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If you bump the fan turn-on temps around 10° lower, adjust cold RPM limit to 4500, increase oil injection map values (or premix 50:1 with 2-stroke), switch to no cat where legal(clogged cats tend to kill these...), you can keep a rotary happy a lot longer.

I have a full license of mazdaEdit, so if you wanted I could probably bench flash the PCM for the longevity tweaks in a weekend.

Rear O2/air injection system can also be removed rather painlessly if you don't have a cat requirement.

The K24 should be a good mill if you don't succumb and buy a spare 13B-MSP to rebuild.

Another oil cooler question.

In a stock RX8 the oil coolers have the fittings on the bottom. I was wondering if there is any issues in me mounting the oil coolers upside down or even at 90°? Just trying to plan out fitment and getting 2 oil coolers in the nose cone area... I still don't have a nose cone so I'm just trying to keep everything as tight to the frame as possible.

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Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

Typically oil coolers are mounted with the fitting on top so all the air bleeds out. If its mounted vertically, then the inlet is on the bottom.

With the inlet at the bottom, it aids oil changes but all the oil drains out of it so each time the engine is started, there is a delay of oil pressure to the main bearings unless you have a preoiler. This also means the crank case is over filled after shut down from the oil normally in the coolers and the dipstick should be remarked for the correct level.

Ideally the lines go on top and the cooler has a plug on the bottom for draining but most do not.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

So on the RX8 because it is on the bottom from factory, my understanding is I should see no issue regardless of how I mount things in any direction I choose? For ease of packaging I have considered running a single oil cooler like the Automatic RX8'S do, but I don't really like that choice.

If this is true I can figure out how to use the factory oil cooler hardlines and save even more funding on this car. So far the only additional costs mechanically I am going to incur are the Radiator and a fuel cell. So I will have a driving (not street legal car) for less then $1000, that is a true win and proves after inflation that the book is absolutely no lie! Or at least close enough.

_________________
Convincing yourself you can do it is one thing, convincing your wife it is a good idea is another. Glad I have a great wife!

1999 Dajiban build
Autcross car currently 2009 Mazda RX8 R3.

Build is a plus 4" width, 13B Renesis. Wish me luck.

I don't foresee any issues with orientation, as long as your flow path goes through the bypass thermostats the proper way.

If you keep the entire flow path at or below sump level like factory, you shouldn't have air bubble issues.

Absolutely keep the dual coolers.
The oil coolers are arguably of more importance than the radiator on these engines, since the rotors and eccentric shaft are cooled by the oil system only.
The automatic cars were switched over to run two coolers later in the model years due to overheating issues caused by the single cooler.
If memory serves there was a TSB to put a second one in on hot climate cars.


An option for the packaging constraints is to mount fans to the coolers, then duct air to/from them with dryer vent tube or something similar.

It sounds like the original config cooler drains back to the pan at shut down and has to be refilled before the mains are pressurized when starting by design or maybe there is a check valve in there. I don't know enough about RX8 oiling systems.

If you mount the cooler where it doesn’t drain back to the pan at shut down, you will not be able to change all the oil just by pulling the pan plug and filter.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

They don't drain back, at least not noticeably. I get ~4 quarts out of the coolers when I pop the thermostats out on an oil change.
Stock oil change is 3.7L (roughly 4Q) sump only, capacity of whole system is 6.7L.
The early auto cars with one cooler have a total capacity listed as 6.0L.

No check valves in the system that I'm aware of, unless they're built into the thermostats.