Front Air Dam

[D7N7MASTER]

Anyone notice any oil temp differences after installing a front air dam?

[skline]

I have a LE spoiler on the front of mine and it ran a little warmer but when I changed my exhaust system it dropped right back down. If it is an early model, get the little deflectors that mount on the bottom of the front firewall. I hear they make a difference in cooling.

Yellow cars are faster

[Marv's3.2six]

I don't see how there could be a difference in temp because of an air dam?

Intake air for combustion and cooling is sucked in from the top, thru the engine cover and exits under the car and out the back and that air is under pressure and unless it can't escape, please explain to me how an air dam makes a diff?

[Brant]

Marv,

If less air that flows under the car this can result in less of a low pressure area...

thus air is not pulled through from the top with as much efficiency.

Yes it does make a difference. Yes I have noticed it as a change in oil temp.

I recommend using a guage.

brant

[chrisreale]

No, I have not noticed a difference. At all. Yesterday was 75 degrees on the freeway, I was driving from Portland to Seattle at 3500 rpm pretty much the whole way and my oil temps were 210.

[D7N7MASTER]

WoooHooo! So let's see... it does & it doesn't? I'm talkin' about driving from Orange County, Ca. to Las Vegas in July kind of hot. I asked because a design engineer at work asked me if I had enhanced my 914's cooling system (cooler/fan/sump) when he saw my new air dam. I said no, but that I had bought oil temp & pressure guages & senders. Just haven't had the time to install. He said that the underside of the car is "starved" for air by the air dam. That's why the car has less lift at speed. But, if the cooling system needs the air turbulance to enhance efficiency, the system may run hotter due to the air dam - based on ambient temp diff - hotter may not matter. Or it does. Alot. I've heard that adding RX7 oil coolers are a good insurance policy against overheating. Is there a "914" (common) upgrade?
Thanks,
Gary

[Marv's3.2six]

"If less air that flows under the car this can result in less of a low pressure area...
thus air is not pulled through from the top with as much efficiency. "

...Sorry I just can't buy that argument.

"That's why the car has less lift at speed. But, if the cooling system needs the air turbulance to enhance efficiency, the system may run hotter due to the air dam - based on ambient temp diff - hotter may not matter."

.....This argument is more plausible, its possible that the increased air flow under the car will help scavange the FORCED air being exhausted under the engine.

If the top argument were true then PORSCHE would have had overheating problems for over 50 years on air cooled race cars that the air dams were just an inch or two above the tarmac.

[skline]

It doesnt have to be an RX7 cooler, there are companies that make coolers for the VW's and Porsches. Anything is an improvement but the multipass coolers and fans work much better. There is a 72 pass with fan on Ebay for $139.00 but I have seen them at VW Parts Unlimited for less. I am running the CB Performance remote oil filter and cooler and it works fine. Much easier and cleaner than the sandwich adapter. Cheap too.

[Brant]

Marv,

I think the 2 arguments are making similar points. It may be that I'm just not expressing my thoughts very well.

The air under the car does create lift, but it also aids somewhat in helping to drawl air through the cooling system...

The factory race cars... Well, for one the factory 914 race cars didn't have huge aggressive spoilers in part because aerodynamics were not as well understood in 1970.

Second, They ALL ran front oil coolers.... They cooled the motor oil with a different and improved system.

If you add a front cooler then the needs of the factory cooling system is reduced.

My own experience in playing with this.. was that with the minimum clearance of a few inches and a factory cooling system, you could redline the oil temp at 90mph sustained. Further that just by increasing the front ground clearance (changing the spoiler) you could reduce the temp.

put a guage on it, and try measuring temp with different spoilers

brant

[Dave at Pelican Parts]

The flaps that stuck down just in front of the engine bay create a low-pressure area directly under the engine. This helps suck the air out from around the engine--cooling air that has been heated up by contact with the engine's fins. More air gets pushed in by the engine cooling fan. The result is a reduction in oil and head temperatures.

If you don't have these flaps (which were added in 72 or 73), it is a Very Good Idea to add them. There are measurements in Haynes for adding them.

I would expect a similar thing to happen when a front air dam is used--I would expect better cooling, not worse.

Then again, aerodynamics is a really weird and wonky subject. So it is possible that things get worse--but I would be somewhat surprised.

--DD