G.M. 4 blade fan?

[jrkracing54]

Where do I buy an actual G.M. 4 blade fan? I don't want the afco knock off fan. Do I have to get it from a dealership? Any help would be greatly appreciated. John 1*

[lazermod3]

Where do I buy an actual G.M. 4 blade fan? I don't want the afco knock off fan. Do I have to get it from a dealership? Any help would be greatly appreciated. John 1*

"YES"go to your local GM dealer.

[perfconn]

Not the same fan.GM 405442 is 19 inch.Pitch is probably different like the AFCO is.

[joedoozer]

What is the "love" with the GM fan over the AFCO? I thought the only difference was the pitch of the blade. Don't you want to use the smallest, least pitch fan that will adequately cool the engine?

[perfconn]

The GM 405442 has proven over many years to get the job done in circle track racing.Yes there may be sitiuations like low hp crates or alcohol applications that you don't need as much fan.I have seen many guys try the AFCO and have overheating troubles and then go to the GM and solve their problems.The GM 405442 has gotten really expensive but the CV Products 19 inch is an exact copy with some improvements and is less expensive.

[dirty white boy]

www.performanceautobody.com got the good fan at a fair price...

[perfconn]

18 inches and 19 inches are not the same unless you can't read a tape measure.

[MasterSbilt_Racer]

What is the "love" with the GM fan over the AFCO? I thought the only difference was the pitch of the blade. Don't you want to use the smallest, least pitch fan that will adequately cool the engine?

I'm with you on this. Don't fix it if it isn't broke. Don't run a mult-pass radiator either if you don't need it.

Rob the least amount of power and use the lightest parts possible to still cool your engine.

[jrkracing54]

I currently have the AFCO fan and down here in Florida the temps are getting up there. My engine is starting to run a little hot. I was told the GM fan would drop temps up to 30 degree so that's what I'm looking for. If your engine runs o.k. with the AFCO fan then I guess you are lucky.

[Rayburnt1]

I'm with you on this. Don't fix it if it isn't broke. Don't run a mult-pass radiator either if you don't need it.

Rob the least amount of power and use the lightest parts possible to still cool your engine.

What are the disadvantages of a double pass vs. single pass radiator? Horsepower robbing?

[MasterSbilt_Racer]

More fan takes more horsepower to turn. More radiator is heavier and holds more water at 8 pounds per gallon. It also costs more.

[stockcar5]

does a double pass radiator hold more water than a single pass radiator of equal size? if so how much?

[racinjj]

does a double pass radiator hold more water than a single pass radiator of equal size? if so how much?

They hold the same amount of water. The tank size is the same, they are just seperated top and bottom.

[MasterSbilt_Racer]

When I went from a 31 to a 27 the difference in the water it held was almost a half a gallon. The 27 only has 4 inches shorter tubes side to side....

I saved at least 20# by going to a small thin one on my late model. I think it was a 27" single core. I had no trouble cooling plenty of engine and I know someone using the same radiator in a super right now.

[stockcar5]

They hold the same amount of water. The tank size is the same, they are just seperated top and bottom.

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.

[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.