John Senini

Running my Bridgeport 12A with PASA in Phx, AZ. ambient about 90F track about 135F. could only run hard about 7- 8 minutes until the temps ran past 230 and I backed way off and cooled down to about 220 F. I know this is too High but do you think that it is really a problem as far as any engine damage? Normally this car cools pretty well usually about 190 to 200. Oil temps were only 190F. Any thing I can check?, there are no obvious signs of leaks.

Dick Elliott

Rotarys make best HP at 160 degs. This pup will not last long at 230 degs. Needs a bigger radiator or re-enginnering of what you've already got.

John Senini

So what failure modes occur at temps around 230 to 240?

Carl Byck

Housings warp, at lesser loads, but still in that neighborhood the O rings start to get brittle, plus since aluminum, and cast iron expand at different rates every mechanical connection, and seals between the housings are slowly compromised.

John Senini

what can I test or inspect that would tell me the condition of the engine.
JLS

jgrewe

iTrader: (1)

Any idea what your oil temps were when this was happening? We had oil(synthetic) up to 270 in a race and the thing survived. Went back and changed the whole oil cooler system after that one!

Gene

iTrader: (1)

Compression test, coolant system pressure test. You can also do the "run the motor at idle with the radiator cap removed and look for bubbles" test.

DriveFast7

iTrader: (1)

Is oil pressure still okay?

Prolly shortened the engine life a little.

I use a Howe radiator, 19x22x1.5", water temps are actually cool like 160F at full song and I have to tape up the radiator to make it warmer.

I have seen guys in the South East run their ITS oil and water @ 250 each all season.

And get a new motor every year.

RX-Heven

iTrader: (1)

230 is nothing to worry about, especially if your engine only saw that temp for a minimal amount of time and your oil temps were still in normal operating range.

Basically you are getting more severe hot spots and more of them in the engine where the coolant is not even in contact with the irons. These basically spiral out of control in a vicious cycle that is detrimental to your engine life. Rotories in particular are susceptible to this. The increased pressure with the heat is bad for seals too.
If you use Evans coolant, a waterless coolant , you can run your coolant system at 0 pressure (biggest advantage to rotaries) and still cool the engine better. Evans feels like brake fluid and is resistant to these hot spots within the engine so the coolant remains in contact with all parts of the engine under all circumstances.

However, it still sounds like you need a better designed system. Perhaps better ducting and/or a better radiator.
Does the air have anywhere to go after it passes through the radiator?

RETed

Oil temps?
We had our race car up at Thunderhill at close to 100F ambients.
The FC running a 13B-REW with no turbos hit 250F on the water temp and 240F on the oil temps, and it was still climbing!


-Ted

John Senini

I run synthetic, Mobil 1, only saw 190F, My oil cooler gets great high pressure air because its in the nose, more tip on troubleshooting are appreciated.

DriveFast7

iTrader: (1)

what size radiator? have you supersized it yet?

got a shot of the nose of the car?

waterpump and belt been replaced lately, you should gut the water thermostat with dremel tool, just keeping the outer ring. i assume not using a fan, not needed on racecar above 25mph.

spraying self expanding foam in the nose of the car to seal up all cracks and areas that air can pass AROUND the coolers lowered my oil and water temps 10*F each.

aluminum ducting to direct air where you want it really helps too, as does an air-dam.

I also cut a nice hole in nose of car so that radiator gets all air going thru that, and oil cooler gets all air going thru nose. see sig. is that allowed in your class?

John Senini

The car has cooled well in the past, I think I just have crudded up radiators from sitting too much. I added some scoops on the ducts to try and force more air through the rads but no improvement. I will remove and rod out the radiators adn go from there. Comments welcome!

its66

iTrader: (2)

I happen to have 5 gallons of Evans in my garage that i have been debating "installing" in my ITS RX7. Any Pro's or Con's I should be aware of.

Thanks

RX-Heven

iTrader: (1)

You need to properly flush the entire system before adding the Evans. Any amount of water/coolant will contaminate the Evans coolant and degrade it's abailtity to perform proplerly.
You can check out Evans coolant website for the proper proceudres.
I have yet to have to do this as I have only used it on new engines.

Pros: Eliminates internal hotspots / Can run higher coolant temps safely / Reusable / Environmentally safe / Operates @ 0 pressure = no boil overs / Water soluble / Absorbs heat better / Reduces corrosion and scaling within system / Prevents pump cavitation

Cons: Expensive / Not readily available at the local auto store / Cannot just add water to top off system which means toting some around on track days / Feels nasty on your hands (like brake fluid)

Some claim overall higher operating temps after installing Evans though I have not experienced this as I have only run it on new engines w/ different setups.
My car runs cool for a whole session with a 4" thick fmic. @ 15 lbs. boost.
The hottest day I have tracked my car was low 90's and I still had no problems.

DriveFast7

iTrader: (1)

Is Evan's coolant allowed on real road race cars? ex: SCCA does not allow coolant, they just want you to run water + some water wetter because coolant is very slippery when spilled on track.

I have seen road racing guys running coolant get chewed out by competetiors and officials.

Julian

iTrader: (14)

Mazda's notes on the subject (pre FD)

RECOMMENDED TEMPERATURE, PRESSURE & COMPRESSION
BREAK-IN RANGE / NORMAL RANGE / MAXIMUM LIMIT

Coolant Temperature
(Outlet Side) 160° - 175° F / 160° - 195° F / 205° F

Oil Temperature
(Oil Pan) 160° - 175° F / 195° - 230° F / 250° F

RX-Heven

iTrader: (1)

Thanks for the info.
The coolant ranges listed above assume a pressurized coolant system which Evans is not (or could be if not run that way). That being said, a larger/higher normal range and higher max limit can be run.

RETed

Actually, not entire true...

Water makes the track slippery too.
Coolant has the tendency to not evaporate as fast as water and sit on the track all day long with very little evaporation...


-Ted

cpa7man

iTrader: (2)

I know these are 3rd gen threads but a lot of great info.

https://www.rx7club.com/showthread.p...ight=ice+water

https://www.rx7club.com/showthread.p...ight=ice+water

Cool car btw.......

I was seeing 230+ oil temps untill I installed a Mazda Comp oil cooler. Last race in the Texas heat I was 200 water and 190 oil.(1st gen EP car)

Keep in mind that the 3rd gen cooling fans don't even kick on until like 224. (I don't remember the exact #)

Speedtoy

I would rather run water/water-wetter racing, and size the radiator appropriately.

NPG is heavier than water, and likewise will add additional drain in HP to pump it.

Carl Byck

Water+ water wetter for competition so sayath Da Rules...