Jmc007

FYI guys, I run the 2,6" pulley since yesterday. I did measure the crank pulley (the most precise way I could, since it's a pain in the ass to have an access to it) and it measure at the most 6 inches or a bit less. Doing some calculation, it means that the supercharger's RPM is higher than 14 000 RPM's ONLY when the motor spins MORE than 6 000 RPM's.

Also, FYI, the 2,6" pulley max PSI is 19,5 PSI.

Since I'm in the winter here, my supercharger post temperature stays very low, even lower when I run it hard (opened throttle body let the cold air enters the blower and cool it).

The cars runs more like a beast now, making more HP even if it's a way richer with the 42 lb/hr injectors thant with the stock injectors and 3" pulley. But I think the 05 PCM seems harder to tune than the 06 to achieve a flat 12:1 air fuel ratio curve.

I don't have all the dyno sheets with me at this very moment, but roughly I achieved 22% more maximum WHP and 22% more maximum WTQ than stock. That is untuned for now.

At 5900 RPM's, it makes 43 WHP and 39 WTQ more than stock, but the air fuel ratio there is around 11, so it miss some power there.

Between 3 000 and 6 000 RPM's, the air fuel ratio is way lower than 11.5, even at 10 for some points. Yes that's a lot of ponies on the table.

I will run like that for a couple of weeks, then will surely be back on the dyno for a couple of runs.

I notice that the PCM doesn't like when I owered the MAF signal more than 7%, instead of lowering the injector pulse width, I think the PCM "see it" and throw even a lot more gas. So I'm kinda stucked with a too rich air fuel mixture curve for now.

Also, I will have to check the pulse width at the higher RPM's.

Also, we logged the fuel pressure to stay at a steady 60 PSI at all RPM's.

I take a brief time to wish to all of you a happy holiday !

Be careful on the roads too.

Sincerly, Jean-Marc.

Drewfu$

Wow, I bet that thing is a beast. So did you get a good dyno run yet? Looks like you've got headers and intake over Rob, who put down 270whp. You could be the first to break the 300whp mark. Good luck!!

And get some videos of the dyno runs!

Chevypowered

Nice to here the crank is smaller, now i can think a bout a 2.7" pulley!! i think those can fit over the stock snout, just need to find someone who makes it. Thanks for the update!!

Tofu

Great info Jmc, could you fill us in on the machining process for the snout when running a pulley that small?

selfinfliction

that's cool if the pulley is 6" or a smidgen above it, but if it's 7" be careful because that will put you at 13,996~rpm at 5200rpm and 17,499~rpm at 6500rpm

ExHondaMan

So you are using the Mini AFC w/ 42lb injectors ?
Throwing any codes ? If so what are they ?

bdwarr6

I plan on putting very close to 300whp on tuesday I cant wait,

1MEANSS

hey you getting any knock retard at all??? im only hitting 15.9psi on the aeroforce.and the most kr i have had was 5.9 at 6k rpm....

Blue04RedLine

Billetflow will have the 2.7" pully available shortly I beleive (should be a week or so maybe?) and Intense Racing (where JMC got his pully from) I believe has the 2.7" available.

Jmc007

There is at least two way to get the snout machined.

First one is to remove the snout from the supercharger, then get the snout machine on a machine tool. Or another way is to get the blower removed from the car, then put some duct tape on all the blower's opening, then get the snout grinded with a kind of air tool (Dremel). That is the way we did. It took around one hour to get it grinded properly. Aftre that we get it polished. At my opinion, the 2.6" pulley is the smallest we can go to be sure the snout has still enough material around the seal and bearings.

Jmc007

For sure I got some dyno runs ! As I said, it have roughly 22% more maximum WHP and maximum WTQ compared to the stock runs. Did notice also that the largest percentage increase is at 5 900 RPM's, 24% more WHP and 25% more WTQ.

About the fact that a lot of people wants to put 300WHP to the ground, it will always depends on the dyno used. Remember you have to be very careful about the dyno numbers ...

As I can remember, we've seen stock Cobalt SS/SC or Ion Redline's get dynoed as low as 185 WHP for the lowest and as high as 240 WHP for the highest (on different dynos for sure).

A common error (as a pure example) is to think that a stock SS that has been dynoed at 240 WHP is a beast compared to the other SS that has been dynoed at 185 WHP. Does it means the 185 WHP stock SS will trap for say at 10 to 12 MPH lower on the quarter mile than the 240 WHP stock SS ? For sure NO !

Guess what, you can get both car lined on a track, and they will pass the quarter mile mark in the same time ... asuming that both drivers have the same skills.

That's why we saw some barely bone stock SS/SC told us that they made nearly 240 WHP on a dyno, but told us that their quarter miles results are still in the mid 14's on the track.

Another thing (please guys correct me if I'm wrong) is that I think most of us are looking for the best acceleration possible. But the acceleration depends mainly on the Torque (not HP) versus the weight of the car. So we all want to get the more possible torque, and to get it the sooner possible on the powerband ...

Jmc007

No it is not bigger than 6" ...

Jmc007

Yes at this moment I use the Mini AFC 2.2 with Delphi / Lucas 42 lb/hr injectors. I have to say the idle is VERY good, the car runs even a bit smoother than before, no codes yet !

But I still have to get my air fuel ratio curve fine tuned ... so I doubt I will be able to get it tuned as flat as I want with this Mini AFC 2.2, since the injector pulse width is also influenced by the MAP sensor.

I will run like this for a couple of weeks and will keep to post if there is any changes ...

Jmc007

No knock retard for at least 90 % of the powerband, then between 2.8 and 4 degrees only when higher than 6 000 RPM's.

You have to remember it can depends on the engine operating temperature too.

selfinfliction

well damn that's pretty good then cause it breaks 14,000 rpm @ 6067rpm... the bad thing is how much further can it go cause that extra 500 rpm push it to 15000 dead even

a 2.7 will put it at 14000 @ 6300 rpm and 14444 @ 6500 rpm

a 2.75 will put it at 14000 @ 6417 rpm and 14181 @ 6500 rpm

a 2.8 would be the safest for those who don't want to push it past the 14,000 limit (if that is the actual redline) cause it will put them at 13928 rpm @6500rpm

this is all based from a 6" exact crank pulley.. but even a 1/2" difference can throw those numbers off by more than 1500 rpm

Jmc007

FYI, I got the crank pulley measured with an outside diameter caliper, but with the belt in place for sure. Even with the thickness of the belt included for one side of the caliper, it doesn't seem to measure more than 6". Only when someone will get it unscrewed from his location and precisly measured, it's still speculation. But I'm 95% sure it is not past way 6,0" for the effective diameter.

FAST06SS

Now to throw a wrench into all of this! When we get some tuning software and raise the rev limiter to where it should be, 8K rpm, all this pulley math will have to be adjusted!

Drewfu$

Wow, that will limit you guys to like a 3.2" pulley to stay below the 14000rpm limit for the blower. Looks like we'll be finding out if they can handle more rpms than that! Because most people won't want to sacrifice the torque down low for that high rpm power.

selfinfliction

you go ahead and turn the rpm's up to 8000 and tell us how it works out for you... that's turbo land there

but anyways the calculations are easy:

crank pulley size x pi = A
blower pulley size x pi = B

A divided by B = C

C x engine rpm = blower pulley rpm

Jmc007

Again, the 14 000 RPM limit of the M62 blower have been established the SAFE maximum CONTINUOUS rpm by Eaton. There shouldn't be any problem to run a part time over, unless you watch carefully the temp of the blower.

Jmc007

My thoughts is roughly 255-260 WHP (Dynojet 4th gear) with the stock header and catback.

Jmc007

For those who wants to know, I'm running up to 21,6 PSI of boost with the 2,6" pulley, logged with the Aeroforce Interceptor gauge.

BUT there is a GOOD amount of knock.

More to come soon, I would just say do not plan to go smaller than 2,8" for now.

)

Chevypowered

I was considering a 2.7" pulley if i feel the S/C isn't spinning too fast. I'm going to measure the crank pulley today and make my decision. I'll be soo close to the stock 12.5 PSI

BLKSS

Wow! Thats all I have to say. Almost 20lb of boost is crazy. Me and my friends are N/A freaks and im the only one with a SC. My plan was to stick with the GM kit coming out soon just because I dont want to be liable for the damage I can cause and I want to make sure the job is done right. Then again the gains that GM will have will not be close to you guys at all mainly because of pulley size. Is it still worth sticking to GM on this mod? Or should I go for more power and go with a diff kit? Is there something I should know about GM that I don't already know?

bdwarr6

How do you figure, ive got more mods than rob and he put down 270?