Pulley change 3.75 to 3.5

[Stage 4.6]

How drastic of a change in boost can i expect from swapping my current 3.75 to 3.5 pulley on my Kenne Bell 2.6H? Comparing them side by side there isn't much difference in size.

 

[01yellercobra]

Not apples to apples, but on my D1 .1" was good for about 1psi. Either increase or decrease depending on which way you were going.

 

[MG0h3]

@2 on G2 2.9 non crusher


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[Stage 4.6]

I was wondering if i should go with smaller pully, upon completing the switch to E85?

 

[01yellercobra]

I was wondering if i should go with smaller pully, upon completing the switch to E85?

Might as well. Take advantage of the E85.

 

[04DeadShort]

In my experience each pulley size step is about 2psi. I would drop it down to 3.5, make sure the fuel setup is enough to supply the E85 and let her eat.

 

[Stage 4.6]

In my experience each pulley size step is about 2psi. I would drop it down to 3.5, make sure the fuel setup is enough to supply the E85 and let her eat.

yeah Ill put the 3.5 on, I purchased the Fore Level 4 kit, so it will definitely have the supporting fuel system. I just don't want to keep going back for tunes, so debating if i should just purchase a 3.25 pully and get her done?

 

[04DeadShort]

Have a talk with your tuner and see what he recommends.

 

[Stage 4.6]

I will! appreciate all the advice.

 

[Stage 4.6]

*Update!
I went with a 3.25in pulley and put it on the E. To my surprise on a conservative tune It only went up 2psi (16-18psi) from my previous set up?

 

[MG0h3]

Well the tune is irrelevant as far as air volume/boost goes.

I’ve experienced a decreasing amount of boost increase with blower RPM increase


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[Stage 4.6]

Well the tune is irrelevant as far as air volume/boost goes.

I’ve experienced a decreasing amount of boost increase with blower RPM increase


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Makes sense! i just figured that pushing the motor harder on E, I would've seen an increase in boost. Regardless i am very happy with the results.

 

[c6zhombre]

*Update!
I went with a 3.25in pulley and put it on the E. To my surprise on a conservative tune It only went up 2psi (16-18psi) from my previous set up?

The increase sounds a little short for a 3.75 to 3.25 swap.....but regardless....I think you need to spin that blower even more on E85. I think that KB 2.6 is capable of 24psi (sea level) with a 2.75 upper.....so maybe that's 22psi at elevation. The 3.0 upper says 22psi sea level.....I think at a minimum I'd go with the 3.0 on ethanol.

 

[Stage 4.6]

The increase sounds a little short for a 3.75 to 3.25 swap.....but regardless....I think you need to spin that blower even more on E85. I think that KB 2.6 is capable of 24psi (sea level) with a 2.75 upper.....so maybe that's 22psi at elevation. The 3.0 upper says 22psi sea level.....I think at a minimum I'd go with the 3.0 on ethanol.

You are a correct sir! Blower is capable of at least 22psi up here. My tuner said pretty much exactly what you did. It is also on just 20 degrees of timing. I was planning on a 3.0in pully but i thought with the 4lb. lower combo Id be at 20psi?

I was also considering switching blowers and getting a Whipple 2.9 Gen 3 crusher or Gen 4 standard inlet? but I wanted to see what the old KB 2.6H would do up here (722hp/693tq) with my current combo. Obviously it still has more to give.

 

[c6zhombre]

You are a correct sir! Blower is capable of at least 22psi up here. My tuner said pretty much exactly what you did. It is also on just 20 degrees of timing. I was planning on a 3.0in pully but i thought with the 4lb. lower combo Id be at 20psi?

I was also considering switching blowers and getting a Whipple 2.9 Gen 3 crusher or Gen 4 standard inlet? but I wanted to see what the old KB 2.6H would do up here (722hp/693tq) with my current combo. Obviously it still has more to give.

Damn....722 is no joke! What is your ultimate power goal? I think you're at a great place right now.....but if you want to really push it towards 800 you'll need to swap for either the gen3 or 4 2.9. Just remember for every HP you start pushing past say 750...an entire new set of weak links will come up. You'll need ARP head studs for starters! Possibly a T56 magnum too.

 

[Stage 4.6]

My goal was to have a reliable 750hp Cobra, I never gave my tuner a number just told him get what he can out of it, driveability being the priority. I am aware and realize that if i push it any further i will be needing head studs. I am new to the E85 game so i think i will enjoy as it sits for awhile.
The tranny in this car has been a thorn in a$%, never shifts smooth so that will mostly be my next mod.