Just got a 4.50 pulley to replace my 4.88 for my D1x, how much more boost will it make?

[Dominant1]

Hey guys my current 4.88 pulley stage-2 gets me 12 lbs of boost at 7500 rpm with the stock balancer. I just got a 4.50 pulley, how much more boost will I make with the smaller pulley? I'm guessing 2lbs or 14 total. I'm currently at 750 whp on 93 pump gas plus octane booster. I have no intention of going e-85 because there is none in my area. I will use VP racing fuel for track events.

Sponsored

 

[Dominant1]

Bump

 

[Wolvee]

PBD said in a video a while back that these blowers see 1-2lbs of boost per pulley size when dropped one size smaller. On Youtube, it's the video where they dyno run 3 Centri cars.

 

[Dominant1]

Here’s the pulley size order:

4.88 (mine)
4.75
4.63
4.50
So according what you said in your post, i will use 1.0lb of boost per pulley size as a measuring stick. I’m looking at 3lbs increase minimum.
My D1x added 295 whp over my previous n/a build. So a ruff estimate can be determined by dividing 12lbs of boost into the 295whp increase which equals 24.5-whp per pound of boost increase for total of about a 73.5-whp increase with this pulley. This may be to much extra hp for my stock Gen2 motor. That would put me at 820+ whp. I will have to see what my tuner says.

 

[Slow306stang]

Like what @Wolvee stated I'd expect around 1-1.5psi per pulley size.

@Dominant1 If the Gen 1 pulleys are the same as the Gen 2, I have a 4.62 that you can have for free. Id expect the car to pick up 75whp with the 4.5"

 

[fuelforfire87]

Procharger rule of thumb is for every 0.1" decrease in pulley size should increase boost by 1 PSI. I went from a 4.25" pulley down to a 4.0" (decrease of 0.25") and went from 13.5 PSI to 16. I would imagine you should gain 3 or 4 lbs with your pulley decrease.

Also superchargers pulleys are the same between Gen 1 and Gen 2, at least for the Stage 2 kits with the dedicated drive.

https://shop.brutespeed.com/ATI-DPxxx-ProCharger-Pulley-6-Rib-and-8-Rib-w-belt-option-ATI-DPxxx.htm

 

[Bmaughan]

Interesting... I’ve always heard that rule of thumb but it never quite added up for me. I think it depends on the efficiency range you’re operating the blower in. Also belt slip can become an issue depending on the sizes. I wouldn’t think you would have much/ if any issues at a 4.5”

 

[Dominant1]

Procharger rule of thumb is for every 0.1" decrease in pulley size should increase boost by 1 PSI. I went from a 4.25" pulley down to a 4.0" (decrease of 0.25") and went from 13.5 PSI to 16. I would imagine you should gain 3 or 4 lbs with your pulley decrease.

Also superchargers pulleys are the same between Gen 1 and Gen 2, at least for the Stage 2 kits with the dedicated drive.

https://shop.brutespeed.com/ATI-DPxxx-ProCharger-Pulley-6-Rib-and-8-Rib-w-belt-option-ATI-DPxxx.htm

sounds about right, what rwhp are you making @ 16lbs?

 

[Jay-rod427]

You'll see about 3 lbs assuming same atmospheric conditions. But it won't be 75 hp.. Like always don't get hung up on boost reading. More importantly is power output, and CFM.

 

[fuelforfire87]

sounds about right, what rwhp are you making @ 16lbs?

Unkown, have not been back to the dyno. I made 805 wheel on the 4.25" pulley so hopefully I'm around 850 now.

 

[80FoxCoupe]

Unkown, have not been back to the dyno. I made 805 wheel on the 4.25" pulley so hopefully I'm around 850 now.

Whats it run?

 

[fuelforfire87]

Have not been to the strip yet (hopefully going this month) but in mexico using my dragy i ran a 5.98 60-130 time. Quarter mile and 60' was crap at 11.30 not getting any traction in first and most of 2nd. Also this was 305/40/18 NT555r's.

 

[Dominant1]

Mickey Thompson’s FTW..

 

[fuelforfire87]

Yes i have a set of 15x10 poverty stars with some 295/55/15 ET Street S/S's for track use

 

[80FoxCoupe]

Have not been to the strip yet (hopefully going this month) but in mexico using my dragy i ran a 5.98 60-130 time. Quarter mile and 60' was crap at 11.30 not getting any traction in first and most of 2nd. Also this was 305/40/18 NT555r's.

60-130? Is that a honda standard of performance measurement? LOL

Sponsored