I was doing HPDE 3 at this year's hyperfest and it was pretty hot, and although my water temps were perfect (went quickly up to 198 and stayed there) my oil temps were a bit high. Oil would get to 205-210 and I'd take a lap at slower speed to cool things down a bit.

I was running valvoline 20w50 at the recommendation of my mechanic, he said that it shows better temps than running castrol 20w50.

I figure running a synthetic may bring the temps down some more. All of the synthetics claim a small HP boost, and the only place that it could come from is reduced friction, which means reduced heat in the oil as well.

He said Amsoil is what he recommends, but thought that the 20w50 might be too heavy. I've always heard that 20w50 is the best choice in hot weather and heavyt duty. Anybody have any thoughts? The car is a 1990 T2 with street port and a pretty open exhaust, stock turbo and IC, with a Microtech ECU and making 213RWHP at only 8lbs of boost. No OMP to worry about, I'm running premix.

Any general tips for getting the oil temps down would be good too. I have a nice big
fluidyne rad, the FC stock oil cooler, no AC, and some ductwork, weather stripping, and a radiator panel to make sure the air gets where it needs to go. I also still have the stock undertray.

 

I'll be brief -

20w50 is a good weight. As for the synthetic v. dino-juice debate, I'll just say that both will be fine as long as you change your oil at regular intervals (esp. before track events).

IIRC, in general your oil temps will tend to run a bit higher than the coolant depending where you are taking the temps (oil filter pedistal?) 205-210 may not be too bad.

Claims that synthetic oils increase HP in any significant way have never been proven on the dyno (AFAIK). As for reducing oil temps - I do not know.

You will not reduce oil temps by reducing engine friction. The combustion cycle generates most of the heat.

There was a recent discussion on adding a second oil cooler for FC's. Go back and check the archives. Many of the club racers add the second coolers to their NA FC to keep oil temps under control.

Good luck,

-bill

 

A lot of folks (including me) run synthetic at the track with good results. If you're afraid of synthetic in a rotary (no need to be in my opinion) you can always change back to regular oil after each track day.

 

I'll look into that second oil cooler idea.

I'm not afriad of the synthetic, and I've got no OMP and am running redline synthetic two stroke premix. I'm just trying to pick the best oil to use. I change the oil before (if needed) and after track events as a matter of course.

 

Ducting. The stock oil cooler will work fine, duct the oil cooler with light aluminum so the air has to pass through. I use a small chin poiler with the air ducted through the oil cooler and rad. I've riveted the aluminum to the bottom of the rad for a tight seal, so all the air has to pass through the oil cooler and then the rad. My car is making 341 hp at the wheels and the oil temp is 190 tops. This is a road race car and in an hour long race it ran without a hitch on a warm day (85 degrees outdoors). I was driving it as if it was a sprint race, so it was taking a good deal of abuse.
In my old 1st gen my oil routinely got up around 220 without issue. I run Mobil 1 20-50W.

-Trent

 

According to Racing Beat they experienced lower temps when running synthetic v. conventional. According to Red Line straight weight oils have better high heat properties than multi-grades.

And IMO and experience, for serious track use, a single stock cooler is not sufficient regardless of ducting. The solutions are plentiful but the fact of the matter is that every seriously competitive FC I've seen needed some form of added oil cooling. And most of those are well under your 213whp.

 

Hey Gene, this is BJ the guy from hyperfest. Just wanted to chime in here what else is required for the dual oil cooler setup. Do I need to increase the oil pressure to compensate for the drop in pressure? I know the added oil capacity alone will help with dissipating the heat.

thanks for any help on this

 

Haha, you're asking the wrong guy(not the wrong Gene, that was me at hyperfizzle), I don't have two oil coolers yet. Here's the thread I found with some useful info and pictures:

https://www.rx7club.com/showthread.p...ght=oil+cooler

I like the idea of using two stock coolers since I can get my hands on a second cooler and some hoses for quite a bit less money than my FD3S R1-inspired idea of putting coolers in the side ducts. If it's not adequate I could always try that idea later and reuse the hose ends since they're not cheap.

I have a racing high pressure regulator in mine, but in theory, running two coolers in parallel should actually reduce pressure drop, not add to it. Running them in series would increase pressure drop.

 

Where are you measuring from?

210 is no big deal, I wouldnt be worried until you get over 240. Even Mazda says up to 230 is normal...

http://www.mazdamotorsports.com/weba...1&subject=misc

 

^agreed

 

I have always been curious as to why rotary guys sweat soo much over temps.
My fathers Z06 regularly sees 260-280 oil temps at teh track and so does every other vette owner.
My audi sees 225-230 just driving on the highway to and fro to work.

I am a person that likes to play it safe and I want my car to stay cool but damn if I am gonna pay 1000 bucks for the dual oil cooler kit that one company is selling.

Right now I have a dual pass Koyo, stock oil cooler, and soon a front mount intercooler. I believe with proper duct work it will be cool.

And yeah I was shooting for 235 max oil temp.

 

On the oil filter pedestal.

 

Which should be significantly cooler than the temps found in the pan.

 

Because IIRC in a rotary engine the oil plays a much more significant role in cooling than in piston engines. Also as we all know over heating a rotary tends to be much more terminal than in a piston engine, so we pay a lot closer attention to it.

-b

 

the oil cools the rotors, so not only do high oil temps hurt durability, they also hurt power.

we asked jim mederer about this and his answer didnt make sense right away, but the higher the oil temps the lower, to use his word, delta T. in other words the hotter the oil, the less it can cool the rotor. and at some point you get into a temp spiral, where oil (or water) is too hot, and it starts heating up the coolant, and so on.

 

oil cooling is responsible for 1/3 of total rotormotor engine cooling.

 

You were only seeing 210 at the oil pedestal at Hyperfest with a single cooler??

I was seeing over 250 with my touring and then I'd pit in and cool down halfway through my run group (HPDE2).

I installed an R1 dual cooler last weekend. Will see how that helps at Shenenadoah this weekend.

 

I'm pretty sure the FC cooler is better than the FD single cooler. How much power are you making? More than stock? Any cooling mods? I'm running a big fluidyne aluminum radiator and water wetter in the coolant, with some ductwork to get all the air onto the radiator and oil cooler, and have the coolant jacket mod and an underdriven water pump. All this keeps the water temp down to a nice 195-198, which will help keep the oil down to some degree.

Of course, part of the reason the highest oil temp I'd see was 210 is because when I saw that temp I'd back off for a lap, rather than keep going to see how high it could climb.

Rather than pit to cool down, I'd just go into 4th and cruise, and start throwing passing signals like a madman. Even half a lap in 4th and light throttle and the temps would drop like a rock.

You were the black FD in HPDE 2? Should have come by my paddock (conviently near the restrooms) and said hi.

 

Ahh, FC that makes sense now ;P Yea I have an upgraded radiator (Koyo) and was running less than stock boost (7). Hopefully the dual coolers will do the trick Yea, that was me but I never saw an FC there all weekend. There was a lot going on though ;P

 

Keep in mind the only thing cooling the rotors is oil. As the temps rise the rotors grow and eventually kiss the side irons. The rotary is also unique in it's use of rubber o-rings to seal the oil passages. Doesn't take much constant use at 250* to ruin the stock, black rotor seals.