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djbrodie
01-21-2003, 06:50 PM
Hi everyone,

Just joined this forum. I am the team leader for the engine for Full Boar Racing in Australia.

We are currently stuck in terms of how to calculate runner lenghts for intake and exhaust. Are there any calculations or books you can suggest. Your help would be greatly appreciated.

We are using CBR 600f4i, and thinking of running dual injection.

Charlie
01-21-2003, 07:09 PM
Winterbourne-Pearson, Design Techniques for Engine Manifolding is a very good book, but you need the Heimholtz resonator equation to get started.

-Charlie Ping
Auburn University FSAE 1999-present

Scott Wordley
01-21-2003, 09:03 PM
I just thought I'd throw my set in the air...

Hey man did I meet you at your launch last year I can't remember?

Its quite strange that you ask about about intake and exhaust tuning as I borrowed some books from your school library about 8 months ago to design our intake and exhaust. Still haven't taken them back yet

The best one was Scientific Design of Exhaust and Intake Systems by Smith. Anyway I thought it was a bit of a coincidence that someone from your uni put a hold on it the other week and now I have to return it... was that you?

Anyhow I remember visiting your workshop a few times last year and I think I recall seeing no less than 4 different intakes, all with different runner lengths, tube diameters plenums etc. I know we spent a fair bit of time with theoretical calcs but in the end they weren't much good for anything. In my very humble opinion the only thing to do is to build yourself a modular intake (and exhaust) system to vary plenum vol(doesn't do much), runner length (does heaps), injector positioning(makes a difference) etc and then dyno test your arse off. There is no substitute.
Here is one that I prepared earlier

http://www-personal.monash.edu.au/~fsae/monashplenum.JPG

Not sure if I remember correct but I think Ben Shute was saying that you guys struggle for dyno time(?), in which case I would look at the three years of competition benchmarking data that you have(right?) and correlate the basic intake and exhaust geometries with all the cars' performance(split times, observations etc) in what ever event(s) you think are relevant, taking into account the other factors that may affect a cars performance(drivers, weather, level of development etc).

Or in other words look at what works, try and understand why and then copy it.

Scott

ps what happened to the motorbike mechanic guy on your team last year? didn't he do a good enough job?

pps where do you dj?

Regards,

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

Alfonso Ochoa
01-23-2003, 11:20 AM
We are also using the Smith and "Design and simulation of 4-stroke engines" bye Gordon Blair. He has some interesting works on exhuast tunning.
But I also agree with Scott in the fact that the more effective work you can do to desing your intake is to test in a dyno diferent configurations: plenum volume, intake runners lenght and diameter(important) and throttle diameter too. About the exhaust it is more expensive and you should take a little more time in calcs.
We were supposed to have quality time in the university engine dyno but since the U has been closed because of the strike since December we have decided to based our engine works on 4 stroke virtual engine simulation software. We got it this january. But remember you need a good parametrization of your engine so the results can be reliable.
Thanks, Alfonso Ochoa.