Paxton/Vortech 3.125" Pulley and Belt

MassMustang

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Limiter is set at 6500. I won't go any higher than that with stock valve train. I started with a 3.125 pulley and was at ~550WHP for about a year or so. Same tuner VMP, same mobile dyno.

Interesting! I'm at 540rwhp with my existing setup using a 3.125" pulley. What did the smaller pulley net you for boost and power?
 

TheKurgan

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Interesting! I'm at 540rwhp with my existing setup using a 3.125" pulley. What did the smaller pulley net you for boost and power?

Peak boost is around 13 psi but I have FRPP hot rod cams so those cams will rob about 3 psi of boost. Peak power with the 2.62 is in my sig 637whp and dyno in my profile pics. Also, this is on a Novi 1500, not the big boy 2200.
 

46addict

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Is the boost loss from the hot rod cams due to a reduced restriction (meaning less psi & more power) or is it more of a parasitic loss from too much overlap?
 

MassMustang

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Peak boost is around 13 psi but I have FRPP hot rod cams so those cams will rob about 3 psi of boost. Peak power with the 2.62 is in my sig 637whp and dyno in my profile pics. Also, this is on a Novi 1500, not the big boy 2200.

I'll have to review your signature from a PC. It doesn't show on my iPhone (Safari).

I'm wondering what power I'm leaving on the table with my setup. Boss block bored/stroked to 326 with 9.6:1 compression, 127350 Comp Cams, Novi 2200SL in a blow-thru setup with PMAS HPX-E MAF, TurboSmart 52mm BOV, 3.125" pulley & stock damper, and 305/45/18 rear tires (28.8" tall as compared to 27.1" stock height).

I was dyno'ed on a 90-degree day in Aug after a 2.5 hour drive and a 30 minute cool down. Possibly detrimental to the results along with taller tires.
 

46addict

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I'll have to review your signature from a PC. It doesn't show on my iPhone (Safari).

I'm wondering what power I'm leaving on the table with my setup. Boss block bored/stroked to 326 with 9.6:1 compression, 127350 Comp Cams, Novi 2200SL in a blow-thru setup with PMAS HPX-E MAF, TurboSmart 52mm BOV, 3.125" pulley & stock damper, and 305/45/18 rear tires (28.8" tall as compared to 27.1" stock height).

I was dyno'ed on a 90-degree day in Aug after a 2.5 hour drive and a 30 minute cool down. Possibly detrimental to the results along with taller tires.

Steeper gears have netted less power on the dyno. Applying the same logic to tire diameter, your taller tires should have yielded more whp if anything.
 

MassMustang

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Steeper gears have netted less power on the dyno. Applying the same logic to tire diameter, your taller tires should have yielded more whp if anything.

I've read that gears have little effect (positive or negative) on the dyno depending on manual/auto, gears and what gear you're dyno'ed in (shooting for the 1:1 gear ratio).

I've also read that taller rear tires will negatively affect your dyno numbers (minimally). I'd love to do back to back dynos with the taller tires and some stock sized tires for comparison.

Plenty of factors including atmospheric may impact dyno results too. So it's probably all a waste of time chasing a few hp.
 

TheKurgan

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Is the boost loss from the hot rod cams due to a reduced restriction (meaning less psi & more power) or is it more of a parasitic loss from too much overlap?

The cams have too much overlap so as I understand it, the boost goes right out the exhaust valve so it's less restriction, but don't hurt power all that much with a supercharger. Turbo would see more HP loss. I also have accompanying mods FRPP intake, FRPP TB, headers, BOV, big A2A FMIC, etc.

I'll have to review your signature from a PC. It doesn't show on my iPhone (Safari).

I'm wondering what power I'm leaving on the table with my setup. Boss block bored/stroked to 326 with 9.6:1 compression, 127350 Comp Cams, Novi 2200SL in a blow-thru setup with PMAS HPX-E MAF, TurboSmart 52mm BOV, 3.125" pulley & stock damper, and 305/45/18 rear tires (28.8" tall as compared to 27.1" stock height).

I was dyno'ed on a 90-degree day in Aug after a 2.5 hour drive and a 30 minute cool down. Possibly detrimental to the results along with taller tires.

I don't think the temps had that much to do with it. My first dyno was in Florida and the 2.62 swap I did at Texas Motor Speedway on Justin's same mobile dyno but it was a little cooler and I had been running hot laps.

Only reason I could think is you have a little less compression, I'm at stock compression with a 302 stroker so a little less moving weight as well probably. The 1500 is a very efficient blower with a higher step up rate than the 1200.
 

MassMustang

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Vortech shared this with me. Pretty helpful when comparing various dampers and supercharger pulleys.

https://vortechsuperchargers.com/pages/impeller-speed-calculator

An example calculation:

Using the stock 6.7" damper, shifting at 6,500 RPMs with a 3.125" pulley will be about 50,170 RPMs
A 15% overdrive damper at 7.5”, shifting at 6,500 RPMs with a 3.125” pulley will about 56,160 RPMs
Using the same 15% overdrive damper, 3.125" pulley and shifting at 6,000 RPM's gets the impeller speed down to 51,840 RPMs

I'm told the overdrive damper is a better option as the diameter of the pulleys are larger, thereby increasing the contact patch and reducing belt slippage. The trick is balancing out the pulleys to get the right impeller speed on the supercharger.

Most will agree (wink, wink) that the "max impeller speeds" are suggested values.
 

MassMustang

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Ok. I’m picking up a Metco 12% OD crank pulley and I’ll keep my 6-rib 3.12” blower pulley for now. I found a good deal on a UPR tensioner too. Anyone familiar with a calculator to determine if I need a different length belt?
 

Jbarker83

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Bringing this back from the dead but did anyone run the 3.125 pulley on a stock engine 3v?? Is it to much boost or can it be detuned to be safe
 

Titan

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So my car made 731 horsepower with 3.3 pulley, torque boost set at 10lbs on the wastegate, on radials which they said prob cost me about 50hp give or take. About to pulley down to a 3.125 griptech.
 

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