Today I got my Pulley Technology 3,0" pulley installed on my 2005 Victory Red Cobalt SS / SC ... (We measured it and it measures 2,95" instead of the stock 3,35").

Here is the data we measured: HP, torque, air / fuel ratio, timing and boost. Remember it's was a Mustang dyno ! All test are in 4th gear. Each pull reached the cut-off (6500 RPM on the tachometer; 6300 RPM on the dyno !). Air temp was 65 farenheit degrees; pretty good.

At this very moment, I am only able to post these quick results. All my dyno graphs (HP, torque, air / fuel) will be posted next monday, since I haven't any scanner at my house but at work.

Bone stock : 191 WHP, 170 ft-lb torque, air / fuel ratio varies slightly from 10.9 to 11.4 between 3500 and 6300 RPM.

Magnaflow 2,5" exhaust + 2,25" rear section replaced to 2,5": 200 WHP, 174 ft-lb torque, air / fuel ratio varies slightly from 10.5 to 10.9 between 3500 and 6300 RPM.

Magnaflow + 3" pulley : 215 WHP, 187 ft-lb torque, air / fuel ratio varies slightly from 11.3 to 11.5 between 3500 and 5200, then is rising in straigth line from 11.3 to max at 12.8 at 6300 RPM.

Magnaflow + 3" pulley + one range colder BKR7E plug: 213 WHP, 185 ft-lb torque, air / fuel ratio varies slightly from 11.1 to 11.3 between 3500 and 5200, then is rising in straigth line from 11.1 to max at 12.45 at 6300 RPM. The goal of the colder plugs was to get the air / fuel ratio richer a little bit, and it worked for a 0.2 to 0.35 air / fuel ratio rise.

(One comment: I think the stock injectors are giving their max flow at 5200 RPM.)

About the timing, we recorded 0 knock, but last 100 to 150 RPM before redline were between 0.5 and 1.5 degrees of knock.

General comments: The very first dyno run after the 3" pully has been installed, the following thing happened: The max boost achieved 14 PSI near 5500 RPM, then drop at 10 PSI the reach 12 PSI for the last RPM's. As we all know, it has been caused by the signal the PCM give to the selenoid that control the max boost.

So I had to disconnect the vaccuum hose between the selenoid and the by-pass valve actuator. This way the maximum boost has been reached.

My bone stock max boost have always been 12 PSI on the stock gauge, and with the 3" pulley we recorded a max of 15,2 PSI on a mechanical gauge and 14,5 PSI on the stock gauge. At this very moment, my vaccuum hose is unpluged from the actuator, and the hose's tip is plugged with a screw. I installed a little filter on the "now opened to air" by-pass valve actuator's nipple.

To conclude, I gain roughly 25 WHP and 17 ft-lb torque from the 2,5" catback and the 3" pully. (The 3" pully itself gives roughly 15 WHP and 13 to 15 ft-lbs torque.)

Remember that a Mustang dyno is usually 10-12 % lower than a Dynojet. Making the calculation (3" pulley and catback) gives 238 WHP and 207 ft-lbs torque. Plus the 16% drivetrain lost, it gives roughly 275 BHP (at the motor).

Last week (on another post) I said that we tested a K&N conical replacement filter (and got the lower cover of the airbox removed). I repeat that on 2 different Cobalt SS / SC, we Mustang DYNOed a LOSS of 8 to 10 HP. My point of view is that the MAF is too close of the air filter, so the increase of flow and turbulency cause the PCM to compensate and getting the air / fuel ratio richer (0.5) than stock.

I am very proud of the result, the boost is achieved sooner also; it gives 13 PSI at 5000 RPM and 15 PSI near redline !

Have a nice weekend and have good kills !

 

I am not sure I agree with you about the injectors giving out. How did you determine this?

 

Awesome results!! Let us all know of any problems as you drive it more. So on the 2 SS/SC's you've tested with the airbox mod you recorded an 8-10hp LOSS?? I'm not sure if I understand why it would do that. I thought the whole point of using a cone filter was to get more air into the engine to make a couple extra ponies. I never thought it would work opposite

 

Zinner, since we didn't saw any timing degrees being pulled on the last RPM's, I asume that the air / fuel ratio is rising quicky from the time that the injectors are maxed out.

I think that's the reason why the GM's stages will probably included injectors. That's my point of view.

Zinner what is your own point of view ?

CobaltSS422 I know that usually, giving more air will produce a leaner air / fuel ratio, but the Cobalt SS PCM is unusual, it tends to richen when it see some mods. Maybe PSI-FI or Revitup could give you their opinion about that, they made a lot of tuning on the SS and Ion Redlines.

 

With the stock pulley, I think that the injectors are able to feed the air volume pushed by the 3,35" pulley, but are near to the maximum load.

With the 3" pulley, the 10% increase of air volume and 25% increase of boost is high enough to get the stock injectors maxed at 5200 RPM.

On another (SS.COM) forum, another guy says with the 3" pulley that "... my injectors are wide open by 5500 rpms which is around when I hit 15 psi."

 

I guess that I am not quite sure how things work enough to make any authoritative statement but I think with a 3 inch pulley you are not putting in more air than the stock injectors can handle. Maybe it's possible they are running at their max capacity, but I don't think the fact your running a bit leaner with a 3.0 inch pulley is enough data to say that. It possible that your running leaner because the ECU maps say inject X fuel at WOT and thats what it is doing. Not that it's can't inject more fuel. Also I don't think timing has anything to do with injector capacity. Timing is pulled because of knock or a based on the timing maps, so maybe at the higher RPM's it pulls timing because that what the map says.

I think if GM releases new injectors with the stage upgrades that it's possible they are doing that to allow for more power to be made and not specifically because they have to have that option. I think maybe it's more of a safety thing?

ALL PURE SPECULATION....

 

I acutally have seen close to 90% on my injector duty cycle with the DTEC at WOT with a 3.25 pulley.

Again that was at WOT when the ECU goes into open loop, dump fuel at the engine mode.

 

The 3" pulley (which measures 2,95") is 10 % smaller than the 3,25" pulley, so the blower spins 10 % RPM faster at all RPM's. And it produces roughly 15 % more boost than the 3,25", so I think the injectors are probably very close to their max capacity, since yours are already at 90 % at WOT.

 

Find someone with a scanner and log IPW and that will tell you whether youre maxing out or not. Itll give a number and (for GPs at least) when it hits ~20 pulse width, youve pretty much maxed them out. However, different types of injectors max out at different values. What type of injectors do you guys have anyways?

 

Injectors are at 90% because the PCM is in open loop and just providing fuel according to a fuel maps. in most of our cars it's pretty darn rich. So you put on a smaller pulley and you are still 12.8: 1 AFR at 6300 RPM. Injectors still aren't max'd out if your still running rich right ?

Some ppl have reported (DarricksZ28 I think) being able to do a 50 dry shot of nitrous and still not run lean at WOT. I think more was going lean. And we really don't know if the injectors where max'd out of if the PCM just wasn't going to let them provide any more fuel.

 

20.96MS is the highest I have seen and the AFR was 11:1 at that point in time.

all according to my scan tool at WOT.

 

Why exactally are the mustang dynos off?

 

I was gonna type it out, but it's too long and I gotta go now. So just read this. Mustang dynos aren't "off", in fact they're really more accurate than a Dynojet. Arguably Dynojets are more the "standard" though. But if you ever wanna get your car tuned, make sure you do it on a loading dyno like a Mustang.

http://www.germanmotorcars.com/Dyno_...0inertia_1.htm

 

Not sure if this as been said but do you void your warranty by putting a 3 inch pulley, don't want to ask that question to my dealer, don't want them to suspect nothing.

 

If you do any modification to your car that cause it to fail and break something then you are responsible for fixing it out of your own pocket. If you put on a pulley and your windows motor breaks, the windows motor is still covered under warrenty.

 

correct

And the fact that this engine is built very solid and is holding up well on the sport touring circuit is a sign your good to go.


Awesome post

 

You want your a/f around 11.5-11.7. Cant be 100% certen with out logging IPW's if they are maxing out. Might just need an adjustment. The Knock came from two reasons. One becuase you went lean and also because of poor air cir. on the dyno. On the street you might not have seen any knock becuase of the better air cir. threw the front core.
Nice numbers though. Keep it up.

 

you guys are richer than richie rich , compaired to my cav with the gm s/c

im seeing mid 13's on my wideband

im currently looking for bigger injectors to try to richen it up some


nice #'s

 

I did scan my dyno sheets today and all the 6 sheets are included in one single PDF file. Since the file is 500 Ko, I was not able to upload it. People who wants to see my dyno sheets, just e-mail me. The answer time can be up to one day. It's the better I can do at this moment. Have a nice day !

 

http://stuff.urbanghetto.net/Jmc007_Dyno_Runs.pdf

Thanks to nka from the Ion Redline forums for the hosting !

 

Nice runs and great #s!

BUT ... watch your AF really carefully man. Shooting up like that at the end, you're getting pretty close to the danger zone at 12.8. The way it's going up almost linearly like that at the end seems to indicate something in the ECM is pegged ... "normal" operation should actually show your AF dropping at high RPM when the ECM goes into converter protection. You seem to be okay now, but I wouldn't try any more pulley than that without some other mods, or you risk killing your cat, or worse, a piston.

 

WOW thats a beast of a cobalt ya got there.. that sucker should be pealin the pavement apart... lol

 

stock plugs are better than for the 3.00 pulley

 

I got my stock plug re-installed ...

 

No CEL yet with the 3,0" pully. Running it for 3 weeks now and roughly 500 miles of hard and moderate driving ...