RX7 Oil Cooler

Now that the car is running, one issue I'm having is over-cooling of the engine oil. I'm using a Mazda RX-7 FC unit with an integral thermostat which seems to open around 140 F. On track my oil isn't even getting over 150 F which is too cold. Does anyone know of a replacement thermostat for the OEM RX7 oil cooler that opens more like 190 F?

Thanks,
Rich

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Drive harder

You could always cover part of the cooler if needed.

Heh, how'd I know someone would say that.

I sure could cover part of it. Or even install the original non-vented nose panel. I just worry it'll be a constant battle of too much / too little cooling. Ideal would be a more appropriate thermostat.

Thanks,
Rich

Or wait to change anything until summer time temperatures hit. You may find things are more than hot enough then.

You guys have it easy as far as temps, I have to deal with Alabama and Georgia temps in the high 90's as well as 95% humidity. I'm just hoping to keep my car from melting this summer

Not so easy for me. Thin air due to elevation and temps in the high 90's to low 100's during the summer...

True. I'll be dealing with 90s in eastern Oregon this summer. And we're planning a trip out to Miller in Utah this summer, that'll be hot. But this past Satuday was a sunny 60 degrees at about 200 feet of elevation. Hah!

Rich

My high oil temps last year were 270. Coolant temps lagged that by a little bit. Before that oil and coolant temps of 230-240 were typical.

I replaced the radiator and did some more ducting in the off season, we'll see what happens now.

I hope that helps, Doc. What radiator did you use? I'm running a new turbo radiator, so far so good with water temps staying right at 190 degrees.

As for my oil, I'm looking into adding an external Mocal "high temp" thermostat. However, the plumbing is tricky given how I've got the external filter physically arranged. I have them inline and really like both the location and the plumbing and don't really want to set things up as Mocal specifies.

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Do y'all think it'd be okay to not route the return oil through the thermostat? I'd plug the "from cooler" port and use it as a Y instead of as an X. The remote filter mount I got from Eric and is nice as it has 2 inlet ports so that part would be easy. Would this work?

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Rich

I went with a new turbo radiator. I have that same Mocal oil t stat, but have it plumbed the "standard way". I'm not sure if it'll work the way you propose, but nothing ventured, nothing gained....

I've been driving my car on the street lately and have 190 water temps, but that's typical. They don't climb until I'm on the track...

Cool. (get it? cool...)

I have an SLP 160 degree thermostat on the way to try.
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And an interesting book:
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It's convinced me the best temps are 70C for water and 100-110C for oil. So that coolant thermostat above and the "high temp" Mocal oil thermostat should be ideal. This assuming the radiators themselves can keep up.

Cheers,
Rich

You may need to put in a one-way valve or two with that setup.

My radiator wasn't keeping up last season. I hope that the new one can, otherwise I'll have to pony up to the Wizard radiator...

docwyte wrote:otherwise I'll have to pony up to the Wizard radiator...

Griffin for around $250.

If my turbo rad doesn't keep up, I'll probably follow your lead on the Griffin. I've left the Porsche coolant thermostat, relays and fan wiring for now. But I'll rewire to use the PCM signals if/when I do a new rad.

Back on my oil system, here's an updated diagram. I do have a check valve in there to keep flow from the accusump going to the engine. I think I see what you mean about adding another in the bypass line, but if the thermostat is closed there would be backward pressure in that line but not flow. The odd thing is the oil would cool in that bypass line given the lack of flow and I wonder what that cooling would affect within the return side of the thermostat.

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I use a mocal thermostat, works great.

Lemming wrote:Griffin for around $250.

Which Griffin?

acorad wrote:

Lemming wrote:Griffin for around $250.

Which Griffin?

Mine is not a direct fit, a bit too wide and has to be angled forward. Call them and tell them the dimensions, they will make it to fit. I was in a hurry, so had to take one off the shelf (race was coming up).

Okay, it's done. I installed a Mocal 501 thermostat capping the "in from cooler" port. In a test drive last night the oil came right up to 160 F, and then fluctuated around 165-175 F in traffic. The thermostat is supposed to start to open at 160 and be fully open at 180. It's also got 3 handy 1/8" NPT ports for sending units that I made use of and simplifed the ugly tree of brass fittings I had before.

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So far so good. Saturday I'll see what it does on the track.

Rich

Guys maybe someone can help him out, there was a huge phd dissertation on rads and cooling with Ls1 or a pirate board link or something, I recall thinking I will never need to know this. It was on the last board. And like 15 pages.???

I'm giving up on the RX7 cooler and pulling it out. It was an interesting idea to leverage the in-line thermostat but it's just not working out. I'm installing an Earl's bar&plate cooler and will plumb the thermostat in the standard way.

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Thanks,
Rich

all my stuff goes through filte first, them thermostat, cooler, etc.