Ok, long story short, I have a D1SC with an 8-rib setup on a 383, AFR heads, etc. With the 4.25 pulley, according to the EBL datalog, I'm making 4 psi with a TR1045 Treadstone intercooler. I would like to get it up to 8-10. What pulley would y'all try next? 4.00 or 3.85? I have a friend with a 3.7 but I think that's too small. I don't want to go over 10 psi with my compression being a bit less than ideal for boost. Also, how much shorter of a belt will I need? I saw on the vette forums that with a 4.25" to 4.00"..they were saying about .5" shorter but I don't know that for a fact.

Thanks!

PICS!

<---has a Procharger D1 too

Bump...anyone know which pulley would net me the above boost level from the 4.25"?

When I contacted procharger and told them I wanted 10-12 pounds of boost, they sent me the 3.70 pulley. I have a 383 with afr's as well. So either of the two that you listed should get you close.

I'm currently running a 3.7 pulley and pulling 16 to 17 pounds @ 6900 to 7000 rpms. I believe i had a 4.0 pulley and ran 10 to 11 pounds we I first started. You will need a different belt but I can't offer much help as I have installed a spring belt tensioner on my to prevent belt at higher boost levels.

That's good info. What boost were you running around 6300-6500 as that'll be my shift point. 500 rpms less than you...would probably be 9-10 psi on the 4.00"? What heads are you running? Are you running an intercooler as well?

I've read and was told that .2-.3 in diameter should net about 3 lb of boost gain. So, if I'm running 4 psi currently then a 4.00 would net about 7 lbs of boost and a 3.85 should make about 8.5-9??

Its been so long ago I dont remember exactly. I've got a set a of Dart Pro 1 aluminium heads (72CC). Yes, I have procharger intercooler.

Awesome. Thanks!

For most applications, every .10" in blower pulley size is equal to 1psi. This can vary by applications depending on what rpm you are at as the impeller speed ramps up.

For example: 6000rpm redline, 4.10 gearset, 7.65" crank pulley...
Impeller speed increase going from a 5.00 pulley to a 4.50 pulley is 4182rpm; from 4.50 to 4.00 is 5228; and from 4.00 to 3.50 is 6721.
Going from a 5.00 to a 4.50 may only net you an increase of 2 or 3psi, whereas going from 4.00 to 3.50 could be an increase of 5psi. Having said this, you cannot simply go from 5.00 to 3.50 and pick up 15psi.

To further complicate the issue, every combination of displacement, compression, heads, cam, intake, and exhaust, can cause the airflow to behave in a different manner. Having said that, not all 383 (example) combinations will see the same increase in boost going from one pulley to another.

I go into detail about this to help avoid spread of internet confusion. The first line of this post is the average increase that you will see. You already have the important information in knowing the what boost it is making with the current combo.

By any chance can this kit fit on a 87 gta? Or only 88's

I don't see any reason why it wouldnt, but I would talk to procharger before pulling trigger. Or some may speak up if they got a 87'

there is no serpentine setup on the 87 and down cars they use a 3 belt setup if it was carb/d yes u could use a carb bracket if it's tpi you would have to switch to serpentine