Size and location of the cooler also matter. Being that you have a large cooler mounted behind the radiator, I expect that the heated air leaving the radiator serves a warming role for the oil cooler to some 'degree'. At a certain temperature, the threshold is reached, at which the warm air serves a cooling role. It would be interesting to know that threshold in various conditions. Front mounted coolers surely behave differently.

Has anyone mounted a fan to their cooler? I've been considering ducting a cooler in but I'm space limited so I was thinking of mounting it to my undertray and slapping a temperature controlled fan to the 25row and having it kick on w/e temps get above a threshold (undetermined, maybe 225-250*?) - It's not ideal (fan had a 330 cfm rating) but certainly would be better than just leaving a cooler hanging with no ducting no?

Edit; This is the fan I was looking at. Unsure yet how control it yet though. $170 is a lot better than the Setrab vendors are selling the official 'kit' which includes a new radiator with it for ($400+)
https://cimg1.ibsrv.net/gimg/www.mia...3fa9a8e982.jpg

I believe Mocal/Setrab sells a thermoswitch setup for this specific purpose? Can't find it atm because phone, but like the tooth fairy, I believe it exists somewhere.

Do you have an oil temp sensor going to your hydra? Did your car used to have AC? If so you could probably use the AC fan wire to run that fan based on oil temps.

At least that is how I would do it on my Ms3.

They do but the one I found has a ON temp of 190 which would basically leave it always on if I put the 205* tstat in. There might be other (unlisted) options, I've emailed Setrab to inquire.

Good idea, I don't have A/C on this shell (did on my last one though..) if I have the outputs I could have the Hydra kick on a relay. I'll have to see what the draw on the fan when ramping up/running would be. Amps are gonna be tight once I put lighting in.

Another idea I had was to place the oil cooler parallel with the ground (on top of the undertray) and cutting a hole in the tray and putting a small gurney flap in front of the hole to draw hot air down and out to below the car, but I don't want to overcool my car since we get some cold days up here. I just wonder how effective 330cfm would actually be though.

That is very common on race cars where pakaging is very important and real eastate is at a premium

BUMP>>>>> Just curious how to handle an enduro car (8, 12, 24 hour races). Stock 1.8 na motor, stock radiator & oil temps 250+, have lost 2 motors. Car owner needs some direction.

Without more information no one can help you. Do you have an oil cooler?

What is the failure mode? Is it rod knock due to a bad bearing from oil or lack of pressure, Pistons gouging the cylinder wall due to overheating, or is it Rod through the block possibly due to stretched stock rods?

Ducting is usually the most common problem. All of the air that enters the bumper mouth must be forced to go through the radiator and not escape around the bumper cover into the wheel wells, underneath the car, or over the radiator. This usually calls for lots of plastic or metal paneling, sealing tape, and sometimes foam padding to block openings. It must be perfectly sealed. Stock cars fail on the street without proper ducting and undertray. Even more so on the track.

Beyond that a coolant reroute from 949 racing or similar will make a big difference. Additionally, sourcing a larger, competently designed radiator from them or from track speed will take you the rest of the way there with a stock engine. But none of this is any good without sealed ducting. Once you have sealed ducting, a reroute, and a properly designed radiator you should not see any overheating ever at stock power levels. I didn't need an oil cooler in the Florida heat on track until I reached the top side of 200 horsepower with a turbo.

What oil are you using?

We run a Champ/Chump car with a refreshed BP4W in an NA running an OEM radiator. All our races are in the Southeast (KY, GA, FL). Four things we do to keep oil temps down.

1. Use the factory oil cooler. Contrary to what most people think, they do work to keep the oil temps down after warm-up.
2. Coolant reroute. The cooler the water temp is, the cooler it'll keep the oil temp.
3. Ducting. Same as No. 2, more efficient radiator = less heat in oil.
4. Don't over fill the oil! If you're motor is burning/loosing oil, fix or rebuild it. We've seen a 10-15° increase in oil temps when we've added even as much as .5qt of oil more than needed. It whips the oil up and reduces its heat capacity.

Number 4 surprises me. I usually run a little extra oil for starvation prevention.

We run right at top of the stock dip stick (presumed to be the matching one to the motor). We usually burn/loose a little oil (.25qt or less) in a 2 hour stint. At the start of a race someone had added oil twice to the motor and we were seeing 250+ oil temps. As it burned down it the temps dropped to 230-240° which is right about normal for our summer races. We run Redline 5w30 Race. If the oil gets whipped up by the crank too much, it gets air bubbles in it which don't transfer heat as well (at least that's the theory I was told).

Car is basically stock w/o oil cooler or "big radiator". Also starting a build on a second car for the same purpose.

SIXSHOOTER. Thanks for your thoughtful response. We do not have ducting and are running the stock radiator. Lost both motors due to rod/bearing failure. One at High Plains and the other at Hallett. Car owner runs various oil brands, generally a 10w40 weight.

Ducting, reroute, bigger radiator, proper oil, problem solved.

If you are racing you should be using racing oil. It won't solve the problem by itself but it can be a little more forgiving when the temps get out of normal operating range.

Well, as a quick google search will tell, its not abnormal to see miatas with near 300F oil temperatures without any oil cooling.
First step is to definitely add one. Trackspeed sells a kit with various setrab cores which appears to be very inexpensive for the components you are getting, so much so that its basically a no brainer rather than piecing all the parts yourself.

As said, dont bother removing the OEM oil cooler/warmer unless its rotten or something.

TIL about running high oil levels.

A lot of Spec Miata racers run 20W racing oil at the bottom of the dipstick to keep it from frothing, and have no troubles maintaining pressure with oil that light, and an oil level that low. I run mine halfway between L and F. If I run it any higher than that, the balance ends up in the catch can under track forces.

Since I just track my (normally aspirated) car for fun and don't have to follow any rule book, I put the equivalent of a Trackspeed oil cooler kit in front of my radiator. Between that and the Koyo radiator (with proper ducting and sealing), I see a peak coolant temp of 208F and a peak oil temp of ~230F in the Texas summer heat. For oil, I run Mobil 1 0W40 and drain it every 8 track hours, but if I were actually racing, I would use a proper racing oil.

If you are running only 1 fan, you can put a large cooler, like an 11x11 Long TruCool, behind the radiator and utilize the fan mounts and save a little money. Racer Parts Wholesale sells inexpensive kits based on Mocal, Aeroquip, and Long parts.

.

Thanks everyone. This confirms what I have believed. It is not just one thing but a few details. It is the Miata way. We typically see 250+ oil temps and 210 to 215 coolant. And we run for 8+ hours this way. I will pass this along to the owner (I am just the wrench).

Is there any advantage to eliminating the piston squitter's in a na motor? What disadvantages?

What about Rotella Synthetic T6 for oil

You guys actually have that much faith in Miata dipstick readings?

I usually take a few readings and if one of them looks like the oil is between MIN&MAX I pray that it's correct.

Not sure if this is a Mazda thing, my SP23 is hard to read too - never had issues with other manufacturers.

Given how sensitive rotary engines are, you'd think that Mazda of all companies would have idiot-proof, easy-to-read oil dipsticks!

Start from empty.
Insert 4qt.
Read dipstick.
Take note if not correct on dipstick.
Re-mark dipstick if necessary.