Step Down in Pulley Size on E-force?
Thread Starter
Safety Car
Joined: May 2016
Posts: 4,662
Likes: 1,846
From: Erlanger, Kentucky
Step Down in Pulley Size on E-force?
So been thinking that I might step down a pulley size or two on my E-force powered Grand Sport (6-speed manual, dry sump). (I clearly need more power).
Right now I am running a 3.5" pulley and making 520/520 wheel hp/tq. This is on a completely stock engine except for Kooks catted headers (and E-force of course). I do have a DeWitts radiator, Monster LT1-S twin disc clutch (700 hp), BAP with Racetronix fuelpump upgrade harness, and CPR expansion tank.
I know I will need to upgrade to larger injectors and a re-tune. Was thinking FIC1000's. (ID1050X would be nice but much more pricey).
What kind of gains could I expect going to a 3.25" pulley? or even a 3.0"?
I know that on the 3.5: pulley I am at about 7.8 psi. From what I understand for every pulley size down, it increases the boost by about 1.5 to 2 psi.
Was thinking that 600 wheel hp would be nice.
Right now I am running a 3.5" pulley and making 520/520 wheel hp/tq. This is on a completely stock engine except for Kooks catted headers (and E-force of course). I do have a DeWitts radiator, Monster LT1-S twin disc clutch (700 hp), BAP with Racetronix fuelpump upgrade harness, and CPR expansion tank.
I know I will need to upgrade to larger injectors and a re-tune. Was thinking FIC1000's. (ID1050X would be nice but much more pricey).
What kind of gains could I expect going to a 3.25" pulley? or even a 3.0"?
I know that on the 3.5: pulley I am at about 7.8 psi. From what I understand for every pulley size down, it increases the boost by about 1.5 to 2 psi.
Was thinking that 600 wheel hp would be nice.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
I have a 3.5" (90mm) pulley on my Heartbeat .... Like yours, my GS is stock except for the SC and a set of 1 1/2" headers.
I removed the 52 Lb/Hr @ 58 PSI LS9 injectors and installed a set of FIC/Bosch 72 Lb/Hr @ 58 PSI injectors ... My injector duty cycle went from 90% down to 72% after the injector change.
Fuel Injector Connection P/N: FIC60LS
If you change injectors, the car will need to be re-calibrated (dyno tuned) to get the new injectors to work properly.
FIC link to the injectors I purchased: https://fuelinjectorconnection.com/c...high-impedance
Do a web search for the cheapest price for FIC60LS (cost runs between $420 and $460 a set)
.
I removed the 52 Lb/Hr @ 58 PSI LS9 injectors and installed a set of FIC/Bosch 72 Lb/Hr @ 58 PSI injectors ... My injector duty cycle went from 90% down to 72% after the injector change.
Fuel Injector Connection P/N: FIC60LS
If you change injectors, the car will need to be re-calibrated (dyno tuned) to get the new injectors to work properly.
FIC link to the injectors I purchased: https://fuelinjectorconnection.com/c...high-impedance
Do a web search for the cheapest price for FIC60LS (cost runs between $420 and $460 a set)
.
Last edited by Turbo6TA; Mar 29, 2020 at 01:08 PM.
Burning Brakes
Joined: Aug 2011
Posts: 810
Likes: 188
From: andover mn
Like Turbo I have the Heartbeat also. Have 84mm pulley on top 1 7/8 ARH ,65lb Fast injectors. Wanted to put on the 81mm last year but the injectors were at 95% duty already. Looking to get that done this year. At 625rwhp now.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
If you're upgrading injectors, jump up enough to accommodate E85. Not much down side to running bigger injectors than you need at current power levels.
A pound of boost adds 15 to 20 hp. The higher your boost is before the upgrade, the lower the hp increase. If you're starting at 7psi and go to 9, I'd bet you'd see 40 more hp. If starting at 10 and going to 12, your hp increase may be closer to 25-30.
I'd stop at the 3.25" pulley unless you're going E85 or adding a cam into the mix. With E85 and a cam upgrade running the 3.0" pulley + E85 = BEASTLY.
A pound of boost adds 15 to 20 hp. The higher your boost is before the upgrade, the lower the hp increase. If you're starting at 7psi and go to 9, I'd bet you'd see 40 more hp. If starting at 10 and going to 12, your hp increase may be closer to 25-30.
I'd stop at the 3.25" pulley unless you're going E85 or adding a cam into the mix. With E85 and a cam upgrade running the 3.0" pulley + E85 = BEASTLY.
Thread Starter
Safety Car
Joined: May 2016
Posts: 4,662
Likes: 1,846
From: Erlanger, Kentucky
If you're upgrading injectors, jump up enough to accommodate E85. Not much down side to running bigger injectors than you need at current power levels.
A pound of boost adds 15 to 20 hp. The higher your boost is before the upgrade, the lower the hp increase. If you're starting at 7psi and go to 9, I'd bet you'd see 40 more hp. If starting at 10 and going to 12, your hp increase may be closer to 25-30.
I'd stop at the 3.25" pulley unless you're going E85 or adding a cam into the mix. With E85 and a cam upgrade running the 3.0" pulley + E85 = BEASTLY.
A pound of boost adds 15 to 20 hp. The higher your boost is before the upgrade, the lower the hp increase. If you're starting at 7psi and go to 9, I'd bet you'd see 40 more hp. If starting at 10 and going to 12, your hp increase may be closer to 25-30.
I'd stop at the 3.25" pulley unless you're going E85 or adding a cam into the mix. With E85 and a cam upgrade running the 3.0" pulley + E85 = BEASTLY.
Hmm. Might be better to stick with my existing boost level and upgrade cam and springs instead. Would still have to upgrade injectors regardless.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
You're good on fuel down to a 3.25" and blower cam. I ran that same fuel setup with 3.3" pulley and 60# injectors to 642rwhp. Getting to that power level on 52# injectors might be cutting it close though.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
They were Siemens/Deka Mototrons. Hell, Bosch may own that outfit by now. I believe you are correct on how they were rated. Magnuson sent the first jackshaft TVS 2300's out with those injectors. Those first kits also came with a Callaway Honker CAI.