When I get my new Cobalt SS/SC in a few weeks I plan on getting the GM Stage 2 kit right away. I was also looking at the GM Spec 2.8 pulley.

However, after searching through all the threads it looks like I might have to go to 60 lb. injectors in order to avoid leaning the motor out past 6,500 rpm. I dont want to go to 60 lb injectors.

Is 250-260 fwhp and 225-230 ft-lb tq. attainable with the following mods?

GM Stage 2
Header back exhaust
CAI
HP tune
mounts to get more power to the wheels

 

spooner did 260whp in his redline with

gm stage 1
2.8" pulley
K&N CAI

 

That's not too far out there at all.

Get stage 1 (stage 1 and 2 pcm is the same) and a 2.8" pulley and a CAI, that should put you somehwere near 250 with out the header I would think at least!

 

So the header back exhaust (im looking at the CTI kit) would probably make up for the lack of 2.8 pulley and get me around there?

I hate adding horsepower like this because it's inaccurate but for some reason I can't rationalize going to 60 lb. injectors. I want to keep the motor running good for a long time as this will be my daily driver.

 

lol my 30k a yr driver has 60lbers and a 2.5..tho i just go a jeep so itll go down to 15k a yr while it rests in the winter

 

You'll need a friendly dyno to get 250 whp, but it can be done. Also, mounts don't get power to the wheels, they help get power from the wheels to the ground. They won't affect your dyno readings at all. Good luck!

 

Thanks for the reply but what I'm asking is if I can do it without the 2.8 pully because I don't want to have to re-upgrade the injectors to 60 lb. I am scared of leaning the car out to much in the upper rpm range with a 2.8 and the 42lb injectors

 

Also, wouldn't going to 60 injector's require a new fuel pump???

I dont know the answer.

 

42lb injectors will be fine with a 2.8, if that's your only worry.

 

imho getting 42.5lbers is like banging a midget prostitute...sure u got laid but u could have done a lot better with just a lil more cash

ull have fuel but for anythign else ur gonna need to upgrade again...I had my 42.5lbers for like 3 months before i sold em for 60lbers

also if ur getting hp tuned skip the gm stuff completely...its redundant

if u know someone who wont say a word about having no cat get the weapon r header and the corsa touring exhaust then just diable the codes with hp tuners

60lbers
K&N CAI
Weapon R header
Corsa Touring
2.6 from zzp
tensioner upgrade from intense
custom hp tune should actually put u n the 270-280 range easily

 

I am not questioning anyone's expertise as I am a complete noob to F/I car's.

I could have sworn on the 2.8 pully thread that some people with the stage 2 and 2.8 pulley were maxing out their injectors in between their old and new redline.

I know that stg 1 and 2.8 is safe but I am still unsure about stg 2 and 2.8

 

stage 2 is just a belt and a pulley over stage 1 that is it

injectors and tune are the same

if ur gonna hptune forget the gm tuens all together

 

stg 2 = stg 1 + pulley

they are the same thing

 

Exactly. You would get HP / injectors / 2.8 pulley / smaller belt and/or larger tensioner *instead* of the GM stages. For the power you're aiming for, the former will be the better route.

 

What i was trying to say is that the LSJ may run lean in_between 6,500 and 7,000 rpm with a 2.8 pulley which I thought was what you got with stg 2.

I may just get the stage 2 and forget about the rest now because I don't want to have the warranty voided as soon as I get my car. I wasn't going to worry about the pulley because I know my stealership would not put up a stink about that but they would about out of spec injectors.

I can settle for 230 or so HP I guess

 

here is what you do then.... get stage 2 ($550 if you know where to look) and then get pulleyboys' 2.8" bulley that goys on the stage 2 hub.

that's $650 and will put you around 250ish I would think

 

that'd be the best bet

 

Yes but then won't I be running lean in the upper rpm range??

I dont want to max anything out, and keep everything nice and safe.

 

It will be safe.

I havn;t personnaly heard of any problems with using a 2.8". I know of a lot of people who use a 2.7" and heard maybe 2 complaints. I even know someonw who used a 2.6" and it ran a little lean, but not too scary lean.

You'll be fine with a 2.8" at 7000rpm

 

probably wouldnt hurt to drive it stock for a lil while...

 

I was thinking of going to the 2.8 GM spec pulley myself and was worried about the injectors. I went out and found the calculations for how much the injectors will handle, and the 42.5 pound injectors should be capable of handling a 2.8 without trouble. The HP range for the 42.5 pound injectors is about 260 HP Crank. GM stage 2 w/2.8, exhaust and intake should put you about 255 - 260 HP @ Crank which would be safe. If you do any other mods you are going to have to go with the 60s though.

 

I would like to thank everyone for their imput. It has been extremely helpful.

rnjmur....that's what i was worried about. I plan on doing a lot of other supporting mods besides that. Maybe I am too used to modding my camaro, where you can pretty much bolt on anything and not worry too much. Like I said I am very new to F/I.

I would be happy with 260 crank HP. I think that i can get there though with stage 2, bolt ons, and a very good tune. I was asking if 260 hp to the wheels was possible which I have now concluded will be imposible for what I am willing to do to a car that is going to have to last me 4-5 years.

Does anyone on .net have stage 2, header back exhaust and intake dyno for me to look at. I am interested in seeing the numbers. I think 230-235 on a dyno would be about right to make 260 crank hp right?

 

Bro 250whp is easy with those mods.
I have GM Stage 2 and a CAI and I made 242whp. Click on DYNO in my sig.
So with that, full exhaust and a tune, 250whp is easy.
It should put you near 260whp.
A tune and exhaust is worth at least 15hp. So 245+15=260!!

 

Well that's great to hear

I see you posting a lot in the same threads that I read for info. How does your car run?? Do you like the .40 gap that you have your plugs at? I was going to go to .037 but I think now that I will back off a little to .40.

ALso excuse the noobness, like I said Im going from LS1 to LSJ, still have lots of learning to do

 

Hey no problem bro. We all start somewhere. The car runs outstanding. Pulls hard. I don't beat on it I just use the WOT when needed.
I have tested .35, .37, .40 and .45 for gaps. It took like 2 hours but I did it.
The .40 gap seemed to be the smoothest under heavy boost. No hesitation.
Hope that helps and Happy Moding!