[luckyguyinla]

Underneath of the 335i, you can see how factory setup right?
Factory have 2.25 in pipping from the down pip.
335i have 4 cats for their exhaust system.
2 pre-cat with o2 sensor.
2 after burner cat without senor
1 x style Resonator?
2 dual muffer


For BMW to sale in United Stated on the 335icar . they need to get epa and other agency (Clean air act) to proved for mass production right? that is why they have 4 cat and resonator to ren pass it.

Turbo 101:

Turbo does not need back pressure. Majority of the Hot Rod. You can see huge exhaust pipping to let the mass flow to come out of the exhaust. Turbo work on air induction. n come out thru the muffer.

Problem:
if u have twin turbo, you need large piping n less restrict on the flow right? because u need to get the flow out as fast you can right?
They way BMW Setup(engeirring ) for the exhaust system have too much restriction. If you have too much restriction on the exhaust system, flow cant get out to the muffer asap right? It will cause Flow to backup a little during High accerl or hard stoping or amienbian temp. ( spell check plz) lol. When you have back up flow, it will get hot and much hotter. Therefore, on the OIL TEMP GUAGE Indicator show you get about 225 to 275 degree right? too high temp people complain or concern to the dealer about it. BWM Dealer said it is normal. am i right? That is why people have an issue with the OIL COOLER. The oil Cooler over working to cool down the over heating engine to prevent pre mature manufunction.

Solution.
If you remove 2 after burner cat, Resonator, and increase the piping size from the pre-cat to the dual muffer. You just ease the flow and less restriction on the flow.. I suggest to do 3 inch pipping for max preformance. You can also setup 2.5 inch pipping.

Result:
10-20 Degree Less . what do i mean by that?
Each of the Line on the OIL Gauge INdicator is about 10 degree.
PRevent premature engine failure.

Class is over. YOu may dismiss. lol jk

[ironic]

thanks very well written

[Chesmu]

you reposted yourself
http://www.e90post.com/forums/showthread.php?t=54503

[M4TW]

So what your saying is that replacing the factory exhaust downpipe with a larger one may help the engine run cooler?

Or am I missing something?

[luckyguyinla]

Originally Posted by Sparkplug

So what your saying is that replacing the factory exhaust downpipe with a larger one may help the engine run cooler?

Or am I missing something?

I suggest replace with bigger pipping after the downpiping and aftermarket exhaust. You need to keep the pre cat with o2 sensor on to prevent the engine warning light turn on.

THIS IS JUST A THEORY

i have 335i e90 sedan. T

[E90Fleet]

Or maybe just stop worring when the engine is running within its designed temp range

[dxb335d]

we dont seem to have a problem over here in the uk, maybe we are not so strict on the emissions and our engine is not strangled like yours?