BryanH

I have a feeling we don't know yet, but I figured I'd ask anyway. Some of you are much more 'in the know' than I am, and more familiar with Mazda.

So will we be seeing one on the RX-8? When/if I get one it might see a track lapping day or two... Not having an oil cooler could stop me from doing that.

Quick_lude

Is an oil cooler that necessary to have on a rotary engine for lapping purposes? I'm planning to do the same.. Just like with my Prelude.. I never had a problem yet, would this be an issue with the Renesis?

MyT13B

The oil cooler has typically expelled 1/3 or more of the heat inside the rotary by cooling the inside of the rotors.

The RX4 13B had a very large oil cooler that was aluminum and four rows of coring. It was about 1/3 as large as the water radiator.

The new design still needs that oil cooling capacity and probably needs a higher flow of oil to assure the higher rpms and higher power output.

The water jacket is totally changed also from older engines. Aside from the noticeable increased thickness of the rotor housing, (for strength), the passages seem to address some of the typical hot spots around the compression and combustion areas.

For a racing application I can see many opportunities to enhance the cooling properties of the water jacket. To increase the oil cooling, larger or more (2) oil radiators would be just fine as well.

Full throttle at 8000 rpm around a speedway without modification could be hard on something in the chain of force moving you along....

If you want to push the car to its limits, do everything you can to be prepared for the worst.

Every day traffic situations will be covered fully by the stock set up .......

this is true for most any type of car

BryanH

Thanks for the info, MyT13B. I wouldn't plan on running any car around a super speedway at top speed for any length of time. What I do is drive road courses like Laguna Seca in short (20-30 minute) sessions. Still enough to work the car.

My MR2 has a genius little oil cooler that's actually just a coolant line inside (or was it next to...) an oil line. This car has survived such track sessions at 100+ degrees with no oil issues. Perhaps I've been lucky, but I like to think the car is designed to take this.

I'd assume the RX-8 is, too. I just wanted to reassure myself, I suppose. It really surprised me when I found out the 2000+ MR2 Spyder does *not* have an oil cooler.

wakeech

i wouldn't worry about an oil cooler for track lapping in comparably short sessions...
this engine i would expect will run fairly cool under street operation, and even under duress of that sort i don't think it would permanently damage the engine. now, in +30 degree heat like you say around Laguna Seca, well, maybe as a precaution, but i don't think that the RENESIS will "CERTAINLY REQUIRE" an oil cooler just for light track lapping and autocrossing to keep it from blowing up...

Sputnik

And what do you base that on?

---jps

MyT13B

Do you understand that an oil cooler is standard equipment? It is not an accessory you get from the speed shop nor is it an optional item from the factory.

Hot laps around any racing facility will stress your machine. Unless you are held by classing rules, it doesn't hurt to be safe than sorry.

In stock form, the Mazda rotary is typically held within its limits. Generally when the engine gets near the red-line it runs out of fuel or a rev li miter kicks in. For an autocross, make sure the engine is fully warmed. This will ensure the thermostats in the cooling system'S' are wide open for maximum flow. If you don't, some of the coolant may be routed through a bypass instead of through the radiators.

Takumi

speaking of oils. Once again an early forgivness to those who find my questions stupid. What about the oil for renesis. Sythetic. or standard oils. ?

wakeech

alright, alright, i feel a little embarassed...

clarifying, when i'm thinking oil cooler, i'm thinking a huge-*** racing outfit cooling system. (i apologize, i wasn't thinking so clearly... past my bed time )

yes, i know that many cars have oil coolers, and some for the auto trans (like public transit busses), stuff like that.

thanks MyT13B for backing up my ideas, in a far more coherent and detailed way. of course, i didn't say this, so it's sort of moot that "it's what i meant", thus my embarassment... :o

precisely what i mean that this engine will not blow its self up without an additional/serious-aftermarket oil cooler even when whizzin' around a bit.

Taku, as for the oil thing, i know nothing about that, other than Mazda in the past has stressed using only mineral oils, and a few enthusiasts on this forum (most notably Dazz, who's got tons of experience with that stuff) and Racing Beat as well endorse synthetics heartily.

Quick_lude

Synthetics outperform conventional oil in every way.. but I guess we'll have to see what Mazda says about using synthetics in the Renesis.

wakeech

performance of the oil wasn't the concern, it was about carbon deposits building up around the cool spots in the combustion chamber (like the edges of the rotor, around the plugs, or something...), but Dazz emphatically denies this is the case...

not that i don't trust his expert opinion, i just don't know what i'd do for a new car... for a beater FC, i'd go synthetics all the way :D

Takumi

What about that Prolong stuff thats on infomercials has anyone ever used it? I'm starting to see it in the local auto parts store.

Grimace

All that stuff is garbage. Just change your oil regularily, with synthetics or conventional.

Takumi

are u basing on facts that its garbage or have u actually tested it?. Either way I plan on using conventional or sythetics and changing regualary

MyT13B

In my opinion, absolutely NOT.

Any additive that claims this sort of thing is too good to be true.

I am not sure what Prolong is and I have seen the TV info-mercial.

Most of these products are a form of Telfon (PTFE) which makes a non stick surface on your internal parts...

Sounds good at first, until you rebuild the engine This baked on coating makes a mess of your main bearings and their journals. Why? The main bearings are made up of a material or plating that soaks up some oil like a sponge to improve the lubrication.

These wonder additives will also soak into your bearings in place of the oil and will take away from the cushion the oil would normally make.

Over rev the engine and watch main bearing failure very soon behind that.

The additive is acceptable for steel to steel surfaces in the hoopla and does promote friction loss in mechanical valvetrains. But steel to babbet (sp.) doesn't quite work the same way.

If your main bearing touches the journal with PTFE, this (now dirty)plastic, it acts like sandpaper and scores the journal (yikes!).

The rotary has four bearings like this and the slightest failure is very costly.

Without the PTFE, a minor touch of the bearing and journal could tolerate itself since the bearing is softer than the steel journal.

Takumi

Ahh thank you for clearign this up. Cuz i always thought it was to true to. But I never heard of anything bad of them.

wakeech

yes, these solid additives (PTFE as MyT13B pointed out) in things like Slick50 are actually terrible in the tests as well...

i can't remember, but another show (promoting some other product) i caught for a second whilst riding the wave on the remote, compared one of those wonder-products to bleach in the grind-a-bearing tests... and the bleach outperformed it... but, again, who can believe the claims of people who promote the same sort of stuff in a different bottle, right??

neato info on that MyT13B

SPDFRK

There is one product that I believe in "Z max" I haven't used it in my motors but some of my friends have. It doesn't contain any PTFE or solid particals, the magic ingredient is linkite (think thats spelled right) but it was originally developed in the aerospace world and have never heard anything about it not performing. From personal experience it was pretty evident that my friends tahoe idled smoother and we have put it in a few sportbike motors, I have only seen the internals of one that had it in but the motor appeared to be clean, however it had limited mileage (about 2000) since this was to upgrade not a rebuild.

MyT13B

I'll stick with pure synthetic oil. I know that works.

STP also works for awhile but it will break down along with the conventional oil between change intervals.

I bet a replacement engine is not too cheap.......