Tuned Intake RPM

[cheezoto(OU-FSAE)]

Do you think tuning our intake manifold for about 10,500RPM would good for the dynamic events at the SAE competition. I dont want a really peaky motor that you have to keep in the high rpms during racing. We are using a 2002 cbr600F4i motor with stock cams.

University of Oklahoma
FSAE Vice President
FSAE Engine Systems Leader

[cheezoto(OU-FSAE)]

Do you think tuning our intake manifold for about 10,500RPM would good for the dynamic events at the SAE competition. I dont want a really peaky motor that you have to keep in the high rpms during racing. We are using a 2002 cbr600F4i motor with stock cams.

University of Oklahoma
FSAE Vice President
FSAE Engine Systems Leader

[Alfonso Ochoa]

Ours is tunned for 9500 RPM and it's no peaky at all...We have a very flat curve from 5500 to 11000 RPM....It has a lot to do with your exhaust, play with it and you'll have a flatter or peaker curve wahtever you do.

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

[woollymoof]

Not sure that it matters that much where the actual peak is just as long as its a fat, flat torque curve. Depends on the track as well. In Australia last year a peak at say 7 or 8 would have been good. It was small.

[Angry Joe]

10,500 rpm power peak or torque peak?

I tuned our intake for a torque peak of about 8,000 rpm (theoretically, still working on the tuning issue...)

Lehigh Formula SAE

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Alfonso Ochoa]

Torque peak at 9600 and power curve at 11000, where the torque curve starts to fall down hard.

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

[Kevin Hall]

Just out of curiosity, how do you know which peak you are seeing? Right now, we are running an intake with a ridiculously high tuning peak (estimated 19000 RPM), and we are seeing a slight fall in power around 11500 (about 4 hp drop in either direction). How strong does the exhaust scavenging peak come through? Is this a reasonable tuning method........I mean moving the intake peak out of reach, tuning the peak of the exhaust to where you want it, and then building an intake to match approximately the same peak and tuning it to match exactly? Is there a better way, or for that matter, will this work http://fsae.com/groupee_common/emoticons/icon_smile.gif

Kevin Hall
University of Saskatchewan
Engine Guy Extraordinaire

[Alfonso Ochoa]

Kevin,
I think the best way to tune your engine is to calculate some intake diemnsions (plenum volume, runners lenght and diameter, etc) within some maximum and minimum values. Build a manifold were you can easily change the parameters you based your calculations and test them in a dyno. You can test your intake independently of your exhaust and see its Torque peak. Then calculate an exhaust manifold tuned to an RPM peak that flats your torque curve as much as you want or maybe increases your power peak, those are your design considerations.
We have problems to access the university engine dyno this year, so we based our engine testing in 4-Stroke Virtual Engine software. You can also simulate a one cilinder engine (150 cc) and test your intake and exhaust configurations independently and see their torque and power peaks. In the next weeks we will be testing our engine in the dyno with the finals configurations obtained by virtual engine.

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

[biggie]

What books/authors have good information about exhaust tuning?

[Kevin Hall]

Well, we have calculated the peaks of our exhaust, but we also designed it so we can change the primary and secondary lengths. Being that we can change those lengths easily, we would prefer to tune that first, as our new intake is not built yet.

How easy is it to see changes (will they be evident)? We have a set of Hindle headers coming, and we are hoping to use those, but until they arrive, I am simply hoping for the best with what we've got.

Our intake is going to have easily adjustable runner length, and we are making 2 airboxes, with 2 considerations
1) Minimal flow losses in the first
2) Protruding bells in the second

Hopefully we'll see a change in the shape of the curve and go with the more driveable one

Thanks for the help

Kevin Hall
University of Saskatchewan
Engine Guy Extraordinair

[Alfonso Ochoa]

Our simulation for the one-cilinder engine changing the primary exhaust lenght (with no intake manifold) showed a super flat torque curve (a straight horizontal line) where no peaks were visible, that felt down earlier or later depending on the exhaust lenght we choose (shorter or longer). So Sincerely I don't know if you would find your exhaust peak easily.
In the other hand, you can see the intake manifold peaks pretty easily.

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

[Bam Bam]

Kevin,

Dude the power loss at higm rpm's MIGHT have more to do with your restrictor than your exhaust.

Just a hint.

[Kevin Hall]

Bam Bam

The intake at the moment is HORRIBLE. I know very well that we shouldn't be making much power with it. I am almost proud to make 60 hp with what we have now. The new intake is being fabbed, and will be much better.

I was simply hoping to find what Alfonsoa said, which is that the exhaust should make a flat line, and not a peak, therefore being almost impossible to notice.

Kevin Hall
University of Saskatchewan
Engine Guy Extraordinaire

[Bam Bam]

Ok gotcha now. If you're trying to locate your exhaust tuning peaks using a non resonant intake (ie tuned to like 19,000 should be the best way to look at the effects of your exhaust without having them muddled (much) by your intake Essentially the height and length and rpm at which your peaks occur can be controlled by runner lengths collector volumes and valve overlap periods. So what alfonso is getting may not be what your getting. It's a matter of deciding what you want and then adjusting the variables to meet it.

Now I'd be guessing that there is some interaction between the intake and the exhaust so to "Optimize" this problem the best way to do this would be to perform a very well plannedDOE that would allow you to vary your intake and exhaust parameters simultaneously to find the best set up for your car and your drivers.

Either that or just close one eye, extend your thumb at arms length, turn it to the side and say THAT THAR LOOKS 'BOUT RIGHT.... and then proceed to blast out over 80hp.

Do what works for ya in the time you have,
At the end of the day you'll learn a lot.

Good luck

[MercerFSAE C. Burch]

I'm curious as to how many people use adjustable intake runners, somewhat like BMW's DISA(dual resonance intake system) system. From what I understand of their system it is designed with a valve/flap that changes the length of the intake runners for max torque at low engine speed and max power at high engine speed. Long runner length for slow speed and short length for high speed. Do any teams use this or similar technology?

How about Variable Valve Timing? Does anybody use that technology? I don't know if the CBR 600F-series engines use it already.

-Chris

Mercer University - Drive
Coming to a race track near you, May 2004
God(Administration) Willing.

[Kevin Hall]

Bam Bam

I know it's not a pretty way of doing things, but without some EXTENSIVE funding, most teams are left with little, or no engine budget. I'd love to be fab'ing a new intake every week to try some new geometry http://fsae.com/groupee_common/emoticons/icon_smile.gif but that simply won't happen. At the same time, I'd move to be able to make 100 hours worth of dyno runs, and have a perfect engine, but that probably won't happen either.

If "THAT THAR LOOKS ABOUT RIGHT" will make me 80 hp, whether by luck, or by perfectly matching intake and headers after a few runs, then thats the way she'll have to be

Keep makin the power, and feel free to send me a turbo or something. Everybody has a spare around.......who'd of thunk you could eliminate resonance, and go with duct flow priniciples.

Thanks for the help guys

Kevin Hall
University of Saskatchewan
Engine Guy Extraordinaire

[Scott Wordley]

Kevin,

If you don't have the time to fiddle with lengths make a good guess. Intake and exhaust lengths are probably the easiest dimensions to estimate from other teams. Simply look at photos of the teams that get good power and take an average of the dimensions. Maybe even read a few design boards. This will get you probably 80% of the way there.

Chris, Melbourne Uni from Australia used a variable intake in the 2002 Oz comp. Two different runner lengths, butterflied near the ports with electric motor controller. Very neat and seemed to work well.

One of the Michigan(?) teams also had variable intake at the 2001 us comp. The car had a carbon body(with a dodgey radiator cut out) and yellow frame.

Regards,

Scott Wordley & Roan Lyddy Meaney
Monash FSAE Wingmen
http://www-personal.monash.edu.au/~fsae

[Charlie]

Variable length intakes have come & gone. Many teams have run them in the past but they never stick with it. From what I have simulated it seems like far too much trouble for little gain.

-Charlie Ping
Auburn University FSAE 1999-present

[Kevin Hall]

Scott & Roan

We do have time to fiddle with lengths, just not a whole lot. We'll get our new intake on in the next little while, and after we get our torque curve figured, we'll try adding and subtracting 3 inches in either direction with the exhaust primaries, and see what that does. The intake will be very easy to adjust, and hopefully we can get the power curve we want.

Thanks for the pennies ($.02)

Kevin Hall
University of Saskatchewan
Engine Guy Extraordinaire