less backpressure = hp loss ?

[Atzek333]

hey guys im tim from germany and i have a lill problem,

my car got an lil sc pulley, software for engine and stronic, i got also supersprint test pipes + awe touring ... injen intake

after all i got only 440hp out, i have the same power than a stage 1 s4 ....

my tuner sad it depends because i drive without cat, and the 3.0tfsi need some backpressure .... i should reinstall the oem cats to get the 470-480hp .....

is thet true ? i cant immagine that less backpressure lose horses ?


best regards

[maf9]

I don't know why test pipes don't seem to help this platform, but lot of people around here haven't had any luck with them.

Regarding backpressure: This is an old myth that's been floating around for years - it is rooted in a bit of truth. For the most efficient removal of the exhaust, the gases need to flow smoothly out of the cylinder, into the head, and finally all the way through the exhaust system with the highest velocity. It's a smooth, fast stream of gases. If the pipes used are too big, the stream is disrupted and some turbulence is introduced into the exhaust system. This slows down the stream and ends up reducing the flow - reduce the diameter of the pipe accordingly, and the flow smooths out again. It's this last fact that is the source of the myth - how could a smaller pipe improve exhaust efficiency? The answer most arrive at is that some backpressure due to a smaller pipe must help, when in actuality you are smoothing the flow back out and *reducing* backpressure.

[Edit] more details here: http://www.gomog.com/allmorgan/exhaustbackpressure.html

[cspcrx]

Additionally it is typically less of an issue on force injected, turbo supercharged, motors. My CRX with a 1.6l motor makes a bit less power up top with the cat installed but picks up torque down lower in the rpm range.

[doug97gxe]

test pipes and aftermarket exhausts don't work because Superchargers use belts and pulley's connected to the engine to make power... the exhaust design on the 3.0T is already efficient from the factory

[Woodybangs]

It can and will make an improvement but mostly in the header / cat / downpipe, and it's not a ton of power on this platform. The tuners most likely will need to tune specifically for this in order to take advantage. My E55 woke up after mid length headers deletes the cats on that platform. The tuner had files for stage 2 and stage 2 with headers. The tune was different and specific to that mod.

[cspcrx]

doesn't APR have a test pipe file for that very reason?

[mrmomo313]

doesn't APR have a test pipe file for that very reason?

It only codes out the CEL