Exhaust Question

[Twich_c34]

OK this might be abit silly but i wanted to clear it up.

i have 3" cat back on my s2 stag no mufflers other than a cannon and 3" front pipe to a split dump (2 piece)

the issues is the 2.5" cat is still there does this defeat the purpose... will i see much power or will the cat restrict the shit out of it.

other mods i have are - Turbotech valve @ 10psi

- k&n pod with heat shield

- turbosmart kompact plumb back (stock one was stuffed)

the car still feel sluggish or i that just the auto

thanks

[XRATED]

1. RandR

2. Hot air intake

3. hmmmm..

4 speed auto

2T wagon+2.5lt engine= a little sluggish to start with.

last issue you will have is a 2.5" pipe being a restriction at that power level.... must be droney as buggery.

Cheers

J.

Cheers

Justin

[Twich_c34]

thanks for the reply

how do you eliminate rich and retarded?

Ive heat shielded the pod or is a pod a huge issue with rb25's?

stage 2 shift kit come up soon =)

[GTSBoy]

Yuh....big exhaust doesn't really "unleash" any extra power. Maybe a few kW between std and a complete 3". The biggest benefit will usually be felt with it coming on boost a bit quicker. What a big exhaust is for, is for allowing you to add a bunch of power via other mods, and still get the exhaust gas to go where it's supposed to.

FWIW, there is little point having a 3" exhaust with the stock cat. Get a decent cat in there, even if for no other reason than the original one probably being buggered anyway.

[GTSBoy]

thanks for the reply

how do you eliminate rich and retarded?

Ive heat shielded the pod or is a pod a huge issue with rb25's?

stage 2 shift kit come up soon =)

The std RB25 ECU sucks balls. The only way to avoid R&R is to not wind the boost up very far, or piss the ECU off and replace with something that won't do it (Nistuned Z32 ECU or and aftermarket ECU).

Pod filters just suck hot engine bay air. Heatshields do pretty much noting unless the only air inlet to them is from outside the engine bay.

[Twich_c34]

Would i be hitting r&r @ 10psi tho?? alot of people have told be its fine... if not what would be a stable setting that would see more power.

Looking into a 3" high flow right now!

also ill look for my airbox!

[GTSBoy]

You might hit R&R at 10. It might start with almost no boost increase at all.....depends on lot on what other flow enhancing mods the car has and how precious the ECU is.

R&R is nothing more than excessively rich commanded fuelling in cells at higher than normal loads in the map and very retarded timing values at matching loads in the timing map. At normal loads the mixtures in the R33 ECU are bad enough - easily getting down to 11 or less. As you push deeper into the map the commanded mixtures go horrible. The commanded injector pulsewidth is well over 100% (so they just stay open and spray!). As soon as you raise the boost (or really, the flow) of the engine at all you start working into the R&R region and it just gets worse as you go. There is a reasonably large step into alarmingly bad R&R that does come in at around 10-12 psi on most cars. That's what people call R&R, but it's really just accessing the next row in the map and that row has even more terrible numbers in it.

[iruvyouskyrine]

I appreciate the fact that you always take the time to explain what R&R is GTSboy. I think I have now read about 7-8 different explanations on what it is from you and always tailored to the OP's question.

As someone who was in the same position as some of these people not long ago it really is very helpful.

[GTSBoy]

I have to do something to offset the times when I'm a crabby bastard!

[Ben C34]

S2 stag ecu can be nistuned. so do it.

[XRATED]

Stags will RandR earlier due to the weight...

30+ rwk through the mid range gain with a proper tune on a s2 stag.

I highly rate the shift kit and billet solenoid in my s2.

J.