S2Kinside

Ok, so obviously I

sabry

[QUOTE=S2Kinside,Jul 12 2006, 06:33 AM] Ok, so obviously I

Wisconsin S2k

No need to worry about the mathematics behind back pressure.

If you have a header, test pipe, and exhaust, you're going to get some very good gains.

afwfjustin

the 70mm singles seem to be all the rage amongst owners. People usually dyno around 20hp over stock with the 70mm and top end header. With tuning, you should see mid 220s or so. Stock, the car makes just below 200 on average.

S2Kinside

What does that mean? You agree on what?


I still don't really get it because I've tried higher flowing piping on my car, eliminating the resinator, etc and It felt like I lost torque. I guess I'll just have to get to a Dyno and see what Im putting down, then play with it some more.

7gk20a

Hmmm, I am getting a custom test pipe done...I hope I don't lose any torque or HP from this. Anyone ever just decat on all stock motor and exhaust?

mxt_77

Can you reference some dyno charts? I haven't seen anyone get 20hp from any IHE combo. (Except maybe some of the tuners that also just happen to sell the parts).

S2Kinside

Id like to know why everyone I talk to tells me messing with the backpressure lowers output power and can throw a CEL because of the OBD2 system. Id like to see some dyno charts too if anyone has any.

Red_Devil

I got my '06 install a Invidia cat-back exhaust & Invidia test-pipe less than a month after I bought the car. I can't tell you how much HP or performance gain by this setup, but I definitely can feel how much POWER I lost after I install all my OEM stock back on my car

I admit that my initial reason was for SOUND (i love '06 oval tip ), because I can't stand some 20K sport coupe or old V8 always rev beside me

mxt_77

Lowering the backpressure won't cause you to throw a CEL, but removing the catalytic converter will. This happens because there is an O2 sensor in the cat for emissions purposes. If you remove the cat and replace it with a straight pipe (test pipe), then the O2 sensor will detect 'bad' readings and throw a code. There are ways to work around that, though.


Lowering backpressure won't necessarily cause a loss/gain of power, either. There are some very big equations that could probably tell you exactly how a change in backpressure will affect your power output, but I wouldn't have the information needed, or the mathematical expertise to build & solve them.
As a general rule of thumb, what I've heard (second-hand) for low-displacement, naturally-aspirated engines is that lowering the back-pressure causes a loss of torque at low-RPMs, and an increase in in torque/power at higher RPMs. YMMV.