Oil Pump O-ring Mod - Testers NEEDED

[TitaniumTT]

So here's the backstory, my last engine was a 13B-RE Cosmo motor with the stock oil pump, stock OPR, stock bypass valve and stock casting under the pump itself. At idle I would see about 15ish psi and on decel the low psi warning light would come on @ 15 psi I believe. I've seen as low as 7psi and the most I ever saw with that motor, I checked the logs, was 67 psi @ 6k+rpm. Not great but "acceptable." I use that term loosely. The pump, when I broke the motor apart was visibly scored.

The engine needed a rebuild and I wanted to really address the oil system for a myriad of reasons. I decided to go with
1) FD OPR
2) Shim the bypass with 2 washers
3) Clean up the casting under the pump
4) MAKE A POSITIVE SEAL BETWEEN THE ALUMINUM PUMP AND THE IRON MOUNTING SURFACE.

A friend of mine has a CNC mill and when I approached him about the idea, he kinda scoffed at it saying that no-one has ever done it to his knowledge and people don't seem to have problems so why bother? It didn't take long for me to convince him to try it and I sent him a stripped down and cleaned up pump. It was actually the one that was visibly scarred. There was no scaring on the pump body, just the troicoids and the pieces between them. I had a second pump on it's way to me anyway. This is what we have.

I cleaned up the casting, nothing crazy, about 20 minutes of work



And here is the pump body



And here is the o-ring installed with a smear of hylomar on the seam between the o-ring and the outside sealing surface to keep the o-ring in place and on the mating surface itself. THe hylomar cannot get into the pump.



Also of worthy note is my dual mocal oil coolers run in series with -10 line. Theres close to 15' of -10 line which should also reduce the pressure some.


bulkhead fittings


T-Stat


The results, well the are RIDICULOUS. At a fast cold idle I'm seeing close to SEVENTY psi. (I'm going to type out the numbers so you know it's not a typo) At a normal hot idle I'm seeing thirty-five psi and by Two-thousand eight hundred rpm's I'm seeing over a hundred and nine psi. I have the standard 0-100psi 0-5v sender and it's pegged at 109. I don't know what my max psi is yet becuase I just don't have a sender that reads that high. One is on order. Right now my dash is throwing a "code" and readin 0.0psi which obviously causes me concern. Upon first start-up when the rpms climbed high enough the dash read 0, it's default error. I quickly shut the motor off. It took me a minute to realize what was going on. I had to open up the Motec and bring up a dial gauge that read the voltage from the sensor. With the voltage pegged I realized what was going on.

I called my aluminum chip eating friend to tell him and he was pretty surprised. However, we are not sure how much of it is the o-ring, and how much of it is the motor itself, the builder, the tolerances I used, the FD OPR, etc etc etc. It's all me, the builder

Anywho, what we are looking for are people that are rebuilding motors that aren't going to change ANYTHING else in thier oiling system. We can't use my experience as an example becuase I did so much at once we cannot be sure what mod effected the pressure. For all we know the o-ring did nothing and it was the change in pump internals and the FD OPR. I doubt it. My gut is telling me that the o-ring made a significant difference but with so many variables, we cannot be sure. I have however done some research in both the FSM and with other peoples experience and it looks like my pressures are MUCH higher than other peoples with similar mods. I should also mention that the pump was actually worn PAST the FSM specs as measured with the feeler gauge. I didn't have a third pump on hand so I played musical internals until I got the closet tolerances I could. They were still out of spec though. In otherwords, the pump should've been thrown out but instead, it's making more pressure that the FSM states as minimums. In most instances, 2x the amount.

Is there anyone that wants to actually test this mod? The o-rings came in packs of 10 so you'll be getting a free o-ring. The machining we are not sure of the cost. He seems to think there won't be any interest. I told him I thought he could make a decent coin offering this service if we can prove that it significantly raises oil pressure. The first testers would pay very little if anything for the machining. It's up to him, not me. But if we could get a group of people that wanted it, I'm sure the cost would be insignificant.

So, if there's anyone who wants to try this - post up, or PM me. I'll be putting this thread in every relevant section just so it can get attention. However, if all responses can be placed in the "General Rotary Engine Related Tech Section," that would be great. Thanks guys

[j9fd3s]

very interesting! ive been using silicon on the pump/iron surface for sometime, it seems like using nothing might be ok on a NEW pump and iron, but used needs help!

[neit_jnf]

any updates? i read somewhere that judge ito uses a paper gasket in here to improve oil pressure...

[TitaniumTT]

paper gasket soaked with locktite I believe. I know Joe uses a small silk tread (cool idea).

So far the results are impressive. I'm getting >120psi >6krpm and idle is ~30 psi. Cold start idle oil pressure is around 100psi.

All this and I BELIEVE my o-ring in the front cover squeezed out too! I found about 1/3 of an o-ring lodged in the filter on the last oil change.

[neit_jnf]

what weight oil do you use? at what temps are you seeing those pressures? maybe you can go to thinner oil now for more flow and less drag while maintaining a healthy pressure!

[TitaniumTT]

I run Mobil 1 10w30. Cold start the oil is usually ~50*. I'd have to double check the logs but I'm pretty sure that the 120>6k really doesn't car about temps. 170-220* will net about 20psi @ idle

[Whizbang]

how much would it cost us to have your friend do a little milling on our oil pump housings?

[TitaniumTT]

Dunno, I'd have to ask him. We we're honestly expecting a lot more interest in this that what we've had.... A GB on them would be something to explore though so he can just crank them out.

It's also a matter of which pump you have as well. I have the higher volume one with the inlet that leads down. All the N/A ones that I've come across are perfectly circular.

I know Ejay is interested, which pumps do you guys have?

[Whizbang]

i might be getting the mazda hi performance one unless of course a turbo one works the budget better

[TitaniumTT]

Oh really. Why have I never heard of this mazda hi-perf oil pump. Do you have a PN by chance?

[Whizbang]

it appears the Turbo pump (86-91) is listed as their performance pump

#N318-14-100A

[TitaniumTT]

Ah, interesting. I wonder what the difference between the S4/5 TII pump and the S6+ pump is.

[C. Ludwig]

Originally Posted by TitaniumTT

Ah, interesting. I wonder what the difference between the S4/5 TII pump and the S6+ pump is.

The S6+ pump has an additional cavity on the inlet or outlet side (can't remember and don't have one in front of me). The 3rd gen pump won't work on the S4/5 irons unless you port the iron to match the pump. Think it's been done but a quick search hasn't turned anything up.

There is/was a "comp" pump offered by Mazda Comp for the 12A. It has heat treated shaft and rotors. Other than that there are only stock pumps.

[Whizbang]

not sure. wouldnt be hard to compare. Im sure Atkins would know or easily be able to tell.

[TitaniumTT]

Thanks Ludwig. So just to clarify, the one that I have pictured is considered an S6+ pump correct? Does anyone have pictures of an S4/5 turbo pump?