Im sure you have heard this enought ims, But I was wondering....who has or anyone know of anyone who has GM Stage 2 with GMPP Header and Exhaust....And WHP and WTQ? Possibly dyno??

I am wondering because someone is going to buy my car! YES!!! I can get a new car next weekend...possibly if they find me one,haha. Since I don't really want to upgrade non warrantied parts...but my mother(since I live at home still, we run our business 10 feet away,haha). Anywho...I think the Cobalt SS SC is top dog now....

Thanks

possibly intake also...but with the tune...does it run lean? I know it runs rich with tune alone....but I am hoping with intake and full exhaust it runs just right...

 

I got all that...but i replaced the stock downpipe with a 2.5 inch one with an aftermarket cat. My car dynoed 247 with the stg2 and exhaust, without the cat. the numbers are on my signature... just keep the cat on the downpipe...

 

Only 215tq? ewww...seems low...I would like to see 245whp(which you have more) and at least a good 240wtq....anyone?

How are your A/F ratio?

 

at that dyno run it was way low...9.3:1 with the cat back on...its back to 14.7:1. that should get me some more hp...

 

14.7:1 should get you a blown motor if that is your a/f at wot.

a f.i. car should be in the high 11s for the a/f.

 

seriously think about that, thats stoich.....
we both realize something
My car is a constant 12.3 (+/-.1)

 

What timing are you seeing across your RPM band?

 

11-14* from 5-6k & 24* at 6-7k, I could ramp that up now that my wideband is working.
You should have my tune, if not access to it.

 

I've got 244whp and 216wtq with my mods, no manifold. The manifold is good for 6 whp and 5 wtq I *think*
I've got a link to my dyno sheet in my sig

 

I have all the gm parts(stage 2,toruing exhaust, manifold) and a xtc down pipe 2.5 with high flow cat. Car went 13.7 @ 103 2.2 60ft.

 

Why get a cat in the downpipe? any real reason why not to go catless??

 

any real reason not to have a cat? its only a 5-10 hp(on a really high powered car, so for a 200-300whp car, its probably around 5whp) loss to not have to worry about the huge fine for not having one.

 

I suppose. Im in NJ and never knew anyone who has gotten any fines for having a catless exhaust. But if the cat does make the car sound better then im for it.

 

cuz the cobalt has two sensors on the exhaust...before and after the cat that measure the O2 ratios to control the fuel mixture... No cat, way rich (9.3 on mine) Put the cat on...right on stoich. and you can feel the difference when driving.

this is all with a sensor mounted after the cat...so its readings are biased by that. im going to put in a new bung so i can put it upstream from the cat to get a more accurate reading.

 

The rear O2 sensor has nothing to do with the fuel ratios. It performs functions, not limited to, checking the cat temp and operating the COT setting.

 

This may sound cheesy, but its better for the environment. As others said, its a very small gain, and it will make you exhaust sound worse...

 

Cheesy yes but your still cute! lol yea figured it made the car sound like poop with out a cat.

 

Hey, its a nice gain though with no cat. You can feel the difference. I don't love the sound, but I can throw flames when shifting, so its worth it.

 

any audio clips?

 

Not of my car. There should be others on here with a similar setup though. It does sound better after I ported the exhaust manifold though. Made the note deeper for some reason. Idle sounds like it has cams.

 

Who installed it like that? Your not supposed to take readings after the cat because they will mess with it. The reason why you have two sensors is the first is for the a/f ratio and the second is to make sure you cat is working. You can't relay on the second sensor. Also, on top of that, your a/f shouldn't go from 9.7 to 14.7 from jsut putting in a cat. You should research and learn before spitting out stuff that doesn't make sense or could damage someone else's car. Imagine if someone actually tuned their car for 14.7:1 at wot.

 

you should read more carefully before you start spitting out stuff...i never said i had it tuned that way... its still on the stock stage 2 tune... and the sensor bung was put on before i replaced the cat so i had little to do with either.

 

both of you mixed up what you meant to say...each were right to an extent and wrong at the same time.

 

It happens... Having some one to say 'chill out' is always a help.

to clarify...The original set-up was a downpipe without a cat. the bung was put on with that set-up. the ppl who put it on put it next to the #2 sensor toward the end of the pipe. When i put the cat back on the pipe i had to put it in the original position or it wouldnt trigger the sensor. so right now...the wideband sensor is after the cat. im going to put in another sensor bung to move it upstream from the cat so i get correct readings.

that make things a little clearer?