Supercharger with Underdrive pulleys?
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
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From: Custer, WI
Supercharger with Underdrive pulleys?
If you have underdrive pulleys and installed a supercharger, would the larger pulley on the crankshaft make it run abnormally? Could you change the pulley size on the supercharger to counter-act the underdrives?
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
re supercharger with under drive pulleys
Hi
I have a vortech supercharger on my 85 vette . with the standard engine crank pulley and the supercharger pulley is around 2 1/2 inches in diameter that gives me 8 psi boost ... so if you have an underdrive pulley set on the supercharger will spin slower and less boost.
I assume you can get the supercharger gear ratio changed to speed the impeller up ,,, if not you are limited in the boost
Also you will struggle to put a bigger crank pulley on .. A lot of the kits come made to fit a standard pulley setup and have a supercharger serpentine pulley to to give a known boost ... you may have to mix and match supercharger pulleys to get the boost you want .
Also the smaller the supercharger pulley the less area for the belt to grip it
So if you want an easy bolt on kit use the standard crank pulley ... you can always fit a larger pulley on the water pump and alternator if you are worried about drag ... supercharging is not as efficient as turbo charging however there is a push in the back / extra torque to make you smile !!! and light up your tyres so you wont care for the 1 or 2 h/p lost in driving the accesories
( the supercharger serpetine pulleys are not chaeap if you want to mix and match )
I have a vortech supercharger on my 85 vette . with the standard engine crank pulley and the supercharger pulley is around 2 1/2 inches in diameter that gives me 8 psi boost ... so if you have an underdrive pulley set on the supercharger will spin slower and less boost.
I assume you can get the supercharger gear ratio changed to speed the impeller up ,,, if not you are limited in the boost
Also you will struggle to put a bigger crank pulley on .. A lot of the kits come made to fit a standard pulley setup and have a supercharger serpentine pulley to to give a known boost ... you may have to mix and match supercharger pulleys to get the boost you want .
Also the smaller the supercharger pulley the less area for the belt to grip it
So if you want an easy bolt on kit use the standard crank pulley ... you can always fit a larger pulley on the water pump and alternator if you are worried about drag ... supercharging is not as efficient as turbo charging however there is a push in the back / extra torque to make you smile !!! and light up your tyres so you wont care for the 1 or 2 h/p lost in driving the accesories
( the supercharger serpetine pulleys are not chaeap if you want to mix and match )
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Well i wanted to put new heads on my 85, because they are so crappy.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
Drifting
Joined: Feb 2008
Posts: 1,267
Likes: 27
From: Texas
Well i wanted to put new heads on my 85, because they are so crappy.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
I dont know the tables but it does.
03-04 terminater ford cobras go from 400 to 450rwhp with just a pulley swap since they make more boost.
Team Owner
Joined: Mar 2001
Posts: 30,856
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Well i wanted to put new heads on my 85, because they are so crappy.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
i have 76cc chambers now, and would put a 70cc head on them, which would bump compression..i don't think i could run 8 lbs of boost with my bumped compression, so i was wondering if pulleys would be a way around it.
What's your compression now?
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Team Owner
Joined: Mar 2001
Posts: 30,856
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
So dished pistons will allow me to get smaller combustion chamber heads?
I was planning on rebuilding my motor this winter, maybe going 383. If i get a kit with dished pistons i can get 64cc heads?
I was planning on rebuilding my motor this winter, maybe going 383. If i get a kit with dished pistons i can get 64cc heads?
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
So dished pistons will allow me to get smaller combustion chamber heads?
I was planning on rebuilding my motor this winter, maybe going 383. If i get a kit with dished pistons i can get 64cc heads?
I was planning on rebuilding my motor this winter, maybe going 383. If i get a kit with dished pistons i can get 64cc heads?
