Engine Bay Heat

W

Jim Kreber

I am having concerns with the possible heat build-up in my RCR P4 when stoping / shutting off the engine after a hard run. Not having really driven it much yet, I'm imagining my carbs boiling over.
2002_0101p4fan0060.jpg
I usually try to open the hood on my GTD after a hard run, but can't always do that. Fran made a nice pair of heat shields, but with no air movement, will the carbs perculate? The stock engine headers went down instead of up, so there wouldn't have been an issue.
I was thinking of installing a fan on each side, using an "off delay" relay, so the fans would run a few minutes after shut-down. There are two access openings I could pull cooler air through to blow around the carbs & header.
2002_0101p4fan0058.jpg
2002_0101p4fan0059.jpg
Any suggestions? Is this stupid?
Jim
 
C

Cliff Beer

Jim, super nice P4 - absolutely stunning.

Is there any way to vent out the back of the clam shell? Hot air rises, so, pulling/venting out the cavity from as close to the top may be most efficient. Also, if your fans are running while you're driving then you're not adding positive pressure under the car.

Spal makes very nice high output fans in 8 and 10 and 12 inch sizes - come with very nice plastic shrouds and mounting tabs. Just a suggestion.

More pics of your car!
 
IanAnderson

Ian Anderson

Lifetime Supporter
Jim

I did a similar thing on my GT40

BUT
I use 2 bilge vent fan motors (From Ebay) that move 250cfm each like
2 - NASCAR TYPE BRAKE or BILGE 4" BLOWER FANS -- 41841 : eBay Motors (item 230439515469 end time Feb-25-10 17:00:00 PST)


When I get stuck in traffic the heat used to come back through the bulkhead (fiberglass) so much it got almost too hot to hold my hand against

After fans run for a minute I can comfortably hold the bulkhead

The fans on mine are on the chassis rail - reasonably far forward near the bulkhead and angled in slightly towards the engine / headers and so will draw air in from side scoops and from under the car (no bellypan)

They are noisy but not on unless stationary and needing to cool down

I run them through a simple toggle switch

Ian
 
C

Chuck

Supporter
Where did you get those fans? They look like they were made for that application.

Do they move enough air?

I pre wired my GT40 with the expectation of doing something similar, although have not done it yet. Your approach would be a simple add on without any extra holes needed.
 
D

David Briggs

You can turn the fuel pump off and let the engine run for a couple of minutes before you shut down, that will depressurize the lines and lower the float level and it restart easier.
Do you have any type of insulating material on your heat shields?
Dave
 
W

Jim Kreber

Thanks for the feedback. I got these fans on ebay.
250 Quad Go Cart Pit Bike Electric Radiator Cooling Fan : eBay Motors (item 280464376012 end time Mar-13-10 16:28:46 PST)
I'm making a shroud for them now. I was planning on using them only when stoped or after shut-down. That's where the off-delay relay would come in. I wouldn't want to forget & drain the battery.
David, I like the idea of turning off the pumps for a period before shut-down. Also the less fuel that boils or evaporates means less gunk build-up in the weber bowls.
I have openings in the cover above the engine. I'll post pictures later.
Jim
 
IanAnderson

Ian Anderson

Lifetime Supporter
If the measurements are correct 6 inch diameter (150mm) - No CFM rating advised

The Detmar blowers are inside a 4 inch tube (plastic) that is easily modifiied (Cut) or painted to blend in - using the tube it certainly cancentrates the airflow in a set direction.

You could also gut the motor and fan from the units if you wanted

They are also very light and could be mounted in the rear clip and move with the clip thus leaving the engine bay uncluttered once open. (In fact it could even be "ducted in"

IAn
 
W

Jim Kreber

Ian, if they do move more air, I wonder if part of that tube would fit down in my existing access hole. I could trim the top, and angle it to direct the air flow.
I'll have to see if there is a way to mount them to the rear clip as an alternative, as you say. That might also work.
Jim
 
IanAnderson

Ian Anderson

Lifetime Supporter
Jim

I looked into this quite a bit a couple of years back and got a good selection of computer fans that were said to move high volumes of air

Connect direct to car battery and I could fart harder!

I looked at bike rad fans and a lot of the specs I found rated thaem at about 100 - 150 cfm - yes they move air but not an awful lot!

That said
If you work out the volume of air under your rear clip and then subtract the volume of your engine and gearbox exhausts etc there is not a massive volume of residual air. And if you are even putting in 100cubic feet per minute you are doing numerous air changes.

Perhaps 250cfm per side is overkill but I know it works!

Ian
 
J

Jim Cowden

Jim love your car

As you stated in your first post you havnt driven the car yet.
Why bother doing anything until you have, as there may not be a problem at all?.
Why complicate if you dont have to.

Jim
 
A

David Sturch

Jim,
I have some computer chassis fans left over from my computer buisiness that I closed this year. They are 120x120x25mm ETRI 298DH1LP two speed fan 40,8 lps 2490 rpm 12v 4.32w or 17cfm and 85cfm if you can use them. I may have some temperature sensors you can wire in also in 140-180 deg range. You can place the sensor where you want to kick the fans to a higher speed. PM if you are interested. These are a good quality fan.
Dave
 
W

Frank Catt

Another idea to play with, we did this years ago to reduce heat soak after track use.
 

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Big-Foot

Randy V

Moderator-Admin
Staff member
Admin
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Frank - That's a pretty cool Type-R Supercharger you have there :thumbsup: :lipsrsealed: :thumbsup:

At first I thought it was just something you set on top of the carbs when you're done racing for the day, but apparently it's mounted for the ride as well...

Never thought of doing that...
 
W

Frank Catt

No guys, it was designed to rapidly reduce heat soak into the carbs after stopping at the race track. Webers suffer from boiling the fuel in the float chambers, expanding it to overflow and lay on the butterflys, which can then readily catch fire. I have seen many fires under the closed rear decks of a GT40, usually the next time the car is fired up hot. A no Scott, the sealed motor has never caused any problems ! Frank
 
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