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I have a car in the shop that I have been reworking all the problems created by another shop (will remain nameless unless the owner wants to chime in). After getting the car to the point where it could actually start, the car blew a hole in one of the oil coolers, reworked the oil coolers, started the car and blew a hole in one of the new oil coolers. Immediately I suspected something internal, so I dropped the oil pan and sure enough found an Oil Pressure Regulator that had been flattened out. I decided to do some side by side tests in my press, had to use a bathroom scale since the gauge on our 50 ton press reads in tons.
Now I have seen this mod many times over the years and always scrap out the part for a new 110 psi FD regulator
The car also has the front cover bypassed, oil exits the side of the front iron, so the pressure bypass on the front cover is not functional.
Blown out oil cooler (first one)
Dropped pan, to find pressure regulator mashed flat.
Comparison
Here is where it gets interesting. I decided to test the opening pressure of the regulators. The OEM FD regulator opened right where is should have, fully open at 110psi.
Modified regulator did not even crack open at 230psi
It actually started bending the scale, so I removed it and just used the press to open the regulator. I bottomed it out and the regulator never opened.
Explains the multiple blown out oil coolers. Customer was talked into this gimmicky mod, actually paid extra for it. Massive amounts of oil pressure was always going to find the weakest link. Now hopefully there is no internal damage due to forcing 300+ psi of oil into the bearings.
This was a mod that started with the earlier models (FB, FC) that had 70psi regulators, by crushing the end it increases the internal spring tension with the intention of increasing the pressure that the regulator opens at.
I've seen the same thing. Stock fd regulator is plenty for most applications. If you want more pressure go with a Racing Beat adjustable regulator. Crushing a regulator to achieve higher pressure is like playing Russian roulette. Good info here.
If I could get your advise on my setup then. Rebuilt motor with new housings, rotor bearings & stat. gear bearings. My engine builder advised and installed the above Atkins pressure regulator and shims. It has not hasd any fluids added yet but is in the car awaiting a harness. Do I swap it out for the stock FD regulator? I'm a little paranoid now about the situation Banzai has shown. If its fine I assume I'll want to run the smaller oil restrictor on the turbo as well?
Your link does not go anywhere. But if it is "69-11 Rx7 & Rx8 Atkins Competition Adjustable Rear Oil Pressure Regulator (4352-14-250)" it was a waste of money. Even on the product page it states "A less expensive alternative is to use the 3rd gen oil pressure regulator, which allows 90-100 psi if you aren't already using it."
This is why we upgrade nearly every engine we build to the FD regulator, it is only about $40.
Edit: I see the other kit with the FD spring and washers. Unnecessary and overpriced, but it should not harm anything. $140 for what equates to .03 worth of flat washers and a regulator that does nothing more than the stock FD regulator.
Last edited by Banzai-Racing; 04-19-18 at 10:40 AM.
But, on a serious note, there is absolutely no reason to ever modify something as crucial as the oil pressure regulator, in a manner that is completely untested and unverifiable. Ever.
This was a mod that started with the earlier models (FB, FC) that had 70psi regulators, by crushing the end it increases the internal spring tension with the intention of increasing the pressure that the regulator opens at.
Getting off topic in the 3rd gen section, but if you have an 88 'vert, leave the oil pressure regulator stock. You won't gain anything.
Mazda did a great job on the oiling systems on the rotaries over the years in general, if you have an engine failure it's not going to be due to oil pressure.
04-18-18, 01:10 PM
