What exhaust system is most efficient for S50 engine?

[Adrian_Visser]

Dual with a proper X pipe, that is designed around the header set-up, WILL perform better throughout the powerband. The exhaust pulses and velocity usually aren't tuned with many single systems. 3" is too big for any m/s 50/2 without high duration cams and headwork.

I ran 3" and 2.5" on my s52 car, and the 2.5" dyno'd better numbers throughout the powerband except for maybe 3-4whp up top. The 2.5" had better drive-ability, and made better midrange torque.

So what you're saying is I should hurry up and get some Sunbelts in there to match my exhaust?

I agree!

[e30polak]

So what you're saying is I should hurry up and get some Sunbelts in there to match my exhaust?

I agree!

That wouldn't hurt... :twisted:

[87e30]

How does the euro e36 m3 exhaust compare to the US version? and how does the s52 exhaust compare to the 328i exhaust?

328 is what I'm running.

[nando]

Dual with a proper X pipe, that is designed around the header set-up, WILL perform better throughout the powerband. The exhaust pulses and velocity usually aren't tuned with many single systems. 3" is too big for any m/s 50/2 without high duration cams and headwork.

I ran 3" and 2.5" on my s52 car, and the 2.5" dyno'd better numbers throughout the powerband except for maybe 3-4whp up top. The 2.5" had better drive-ability, and made better midrange torque.

No, it won't, because an X pipe and a Y pipe perform the EXACT SAME FUNCTION. after the X or Y pipe, the only thing that matters is getting the exhaust out of the car. Velocity effects only happen from the headers to the final merge.

if 3" performed worse it's because your headers and merge (either X or Y) weren't that great (which is true about 99% of the headers people here buy). I'm running 3" on a piddly M20 and I definitely didn't lose anything. I don't even like my current Y pipe, it's not a true merge but rather 2 pipes cut flat and banded together. that's also what 99% of the people here are running.

I'll say it for the 100th time. A 2.5" single pipe has about the same flow capacity as the STOCK exhaust. all you really did was ditch the cat and make it louder with a single muffler.

[e30polak]

I agree that the merges weren't optimal, as most aren't. However, I drove the car daily with both set-ups, which were built nearly identical, and the 2.5" definitely performed better. Both systems ran 2 mufflers, the same y-pipe, and the same end muffler. For day to day driving, I say that 3" is just an obnoxious noise maker. And I don't care if you say it's muffler choices, larger diameter piping is louder, period.

M20s barely gain any kind of performance from opening up the exhaust. The stock manifolds suck, and there aren't really any good header options out there. You usually lose power from switching to headers, so 2.5" or 3" wont really feel any different.

The same can't be said for the 24v engines, exhaust changes have a noticable effect on engine performance and drive-ability.

[nando]

I wish I had a sound clip, but you are wrong. My exhaust is *barely* louder than the stock cat and supersprint cat back I had before. It's definitely your muffler choice (I love the looks and quality of vibrant, but damn!).

as far as M20s, which we aren't discussing - again, you're wrong. There are several excellent headers available, but most won't pay for them. And my particular engine isn't stock. Finally, my old exhast was simply awful (mostly the headers and Y-pipe).

[e30polak]

I wish I had a sound clip, but you are wrong. My exhaust is *barely* louder than the stock cat and supersprint cat back I had before. It's definitely your muffler choice (I love the looks and quality of vibrant, but damn!).

as far as M20s, which we aren't discussing - again, you're wrong. There are several excellent headers available, but most won't pay for them. And my particular engine isn't stock. Finally, my old exhast was simply awful (mostly the headers and Y-pipe).

I'd rather not be as limited with my muffler choice, just to keep the decibels to a reasonable level.

You're right, NO m20 is worth throwing that much money at. I know that Stahl and RD headers are apparently good, but proper headers cost more then the motor. The m20 head and manifolds suck, only thing that motor is OK for is boost.

[nando]

you don't really have to be limited, there's lots of great mufflers. I'm using a Borla and a Dynomax. No rasp, deep grumble, quiet and free flowing. Plus they were cheap.

And a quality, metal core high-flow cat (like the one Vibrant sells) can act as a resonator, which placed behind the X or Y Merge can be a performance benefit (it "hides" resonance effects of the rest of the ehxaust system from the tuned section of the headers). But most people will go no cat because the forums say it's better..

no comment on the M20 ;)

[hoveringuy]

How does the euro e36 m3 exhaust compare to the US version?

That's like comparing the Stig to his American fat cousin, Bubba.

European headers are true equal-length long tube headers. Works of art. I have them...

[Schwarz325]

I'm running m50tu with e34 downpipes (massaged to fit) to 2.5" tubing mated to a Magna flow street series and a high flow cat. Its a nice low tone and a little raspy at high RPMs. It draws attention without being obnoxious.

Munn Manufacturing Tubing... HIGHLY RECOMMEND -fast shipping, cheap!!
1x 2.5" x 4' straight tubing
3x 2.5" 45deg elbow
1x 2.5" x 6" Flex-Pipe
1x 2.5" Thunderblot High Flow Cat
1x 2.25" Magna Flow Street Series Muffler


e34 pipes merged at 2.5"


6" flex-pipe and Thunderbolt High Flow Cat


2.5" tubing running to Muffler


Magna Flow Street Series Stainless Steel Muffler

U got more pics of the muffler?


Sorry to thread jack, but can you post pics of your muffler or magnaflow part number, looks like the one i wanna run?


OP, i'm gonna run a universal cat with ebay headers and 2 1/4 inch pipes into a magnaflow, this should support up to 4-500 hp and is quiet enough for my little m50

[z31maniac]

You guys need to use quality headers to start with.

[e30polak]

You guys need to use quality headers to start with.

True Buddy, but I bet that Racelands will outperform those TMS shorties for 1/3 the price! :p

[Adrian_Visser]

The Racelands sure sound awesome. I should get my car on a dyno and check it out.

[z31maniac]

True Buddy, but I bet that Racelands will outperform those TMS shorties for 1/3 the price! :p

Maybe by 1-2 hp, and only then if you had a properly built collector.

My car threw down 233 on a weak headgasket and off the shelf tune.

[e30polak]

Maybe by 1-2 hp, and only then if you had a properly built collector.

My car threw down 233 on a weak headgasket and off the shelf tune.

Just giving you shit Buddy. The TMS shorties are awesome. :p