2005blueSSColbalt

cobalt comes with 12psi stock what ive been told

NORCALSTI

well talked to the pulley place here is their e mail

"Tony, stock is 3.4" and we offer 3.25" = 1.5lb boost increase, 3.10", 3 lb. boost increase, 3.00" , 4 lb. increase over stock. You will have to change the stock belt, to 1/2" smaller, with any of these sizes. 1 lb. boost is 10 horsepower on these cars. Hope this helps, as also regapping the sparkplugs down .005 setting from stock would be beneficial for optimal performance."

so looks like 3 inch pulley most you can go

2005blueSSColbalt

so 3 inch pulley = 4 more lbs =40 mot hp right? and it will work with the car no problem?

NORCALSTI

yes 4 lbs willbe about 40 hp. id say 30 hp to play it safe

wesmanw02

That sounds really good. There seems to still be a few people saying how "it won't work and it will screw everything up and there will be no power increase", but that sounds like BS to me. The people who actually know what they are talking about, those people being GM and the aftermarket parts maufacturers, seem confident that a smaller pulley will provide a nice power boost over stock.

The numbers quoted so far are look very promising, 30-40HP from a pulley change is very impressive. The stock intercooler should keep the charge temps in check, so we shouldn't really have to worry about that being a issue.

If for each PSI of boost increase the LSJ gains about 10 HP, then with a 3" pulley we should be seeing gains of about 30-40HP. Seeing as Redlines have been dynoing at 200-210 WHP, that should be good for as much as 240HP at the wheels

zstyle

Add that to the dyno results on scdyne.com, who developed a header for the redline that produces another 20hp and ~20 lb/ft of torque on what I believe is an otherwise stock engine.

I like the aftermarket development already, seems that we shouldn't have to dish out that much cash to see some serious gains from modding this engine.

NORCALSTI

stock cobalt with header, full exhaust and pully change and 75 shot i think will be close to 330 at motor

205 stock
pully change 30 hp 235
header change 20 hp 255
exhaust cat back 10 hp 265
cold air intake 8 hp 273
nx 50 shot 320 hp let say
ecm lets say 10 hp

on slicks that should be 12s easy.

Archplsm

You have to keep in mind that adding one part after another does not always give you additional hp. Through the history of the Cav we all saw minor increases with the header, cat back, and the CAI. In other words, CAI at 8 hp, header at 20 hp, and cat back at 10 hp will not equal 38 hp, it will be closer to 22-24 hp at best.

Vita

that is nothing more than ricer math, you have to figure that each part plays on the other, so an intake will make the header make more power, or vise versa, but you can't add up what each does on a stock engine. although a car with a full exhaust will likely see more power from just the pulley swap than a stock motor.

i'm still convinced that doing a pulley swap isn't a good idea until you've done full I/H/E, not to mention that cooling and fuel issues will need to be addressed. also, you have to consider that the PCM is setup to allow a certain amount of boost. freeing up the exhaust track will lower boost, so it's likely that after I/H/E we could safely swap pullies, as long as fuel can be compensated

redd214

u guys keep saying that u will get a 30-40 hp gain from 4 psi. im not so sure about that.LSJ's are dynoing llike 210whp, standard ecos dyno at about 130whp. so thats a 80 hp gain from 12 psi. i doubt 4 psi will give 30-40 UNLESS there is proper tuning software to back it up.

zstyle

Obviously the stock Eco is a 2.2L as opposed to the 2.0L displacement of the LSJ. You also have to consider that the LSJ was designed from the get-go as an F/I application, and thus has different compression ratios, cams, timing, fueling etc. then the stock Eco, so you can't really compare the 12PSI to an 80hp gain.

Either way, I agree that you will need an ECU reflash in order to get the most out of the extra boost provided by a pulley swap.

redd214

i understnad what u r saying. it was kind of a crude comparison but u see what i was getting at. his engine definatley has potential but some of the power gain estimates ive seen are kinda of the wall (not specifiacally talking about u guys^^^). im planning on swapping an lsj into my 03 cav so im just as excited about the aftermarket as u guys are

03gobluecobra

I have an 03 cobra, with an Eaton M112, with a pulley change. There are only two reasons why I think a pulley change might not work on the cobalt. The first is this boost bypass, which stops the car from getting over 12psi, if I understand that correctly. If I'm wrong, or it can be removed, that should be nothing to worry about. The second is the maximum efficiency of the blower. On my 03 cobra, it comes with 8psi, and around 15 psi, the blower stops making more power. After 15psi, it will only increase the torque when you add boost, not hp. So as long as the cobalt s/c isn't at its maximum efficiency at 12psi, you will make more power by putting on a smaller pulley.

Putting on a pulley will hurt your car, if you do not get it tuned. On a cobra that is a surefire way to blow up your engine. If you do get it tuned, its completely safe. You will make more heat, but as long as your tuned, it will make more power/torque.

Vita

i wouldn't mind more torque, we'll have plenty of power to be tapped for a FWD car with a smaller pulley, freeing up the exhaust and intake, and solutions are already being worked on for fuel/timing

MikeSS

In my car club here in Toronto there are ton's of guys with GTP's. Almost all of them have put on smaller pulley's and noticed significant gains at the 1/4 mile track. We have GTP's well into the 12's now (with other mods as well).

HP or Torque, the pulley will increase performance. People with after market S/C that put on smaller pulley's sometimes don't see significant gains in performance because there blower is already maxed out. The Cobalt SS blower is not maxed out....nothing GM does is ever maxed out. Hell, they are even cutting the rev's early in the car even though the engine is still making power.

I talked to the GM guy at the Detroit autoshow and he said.

So although this post may not contain the right pulley, a pulley will work and heat will not be an issue. Once I find a specifically designed pulley for our cars I will buy it and install it along with a catback and CAI at the same time.

zstyle

Sweet. I hope that is the case, the Laminova intercooler certainly has a strong rep. I'd imagine if these "staged performance uprgrades" from GM we've been hearing about ever come out a smaller pulley will be one of the main mods.

CoolCobalt_NY

Just wondering??

zinner

Cold Air Intake.

zinner

If you get the engine to flow more air you won't need more boast. More pressure (boost) doesn't necessarily mean your getting more air into the combustion chamber.

Vita

i'm failing to see the point of your post

Dman

unless i'm incredibly mistaken, a supercharger compresses the air entering the engine, ALLOWING THE ENGINE TO DRAW MORE AIR INTO THE CYLINDER. this allows more fuel to be added creating a bigger bang in the cylinder.

ive always felt that its better to get the most out of what boost you are using. i also agree with vita that it really is a bad idea to try to increase boost right off the bat. its best to open the system up more and then increase boost. with the system flowing the exhaust out better, you will see higher net gains with a boost increase because the system is not bottle-necking and the engine is operating more efficiently. only bad thing about this on the cobalt, is that we arent really able to do this at this time. which is why i cant wait till someone releases a fully tuneable ECU like Hondata's K-pro...so yeah, whoever is reading this, GET ON IT!!

Reefer

what exactly is all involved in tuning the car?

Dman

air fuel mixture ratio (making sure the car isn't running to lean)
ignition timing (although most cars today have this pretty much covered)
making sure the engine isnt knocking (detination)

the smoother the HP curve, and the flatter the torque curve, the better...

zinner

I am agreeing with you that doing the intake/header/exhaust upgrades would be the best place to start with increaing power. Since if the engine has a better ability to breath it will better utilize more boost from any pulley/blower upgrades you do later.

CoolCobalt_NY

Thanks for clearing that up..!! duh I should of figured that out.. I guess I haven't been thinking!