher priority...you just press the throttle and you get more gasoline and starts reving up...please, can anybody tell me how much affect? or if i'm wrong in my suppositions.

About the F4i throttles...yes they are attached together, but that was why we use 38mm in the 2003, we disassembled it and use the plate, the shaft, springs, TPS, and cord actuator we only made the throttle body itself of an alluminum block... keep it simple, do it fast and test it...my piece of advice. Cheers,
Alfonso.

Alfonso Ochoa Vega
cabezota311@hotmail.com
F-SAE USB Team, Venezuela

[Frank]

the way i see the plenum effecting the "response" as opposed to "control"

is

when you open the throttle (wide open)

the restrictor chokes, so there's a period of time until (near) atmospheric static pressure is reached in the plenum

something like 0.1 sec ? I can't remember for sure, I did the calcs once

when a FSAE car leaves a corner (the driver is a hoon, throttle happy) and a driver "stomps on it" at say 6000 rpm, you can hear the sonic rushing sound (sounds like paper being torn) for a short time (something like 0.1 sec) and then the engine creates power

sorry if this was obvious, or makes no sense / or is incorrect

Frank

[Ryan Schoffer]

having an incorrectly sized plenum can also prevent the engine from reaching high RPM ranges - there isnt enough 'stored' air in order to overcome resonance points in the intake system, so it chokes out

think of it like a bucket with holes in the bottom and a tap at the top - if you just had pipes and turneds the tap on it would take a few seconds to get the flow, whereas if the bucket had water in it the flow would come out the bottom instantly, and in the same way you can draw more water out of the bucket before having to turn the tap on more since you have stored water - the fast running engine wont create a large enough vacuum in the plenum to choke itself because of the extra volume

Vehicle electronics leader

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Jackson]

Just out of curiosity... (with regards to throttle control)

How often do you drive these cars at anything other than fully closed or WOT? I would think that you could drive with an On/Off switch for the throttle (if it wasn't expressedly prohibited in the rules)

I guess I am kind of foot happy, but generally when I am karting, that is how I drive.

(Haven't driven FSAE yet...)
Brian
WSU Formula

[Charlie]

Brian, a proper FSAE car is not nearly underpowered enough to drive it that way. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Dan Deussen @ Weber Motor]

Throttle control is vital, especially for the skidpad event. Imagine trying to hold a constant velocity without upsetting the car using an on-off type throttle.

Daniel Deussen
www.walbro-italy.com (http://www.walbro-italy.com)

[Sam]

why do people think these cars have no power?

http://www.users.on.net/georgec82/GeorgeBurnout.avi

throttle control is absolutely necc.

Frank (using Sam's login, sorry Sam an accident)

UQ Racing

[A Reinke]

on a normal engine i would see the throttle body as the restricting part of the engine, correct? my Ford has say a 49mm throttle body if i recall right. it then passes through an EGR spacer of the same bore into the intake manifold/plennum.

on our formula cars the restrictor is after the throttle body, and smaller then the bore. in theory, should the size of the throttle body have any affect on how much air the restrictor can pass through it? i can only forsee the restrictor flowing a certain amount now matter how much air you give it on the frontside.

make sense? comments?

~Adam

[djbrodie]

I totally agree, that the size of the throttle body should not influence mass flow rate. If we look at the continuity equation. AV1=AV2. It is clearly an area ratio. So the closer you can get the throttle to the engine clearly it can be said that throttle response will be maximised. Throttle control from my eperience is greatly related to the plebum geometry and thus distribution of charge. It also relies heavily on the engine map.

Engine Team leader 03
Full Boar Racing
Swinburne

[Charlie]

So you are assuming that turbulence near the restrictor doesn't matter, and placing your throttle in higher velocity flow has neglible effects then?

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

Adam i would say that the most restrictive part of a "normal car" is usually the ports / valve seat, and the throttle body on some cars

[A Reinke]

so relating how a these engines are setup stock to how we run them really can't be done because of the restrictor being after the throttle body.

i'm pretty confident in our 1-inch throttle body. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Dan Deussen @ Weber Motor]

Got a flowbench? Flow your restrictor with and without the WOT (Wide Open Throttle) in place and compare.

Got a dyno? Run your engine with and without the WOT in place and compare.

On the dyno I would recommend to not only look for peak torque and horsepower, but much rather compare both curves.

Daniel Deussen
www.walbro-italy.com (http://www.walbro-italy.com)

[imajerk]

Throttle style and its size do affect engine tunning. In most cases however, it's of no concern. Practically, a slide vrs. butterfly (of same inlet area) will always have a more spiky torque curve compared to a butterfly. The torque peaks are not by chance either. They grow in strength and are spaced exponentially along RPM. Hence, changes in mass flow rate... and there seems to be a critical value ratio involved.

If you are still with me... mass flow rate is critical, not throttle size!
Mass flow rates less than critical value is:

m.=(Cd.Ath.po)/(sqrt(R.To)).((PT/po)^1/y).{(2.y)/(y-1)[1-(PT/po)^((y-1)/y)]}^.5

...at critical value, m. is similar.

So basically, there is a relationship between flow rate, throttle angle and manifold pressure and engine speed. You can figure out what all the variables are – obvious (Cd is the discharge coefficient, similar to valves). Also, it may surprise some that mass flow rate vrs. throttle angle has no meaningful relationship other than at WOT you are getting maximum flow. The relationship is not linear, it is not exponential or logarithmic.

So, I'm off to fail my maths exam.

[Frank]

Dan,

we've done both of those tests

flowbench difference = bugger all

dyno difference = not detectable

throttle size = 34mm OD

Frank

[A Reinke]

what the heck does 'bugger all' mean? http://fsae.com/groupee_common/emoticons/icon_confused.gif

[Frank]

"bugger all" is an Australian (and sometimes British) term for 1% +/- 0.6%

[clausen]

LOL

Regards

Paul Clausen
Uni of Adelaide

[A Reinke]

haha...okay man, thanks for the clarification. http://fsae.com/groupee_common/emoticons/icon_redface.gif

[Jon Prevost]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Sam:
why do people think these cars have no power?

http://www.users.on.net/georgec82/GeorgeBurnout.avi

throttle control is absolutely necc.

Frank (using Sam's login, sorry Sam an accident)

UQ Racing<HR></BLOCKQUOTE>
You need more donuts and more smoke to compete with the likes of us http://fsae.com/groupee_common/emoticons/icon_wink.gif . 60 donuts I do believe was the finally count. Enough smoke that on the loud speakers there was a comment about a fire in the test area, lol.

About throttle bodies; We like our barrel style. We might share our plans now that it's been considered illegal. The restrictor was in the barrel, rules commity doesn't like, oh well. Maybe we'll do a double barrel or gate. I'd stay away from butterfly for the obvious reasons. It's just like running a maf vs map system, why put ANOTHER restriction in the intake even if it is unmeasurable? Every little bit counts and it DOES add up rather quickly. If you're limited by man power then sure, go with the butterfly and focus on the other systems for power. As for us, we'll stick with what works best, time will tell.
, Jon
"Success - it 's what
you do with what you've got." - Woody Hayes
Engine Team

[George]

I've heard about the Ohio state burnout ... does anyone have a video? I believe the Wollongong guys do?

UQ Racing Team Leader 2003
www.uq.edu.au/fsae (http://www.uq.edu.au/fsae)

[Eddie Martin]

It was a great burnout. We have footage of it somewhere i'll see if we can put it on our website.

[runner]

Sad to see such a blatant disregard for safety. People are on here doing everything they can to show their Uni that FSAE is a great learning experience. Please THINK next time.

[Frank]

seriously Runner,

3 hours spent on shock histograms / damper settings

1 hour spent on tyre temps / pressures

2 hours of driver training

at the end of the day someone does a "burnout", takes a vid, and posts it

i think (in general) people know what this is about... and expect that (sometimes) we have some fun

Frank http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Brent Howard]

How is spinning around at very low speeds in the middle of a very open area dangerous?? We have never hit a curb doing dounts or burnouts, but we have hit them just doing autocross.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[runner]

"3 hours spent on shock histograms / damper settings

1 hour spent on tyre temps / pressures

2 hours of driver training"

That's a lot of tesing time to waste on practicing "burnouts". You might want to reconsider and spend some of that time on actual dynamic event testing that is involved with the competition.

"Low speeds," I think not. The driveline assembly was spinning at a very high rate. Oh ya, didn't OSU just prior to that fall out of Enduro because of an upright that almost fell off? Hmmm... You guys can do what you want, but you won't find me around there anywhere watching.

[Charlie]

Who are you?

Frank obviously meant that all that time WAS spent on dynamic event testing, and a 10 minute burnout doesn't take away from the project or testing time considerably.

The donuts were cool, I think the timing was a little distasteful, but it was cool nonetheless. I love doing donuts in our car. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Anyone who won't list thier location or university only gets a passing notice from me on this board. Anonymous comments don't hold much weight.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Brent Howard]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Anyone who won't list thier location or university only gets a passing notice from me on this board. Anonymous comments don't hold much weight. <HR></BLOCKQUOTE>

Agreed.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[chinesefonz]

I agree... I was personally there at competition... I know University @ Buffalo has a video of it... I'll dig it up...

I see no harm in doing some burnouts... you can't be lame your whole life... heaven forbid you should have fun at the possible expense of personal injury... if yur gonna live yur life like that... may as well stay in bed the rest of your life, be careful, you might sufficate on the pillows. LOL

[A Reinke]

i'd really like to see OSU video, or other burnout videos...

if you guys can't get them on a server, you can AOL-IM me at Reinkster - and send em. http://fsae.com/groupee_common/emoticons/icon_smile.gif

~Adam

[Jackson]

Who cares if the driveline is spinning fast. The tires obviously can't hook up, so you aren't going to go anywhere.

Obviously runner hasn't driven a RWD car much, my truck burns out on accident all the time, I guess that is "dangerous." (Of course burnouts in the Vehicles rented from the Uni are that much more fun because the tires aren't yours...)

As per my post earlier-- obviously you need a throttle control, but it shouldn't need to be that sensitive. I hadn't thought about the skidpad though.... Too bad electronic throttles are prohibited, otherwise we could just use a PS2 controller and play real life Grand Theft Auto.

Brian
WSU FSAE

[Jon Prevost]

runner is right, it was dangerous, didn't you guys see the cones punted a few yards? Watch out, I think our car might try out for Penn State's football team http://fsae.com/groupee_common/emoticons/icon_wink.gif, JUST KIDDING, it was a great game.
Our driver/captain was really upset with the black flag on the last lap, especially after how well we did in the other competitions. It was a shame something so simple as a camber bolt took us out.
http://rclsgi.eng.ohio-state.edu/~fsae/Videos/

, Jon
"Success - it 's what
you do with what you've got." - Woody Hayes
Engine Team

[Jon Prevost]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by runner:
That's a lot of tesing time to waste on practicing "burnouts". You might want to reconsider and spend some of that time on actual dynamic event testing that is involved with the competition.

"Low speeds," I think not. The driveline assembly was spinning at a very high rate. Oh ya, didn't OSU just prior to that fall out of Enduro because of an upright that almost fell off? Hmmm... You guys can do what you want, but you won't find me around there anywhere watching.<HR></BLOCKQUOTE>
What do you think we were doing. Wasn't it obvious that we were testing our drivetrain durability and driver comfort? Those things are very important in a dynamic event, especially with the kind of hp we were pumping out of the motor.
Throttle response was good too http://fsae.com/groupee_common/emoticons/icon_smile.gif

, Jon
"Success - it 's what
you do with what you've got." - Woody Hayes
Engine Team

[Frank]

Lords!!!!

Im facing North-East .... Bowing

(although I think the most consecutive circles were 12)

Frank

[karter]

I like what Matt Kenseth did at Homestead, put the nose up against the wall and burned em to the rims! Here is an idea to raise money for your car, its called a "brick in". Have several teams get an old car that runs, throw a brick on the throttle and have prizes for which one runs the longest, blows up the biggest or what ever. charg an entry fee, spectator fee etc. Loads of fun!

[Brent Howard]

I don't get any video for the burn-out video. Just get your logo appearing and sound...what do I need to play it? Codecs?

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[gug]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Brent Howard:
I don't get any video for the burn-out video. Just get your logo appearing and sound...what do I need to play it? Codecs?<HR></BLOCKQUOTE>
its divx codec. windows media player 9 should be able to play it once you download the divx codecs, or get the actual divx player from www.divx.com (http://www.divx.com) i think.

and it is realllllly worth it, that burnout was crazy. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

[Brent Howard]

Hmm, I tried Divx last night...oh well time to upgrade to the newer version I guess.


Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[js10coastr]

did you get the video to work? I have the same problem still...even after reinstalling divx.

www.calpolysae.org (http://www.calpolysae.org)

[Brent Howard]

Yeah, works great now. Try getting the newest version of Divx (9 I think).

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[drivetrainUW-Platt]

ya, the burnouts were sweet, but back to throttle bodies...I'm workin on designing one for the 06 car, as I wait on drivetrain parts...It doesn't appear that any agreement was made, one camp says go small for throttle control the other says go big for more flow...I'm lost, I haven't had any fluids classes, so no knowledge there. The rotary barrel tb is appealing to me just because there is no restricion at WOT, but manufacturing might be a trick, also the slide is a good design, but I have heard of stickin conserns with high vaccuums and throttles slammed shut, also need some creative TPS ideas...the butterfuly is definitely the simplist, pull a butterfly from a stock sumptin, small car or bike and put it in a housing. Really open for opinions on this one both on bore size and design

[BeaverGuy]

The throttle you want really depends on what you are looking for.

We went with a 35mm barrel this year over the 30mm butterfly we had used for a couple of reasons. The reason we ran a barrel was for the controllability, it produced a fairly linear air flow vs. throttle postion response over a very broad TPS range. If you want that type of response then a barrel may be what you want because it will likely take a four bar linkage to get the same from a butterfly. With that fairly predictable response we made the throttle bore larger to allow for flow that was lost when they stepped down to the 30mm for contrallability reasons.

[kozak]

Does anyone know if there is a problem using carbs as throttle bodies. the reason i ask is because our engine is a carb '89 yamaha fzr. i have seen it done on some cars before for accuracy reasons or looks but is their any prob trying to do this with fsae. also it is a slider butterfly carb (slider for the fuel metering and butterfly for air metering), so i gues i'll have to dissable one of them.

[B Lewis @ PE Engine Management]

Kozak,

Yes, you can do this. There are some very good teams out there that use a stripped down carb as a throttle body.

[drivetrainUW-Platt]

carbs..then you have TPS issues, your shaft wont stick out for the sensor and you will have to tap some skrews in the housing to mount it, not to mention all holes from the fuel passages

[kozak]

well its not like the bike is from the 70's it has (had) computers and everything and i'm prety sure it had a tps too. or we could make one.

[drivetrainUW-Platt]

no clue why a carb would have a tps.....

[Draksia]

Originally posted by drivetrainUW-Platt:
no clue why a carb would have a tps.....


TPS infomation is often used to calculate the ignition advance.

[drivetrainUW-Platt]

alright, back to my origional question, what designs do ppl like, barrel, butterfly, slide???

[rjwoods77]

BMW throttleless system. Too cool.

[Chris Boyden]

Rob,

Is that a variable valve system? i.e. voice coils on each valve?

[Greg H]

I believe Rob is talking about Valvetronic (http://www.bmwworld.com/technology/valvetronic.htm).

[Mechanicaldan]

I doubt you could use these components, but it's still super cool.

A real DIY throttleless, camless system:
http://rbowes1.11net.com/dbowes/index.htm

[TG]

Originally posted by Greg H:
I believe Rob is talking about Valvetronic (http://www.bmwworld.com/technology/valvetronic.htm).

Yeah it's Valvetronic along with the VANOS cam phasing. Pretty cool mechanism to adjust the valve lift. Check out page 137 in the February 2003 issue of Automotive Engineering International.

[B Lewis @ PE Engine Management]

Originally posted by drivetrainUW-Platt:
carbs..then you have TPS issues, your shaft wont stick out for the sensor and you will have to tap some skrews in the housing to mount it, not to mention all holes from the fuel passages

Who says you need a TPS http://fsae.com/groupee_common/emoticons/icon_smile.gif ?

[Ben Inkster]

[QUOTE] BMW throttleless system. Too cool.
[QUOTE]

I have been thinking about technology for FSAE for a couple years now. It would be so cool, you could have an huge plenum volume with no side effect on throttle response. But I think the judges would ban it straight away or it is probably outlawed already because you are using the valves to throttle airflow downstream of the restrictor.

Even so, I'm sure this kind of technology is out of grasp for most FSAE teams.

Cheers

Ben Inkster

(former)UWA Motorsport

[John Bucknell]

Personally, if any of you get a throttle-less system running - I will pretty much guarantee maximum powertrain points in the design event http://fsae.com/groupee_common/emoticons/icon_smile.gif

For background, I worked with Dr. Flierl from BMW who invented the Valvetronic system (and actually has a simpler one now where he works at HiLite) and he said it took 34 engineers five years just to calibrate it (tune the engine controller). The programs I work on need about three to four engineers for two years to do the same thing.

[C.Casper]

here is my take on throttle body sizing. Being practially a first year team, all my knowledge on the subject come from Lotus simulations and reading.

32mm vs 50mm just for having numbers. The engine based on its pipe geometrys can only suck down so much air, ie VE. The problem I see with a larger throttle is lack of control/adjustability. Let me explain: If a throttle goes from 0 to 90deg, 90=WOT. If a large throttle at 45deg is supplying the max amount of air that the engine can possibly suck down, then the rest of the 45 deg motion is useless.

I am currently trying to test this theory by varing throttle diameters and a constant rpm and comparing the mass flow rates of the air passing through the throttle keeping all other aspects of the engine constant.

I'd be open to any suggestions, as I know there are many people who have done a lot more testing in this area than I.

Charles C
Portland State University
2006 FSAE Engine Design

[Kamil S]

I base the throttle body diameter on compressible flow equations. I do not have a current example at hand, but most teams go for a converging-diverging (aka venturi) type restrictor, which is governed by these equations. Any compressible flow book, or better still, wind tunnel design books will tell you how to design it.

For us it turned out that something realistic would be about a 40mm diamter throttle body. Unfortunately no testing yet.

What you were saying about maximum volumetric flow rate is true (given you actually account for the needed length from throttle to restrictor), however, if someone is going for WOT you might as well floor the pedal (and you'll get the same performance with a larger throttle body).

The issue then becomes a matter of how sensitive you want your throttle. I would test it as if i were to drive it. If the car is not ready yet place the engine on a dyno and build a foot controlled throttle. If the transitions are really quick and uncontrollable then maybe a downsized throttle bore is needed.

Just my thoughts http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Dr Claw]

Our intake guy this year doesnt believe the TB is part of an intake...so he's not doing one.

His reasoning, not enough time to research materials. My answer to that; I'm making one out of wood and its gonna work http://fsae.com/groupee_common/emoticons/icon_smile.gif

[BeaverGuy]

Charles, I used a similar method to size our throttle last year using Virtual-Engines. I set up a sweep of throttle diameters from 30-50mm over the whole RPM range. The simulation showed that at lower engine speeds the size didn't make much of a difference. Around 7000 RPM a noticeable difference in maximum airflow appeared. However, as the throttle got larger than about 40mm difference in peak airflow rate started to decrease. Essentially a point of diminishing returns.

I also did a CFD comparison of air flow versus throttle position to compare a butterfly to a barrel throttle. They have different characteristics and we wanted a linear relation.

To make sure that we picked a throttle of the right size we planned on physically testing by setting the engine at a given RPM then varying the throttle position and recording the new airflow and power. Because at the time we didn't think to record data while tunining the engine, which would have worked for a couple different things. We ran out of time to test things before we got our physical testing done.

However, I did do a static test of airflow versus throttle postion on our makeshift flow bench. This was compared to the CFD results to make sure we got the type of response we wanted.

[Chuck Dean]

We have a 50mm butterfly-style throttle body on our engine. We see throttle control up to about 80% throttle on the dyno. 80-100% throttle is pretty much the same. So the usuable TPS is 0-80%.

[C.Casper]

thanks Josh, and to everyone else's input. Been working on it a few days now and it does seem that mass air flow continues to increase to about 50mm, but throttle control was diminished starting at about 40mm getting worse to 50mm.

While i haven't driven any fsae cars before, I've driven a fair assortment of gocarts, and highly tuned street vehicles. I think i'm going to go with between a 35 to a 38 to get the increased airflow but retain 100% throttle control, just my 2cents.

[BeaverGuy]

Those are pretty much the same values that I got and decided on a 40mm Butterfly, which was about equivalent to a 35mm Barrel for total free flow area.

Another concern about throttle control is the plenum volume. While on the dyno we had good control, but when we got to the car and started experiencing considerably faster throttle changes some started to complain of throttle issues.

[~~J~~]

anyone tried linearizing a butterfly TB before?

[SpdRcr]

i'm going to be doing some tests soon, so i was curious about what other people have for numbers regarding these topics:

flow rates after the throttle body
flow rates after throttle body & restricter
throttle response time at various pressures

im not looking for anyone to give me these numbers attached with throttle body sizes or design because then it would give everything away. I would just like to be able to compare the optimal numbers. also, if there are any other tests i should be running, let me know. the tests i am running:

time vs pressure (2 pressures)
flow rate vs. throttle position(steady state and dynamic testing)

this will be tested for various throttle sizes and designs. ill share some numbers when testing is complete



thanks!

[John Valerio]

we have also done a flowbench test on our throttle to check the flow rate vs. throttle position.
my question is this: since we're on a homemade shop vac flow bench, we're not even coming close the flow rate across the throttle we would see on the motor but are the results we obtained simply scalable up to the real values?
in other words: will the throttle cam profile we calculated using the flow bench results produce the same flow vs. throttle position relationship when moved to the motor?
thanks.

[BeaverGuy]

Whether the profile is the same would likely depend on the pressure ratio. When I did my comparison I figured it would be but I'm not sure. I'm also a little suprised that you can't get near the flow on your engine with your flow bench. Using a shop vac as the vacum source I got 2/3 of our total engine airflow. I think the bigger concern about whether the flow profile will be the same shouldn't be the flow rate as much as the fact that a flow bench is steady state while an engine isn't.

[John Valerio]

josh,
thanks for your reply. you make a good point about the steady state of the flowbench. however, it seems that steady state flow analysis is the "best we got" because even if you did some kind of transient analysis, say:
d(theta)/dt for the throttle vs d(m dot)/dt
this wouldn't really be valid as you really wouldn't ever see the same d(theta)/dt when driving.
can this be taken into consideration or is steady state the best we can design for?

[SpdRcr]

you bring up a good point about the steady state of the shop-vac setup. but you can still get some reasonably useful data.

however, wouldn't a dyno be the ideal way to test this?

[~~J~~]

anyone done successful tests with a dyno?

[Marc Jaxa-Rozen]

We got pretty good results last year by logging power and MAP on the dyno, then replotting against TPS. Even in transient runs, it was pretty close to CFD data- I don't know if that was just blind luck with that particular setup, we'll see when we try the new throttle and intake.

Marc Jaxa-Rozen
École Polytechnique de Montréal

[illiterate]

Talking about throttle less....
Why not just take a single cylinder, remove the intake valve, weld a small pipe of 20mm dia over it and install the valvtronic on top of that in series with a binary type(just open and close positions) throttle which is controlled manually. That should take care of the rules and get you throttleless.
never hurts to day dream. Now only if i could design a throttle for a car that would atleast be able to compete in FSAE, it would be a real acheivement for me.

[Rohan]

hi guys ,
we are the first team going to hockhenhiem this year.we have selected CBR600RR engine,i have the engine department and i am facing the design problem of engine intake......ihave follow the analytical methode to calculate mass flow rate of air at different section.......can any one tell me how we cal measure the pressure of air after throttle and before ristricter

[Jay Lawrence]

What is between the atmosphere and your restrictor?
These (usually 2) items will produce some kind of pressure loss. Generally, at WOT, you can assume that you are getting atmospheric pressure, or a few kPa less than that, at the restrictor entry. Alternatively, put a pressure sensor in there.

[Max Trenkle]

We successfully designed a rotating gate throttle body. It'll be on the car at Michigan.

Anyone else looked into this?