G.M. 4 blade fan?

[MasterSbilt_Racer]

i figured that. i was just trying to figure out what master was saying about not using a double pass radiator. i dont see a double pass weighing more OR costing any horsepower.

I didn't know about weight. It does cost more and there is a larger pressure drop inside it. How much more horsepower it takes to turn the water pump, I don't know.

[drtrkr244]

Every racer should read the tech section on Stewarts Water Pumps website. It explains all the issues this thread is talking about.


I have a customer running a 24 inch, single core, single pass radiator and no shroud, on a 500hp llm with no cooling problems . In fact it is running too cool, but they race in FL, so hopefully the summer weather will allow it to warm up a little.


I used all the info from Stewarts website to accomplish this. He debunks all the "wives tales" about a cooling system, that we have all heard and practiced.

[joedoozer]

I have read it and it works. My fan shroud probably isn't what they would have designed but it works for me. The one thing that has bugged me with their tech section is they tend to answer more Street Application topics compared to Racing. They aren't quite 100% clear on the pulley sizes. They recommend a max RPM speed for the water pump at 7,000. But then later say not to spin the fan more than 6500 because of air turbulence.

Now ask the question on here if you should under drive the water pump and see what happens haha.

[sj valley dave]

We under drive ours 15%....CV Products pulleys, max rpm is 8400 rpm..No restrictor, good shroud, double pass, Adams pump and we have 4-5 rows of tape across the front of the radiator...Just changed from a 18" fan to a 15" to see if we can keep heat in it better...This is on gas

[MasterSbilt_Racer]

I have always run 1:1 up to 7500 rpm without any problem.

[joedoozer]

I only spin mine at 7,000 anyway. So it doesn't really apply to me that much. But I wondered about the air turbulence and if I should underdrive it just a smidge.

[drtrkr244]

I forgot to mention the pulleys are 1:1. They turn the motor 7500 with no cooling problem.

[stockcar5]

Turbulence is a easy free fix...

haha my buddy has been doing that for years. still cant get his motor over 200! you should see the looks he gets when people see it!

[sj valley dave]

Our 8400 rpm minus 15% is about 7200 rpm...It depends upon your rpm..

[stockcar5]

lol close... i think he even went down to a 15" 2 blade fan. one guy came over to his pits last year and argued with him that it cant possibly work...all while his car was overheating and my buddys car was running the 180 degrees that his t-stat opens up at!

[stockcar5]

youre on the right track with the 2 blade fan. dynoman built a fan dyno just for the peurpose of testing fans and he found +50hp just by going to a 2 blade. he found another +20hp by adding a propreitary coating to the blades which decrease blade drag!

who drives the car now? not chad i take it?

[jrkracing54]

I went to my local dealership today and they told me it would be $170.00 for the fan. I was blown away. John 1*

[Egoracing]

John, when we were looking for a crate we tried the zephyrills
Dealer and they wanted over $7500 we ordered it from Carl Black and shipped to the shop was just over $4500 so check around!

[stockcar5]

www.gmpartsdirect.com would be your best price but you'll hafta pay shipping.
i would go with the cv products fan. they some in 15 18 and 19inches.

http://www.cvproducts.com/ProdDet.aspx?PN=CV1519

[stockcar5]

even better yet

http://www.amazon.com/ACDelco-15-80752-Fan-Blade-Assembly/dp/B000IZ26E0