Smaller blower pulley or bigger crank pulley?

[B-rad]

I've got a maggie 2300 with a 3.6" pulley. I want to up the boost, just not sure which way to go. I know it is easier to downsize the blower pulley, but I don't want to have belt slippage.

Does anybody know how much boost is gained going to a 10% overdrive crank pulley vs. downsizing the blower to a 3.4" or 3.2"?

[Supercharged SS]

Originally Posted by B-rad

I've got a maggie 2300 with a 3.6" pulley. I want to up the boost, just not sure which way to go. I know it is easier to downsize the blower pulley, but I don't want to have belt slippage.

Does anybody know how much boost is gained going to a 10% overdrive crank pulley vs. downsizing the blower to a 3.4" or 3.2"?

You should be able to run a 3.4 with no problem. I got 10.5 psi with a 6 rib 3.4. You could prob even run a 3.2 with no slippage too. I have a brand new 3.2 with the gator grip process machined into it if you're interested. That should make about 12 - 12.5 psi.

[B-rad]

Originally Posted by Supercharged SS

You should be able to run a 3.4 with no problem. I got 10.5 psi with a 6 rib 3.4. You could prob even run a 3.2 with no slippage too. I have a brand new 3.2 with the gator grip process machined into it if you're interested. That should make about 12 - 12.5 psi.

PM me with a price.

Any Idea how much boost is safe to run on a stock LS3 on 91 octane gas? I plan on doing water/meth injection as well.

[lewylew]

I would keep it under 10 PSi without the meth. With the meth you should be alright upto 12 or a little more. SuperchargedSS is running 12.5 on stock bottom end. I am no expert though.

I would like to know the answer to your original question about the overdrive pulley as well

[Supercharged SS]

Originally Posted by lewylew

I would keep it under 10 PSi without the meth. With the meth you should be alright upto 12 or a little more. SuperchargedSS is running 12.5 on stock bottom end. I am no expert though.

I would like to know the answer to your original question about the overdrive pulley as well

B-rad, I answered your pm.

Also, Brad, as I asked in the pm, whats your elevation? Whats makes 10 or 12 psi down (sea level) here won't if you are at a high elevation or if you are planning on adding headers, (if you don't already have them) or a cam down the road. you may make only 10 psi with a 3.2. There is a formula floating around the will "ballpark" your boost.

[B-rad]

Originally Posted by Supercharged SS

B-rad, I answered your pm.

Also, Brad, as I asked in the pm, whats your elevation? Whats makes 10 or 12 psi down (sea level) here won't if you are at a high elevation or if you are planning on adding headers, (if you don't already have them) or a cam down the road. you may make only 10 psi with a 3.2. There is a formula floating around the will "ballpark" your boost.

The elevation where I live is about 1000ft, but the place I had my car dynoed is about 570ft. I don't have a boost guage yet, but during the dyno the boost maxed out at about 7.5 PSI. That is with LT headers and the 3.6" pulley.

[Jessika]

Originally Posted by B-rad

I've got a maggie 2300 with a 3.6" pulley. I want to up the boost, just not sure which way to go. I know it is easier to downsize the blower pulley, but I don't want to have belt slippage.

Does anybody know how much boost is gained going to a 10% overdrive crank pulley vs. downsizing the blower to a 3.4" or 3.2"?

Do you have the actual size of the crank pulley in question? I have a calculation that I can plug the info into if you do.

[Ernie@P]

go with the larger lower so you dont have an issue with belt wrap and slip on the upper

[Supercharged SS]

Originally Posted by Ernie@PSR

go with the larger lower so you dont have an issue with belt wrap and slip on the upper

I think the od pulley is only offered in an 8 rib and costs around $550 which is half the cost of the entire 8 rib set up. It make sense to bite the bullet and go with the entire 8 rib if you plan on changing the bottom. Then you can run whatever blower pulley you want and be good to go.

[Jessika]

If you run a 9" crank pulley you can run a 3.6 @ 12lbs easily.
The stock crank pulley should be 7.527

[B-rad]

I think just because of the extra cost in installing a overdrive crank pulley, I am going to go with the 3.2" blower pulley. If I end up having an issue with slippage, I guess I will know what I have to do.

[old motorhead]

By keeping your crank pulley stock sized, you're not turning all of your other accessories faster than necessary. The proponents of under driven crank pulleys, for n/a builds, claim a 10 rwhp gain from turning the accessories slower. If you turn them faster......well, you get the idea.

[PoleCat2SSRS2010]

Originally Posted by Jessika@Magnacharger

If you run a 9" crank pulley you can run a 3.6 @ 12lbs easily.
The stock crank pulley should be 7.527

(Disclaimer: if all research and tech information from a competitor's web site is correct)

I am not attacking anyone here so please don't take this personal. Just trying to clear the air or my potential confusion.

With a 3.6 SC pulley and a 7.5 crank pulley this means his ratio is ~2.07:1 and multiply that times the engine RPM limit 6500 and a blower RPM of 13448 should get the estimated boost rated at sea level of ~11 psi.

Does being at 1000FT above sea level reduce boost pressure by 4 lbs?

Also isn't the 9 inch crank pulley about 3 sizes larger if they go up by .5 in increments?

Isn't each increment in crank pulley size supposed to change the boost by 4 psi? (again if research is correct)

Wouldn't the 8 inch crank pulley be the preferred size with the 3.6 SC pulley add 4 psi onto the OP's current rating of 7.5 and he should get 11.5? (pushing the limit of stock internals only if he were to take it to 6500 RPM or higher. He might actually have to go up on SC pulley size to a 3.75 to get back down to ~10 psi)

A 9 in is 3 sizes up and would normally add 12 psi making a total of 19.5 psi with the 3.6 SC pulley instead of a total of 12 with the 3.6?

Also, this is with all of the OP's engine internals and exhaust remaining the same.

[Jessika]

Originally Posted by PoleCat2SSRS2010

(Disclaimer: if all research and tech information from a competitor's web site is correct)

I am not attacking anyone here so please don't take this personal. Just trying to clear the air or my potential confusion.

With a 3.6 SC pulley and a 7.5 crank pulley this means his ratio is ~2.07:1 and multiply that times the engine RPM limit 6500 and a blower RPM of 13448 should get the estimated boost rated at sea level of ~11 psi.

Does being at 1000FT above sea level reduce boost pressure by 4 lbs?

Also isn't the 9 inch crank pulley about 3 sizes larger if they go up by .5 in increments?

Isn't each increment in crank pulley size supposed to change the boost by 4 psi? (again if research is correct)

Wouldn't the 8 inch crank pulley be the preferred size with the 3.6 SC pulley add 4 psi onto the OP's current rating of 7.5 and he should get 11.5? (pushing the limit of stock internals only if he were to take it to 6500 RPM or higher. He might actually have to go up on SC pulley size to a 3.75 to get back down to ~10 psi)

A 9 in is 3 sizes up and would normally add 12 psi making a total of 19.5 psi with the 3.6 SC pulley instead of a total of 12 with the 3.6?

Also, this is with all of the OP's engine internals and exhaust remaining the same.

Is all this info based on a jackshaft system? I threw the 9" crank diameter (just guessing a number) into the calculator and that's what I got. Without being at work with resources it seems that is all direct drive stuff.

I am no blower genius... I rely on the amazing engineers and staff to teach me...

And 3000 above sea level results in a 1 lb loss...


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