I took my D1SC 383 out for some tuning runs this week to check the A/F ratio using an Innovate LM1. This is the first time this motor has seen full throttle runs again since i installed the Procharger. I'm using the 4.5 pulley and its hitting right at 7lbs of boost. Is there any magic formula that i can use so i know what pulley size can get me right around 10lbs of boost?

I can honestly say this engine makes insane power now!!!!

 

Boost is a measure of restriction, so varying engine combinations are different in terms of which pulley will equal what amount of boost pressure....

 

Every .10" on the pulley size will roughly equal 1 psi of boost, so if you want to hit 10 psi, I would suggest using a 4.13" pulley.

 

i had the 4.13" pulley on mine and made a max of 11#'s switched to the 4.0 and make a max of 14#'s

 

At least in my limited experience, I called the blower manufacturer, and let him know what my setup was and the amount of boost I was looking to get. He had a formula to determine what size pulley they offered that would get me in the ballpark.

You gotta figure that the cam, heads etc. will have a huge effect on how well any engine will breathe. On an engine that has the ability to breathe really well in the upper rpm range, you may not be able to build 10 pounds of boost since the engine is using almost everything the blower can make - not a bad thing at all.

EDIT: Street Lethal pretty much said the same thing with a lot less babble...lol

 

I'm surprised you guys are making that much boost on these bigger engines with such large pulleys.

I bought my Vortech with a stock 3.6" pulley and it made 8 PSI and 360 RWHP on the otherwise stock 2004 GT it came off of. That's a little 281 cubic inch engine. Compared to 7 PSI on a big 383 with a 4.5" pulley. Wouldn't think it'd make over 4 PSI with that big of a pulley. It's a shame I told myself I'd go turbo with the IROC if anything, so I can have experience both. Seems like fun to have a centri on a big 383 stroker.

I'd run an even 4" pulley and just take whatever right around 10 PSI I could get. If the engine is built for it I wouldn't mind up to 12 if I were aiming for 10.

 

all depends on the combo, my engine is actually a 305 so smaller chambers, that's why i make 14#'s with the 4.0" puller, 380/420 to the wheels

 

Mine can take in the air. Im running AFR 210's and using a Edelbrock Super Victor intake. It ran 11.85 N/A before this Procharger, and i gave the dealer all of that info when i told them i was shooting for 10lbs of boost, guess my engine breathes better than they thought. Maybe i should just dyno at 7lbs then step up to 10lbs.

I got to feel what tire shake felt like the other day when i was out "tuning". Kinda weird having the rearend shaking till about 5K then it smoothed out. I probably should stop doing that on stock 10 bolt axles and put in my new beefy ones!

 

when i put the blower on i had nothing but wheel spin, put on some drag radials for a bit and took 7 teeth off the ring gear

just upgrade the entire axle, i put in a moser 12 bolt it's like butter

 

That's the difference in gear ratios between Vortech and ProCharger.