Allum Radiator choices

[BBC69Camaro]

Hey Chicane -

I was looking at CarlC's pictures of his radiator. I'm sure his setup works wonders. But I don't see a shroud over the radiator. Wouldn't you want a shroud to make sure the air is pulled through more of the radiator instead of just what the fan covers?

CarlC's -


Ron Davis -


I'm certainly no expert but my understanding is the more area you can pull air through the greater the cooling.

[ProdigyCustoms]

Here ya go. $300 cheaper then a Ron Davis. We have Ron Davis also. These are $900 and include dual 13" fans, 3490 CFM, Cross flow design, Steamline, LSX ready. I have them on the shelf, many here are running them.

[WSSix]

Originally Posted by BBC69Camaro

Hey Chicane -

I was looking at CarlC's pictures of his radiator. I'm sure his setup works wonders. But I don't see a shroud over the radiator. Wouldn't you want a shroud to make sure the air is pulled through more of the radiator instead of just what the fan covers?


I'm certainly no expert but my understanding is the more area you can pull air through the greater the cooling.

You're correct to a point. When the car is moving at anything over about 35 mph, you don't need the fan(s). This is why a GM ECM for instance includes a MPH shut off as well as a temp shut off. When air is being forced through the radiator with just the movement of the car, a shroud covering the whole radiator can block the air by forcing it through the shroud opening only. Factory fan shrouds do not cover a radiator completely either. I'm sure full race cars may be different but for a street car, a full shroud is not necessary usually.

[Vegas69]

That's ok in a factory situation where big horsepower is usually not under the hood. Let's face it....horsepower is heat. Who had ever had trouble cooling an engine driving down the road? It's all about city driving at low speed. That's when you need that full shroud and dual spals kicking aise non stop. Especially when it's 100 degrees 5 months a year.

[WSSix]

Originally Posted by Vegas69

That's ok in a factory situation where big horsepower is usually not under the hood. Let's face it....horsepower is heat. Who had ever had trouble cooling an engine driving down the road? It's all about city driving at low speed. That's when you need that full shroud and dual spals kicking aise non stop. Especially when it's 100 degrees 5 months a year.

Very true but the C6 Z06 and I'm betting ZR1 don't have a full shroud. No C5 or normal C6 does. You're also not producing huge horsepower sitting still or idling in traffic so you're not producing any more heat. Of course you have to know the capacity of both the fan and radiator before you can say if a partially cover radiator/ fan combination will work.

[Vegas69]

True but my c5 fan turned on at 232 degrees. Don't need much snort on your fan to maintain that temp. Carbs hate heat and it's not that optimal. 600 hp car still makes more heat at idle than 350. It's all relative. I have a dual fan with full shroud and I can't get any heat in mine when it's 70 crusing. 180 stat and it runs 150-165 on the highway. Summer it runs 180-190 with full shroud at speed. Keep in mind the factory is going to use what it can get by with. For us hot rod builders we want our temps in a specific range and it's usually around town idling that causes issues. On the track then no shroud is probably ok.

[WSSix]

Originally Posted by Vegas69

True but my c5 fan turned on at 232 degrees. Don't need much snort on your fan to maintain that temp. Carbs hate heat and it's not that optimal. 600 hp car still makes more heat at idle than 350. It's all relative. I have a dual fan with full shroud and I can't get any heat in mine when it's 70 crusing. 180 stat and it runs 150-165 on the highway. Summer it runs 180-190 with full shroud at speed. Keep in mind the factory is going to use what it can get by with. For us hot rod builders we want our temps in a specific range and it's usually around town idling that causes issues. On the track then no shroud is probably ok.

The reason the temp gets so high in your C5 is tuning for emission reasons, nothing more. The factory fans are very strong. After tuning and a 160* stat most C5s run 190-205 all the time. C6s use a single fan with a delta controller to maintain a certain temp with every varying fan speeds which is better for the engine versus cyclic heating up and cooling down that an on/off fan setup causes.

You're right it is relative and the whole picture must be looked at. You can have different block designs and cylinder wall thickness greatly affecting coolant temps. Horsepower alone is not the only variable. For instance, in a few weeks I'll have completed a 600+ hp C5. It will not run any hotter than stock at any time other than when I put it under boost. It'll have factory everything cooling wise because it's a street car. Our last blown C5 made 550hp and had no issues cooling.

Also, if you're coolant temps really are that low, are you sure your oil temps are adequately high enough? There is such a thing as too cold for the engine.

[Vegas69]

I have been a little concerned about that actually. I should take a oil pan reading next time out. What is minimum oil temp reccomended? At 150-165 cooland I am assuming oil temp of 175-190. Engine takes forever to get temp in it initially as well.

[chicane]

Originally Posted by BBC69Camaro

Hey Chicane -

I was looking at CarlC's pictures of his radiator. I'm sure his setup works wonders. But I don't see a shroud over the radiator. Wouldn't you want a shroud to make sure the air is pulled through more of the radiator instead of just what the fan covers?

Well... no... not necessarily. The fact of the matter is, that you dont need or want a shroud unless the vehicle is standing still.

In fact... covering the radiator with a perpendicular panel, like that shown in the Ron Davis and Prodigy picture's, actually adds restriction to gross flow and may only help you when the vehicle is at a low speed, or stopped. In reality, that specific design really only works when the fan is operating (and only up to a certain speed)... other than that... it only provides a restriction to any naturally occuring flow through air. You also loose a fair amount of surface area with the fan overlapping the tanks as well. And, I bet if you did the math... that the single fan that Carl is running has more active surface area than that of the two fan set ups shown in the Davis and Prodigy pictures.

(4 pi r^2)

Also... not to forget to mention... that the fan that Carl is running... pulls way more air than that of the two Spal fans that the Davis... or... Prodigy set up uses.

Now... if you do a lot of parking lot cruising, car shows and sitting in bumper to bumper traffic... then it may work, albiet probably not all that much better.

C&R cross flow radiator with a 13 plate heat exchanger = $650
18.5" Ford/Lincoln Mark VIII fan = $150 - $200

$850 for a radiator with superior cooling capacity, a built in heat exchanger for *proper* oil cooling and a fan that pulls over 5000 cfm = no brainer.

[Vegas69]

In a racing situation I absolutely agree.....5000 cfm out of one fan?