Is a 3.2 fender cooler up to cooling a 2.7 RSR-ish spec motor?

[obrut]

Greetings all,

I have a 2.7 RSR-ish spec motor in my track/rally car (MFI, 10.5:1, GE80 etc) and a 3.2 Carrera fender mounted oil cooler. I have also removed the adjacent battery box.

A recent warm track day saw temps of about 235. I removed the turn signal box and they dropped a little, maybe 225-230.

In terms of size, is this cooler up to the task?

Do I just need more air flow?

I am thinking of cutting a large (say 4" by 5") hole in my spoiler and running some ducting to the cooler. I'm assuming that the air presently coming in through the grill is spilling out the bottom instead of passing through the cooler.

A central spoiler mounted cooler is not an option - as I tarmac rally this car and they are just too vulnerable (ie. broke one 2 years ago).

I look forward to your thoughts - especially from those with a similar setup.

[MotoSook]

230-ish ain't bad for a hot track day....you could always add a fan to the cooler.

[obrut]

Hi Souk

I don't think a fan will help - I would be suprised if a fan could flow more air than a vent at 100mph.

I thought fans are only really helpful for preventing overheating at low traffic speeds.

[911pcars]

If the fender is the only viable location, then start ventilating the areas you addressed. The headlight bucket is another large collector for air. Add holes at the back or one large opening. The front bumper directly in front of the cooler can be opened up with a series of 1-2" holes. Use stiff stainless steel mesh at all openings to ward off the heavy road debris. Fabricate some heavy plastic/ABS/vinyl around the cooler to direct all air through it instead of around it.

Early or late chassis? Meaning do you have a battery boxes pointing into the inner fender? If so, delete them. You can also plumb another cooler in series in the LF fender with the same swiss cheese hole patterns for air flow.

Use a fan if operating the vehicle at legal speeds and below. Above that threshold, a fan is probably not necessary, but air flow is. If more drastic cooling is necessary beyond this, let me know.

Sherwood

[911pcars]

If the fender is the only viable location, then start ventilating the areas you addressed. The headlight bucket is another large collector for air. Add holes at the back or one large opening. The front bumper directly in front of the cooler can be opened up with a series of 1-2" holes. Use stiff stainless steel mesh at all openings to ward off the heavy road debris. Fabricate some heavy plastic/ABS/vinyl around the cooler to direct all air through it instead of around it.

Early or late chassis? Meaning do you have battery boxes pointing into the inner fender? If so, delete them. You can also plumb another cooler in series in the LF fender with the same swiss cheese hole patterns for air flow.

Use a fan if operating the vehicle at legal speeds and below. Above that threshold, a fan is probably not necessary, but air flow is. If more drastic cooling is necessary beyond this, let me know.

Sherwood

[obrut]

Thanks Sherwood,

Its a 70 chassis and the battery box has been removed but I can't remove a headlight as they are required for rallies. The sides of the cooler are sealed to the inner fender.

Looks like i'm chopping some holes in the front spoiler and fabbing up a duct to the cooler. I'll let you know how it goes.

[MotoSook]

I've seen a car with a fender mounted radiator type cooler which had a boxed section of sheet metal to direct air up and onto the cooler from below the spoiler lip.

Basically duct the air to it from below...it's hard to explain, but I might sket ch a drawing...later for you.

[911pcars]

Souk,
Good point. Since this is a track/rally-purpose car, then why not go with the best location so far shown in many installs - a large rectangular cooler in the front, but install it far enough from a nerf-reinforced front end to create an adequate crush and rock deflection zone. This presumes you don't need a spare tire. If you do, put it (them) in the back seat.

Owners frequently report their cars with front-mounted coolers routinely have temps in the 200-210ºF range, that in hot weather. I'd say a racier engine with an appropriately-sized cooler shouldn't be too worst than that.

Sheet metal then is all you need to duct air into and out of the cooler from the holey front bumper. Provide a path for exit air toward the rear of the trunk lid or into the inner front fenders, maybe add a couple of thermostatic/manually-controlled inline duct fans to boost air flow at lower rally speeds. A center mount location should also provide better cooler protection from potential fender crushing episodes.

Sherwood

[jpnovak]

cut a hole in the lower section of the front bumper above the lower lip. Then use sheet metal to block off the section from the lip to the fender well and bottom of the cooler. This will force all the air through the cooler. The horn grills are just not large enough to move the large volume of air.

Another option instead of cutting the bumper is to remove the TS housing. Rig some LEDs for the lights and leave that slice open. I have seen some R type covers that could be cut and filled with wire mesh to increase air flow.

[unimog]

Ryan,
You could always add a second Carrera oil cooler in the other wheelwell and tie the two together..... 'ala 4 cam 356 Carreras

[obrut]

Hey Mark

I thought about that - but I'm trying to forget the time/effort it took to remove the first battery box.

I'll try the easier stuff first - if the ducting gets me closer to 210-220 on Sydney summer days then I'll be pretty happy. I think the trick is sealing the underside of the spoiler to the cooler so that the air you admit can't just spill out again (without travelling through the cooler)