The veteran folks here know this stuff already , this post is really for newer owners' benefit.

As this has been a brutally hot summer across America and other parts of the planet that stay hot all-year round, I thought I would relate some changes I made to help my RX8 keep cool.

There are better after-market RX8 radiators out there for better cooling, but these tips below are a lower-cost way to help keep your engine cool and lasting longer.

How To Double The Life of Your RX-8 Engine ? Rotary Performance

1) I had already switched to the lower temp Remedy coolant thermostat from Mazmart, but wanted to do more.
2) I added the fan relay kit available from Mazsport and Rotary Performance.
3) I also added the oil cooler lower temp thermostats from Rotary Performance.

Yesterday the ambient temp was 98 degrees F in Southern New Jersey, and the feel-like temp was 106 degrees F. I went out for a drive on street and highway with full a/c on. I revved freely and went up to speeds of 85mph. My coolant temp (read from an OBD2 reader on my Torque app on my Samsung phone) stayed between 180 and 199 degrees F. This is a much safer temp range than I had reached last summer without these mods.

Folks in hotter climates will probably reach higher temps, even with these mods, but I am sure these mods will work to help you keep your temps lower and your engine lasting longer.

FYI my 2008 40th Anniversary Edition is on its second engine, a Mazda reman (from my Mazda warranty) with 2000 miles run so far. I have a Mazdaspeed/AEM CAI, BHR ignition, Racing Beat oil cooler and ac condenser screens. I am running on new Conti Extreme Contact DWS-06 tires on stock alum. 18in wheels.

Rotary Performance - Oil Cooler Thermostat

MAZMART - Serving The Mazda Community Since 1980. RX8 REMEDY Thermostat


Rotary Performance - Fan Relay Kit for the RX-8

Mazsport RX-8 Cooling Fan Control Kit Installation - YouTube

Hope this is of some benefit to newer folks. I know the experienced folks here have known this stuff for years.

 

A properly working RX-8 doesn't need any of that crap. The stock cooling system is more than capable of handling extreme temps when working properly. We get over a 100 days of 100F weather here in south Texas and there are plenty of stock guys that have been fine with the stock cooling system for over decade. The stock oil cooling system also works great and anyone who actually monitors oil temps will know that.

 

Rotary Performance is in Garland, Texas near Dallas. They know your heat and have years of experience with rotaries. Mazsport is in Australia and they know heat and rotaries also. Mazmart in Georgia knows rotaries and they know heat also.

Hey anything to help keep the engine cooler is a plus. In 44 years of owning, driving, caring for and modding rotaries for street and track, my cars have always benefited from better cooling over their sometimes inadequate Mazda stock systems.

 

Yeah they know selling you ****, that is what they know.

 

9krpmrx8 you can diss Rotary Performance, Mazsport and Mazmart if you like. Lots of folks here have a lot of respect for their experience and knowledge. Sounds like you had a bad experience with them, sorry for you. The fact remains that better cooling will help these Renesis engines last longer, period, whether you believe it or not.

 

I'm not dissing anyone, just because I don't kiss someone's *** doesn't mean I am dissing them. They sell products, so of course they will only have positive things to say about them.

RP has a good rep locally and does good work but that doesn't make them experts on what RX-8 cooling mods offer advantages or not. They are RX-7 owners and yes some of that Rx-7 cooling knowledge transfers over but it's still just an opinion. And I have bought plenty of things from Mazmart and installed many of their products on many RX-8's which is why I can speak to whether they offer any advantages over OEM parts or not. Paul is a great guy who also runs a business that focuses on selling parts.

:MOD EDIT: PERSONAL ATTACK REMOVED

 

The fact remains that better cooling will help these Renesis engines last longer, period.

 

Not that it matters but what is the impact of lower coolant temps on fuel economy and power. Gotta have more powaa.

 

What parts does Mazsport Australia make for the RX-8? I checked their site and found nothing.

As for what parts are better or not, without proper testing there is no proof any of the parts are an improvement over a factory system that is in good order.

 

Racing Beat, Pettit Racing and others with decades of rotary experience on street and track cars have found (over the years and decades) many mods that have improved the cooling of rotary engines, and have found a benefit (especially in racing and other applications) of improved performance and most importantly longevity of engine internals.

This is not new and this is not rocket science. Of course you want your engine up to proper operating temperature, but you don't want it sitting at the high end of the safe operating range for extended periods, or heaven forbid go over the safe range. Not good for your engine.

Mazda has had a history unfortunately of inadequate stock cooling systems for its rotary cars. I personally over the many years have run many upgraded aftermarket radiators in my rotary cars to help keep the engine cooler under stress. Not the cheapest way to go, but not a single one of those upgraded cooler modified engines experienced a rotary engine failure, ever .

I have not been as fortunate with my RX8. With a well-cared for mainly stock cooling system I still needed a reman engine on my 2008. No telling if cooling issues led to the engine problems. I did not get to see the inside of the engine.

As far as the RX8, there are certainly options for better performing radiators you can add from many trusted suppliers. Many have done so. This can be a more expensive option unless you do the work yourself. There are less expensive ways to help.

Keeping track of my coolant temps last summer and now this summer after adding some of these cooling mods, has shown a marked drop in coolant temps in hot weather, with the a/c on and spirited driving. A drop on average of 15 to 20 degrees F is all the proof I need redcivic. Whether you will see a similar gain depends a lot on the health of your engine, the health of your cooling system and how you drive and under what conditions.

There is no golden bullet here, no magic potion or solution, just common sense options and approached to help your engine stay cooler and last longer. Hey if you never need anything more than the stock cooling system, great. I felt I needed more help, and my experience with rotaries guided me on the path I chose. If you folks choose to remain stock, that is fine and your choice. There is certainly a lively debate here about all this, with numerous cooling threads over the years.

 

Wannawankel, I am keeping trip mileage logs with my added cooling mods and so far i see a slight mpg improvement over my log entries from last summer's trips, but not enough data yet for any real conclusions.

 

redcivic, my fan relay kit was from Mazsport (sourced from my rotary wrench, JPR Imports in NJ). I posted Mazsport's video of its installation. We also sourced the similar fan relay kit from Rotary Performance. Similar parts, similar design. I chose to install the Mazsport one. Just seemed slightly better in overall build quality. Don't know if they are readily available, but the Rotary Performance one is. And I am sure the Rotary Performance one would be backed fully by their folks in Texas. My wrench has great relations and history with both suppliers.

 

It seems to me that a lot of products get credit when it is not really due IMO. If you are having cooling issues and then install new products you will typically see improvements (sometimes not with cheapy parts) whether you are installing new aftermarket performance products or OEM Mazda parts. As for turning the fans on earlier, that is nothing new in the car world and that will accomplish nothing to increase cooling performance overall. But if you like to tinker then why not I suppose. But if that item can fail and not allow your fans to work at all then that would be a problem. It all depends on the use but generally OEM components are best for street use.

 

Most of these things aren't likely to significantly lower temps, especially if they aren't used together. They probably won't hurt (unless the install is botched) but there are better things to spend your money on.

The fans don't hit full speed until 207-ish. Having a thermostat open sooner won't matter because the ECU will still wait until the coolant gets over 200 before spinning the fans all the way up.

Unless you add a fan to the oil coolers, any mods there will only be useful at speed. The OEM thermostats in the oil coolers are at least partially open at all times, anyway.

The best thing to do is use MazdaEdit to lower the temperature that the fans turn on. You don't even have to raise the hood for that. If you don't feel like mucking around in software, the fan relay kits that turn the fans on at lower temperatures are probably the next best thing.

I suppose if you pair a lower temp thermostat with lower fan trigger temps, that would help but 180°F is just fine for most people.

 

I agree, and my opinion is that anyone with a stock system that is not performing, is hat it is due to aging parts or improper maintenance. I am sure many of you have seen the nasty coolant that is left in cars forever and not changed like it should be. Flushing the coolant and keeping the radiator and condenser free of dirt and debris can go a long way. Also replacing an aging water pump is a cheap and easy project as well.

 

You mistunderstand guys, my stock cooling system was performing as designed, was tested,maintained and regularly flushed. I was getting the temps that Mazda says were safe. I just wanted lower temps for the hottest and must stressful times. I have been around this block many times in 44 years of rotaries from stock up to 400+ HP.

If you choose not to believe that anyone with a healthy RX8 stock cooling system would benefit from some of these mods, that is your right to believe otherwise. A ton of rotary miles has taught me it can make a difference, even in an RX8. Many RX8club owners, including at least two RX8club moderators have made at least one of these cooling mods to their cars.

That doesn't mean all RX8 owners need to go out and add cooling mods. But like all kinds of mods discussed here on the forum, it does make sense for some owners, even if they have a healthy cooling system, especially in hotter climates, and/or with sustained high heat-high load driving conditions.

Cheers to all !

 

I know you like to think that your experience makes you infallible but it really doesn't. The fact is that you repeatedly treat your individual anecdotes as if they were evidence. The lack of any kind of experimental design in your methodology means you have no actual idea as to what may or may not have contributed to the improved temperatures you saw.

Assuming your improvements are real (and you didn't tell us your before temperatures so how can we know?), I'd bet sex to donuts that the fan relay kit is responsible for 95% of them.

You're throwing good money after bad unless you first change the trigger temps for the cooling fans. You sort of danced around this in your original post but didn't really explain anything. As I said before, having a thermostat open before the fans turn on won't actually improve the situation much, if at all. Especially when sitting at a stop light.

I've read in the that the oil cooling system in the FD accounts for about 30% of the cooling and I doubt the RX-8 is significantly different from this (just look at the relative surface areas of the oil vs water coolers). So, all things being equal, for every unit of your resources you spend to increase cooling there, you only get 0.3 units of cooling. You’ll get more than twice that (again, all other things being equal) by improving the water cooling system.

Also, again, increasing oil flow through the coolers will do absolutely nothing without airflow through the coolers. The oil coolers do not come with fans. The radiator does. This means improving the water cooling system will help ALL the time while improving the oil cooling system will only work at speed.

Also, why are you referencing “feel-like temp”? That has nothing to do with anything other than evaporative cooling. Nothing had better be evaporating from your water or oil systems or you have some SERIOUS issues.

Look, if you had just said, “Here’s what I did and here’s what happened.” 9krpmrx8 would probably still bust your chops but I would have kept walking. But you posted this as if it were good information for new owners and it just isn’t. You had one good idea but didn’t actually explain to anybody WHY it helps and it got buried in amongst other stuff that isn’t really useful to new owners with stock RX-8s.

Here is information newer owners might benefit from knowing:

The fact is, hitting temperatures as high as 210˚F is not cause for concern for stock cars. However, if a person wants to be concerned about it, the first thing they should do is lower the trigger temp for the radiator fans.

If they’re still seeing temps >210˚F, then a colder thermostat isn’t going to help (the thermostat is already open, making it open sooner won’t matter). A better radiator might help and I’d bark up that tree next. $300 for an S2 radiator isn’t a hideous expense and will be much improved over the S1 radiator. You could even go crazy and spend the same money for an S2 Koyo radiator but I don't know if anybody has tried making that fit in an S1 yet.

If that doesn’t help, fans on the oil coolers might be worth exploring but I’m really thinking that you have a serious problem if a bigger radiator and earlier fan activation haven’t helped.

 

Folks here will see through the attack rhetoric, false assumptions and misinterpretations clouding these posts, and be able to grab hold of the useful information being discussed. Many owners with healthy cooling systems have already , and will make some of these choices, to the betterment of their RX8s. Have a great day.

 

Just to further reinforce this for the benefit of newer members:

Most of gwilliams6 first post is bunk. When called out on it, he didn't try to back up his claims with anything resembling facts or logic. Instead, he just called my words "attack retoric, false assumptions and misinterpretations".

If refuting erroneous statements with facts and logic is "attack retoric, false assumptions and misinterpretations" then I'm okay with that.

 

FWIW, This is my story will some of the cooling mods above.

With the stock cooling system I was seeing coolant temps (with obdII) of around 180 at speed. However during stop and go traffic or while mountain driving uphill.(slow speeds, high load) The coolant temp would climb to above 215 at which point I would take action to keep it below 220.

I installed the 172 degree thermostat and the "fans on low" mod with an in cabin switch. Then when i was in stop and go traffic or heading to the mountains, I would turn the fans on low. I was seeing 174 at speed but while in stop and go or mountain climbing I would still see temps going up above 215 although they took longer to get there.

Having not solved my issue I then installed the fan relay kit and removed the "fans on low" mod. Now i see 174 at speed and normally around 190-195 during stop and go or mountain climbing. Max i have ever seen was 203.

In my case the fan relay kit to lower the temperature that the high speed fans come on was what helped most to keep coolant temps below 200.

 

Hey NotAPreppie it doesn't matter what actual experiences and numbers I post here, you will always just refute it, so I have better things to do than get in a shouting match with you over this issue. have a nice day.

 

I wouldn't refute your statements if they were irrefutable. This means couching your statements in terms that don't read like you and your experiences are the be-all, end-all of rotary knowledge. This is why 9krpmrx8 was giving you such a hard time: you post stuff that, in the best case is unsupportable and in the worst case just demonstrably incorrect.

Also, nobody is shouting. This is a debate and the tactic you are using isn't to counter my argument but rather to deflect and misdirect away from the topic at hand.

Just in case you missed my points:

1. The factory cooling system should be adequate for the overwhelming majority of people (210°F isn't a big deal).
2. If that is too high for your liking, use a fan relay kit or MazdaEdit to make the fans turn on at a lower temperature.
   • Making the thermostat open sooner without more airflow does nothing.
   • This applies to both the oil and water cooling systems.
3. If that doesn't completely solve the problem, a bigger radiator is a good next step.
   • For S1 owners, the S2 OEM radiator fits and is thicker. The S2 Koyo radiator is even thicker but I don't know if anybody has tried making it fit.
   • Click here for a list of inexpensive S2 OEM radiators.
   • Upgrading the radiator without upgrading airflow will only improve the rate at which the temperatures drop once the fans have kicked up to high speed (207°F) or you've reached cruising speed.
4. If THAT doesn't solve your problem, oil cooler fan(s) aren't a bad idea but you should probably start troubleshooting why your cooling system is broken first.

Of course, if you're a trackrat, much of this is incorrect and you should be considering most options to improve cooling (bigger radiator, better fans, earlier fan trigger, oil cooler fans, better oil coolers, better coolant, vented hood, etc).

 

And what were the ambient temps thru out this scenario? AC on or off? There are lots of variables.

 

This makes sense and your thought process shows a good methodological approach.

My guess is the "fans on low" setting from the factory is mostly for cool/cold weather. No sense in cycling the fans on/off/on/off if you can just run them at a lower speed with less wear and noise. As always, a single data point is not definitive, but it does agree with other people's observations that the biggest improvement in cooling is airflow.

As an aside, this is something that was observed in the PC overclocking community 15+ years ago. Increased airflow over a heatsink or waterflow in a waterjacket gave the biggest improvement in heat transfer. This is why some crazy overclockers were fine with those insanely loud Delta 80x38mm fans that spun at 7000 rpm and also why coolers with heatpipes conducting to larger radiators with 120mm fans became the norm. 120mm fans could move more air at lower noise levels.

 

Notapreppie, You want numbers, here goes. I had already shared these with another RX8 club member in Arizona long before I started this thread and he liked the results I got.

With a healthy cooling system (checked out, maintained and regularly flushed) I was getting cooling temps with the added cooling mods of Remedy thermostat, fan relay kit and oil cooler thermostats of 180-199 degress F with full a/c on, ambient temp 98 degrees and free revving, spirited street and highway driving at speeds up to 85 mph. This is at least 15-20 degrees F cooler than recorded last summer under similar conditions, without the cooling mods, but with the same stock cooling system.

I always make my modding decisions based on research, logic and fact, not fiction. I don't like to waste my money. If after doing these mods my temps didn't drop, I would have posted that result also.

If you do your homework back through the extensive cooling threads on the forum, you will find similar stories and many additional mods such as ducting etc.

I wont continue to engage you back and forth any further on this. Speak you mind and get on with it. I am satisfied with my results and others are free to try some of these options or not. Always do what fits your particular situation. Many RX8 owners before me have done so, and many more in the future will try some of these cooling options.