Visit The Dirt Forum for More Information

Author Topic:   Pulleys
BnBracin
Dirt Roller

Total posts: 9
posted February 26, 2003 11:09 PM
I was wondering if any of you guys use underdrive pullys? If you know anything about them please let me know. i just saw one in a catalog and it got me thinking. What are you opinions? Thanks, BnB

racer2
Dirt Maniac

Total posts: 166
posted February 27, 2003 06:30 AM
i run 1 to 1 on my gas motor

Pickel
Dirt Forum Champ
Total posts: 564
posted February 27, 2003 08:50 AM UIN: 25419780
I run undrive but not sure how much..I have a lower pully off a chevy 6 cyl(wich is about 6") along with lower pully off a buick fwd (wich is about 4" and the upper pully is off gm truck with double grove..this year I am reduseing it just a little bit more..with an upper pully off a pontiac 400 (pre 74)and my 4 inch lower..hope this helps..thanks pickel

STREET16
Dirt Full Roller

Total posts: 32
posted February 27, 2003 05:30 PM
Current thinking is 1:1 for a gas engine, and reduction on alcohol.

racer2
Dirt Maniac

Total posts: 166
posted February 27, 2003 06:30 PM
thats is what i was told

Pickel
Dirt Forum Champ
Total posts: 564
posted February 28, 2003 08:30 AM UIN: 25419780
ok then can some one answer me this ? why reduse alcohol when it run cooler and 1 to 1 on gas when it run hoter? jus wondering..

factory58
Dirt Roller

Total posts: 19
posted February 28, 2003 09:56 AM
i run 30% reduction alluminum on 355 gas and ran 180 degs all year


uforacing51
Dirt Freak

Total posts: 349
posted February 28, 2003 12:45 PM
Pickel, I agree with you. I ran stock overdriven pulleys on a mod for 1 season. Still didn't overheat. I would run reduction on the gas motors and evcn up on the mod. you can reduce the mod though, it ain't gonna kill it.

Pickel
Dirt Forum Champ
Total posts: 564
posted February 28, 2003 01:27 PM UIN: 25419780
I can understand underdriving the pully for cooler and less drag on the motor..I was jus kind of wondering.. I was told alky was cooler then gas ..lol

[This message has been edited by Pickel (edited February 28, 2003).]

ryan
Dirt Freak

Total posts: 430
posted February 28, 2003 04:22 PM
Unless I am mis-reading something here. Pickel and ufo's thinking is backwards. The more you underdrive your pulleys the warmer your car should run. You should get away with running MORE underdrive with alky because it does run cooler and you would want gas 1:1 to help it run cooler

Scoot
Dirt Freak

Total posts: 330
posted February 28, 2003 07:32 PM
I have to agree with ryan. If you have reduction pulleys your "reducing" the speed of the water pump.

------------------
Scoot
Smith Racing Team
870-365-5989

racinrich1
Dirt Full Roller

Total posts: 42
posted February 28, 2003 09:45 PM
Direct from Stewart Components website...

"Stewart Components does NOT recommend the use of underdrive pulleys on any application. Stewart high-flow water pumps only consume 2.26 horsepower at 4,000 RPM, so the actual savings in parasitic horsepower loss through the use of underdrive pulleys is minimal. In addition, a properly designed cooling system's flow and efficiency are designed to operate at a given speed. In years of testing, Stewart has consistently proven that the engine will lose more horsepower due to higher operating temperatures than any possible gain from underdrive pulleys."

My division Calls for steel pulleys..I am trying to figgure out what pulleys I can use to get the recomended 1 to 1 ratio..
I would consider a stock serpentine setup..
RACINRICH

outlawstock17
Dirt Forum Champ
Total posts: 620
posted February 28, 2003 09:48 PM
if you're running a stock type water pump, it's not designed to run at 7000+ rpms. a reduction pulley will slow it down to the rpm range it was designed to operate in and cool the engine better. i run 40% underdrive on gasoline with no problems. it gets a little warm on the cautions but nothing crazy.

BnBracin
Dirt Roller

Total posts: 9
posted March 01, 2003 01:00 AM
Well, i was thinking about going to a 50%underdrive with a impeller backing plate. that is supposed to stop the turbulence in the water and will in tern make it flow a whole lot more. im not worried about overheating, i dont think that we will. i was also told just about everything above and this is what i decided to do.


racinrich1
Dirt Full Roller

Total posts: 42
posted March 01, 2003 06:56 AM
I run a 400sbc...I was running 240 degrees at the end of a 100 lap feature...I installed a Stewart pump and removed my restrictor (recomended)...I now see about 220 degrees...No problem during cautions...
Rich

Pickel
Dirt Forum Champ
Total posts: 564
posted March 01, 2003 10:12 AM UIN: 25419780
I understand what everyone is saying about the under driving the pully but then why is it when I redused mine (years ago) It got cooler?I run this set up for years it works great..

armintroutracing
Dirt Roller

Total posts: 18
posted March 13, 2003 03:32 AM
I run a30% underdrive on my crank pulley works great this saves hp. on your fan waterpump powersteering and alt. if you are useing stock parts they like the lower rpm. belts stay on better.and it helps keep your powersteering from foaming.

rico 08
Dirt Freak

Total posts: 372
posted March 13, 2003 01:07 PM
One big reason underdriving the waterpump works is the stock pump will cavitate,and slowing it down will reduce the cavitation.

One87Racing
Dirt Full Roller

Total posts: 61
posted March 13, 2003 10:56 PM
I went thru the wrecking yard here and found myself a 6 inch crank pulley on a nova and a 7 inch or so WP pulley off of some other tank. I have no idea what ratio under/over drive I have, but is this setup even close to what any of you run? I'm also curious as to what size pulley I should run on the power steering. My thinking is bigger is better due to not over spinning the ps pump. Anyone have any recommendations? I have to run stock pulleys on my car. Thanks

dirtracer7
Dirt Maniac

Total posts: 106
posted March 14, 2003 02:00 PM
I have run overdrive and underdrive and far as I can tell there was no difference .Getting the air to the radiator and fan and shroud setup seem to have more to do with cooling than the other crap.Especialy when you run a nose thats rounded alot if its open on the bottom it will pull air away from the radiator.An air dam will help that.

Back to the Archives