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Author Topic:   Pulleys
BnBracin
Dirt Roller

Total posts: 19
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 Freak

Total posts: 352
posted February 27, 2003 06:30 AM  
i run 1 to 1 on my gas motor

Pickel
Dirt Forum Champ
Total posts: 784
posted February 27, 2003 08:50 AM  
Current thinking is 1:1 for a gas engine, and reduction on alcohol.

racer2
Dirt Freak

Total posts: 352
posted February 27, 2003 06:30 PM  
thats is what i was told

Pickel
Dirt Forum Champ
Total posts: 784
posted February 28, 2003 08:30 AM  
i run 30% reduction alluminum on 355 gas and ran 180 degs all year


uforacing51
Dirt Forum Champ
Total posts: 570
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: 784
posted February 28, 2003 01:27 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 Forum Champ
Total posts: 517
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: 46
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: 1363
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: 19
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: 46
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: 784
posted March 01, 2003 10:12 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 Forum Champ
Total posts: 1139
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: 68
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 Freak

Total posts: 337
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.

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