Soo my question is this... I know the SS/SC have a fairly restrictive exhaust. I know that exhaust mods definitely help out when increasing power with this car. I also know that running more boost / adding more performance increases the temps in the engine. Soo my question is, is it safe to run 2.8" pulley with 60lb injectors on a STOCK exhaust setup. If it is unsafe, why? My mods are in my sig, and I am running everything now with the stock system. I eventually will get an exhaust, I just haven't found one yet that doesn't sound ricey that I like, and want to afford. Also is it possible to just use an aftermarket header with the stock downpipe and catback? Because I have heard that the exhaust manifold is the part that is extremely restrictive on our cars. Thanks for the info...

 

you'll be fine.

 

not really what id call "unsafe"
but your certainly going to be holding back your power level.

 

Thanks, I was unsure about this... I was trying to call bullshit on people / vendors saying this was "unsafe" and I just needed a second opinion. Thanks!

 

I am in the same boat as you, from what i understand from reading other threads, we just wont get all the benefits of dropping the pulley size and tuning than the individuals with less restrictive exhaust. Shitty exhaust=less power...

 

only problem with it is, ur more likely to clog your cat and clogged cats can give major problems. Other than that i wouldnt worry.

 

i wouldnt worry about it but you should be looking at headerback exhaust with those mods, let that sucker breath!

 

I love my stock exhaust on my 2.9 pulley. I actually feel more firm power than when i had the full 3"

 

Not unsafe, but a massive restriction on power. You'll be hitting some crazy high boost with that setup, high temps, and not making as much power as someone else with 2.8"/60# and a proper exhaust.

Oh, though it is not "Unsafe" per say, if you run it really hard for extended periods of time, you'll have higher heat levels which makes you more subseptable to heat related damage.

That's because a 3" was way to big for you. 2.5" would have been better. The stock is choking your high end and the 3" was dropping your low through mid end.

You have to size your exhaust based on your power level. Normally, you take the exhaust flow required to support the hp range your engine produces in the rpm range you will be using mostly and get an exhaust that will support 80~90% of that flow at the catback level. Your header and downpipe should be able to support close to your required flow for that range. The reason you need less flow at the catback is because as the exhaust gases cool, they will compress and take less space. There for, you require a tighter pipe at the end of your exhaust to keep the gases flowing at a high speed.

There are always trade offs, since your exhaust will be a greater restriction the further you are from the peak hp point it is tuned for. There are things that help reduce the power loss away from your peak point, such as coating your exhaust to reduce heat loss, an active exhaust, etc.

 

Thanks everyone for the information! As far as what I can gather, the best thing appears to be going with a header and downpipe combo? I really haven't found a catback system that I think sounds good (I hate ricey!) soo I would like to keep the stock catback exhaust for the time being. Does anyone think it would be worth it to do a header and dp now to open the exhaust up some? I am also having some hesitation and stumbling problems now, and the car is running rich according to my sparkplugs... Do you think that a head and dp will lean out the car a little and help with the restrictions and the hesitations? Also anyone think that is would be OK to go with the ZZP header and dp combo in the plain steel? Or is it truly worth the ridiculous amount of extra money to go to stainless? I am primarily just interested in making the car run good, as right now my INTENSE tune isn't working to great. Thanks!

 

lol...see like i said...heat damage.....and he was right....your s2 is performing better with a stock exhaust because your not hittin enough boost to actually warrant a 3" exhaust....a 2.5 is what you should run for anything under 20psi boost...20 psi boost or up should generally have a 3" exhaust

 

Soo, what's the vote? Go with a header and dp combo first? Or go with a catback first? Which would provide a larger performance benefit for my mods? Thanks!

 

always start from the motor and work your way back on exhaust

just my .02

 

well im gonna be running the vibrant 3 inch exhaust as of thursday. I thought once you get over 16 psi 3 inch would reap more benefits. to each his own i guess.

 

It has nothing to do with the PSI! ARG! You have a positive displacement supercharger, therefore your psi of boost is [SC CFM output / Engine Flow]. Anything you do that increases your engine flow (Head work, exhaust, cams, etc) will cause your boost level to drop. And that is a good thing too, since it will get you closer to the 10~12psi that the M62 likes the most.

Don't pick your exhaust on the psi your running, pick it on the crank HP you make. If you got dyno'ed, divide the whp by .85~.88 to get a rough idea of your crank HP. Multiply that by 2.2 to get the rough CFM you need for your engine. Your header should flow that much and your catback 80~90% of that much.

If you do the math, a 2.5" is good for about 250chp and a 3" is good for about 330chp. Considering that you only need 80~90% of the peak flow through your catback, a 2.5" catback is good for 275~310chp *Edit: Changed whp to chp*. A 3" catback would be good for 365~410chp, which is by far too much for most of us, unless your putting down over 300 on the dyno.

 

thanks for the math...the psi info was cleared up to be and used as a ref point an i recieved the info from a reliable source *New Era Performance* its more like a rule of thumb...but i'll def keep that hp in mind

 

well i guess im screwed then. at least until i get my 2.7 in

 

i have a 2.6 but i needa get 60's now b4 i can install it...my 42's are less than 3 weeks old and i want more power already!..lol

 

haj ust had my 60's and 2.8 put on and tuned sunday and now i want to go big i want more power!!!!

 

kinda makes me wanna get rid of the balt cuz ikno i'm not far from maximizing its power potential b4 spending like 3k$ to get more outta it