As @Ultramaroon pointed out, I had a significant oil pressure drop with the JR dual rad. JR refused to acknowledge any issue. I kept the rad but installed a Setrab 34 row cooler. It had the least drop without over cooling but I haven't tested it on track yet. Pressure-wise it solved what the JR dual rad created.

It looks like you are running the Accusump as a "dampener". This was the original recommendation from Element Tuning when I had my engine built.

https://www.ft86club.com/forums/showthread.php?t=153186

What temperatures were you seeing before adding oil cooler? 30 psi drop is crazy, would pressure gain from viscosity gain from oil temperature drop due to OC would even cover that?

Interesting results. First Gen car here, I had a JR Oil Cooler that was seeing a larger pressure drop across the core.

I initially suffered a failure due to a rocker arm. Flushed the cooler but reused it (hindsight should have replaced it in its entirety). Saw about a 25-35 PSI Delta after I rebuilt the engine.

Consulted with JR - they told me, within email that nominal drop is 5-10 PSI drop

I just faulted myself on reusing the cooler. But now that I have a new cooler sitting waiting to get installed, I'm convincing myself to approach and go with something different. Based on you using a brand new cooler and seeing the same nominal drop across the core is very concerning

All motors will have oil sloshing away from the pick up under track conditions. The boxer format makes the problem harder to solve. The asymmetrical pickup location certainly doesn't help. We think the motor blow ups happened because the pump loses it's prime, we'll elaborate on our theory about that in another video.


With the stock configuration, we would hit 130*C by the second lap but it would stabilize there. You can't use a thicker viscosity to compensate for the higher pressure losses of the JR dual oil cooler. The best compromise would be to choose an air to oil cooler with less pressure drop. That's something we're developing.

Thank for the reply here and on YouTube. I wasn't suggesting to use higher viscosity to compensate for oil pressure loss due to JR oil cooler, I was asking if your choice of 5W40 would cover the loss of pressure from cooler, which in retrospect doesn't seem to be the case. Looking forward to your oil cooler.

Accusump as dampener? So the 2-qt reservoir is essentially empty when the engine is off.... loads up at start with oil pressure building, and dumps when pressure goes below its threshold? Am I getting this right? This would mean you need 2 extra quarts in the sump with the engine off... and something of a drain at the critical startup phase.

I use a PTO cable that's routed to the passenger side of the transmission tunnel. I open it after start up and close the valve before coming off track.

Here's my set up.

https://www.ft86club.com/forums/showthread.php?t=152642

Oil cooler is addressing a problem that doesn't exist, if causing massive 30psi pressure drops surely it's blocked somewhere? Anyway, I'd just lose it and run good 30- or 40-weight. 130C/266F track oil temps are not a big deal with appropriate oil...

Thanks for the vid! Thinking about Accusump....

With a manual valve setup, yes the Accusump will empty into the crank case. With the valve open it's always active, if there's a pressure differential one way or another, oil will flow in or out.

A 2qt accusump doesn't actually hold 2qts of oil. 2qt refers to the overall volume, but part of it is the pair cushion. It holds closer to 1.5qts.

If you're not at the track, we would recommend storing the excess oil in the Accusump and shutting the valve. In this configuration, your engine's oiling system behaves no different from stock.



While I do agree that 130C oil temps are tolerable with a high quality oil, it was just higher than we'd like to see. There's no magic threshold on what's acceptable or not. On the testing day, we were running 40minutes out of each hour. We want to be able to run our car non stop without cooling laps without concern.

Which do you consider worse: 130C (266F) indicated oil temp, stabilized and never going into runaway, or losing 30psi oil pressure at, what, 115C (240F)?

I've never thought an oil cooler was necessary, and the more I've looked into it the more I think the negatives outweigh the "positives" which are debatable... More cost, more weight, more potential failure points (leaks are common), and in some cases -30psi oil pressure? Damn...

You may know more than I but I've heard that the reported oil [edit]temperature to the canbus is a calculated, estimated "max", and 275F reported correlates to 255F sump temp which I think is what people have historically gone by for oil temps. I know that's the case with C6 Corvette, reported oil temp is calculated, and it doesn't go into "limp" mode until calculated/reported 160C (320F) oil temp!

I think there's a reason the FT86 goes all the way up to 340F, with 270F being at like 2/3 the range.

Agree, Mobil1 FS 0W-40 oil has been used by few at 149C/300F and even at OCI of 5k, the UOA was good. On different platforms than us but oil holds up.

Why can't you just not have both? You can install a low resistance oil cooler setup that keeps good oil temperatures and doesn't add extra pressure losses.

The 30psi loss that we saw was specific to the radiator oil cooler combo, air to oil coolers should not be so restrictive.

I'm not sure what you're referring to about the oil temp and pressure on the canbus. Our cars stock do not have an oil pressure sensor. There's no reported oil pressure.

One thing to keep in mind is that, the oil temperature you measure is not the temperature the oil is at when it's at the bearings. The oil gets hotter than what you measure. What temperature? hard to say.

Back to the first point, in our eyes, the best option is to have lower oil temperatures and not cause extra resistance in the oiling system.

Is it all resistance that's causing it? I assume the added volume would be a factor as well. That's what I think, I don't know.

To me, 275F indicated, or 255F sump, with decent HTHS 30 or 40 synthetic, is "good"

Yeah, seems like the rad/oil cooler deal isn't so great...

Oops, I meant temperature! Fixed it in the post.

Right, but the old rules like "250F is the limit for non-synth" are based on what people were measuring: *sump temp*. My interpretation is that if you have *sump* temps above 250F, you should definitely run an oil cooler *if you are running non-synthetic*. At 275F *calculated*, 255 *sump*, IMO full synthetic 30- or 40-weight should not even be close to being an issue.

To me, the even better option is to just run known-good synthetic 30- or 40-weight for 275F, even if that's the sump temp. Should be good to 300F and beyond sump temp.