So, if you followed my other thread about replacing my engine, I'd like you to know that I'll most likely replace it in April/May. With that said, since they are going to be pulling the engine out and redoing it, what are some things that I should probably do at that time? Things that I should add? Give me your list and why, please.

I already have a BHR Coil kit and an Ultima Red Top Battery. Those are my only updates to the car.

 

Refresh my memory: what's your plan for the car?

If you're planning any track/autocross time (like you should be), cooling upgrades are a must.
I'm partial to the but there are many other good options out there. Also, either a fan relay kit or invest in MazdaEdit to lower the fan trigger temperatures. Since the coolant system is being drained, switching to something like Evans NPG isn't a crazy idea.

I also installed a Sohn OMP adapter with Epitrochoid's kit so I could run whatever oil I wanted (like high-ZDDP diesel synthetics) without worrying about poisoning the cat.

How's your gearbox? Syncros doing okay? If not, upgrading to an S2 gearbox is a good idea.
Speaking of which, proactively doing the clutch isn't a bad plan either. It's up to you to decide if it's worth it but you'll already have the engine and gearbox apart so it's a good time to at least consider it. Flushing the clutch hydraulics is a good plan since getting to the bleed nipple on the slave cylinder is silly easy with the engine out of the car.

After that, it's mostly maintenance items. Getting to everything is easier with the engine out. Clean the intake valves, check the coolant hoses, maybe proactively replace the front O2 sensor. Maybe do an oil pressure mod.

 

Sorry, my rx8 is a daily driver. Wife drives it more than I do. We are a single car family cause, ya, I'm one of THOSE guys. I know, rx8 isn't really the car you want as a single car daily driver but we love it and were super sad when the compression went to crap.

So, far the only thing I've done in 2 years other than routine oils and other maintenance is replace the coils with BHR coils, the clutch replaced, new batteries and new tires.

 

oil pressure mod

 

Definitely do cooling work to add to your reliability mods.

A properly sealed, upgraded radiator is a very good idea. The CSF mentioned above is a great radiator. Koyo also makes a very nice one. Don't be tempted by any others. They all have fitment or performance problems.

The external fan speed controllers are also a good idea--especially if you do any driving while stuck in traffic. I think there are a couple of versions out there. A nearly free version of that is the Fans on Low mod, but you have to remember to reach down and flip a switch any time you want the fans to come on.

Also CHECK YOUR CAT!!! Sorry for yelling, but that can't be said enough. Clogged cats are the #1 killers of rotary engines.

I would definitely replace the clutch while everything is apart. Just buy the Exedy standard replacement clutch kit and a new slave cylinder on the aftermarket and supply it to the shop doing the work. That kit IS the OEM clutch, and it is much cheaper than buying it from Mazda. I need to search around and find out if the release bearing is now OK. Several years ago, people in the know were recommending swapping a Koyo or SKF bearing for the one included in the kit, but IDK if that is still the case. The shop should not charge you much extra labor, if any, since they will have the transmission off anyway, unless the flywheel needs to be resurfaced. Once the engine is back in the car, a clutch job costs $400 to $600 in labor alone, so it is a very good idea to do it now.

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^+1 on checking the cat.
If you're not restricted by emissions testing or ethically opposed to eliminating the cat, a midpipe is a very good mod for a slight increase in HP & MPG, much better sound if you go with the BHR resonated midpipe, (I have it) and most importantly, peace of mind.

 

yes do the clutch while the engine is out. I did.

 

+1 on the cat. I'm watching mine like a hawk to be sure I'm not seeing a partial failure on my S2 at ~ 45K miles. Stealer says everyting is OK even though on occasion I see mild glowing coming from the top side of the cat nearly 90° up from the sensor location. (I can only see it in a completely dark garage and only on occasion. No MIL codes and the dealer blamed "bad gas" on my first and last visit to them). I'll let EGT guide me to take it in to another dealer ahead of failure.)

 

Right on cue. Listen to this man.

 

+1 on check the cat. I've got a catted BHR Midpipe, but, that might change since I live in an area that no longer requires emissions. Edit - I also have the Koyorad. Something no one brought up yet is to take a look at the coolant overflow bottle and check that it isn't dirty and that the sensor at the bottom isn't beginning to bug out, as it can be an issue. Cheap enough part to replace/fix, $140 from Mazda OR you can get a really nice aftermarket one for about $250. I'd suggest doing a full alu rad regardless, better thermal efficiency from the larger aluminum end tanks and a larger surface area generally speaking.

 

Now that most of the threads are so old, is there a certain cooling system that is better now. Some of the old threads said some of the rads were crap, still true?

 

There's not a complete cooling system kit, if that's what you're asking.

Items that actually effect cooling efficiency include radiator, water pump, thermostat, fans, fan relays.

If you're seeing high temps at speed (say, on the interstate or at Putnam Park) then it's time to upgrade the radiator because it should be getting plenty of air but still isn't dealing with the heat. I'm partial to the CSF I mentioned earlier but the various Koyo options are good. Supposedly the OEM S2 radiator will fit and is a bit thicker. Whatever you do, make sure the undertray and the foam around bottom and sides of the radiator is intact; it's critical to channeling air flow through the rad rather than around it.

An upgraded radiator doesn't do anything without airflow. So, sitting in traffic, the main factor is the temps that the fans trigger at. The PCM controls this and the factory tune has them turn on full blast around 207˚F (one of them turns on at a lower temp). So, if you see your coolant temps rise to 207-210-ish and stay there then your radiator is working well enough and it just needs more air. You can fix this with MazdaEdit to reprogram the trigger temps or a fan relay kit to bypass the factory trigger. MazdaEdit + adapter will cost more but will also allow you to increase the OMP output.

The OEM fans aren't bad but when mine died, I just bought a Flex-A-Lite 420 to replace it because it was cheaper.

There's a theory that the OEM water pump cavitates starting around 6k rpm and Mazmart have come up with a new impeller design to address this. If you spend much time over 6k RPM, that water pump might be worth investigating. If you don't, then don't sweat it as the pump is unlikely to be a weak point.

A lower temp tstat won't do much except keep the engine's baseline temp lower. It will do nothing to decrease peak temperatures (like when you're sitting in traffic or blasting around a track).

Good reads:
https://www.rx8club.com/rx-8-racing-...k-cars-262908/
https://www.rx8club.com/series-i-aft...iators-225851/