Exhaust Manifold

[elshone]

Hi everyone,

I'm new in the forum and i am a new team member of ETSEIB Motorsport Team (Barcelona, Spain). I've been searching for this doubt through the forum and i haven't found exactly a clear explanation. Here it goes:

We have an exhaust manifold of the last year, which is very nicely done in my opinion. Looking after a good performance of the exhaust we have measured the exhaust manifold's length and i would like to know if a deviation of around 3% between two different collectors is critical. (It's a hand-made one, and it has been a very rude measure way we have done, so the error could not be exactly this, but not too far away (+-1%)).

Btw, it's a 4 stroke engine, which i've heard those are engines in which the length in the exhaust manifolds are NOT too critical (as long as they aren't too bizarre), because they don't need the resonance that much to work properly.

Thank you!

[elshone]

Hi everyone,

I'm new in the forum and i am a new team member of ETSEIB Motorsport Team (Barcelona, Spain). I've been searching for this doubt through the forum and i haven't found exactly a clear explanation. Here it goes:

We have an exhaust manifold of the last year, which is very nicely done in my opinion. Looking after a good performance of the exhaust we have measured the exhaust manifold's length and i would like to know if a deviation of around 3% between two different collectors is critical. (It's a hand-made one, and it has been a very rude measure way we have done, so the error could not be exactly this, but not too far away (+-1%)).

Btw, it's a 4 stroke engine, which i've heard those are engines in which the length in the exhaust manifolds are NOT too critical (as long as they aren't too bizarre), because they don't need the resonance that much to work properly.

Thank you!

[kapps]

The competition requires a 4 stroke engine so everyone has to use one. Exhaust runner length is important when combined with other things (intake runner length, cam, etc). I wouldn't worry too much about being off by 3% between cylinders, that's going to translate to a few hundred rpm. If the runners look like they will flow good (ie. minimal bends, large bend radius), then it's probably best to just use it. I was part of a Sr. design team that did the intake and exhaust on or car last year. It's a lot of work to do right. If you want to look into it more, do some research and find some SAE whitepapers that involve tuning of an FSAE engine. I believe FSAE teams can get some free copies.

[Dualsaber]

http://fsae.com/groupee_common/emoticons/icon_smile.gif
If you want a smooth exhaust,the exhaust length and the diameter of the exhaust tube need to be carefully designed.
We had deal with a 4 strock motor engine before,one of our teammate told me the exhaust system have somekind of harmonic wave effect,I don't know is ture or not,but the exhaust he made does have positive effect on the power of our engine.