[e90AW335i]

Originally Posted by T Bone

I would also ask your vendor about the methodology on how they derived the 20 whp number!

+1, that seems way to much for just exhaust.....

[T Bone]

Also try a different dyno....run it once with minimal air flow and one with a big fan (pack the intercooler with some ice)....you will clearly see how much variance is in they dyno runs....

Your car / exhaust is awesome and you are going to get power gains..... Just don't live and die by the dyno charts because they are deceptive.

[hl0m4n]

t_bone thanks man. your the man. but what really worries me the most is that i didn't gain anything. if you look i actually lost power. should i hit up another dynojet from another company in a different day?

ps: the hood being open makes a difference b/c stock run hood was closed while the exhaust it wsa open. other then that and the weather everything was the same conditions. same ideal oil temp, etc.

[T Bone]

Originally Posted by hl0m4n

t_bone thanks man. your the man. but what really worries me the most is that i didn't gain anything. if you look i actually lost power. should i hit up another dynojet from another company in a different day?

ps: the hood being open makes a difference b/c stock run hood was closed while the exhaust it wsa open. other then that and the weather everything was the same conditions. same ideal oil temp, etc.

No way that you would lose HP on turbo car.....maybe on a NA car....never on a turbo car unless it were more restrictive but no way SS would put that out.

We all need to remember dynos have variances day-to-day, run-to-run....

[hl0m4n]

Originally Posted by T Bone

No way that you would lose HP on turbo car.....maybe on a NA car....never on a turbo car unless it were more restrictive but no way SS would put that out.

We all need to remember dynos have variances day-to-day, run-to-run....

i guess i will redo a dyno run on a better day. but that would mean the gb is held up for all you guys. sorry.

hey tbone how would i know if i had an exhaust leak? im not too familiar with them.

[Rips335iCoupe]

I think you are out of luck ... it could of been some anomaly the day you got it base lined. That's why you have to keep the variables as consistent as possible. Same day, same dyno, same test environment. I got about a 12 whp with the exhaust, and you are probably getting from 10 to 15 whp increase. That's the most you will get out of any exhaust on a turbo car. If someone tells you differently, they are fudging the numbers.

[Rips335iCoupe]

Originally Posted by hl0m4n

how would i know if i had an exhaust leak? im not too familiar with them.

You would hear it ... but are you asking me if you think the SS exhaust would have a leak .... I highly doubt it.

[hl0m4n]

Originally Posted by Rips335iCoupe

I think you are out of luck ... it could of been some anomaly the day you got it base lined. That's why you have to keep the variables as consistent as possible. Same day, same dyno, same test environment. I got about a 12 whp with the exhaust, and you are probably getting from 10 to 15 whp increase. That's the most you will get out of any exhaust on a turbo car. If someone tells you differently, they are fudging the numbers.

thanks for input. does humidity make that big of a difference? the temp was off by a very few but a big difference in humidity.

[T Bone]

Originally Posted by Rips335iCoupe

You would hear it ... but are you asking me if you think the SS exhaust would have a leak .... I highly doubt it.

+1..... Your car would have Honda Civic VTEC Fart Can overtones....

Record a clip.

[Nikolas]

What a bummer. Sometimes catback exhausts will do little to nothing with turbo cars.

[Rips335iCoupe]

Originally Posted by hl0m4n

thanks for input. does humidity make that big of a difference? the temp was off by a very few but a big difference in humidity.

Everything can play into it ... what gear you use, if you have the hood open, something is going on with the dyno; the operator of the test ran the wrong parameters, IC heat socked. No way to go back and find that out. Kind of sucks, but be assured, that exhaust is putting out more wheel HP then it was stock.

[Rips335iCoupe]

Originally Posted by Nikolas

What a bummer. Sometimes catback exhausts will do little to nothing with turbo cars.

NOT

[Nikolas]

Originally Posted by Rips335iCoupe

NOT

Oh really? Coming from an STI with many hours of dyno time, I have seen first hand, several cat back systems that produced little to no HP. At most you are looking at 5-10 whp with a system that has minimal bends and then that would be tuning for it. With that little of a gain, it is very possible given the humidity difference, the dyno reading would indeed be lower.

The same goes for short ram and many CAI systems. Many of the one's I tried ended up producing no additional HP. One that I ended up with did make significant torque improvements and about 10 hp - Injen CAI.

Cat backs are honestly a waste of money. For the most part they are for sound. A full TBE will make a difference with a tune.

[hotrod2448]

Originally Posted by Rips335iCoupe

NOT

You obviously love the SS exhaust but, bottom line is if the stock exhaust is not much of a restriction at stock power levels even the best exhaust won't be worth much if anything on an otherwise stock car. Now after a tune it might be a different story but, it looks like BMW did a pretty good job on the exhaust.

I have seen some aftermarket exhausts rob HP. Usually they are shitty quality eBay specials and have some type of restriction the stock exhaust didn't. I'm sure SS wouldn't fall into that group but, there are companies out there that do.

There was guy on the Evo forum that bought an exhaust claiming to be 3" all the way through. After constantly making disappointing numbers he learned the muffler's inlet was only 2" and they just welded an "adapter" over top it to meet the rest of the piping.

[Rips335iCoupe]

Do you guys even read the post in these threads?? Anytime you can free-up exhaust energy in a turbo car it is a good thing.

The SS exhaust gets rid of the secondary cats, which are very restrictive .... the dyno I provided shows a 12 whp gain. So many experts on the internet!

[Nikolas]

Originally Posted by Rips335iCoupe

Do you guys even read the post in these threads?? Anytime you can free-up exhaust energy in a turbo car it is a good thing.

The SS exhaust gets rid of the secondary cats, which are very restrictive .... the dyno I provided shows a 12 whp gain. So many experts on the internet!

Well Mr. Expert - if it is removing cats, then it is not a true "Cat back exhaust"!

Also, was it worth 12 whp? I mean really? There is no way someone can feel that physically. That is roughly a 4-5% increase in power. Our cars can spike that power difference on a daily basis depending on humidity and air temp.

I'm sure if is a finely made piece and will be a great start towards a full TBE.

[hotrod2448]

Originally Posted by Rips335iCoupe

Do you guys even read the post in these threads?? Anytime you can free-up exhaust energy in a turbo car it is a good thing.

The SS exhaust gets rid of the secondary cats, which are very restrictive .... the dyno I provided shows a 12 whp gain. So many experts on the internet!

Experts like you?

Yes, I read the posts. There was also one guy on here that had a dyno chart of a stock 335 making near 400 whp. Should we believe that?

Yes, I'm aware that less back pressure is a good thing on a turbo car. I'm sure the SS exhaust will make power at some point. That point will be when the stock exhaust becomes enough of a restriction to start choking the motor. Apparently the stock exhaust flows well enough that there isn't that much a difference at stock power levels.

[Nikolas]

Originally Posted by hotrod2448

Experts like you?

Yes, I read the posts. There was also one guy on here that had a dyno chart of a stock 335 making near 400 whp. Should we believe that?

Yes, I'm aware that less back pressure is a good thing on a turbo car. I'm sure the SS exhaust will make power at some point. That point will be when the stock exhaust becomes enough of a restriction to start choking the motor. Apparently the stock exhaust flows well enough that there isn't that much a difference at stock power levels.

Not to mention the OP's dyno showing no gain.

[Emil@RENN-ART]

We tested ours on the same day .. didn't do any kind of battery/ECU resets.. just unbolted the stock exhaust and bolted ours on. We got a 11whp/9wtq gain.

Stranger things have happened. I've seen aftermarket exhausts actually make a car lose hp compared to stock.. not very common and not to say this is the case here... maybe someone could test it again on the same day.

Just my $.02

[hl0m4n]

thanks for input but to reinstall redyno stock, reinstall and redyno exhaust would cost me major. $200 to put on stock, 90 for dyno, 200 to reput and another 90 again for everything same day.

what if i get a dyno early in morning or very late at night. im talking 8 am/9-10pm. humditiy will be low then no? my first stock dyno was done at 9pm and the exhaust was done at 7pm on a different day.

damnit now that i think of it, i shoulda said yea dyno after the install instead of me saying no i want to break in a bit. but it was 11pm by the end of the install and the installers were supposed to leave work at 6pm. so i kept them extra for my install so im like ill do dyno next time even though they offer me if i wanted to dyno right after. i just felt bad and said nah its ok.

PS: are those cats on your rennart exhaust setup?

[Sharewin@Logic]

To the OP check if your vacuum line in plugged up.


Alot of custom exhaust places that dont regularly work on bmw's will just cut the vacuum line off and tuck it under the rear left fender well.

I had this happen to me and didnt know it.

When I dynoed i lost 15 rwhp but gained 10 wtq. Also my car was running lean as hell.


You might wanna give this a shot if it is unplugged just get a screw and plug up the hole.

I spent tons of money and dyno time to figure out what it was.

Good luck

[OC Guy]

Interesting.