[Cole]

I am using a Zirgo 16 inch 3000 CFM electric puller fan on my radiator to cool the 350HO crate engine. Question is do you need a fan shroud? It is butted right up to the radiator so i am kind wondering if I still need one..

Update... Well after reading old posts the answer i guess is no...

[usmcsawgunner]

yea no you dont need one but what you can get is some high temp like weatherstripping....not exactly sure what its called but you put that inbetween the fan and radiator and it will ensure that all the air its pulling is thru the radiator...

[old cars]

Yes you need a shroud it helps to keep it cooler

[SSedan64]

Easy to answer. If you're having cooling problems you need a shroud. If not leave it alone.

[usmcsawgunner]

whats the point of a shroud on a puller fan thats actuall on the radiator?....btw the weatherstripping stuff will ovbiously go around the circumference of the fan....

[oldbogie]

Originally Posted by Cole

I am using a Zirgo 16 inch 3000 CFM electric puller fan on my radiator to cool the 350HO crate engine. Question is do you need a fan shroud? It is butted right up to the radiator so i am kind wondering if I still need one..

Update... Well after reading old posts the answer i guess is no...

Yes, but in your case maybe no difference in performance.

The purpose of a shroud when using a puller fan is that the fan alone only pulls air thru the radiator core in the area immediatly in front of the fan. The rest of the core is essentially not contributing to cooling the coolant. By moving the fan back a few inches and surrounding the radiator core with a shroud back to the fan, the fan then creates a low pressure area behind the entire core causing air to flow thru all of it rather than just the part in front of the fan.

A pusher fan is a bigger problem, as a shroud between it and the radiator doesn't change the flow pattern in any significant way so most air is blown thru the core in an area about the size of the fan blades.

The solution to a pusher configuration is multiple smaller fans that can cover more of the radiator's core surface. In the case of a close coupled puller fan such as yours, the solution would be the same, more but smaller fans pulling air thru more of the core area.

It is unfortunate that the advertisers want to talk about more CFM from a single fan with a more powerful motor, when the real solution is pulling air over more core area which will take several smaller fans.

Bogie

[malc]

A shroud will ensure the fan pulls air through the whole of the rad not just the fans diameter.
I got two fans and a completely enclosed shroud, no more heat problems.

[usmcsawgunner]

yea thats the concept behind the weatherstripping stuff....i guess thats considered a shroud....

[eloc431962]

hey cole i agree with ssedan64.if it running cool without it i wouldnt worry about it. cole

[malc]

Originally Posted by usmcsawgunner

yea thats the concept behind the weatherstripping stuff....i guess thats considered a shroud....

A shroud is a device that makes the fan draw air from the surface of the whole rad, not just a strip of rubber around the circumference of the fan sealing it to the rad.

[Cole]

Well the problem is that it is gettting warmer (220+) than I would like to see. It's fine on the freeway but if I am on surface streets it does get warm unless I stay off the pedel. I had to take the engine and transmission out last last night to address another problem so I thought this would be a good time to consider installing a shroud. It's been in the 80's here but in the summer we are looking at 100+ on some days. I guess this should be a no-brainer but I am also considering a larger radiator too or maybe both? I guess I should just start with a shroud and see how it goes?
Is there a kit so I can make a custom one for may configuration and if so who sells them?

[timothale]

there's a tech article Wiki about how to build a good looking custom fan shroud.

[Cole]

Thanks for all the help!!
I actually found a company that will build me a custom shroud (w/out fan so I have to send in mine) for only $100 so I think I am going to start there and see how it goes!!!