Non-ducted Oil Coolers
 

I know a bunch of you guys have done similar things with those big ass RX7 coolers.

I've got a big Setrab (around 8x11") but not a lot of room to mount it and nowhere that lends itself to ducting. I'm thinking about mounting it in front of the pass side wheel (ive got an opening there behind the air dam) and just strapping a 7.5" Spal on it to get some airflow.

So, for those of you who have experience with non-ducted fans: Will it work?

The fan adds weight and complexity but the thermal capacity of the cooler is a non-critical system (unlike an electric water pump for example). If you have room for it behind the air dam, why not a naca duct to provide some air?

I am doubtful the fan will help much.

After doing a little calculating, it looks like you're right.

The fan would pull 440 cfm. A 3" hose being fed 60 mph air will flow 1037 cfm. I think I'll do both.

Of course neither of those numbers take pressure or the restriction due to the oil cooler into account, but its a start.

Why not stack it above the intercooler? That's where I put my rx-cooler. Lots of room and lots of air.

Any idea of what current oil temps are around the track? I'm running a cooler that size behind a small vent in my front bumper.

i have the Setrab and suggested to Hustler that we put the oil cooler in the wheel well area. He laughed and told me to STFU. He had his there and it caught all sorts of debris, somewhere around here is a pic of his old setup. He suggested a smaller cooler mounted on the top of the rad area. it's hard to explain, but he has pics and shit and it looks good.

Just get a 13-row Setrab and stick it in the heat exchanger box.

I put mine in the wheel well area and made a shield for the back side of it. Plenty of room for air to flow..

as long as its protected I dont see a problem with mounting it in the wheel well. E9x m3's have their transmission coolers mounted there.

Airflow is defiantly better since you will get more cfm through the core face. Airflow is key to good heat rejection. The problem with the 7.5" spals is that they suck. One 9" will do much better, however the size is limited.

Do you know how much heat you want to get rid of?

All of it. :rofl:

But seriously: no I don't, and I'm way too lazy to pull out my heat transfer book and start doing calculations. All I know is that my current B&M mounted behind the radiator isn't cutting it (yes, Hulster, you told me so)

Hustler: I don't need a smaller cooler to be able to fit it in the heat exchanger box, but I would rather not block air from the radiator seeing as I have water temp problems too.

Why are you having CLT issues at 8psi?

My oil cooler does not block or share air-flow with the radiator:
https://www.miataturbo.net/attachmen...ine=1365427149

Very good question. Its driving me nuts.

I have a fully ducted big ass Chinese radiator, with just straight water and water wetter, and a big B&M oil cooler strapped to the back of it. As well as big hole cut in the hood.

I've also "burped" the system by jacking the front end as high as my jack stands would go, putting a piece of cardboard in front of the radiator, and letting it get nice and hot with the rad cap off to let any air escape.

Possible problems I've identified:
1. I don't have a reroute, but my understanding is that won't help with overall temp issues... so I want to figure that out first.

2.The intercooler takes up 95% of the opening to the radiator... maybe I need to open up the ducting to allow more air around the intercooler?

3. Like I said, the oil cooler on the back of the radiator isn't the best setup... but the water temp overheated badly before this, so I don't think its the culprit.

If your ducting is tight against the perimeter of the IC core but is not thoroughly sealed from the bumper all the way back to the radiator, then there may not be enough air getting back to the rad. If it's not totally sealed, but you are channeling air through a decently configured duct, then some airflow around the IC core will most likely benefit you. Also, having a tray extend from the rear of the rad to the subframe will help keep pressure low behind the rad.

I've ducted a bunch of cars and I always move some fresh air around the IC core because I have not been able to seal them completely (street cars with factory bumper guts) and I see great results that way. I have a pretty big IC core (for a Miata) and my own leaky ducting, so mine dips down below the core so fresh air can get to the rad because it's not totally sealed. My car is not a track-only car so take this with a grain of salt, but I beat the bejesus out of it in the mountains here (6-8000' elevation so worse cooling potential to begin with), and my typical coolant temps are 215* at most. I've had it on track at one lapping day with the same ducting setup and it never got over 225-230* during the 20min sessions.

My oil gets fairly hot in those same situations (no oil cooler installed). Yesterday in the mountains I bumped up to about 240* a couple of times, and IIRC on track it was pegged at 250* for most of the time.

Stock radiator, no reroute, 15g@15psi.

My ducting is a fully 100% sealed tunnel all the way from the radiator to the inlet.

Have you considered that it is not a cooler problem, but rather a heating issue? Just brainstorming/wondering about the basics: What kind of timing are you running? Are your egt's high or do you see signs of detonation? Lean afr's?

You can stack a really big rx-7 cooler in the wind on top of the intercooler, or you can lay a cooler passively; horizontal as Hustler did. But if you are getting unusually high temps, then your problem might be unusually high heat production.

Why not check the basics; even try some race fuel... that'd cool it down if it were coming from a ragged edge tune.

If still too hot, then look at your coolant flow; no thermostat/not enough restriction and too fast of coolant flow? Kinked line/too much restriction? Cracked head or head gasket issue pressurizing the system can also look a little like overheating.

How thick is the IC core?

Hustler... How is your front end/ rad sealed with the oil cooler like that?

Do you have more pics?

I pulled my bumper off and laid my 13 row SETRAB on top of the intercooler. it is a tight squeeze and sealing my radiator to the bumper inlet isn't going to be easy.

https://www.miataturbo.net/attachmen...ine=1365467899

https://www.miataturbo.net/attachmen...ine=1365467899

Ignore the white jizzzzz from wetsanding my fresh paint last spring.