I think you're missing MY point. Please read the post carefully. When you split up an INLINE 6 into two manifolds, you aren't creating more restriction, you're actually relieving it. (see my post). The reason this was done on the e46 m3 was NOT to add weight and was of purely aesthetic value, but because it opens up top end hp at the expense of low end torque, a concious decision made by the engineers of the car.

Youre original post was questioning the design of the m3 dual exhuast, and analogizing that to the splitting of an inline four with a single header, which i argue are COMPLETELY different things. splitting the 4 is, as you said, more restrictive.

You're saying now that, if you have two manifolds, run 2 pipes. But thats exactly what the M3 does; Your original post suggests that either 1) your analogizing two completely different things, or 2) you thought that the m3 had one header and the exhuast was being split in the same way that this person is suggesting the inline four exhuast be split. IS this clear yet?



Apparently not that much; as the point was missed ONCE AGAIN. I never argued that two manifolds on an inline 6 can be easily routed into one pipe. Here's what i said.

by this, i was not refering to ANY inline 6's (which is, uhh, pretty clear if you read it) but rather to cars like the Acura TL and CL, and the Accord v6's, that aren't inline, but have 2 headers that route back into one pipe.

I hope i made this a bit easier for you to understand.

 

Thanks for all the helpful exhaust information. I learned a lot. I wasn't planning on doing a dual exhaust, I just wanted to see what it looked like.

Enough with the "rice" comments. This is my car and I can do whatever in the hell I feel like. Personally, and I think I speak for the majority of people posting, if you want to rant go to the open/no subject post ***** section.

 

You all are missing the point. The design of the exhaust has as much to do with cylinder scavenging as restriction. An M3's exhaust is designed the way that it is because connecting certain cylinders to others with the correct firing order allows one cylinder's exhaust to "scavenge" another at an optimal rate. This effect is caused by the momentum of the exhaust moving through the pipe actually creating a vacuum behind it, and if you time that vacuum correctly it will "pull" exhaust out of another cylinder. This is sort of a no cost exhaust side turbo charger.

This is also why you always see a crossover pipe on a V-8 with dual exhausts, and why M3's have their exhausts connected the way they do.

Interestingly enough, an exotic engine like a Ferrari maximizes this effect though changing the entire firing order of the engine. They do this by the way of a 180 degree crank, rather than a 360 degree one. The characteristic "Ferrari sound" is created by that firing order, too.

 

please stay away from RICE!!!!!!

-thank you

 

Just thought of a really cool idea for a twin exhaust set up (don’t laugh until you read on). On a Ford RS 200E that I was reading about the other day (that’s the one that Stig Blonquest or something drove up Pikes Peaks in 2002 and will do this year), the external waste gate didn’t dump back into the down pipe like they do on most aftermarket external waste gates, but ran its own pipe to the back of the car. I know this has been done in racing for years but I have never seen it on a road car. Could it work? What would you have to do to comply with the law? Colud you have it as a side exit?

 

Not wierd. Stupid.

 

so do you think the srt4 which is dual but no exhaust is restrictive?

 

I believe as a general rule of thumb, 1 pipe is always better than 2. My reasoning is that not only is there a weight issue, when taking gas dynamics into account, exhaust gas will flow on the walls of the tube first. Given the same area, a larger single exhaust pipe will yield less friction co-efficient than a twin exhaust of the same area, thus the single tube exhaust will outflow a twin pipe of equal area.

However often, when designing an exhaust system, it is simply easier (especially in the case of 2 opposing manifolds) to run twin piping in the interests of ground clearance.

My $.02

Cheers,

Gary

 

Yes. The head PVO engineer for the srt4 admits this in an interview. They went with the dual exhaust for appearance, and since the car has no mufflers the setup isn't too restrictive. However, virtually all of the catback exhausts for the srt4 are single pipe with a dummy tip for the left bumper hole.

-n.

 

WRONG. There are maybe 2 or 3 single exhaust systems for the SRT-4. The rest are all dual tip. Most of us prefer the dual tips because of the dual bumper openings.

Including me.




and some like the single..

 

I stand corrected.. but I still stand by my statement that the dual exhausts don't enhance performance. I do agree it looks better, but single is always better in a four cylinder application, even if it's only a small difference.

SCC article
Here's the article that mentions the engineers being forced to go with the dual exhaust for appearance.. and how they compensated by removing the mufflers completely. The lack of mufflers helps a lot, but for the best absolute performance, a single pipe with no muffler would be even better.

 

 

Actually, the M3 has dual manifolds and catalysts, so it is a true dual exhaust. Take a look at the white paper below if you don't believe me

http://dinancars.com/Products/3serie...46_exhaust.pdf