Performance Exhaust = Less HP

[Judge]

After the first run, Brian looked disappointed. We'd mysteriously lost 10whp and 5 lb-ft. We had less restriction, it couldn't be right.

Thoughts?

http://www.eurotuner.com/techarticle...ust/index.html

[Citizen Z]

That is some pretty weak sauce. I was kinda thinking about the performance exhaust but it doesn't have enough... performance.

[BrokenVert]

I have never felt like I lost power out of my perf exhaust...hmmm good thing mine was free then. I don't feel ripped off.

[escobar929]

that sux, its one of the best sounding IMO

[adrean8j]

Originally Posted by BrokenVert

I have never felt like I lost power out of my perf exhaust...hmmm good thing mine was free then. I don't feel ripped off.

To be honest you probably would not "feel" a gain or loss of 10hp or 5lb/ft on a butt dyno. The only way to tell is to make some dyno runs or hit the track.

[BrokenVert]

Originally Posted by adrean8j

To be honest you probably would not "feel" a gain or loss of 10hp or 5lb/ft on a butt dyno. The only way to tell is to make some dyno runs or hit the track.

I auto-x and the car is very powerful and responsive...although that may be my PS2s talking...

[adrean8j]

Originally Posted by BrokenVert

I auto-x and the car is very powerful and responsive...although that may be my PS2s talking...

I am not arguing that around a auto-x track that you feel powerful and responsive. 290bhp and 300bhp would probably BOTH feel powerful and responsive in these cars. I was referring to straight track with trap times and the like. It would also depend on WHERE in the powerband, gear, rpm range you were losing the HP....

[BrokenVert]

Originally Posted by adrean8j

I am not arguing that around a auto-x track that you feel powerful and responsive. 290bhp and 300bhp would probably BOTH feel powerful and responsive in these cars. I was referring to straight track with trap times and the like. It would also depend on WHERE in the powerband, gear, rpm range you were losing the HP....

Fair Enough Good Sir.

[Speed Cat]

I think this is a good EG. that shows, even after an exhaust mod you need to re flash the car to let it know its there, and it ok to push harder...

I have a hard time, that a free flow exhaust looses 10HP....

[Mega Man]

That is discerning. They did mention the exhaust has to be fitted just right to avoid any leaks. Hopefully they double checked for those leaks!

[GtiGyver]

Originally Posted by Mega Man

That is discerning. They did mention the exhaust has to be fitted just right to avoid any leaks. Hopefully they double checked for those leaks!

Leaks would make the exhaust seem to flow even better. In fact, the best exhaust would be a straight downpipe with no exhaust whatsoever.
This is especially true for turbocharged cars.

[MadMan77]

Uh oh.... I think I will duck out before the arguments about back-pressure or lack-there-of start.

[GtiGyver]

Wanting (some) back pressure on naturally aspirated engines is a debatable argument, but on forced induction its a non-issue. Any form of backpressure is bad.

This is why having a loud N54 exhaust with flames n'shit is WAY MORE BETTERER!

[jibaholic101]

i have never trusted any car manufacturer that makes its own 'performance' line for those parts to be any good, and that just proves my point. bottom line, go aftermarket, but risk your warranty, the aftermarket engineers are focused on performance by doing constant pulls and tests while the car manufacturer is focused on branding

[Mega Man]

Man, I was on the fence about ordering a performance exhaust because of the rave reviews on here. On the fence because I haven't been able to get any response from my service department whatsoever, no call back, no email reply, nothing.

After thinking on this for a while, I probably won't go with the "Performance" Exhaust. I like my black chrome tips better anyway.

[BMW-driver]

Originally Posted by GtiGyver

Leaks would make the exhaust seem to flow even better. In fact, the best exhaust would be a straight downpipe with no exhaust whatsoever.
This is especially true for turbocharged cars.

-100. Ofcoure not. lol.

But anyway, it does not surprise me that de PP exhaust does not give you any extra pony. I didn't expect it, that's true. But it does not surprise me to hear from it that in this situation, the exhaust performs even worse. But, without any hasitation, I predict that there are cars around without any powerloss with a PP exhaust, or some of them with 1 or 2 ponies more. All those plug&pray hardware mods (like filters, exhausts, etc.), does not ever gain any possitive effect without softwaretuning etc. on the specific modern car. It is all for the mass consumer.

[GtiGyver]

Originally Posted by acs1.35i

-100. Ofcoure not. lol.

Explain...

On our cars, as with any other turbocharged cars the valve timing is such that it does NOT take advantage of scavenging or pressure pulses generated by backpressure since that would hinder with turbo spoolup as would any backpressure before/after the turbo. This is why getting a downpipe with larger tubing is almost always beneficial.
Also, by default the turbo wastegates are closed when in low boost conditions, so any backpressure felt by the engine is caused by the impellers of the turbos themselves, not by the exhaust, however the exhaust performance plays when it comes to the flow past the turbo once boost hits.
You are correct in saying that without a tune you won't gain much since the boost is regulated by the ECU, BUT you will always gain if the upgrade flows better than stock, especially in loss of turbo lag.

[AchtungF80]

I regard Eurotuner's reviews with a BIG helping of salt. I read them more for the eye-candy than their technical expertise...
Has any 1addicts ever done a before and after dyno??

[ORIGIN M.]

Wow. Good to know!!!

[sonicgrounds]

This is all based on one dyno?!!! Let's at least have a few more before canceling your order. It's the best mod I've done to my car. Even if it does take away a few horses, the sound alone is enough to get this. Plus I've got JB+ at %100 to make up for any loss of a few HP.

[ronnyek]

seriously... I read this thread, and honestly doesnt make me even give my performance exhaust a second thought... I do think its probably the best sounding exhaust I've heard. I know there are craploads of other exhausts to compare to, but I am not for LOUD exhausts, just tuned and great sounding. If it makes a bit more power, great.

[993 911]

There is certainly no noticeable loss in power or torque, car felt better to me after installing the Perf. exhaust. I highly doubt BMW is manufacturing products that make the engine work less efficiently.