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Engine operating temperatures

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I was at a track day a while back (Queensland raceway for those in Australia), doing 5 lap session and pushing hard enough for things to get hot, very hot.

which got me thinking:

what are acceptable temperature for the various fluids used in engines?

for example I have always been told anything over 100'c coolant temp is bad. mine peaked at 105'c with no apparent damage.

oil temps got to 120+'c. (oil cooler and improving radiator efficiency are in the to do list before next track day).

air temps maxed at 50'c (20 above ambient).

I suspect its a sliding scale but do you have a rule of thumb you use?

what about other fluids such as gearbox, power steering, differential even fuel?

just curious, as I know high water temps increase the risk of detonation, but is this the only concern?

Your question is pretty valid and I think you will get a different answer from anyone you ask. My 86 at the track now regularly runs above 100 deg C ECT after 4-5 hard laps although I don't consider this to be ideal. Here's my suggestions:

Engine coolant temp - 80-95 (ideal), 105 max

IAT - As low as possible. This is a little hard to control but if it's getting excessive you may need to adjust your timing particularly to prevent knock.

Engine oil temp - 100-115 (ideal), max will depend on your oil quality really. Personally I don't like to see over 130-135.

Gearbox/Diff - 80-110 (ideal). Again the maximum will depend on your oil.

Hopefully that is of some use to you.

might have to upgrade my oil temp sensors as its maxing at 120'c (GM) sensor.

I use synthetic oil as much as possible so royal purple in the engine and redline in gearbox/differential.

I do run a thicker oil (20w50) as it really doesn't get cold in Australia, my motor is a little older (180k klms) and given I track the car the extra weight gives insurance at elevated temperatures.

has any one used stick on temperature indicators on gearbox/differentials just want a cost effective way to check temperatures.

something like these: http://www.racerindustries.com.au/afawcs0161690/CATID=80/ID=4161/SID=22324332/Thermal-Indicating-Temperature-Strips-10-Pack.html

Andre as you say everyone will be a little different, the figure you suggest sit well with me so given your experience that enough of an answer for me. off to buy an oil cooler!

Yeah those temperature stickers are the way to go. I recommend using Nulon or Penrite full syn 15w/20w-50 + LIQUI MOLY MoS2 additive. I use semi-syn + LIQUI MOLY MoS2 additive in my daily... it works out cheaper than full-syn and performs better in my opinion.

Use RedLine "Water Wetter" in the radiator.

The best option is a modified (or upgraded) sump. This will increase oil capacity (essential for track thrashing/racing)... and increase surface area (if its a proper design... the GReddy/Trust SR20 extended sump is one of the best examples of this) which will act as an oil cooler. It wouldn't be too hard to make your own "extended sump" and get it welded up... if there isn't anything off the shelf for your engine. Im glad you're using RedLine in the gears... its the only way to go!. Penrite "10 tenths racing" 15w50 is definitely what i would choose.

I'm a personal fan of the Motul brand of lubricants, simply because I've seen the results. Back when I was running my EVO drag engine, we would need to replace a set of bearings every meeting. They weren't picking up or being destroyed but they came out heavily polished and scuffed indicating that the oil wasn't providing sufficient film strength. I swapped to Motul 300V 15w-50 and the bearings still looked like new after 4-5 meetings. I'm happy to accept there may be a dozen other brands that can offer this sort of performance but I stopped when I found one that worked :)

I used the Redline Shockproof gear oil in my PPG dogbox and transfer case because I needed all the protection I could get. I can't say if this was any better or worse than other brands for gear protection (my use was probably a little too extreme to expect a lubricant to work miracles), but what I did notice is that on tear down the shock proof gear oil tends to form a paste with the consistency of clay around the bearings. Others have noted the same situation and reported excessive bearing wear as a result.

Oils are another situation where everyone has their own favourites and experiences.

yeah MT90 in the gearbox, not keen on shock proof as I heard it decreases syncro life (already an issue with GT Four gearboxes)

I will look into motul for the next oil change. grab some temp stickers for other temperatures and go from there.

what are my options as far as fluid temperature sensors that measure above 125'c? trying to be cost effective.

I have been running my coolant at 75% water to genuine Toyota coolant with half a bottle of water wetter to help.

side note, why would my water temp sensor turn green (brass sensor corroding) in about 12 months? is it a concern?

Motul 300V and Redline Racing are no doubt the best you can get... but best VALUE would be Nulon and Penrite. It depends on whether or not its a dedicated track only car.

If its mainly a road going car.... i wouldn't bother with the full Ester racing oils (unless you don't mind paying the extra coin and changing the oil more often. (even more coin)).

I would run a cooling system flush through it if i were you. Don't waste your money on Genuine Toyota fluids... use Nulon/Penrite coolant and Water Wetter. Get a new radiator cap if its old.

Definitely don't use "shockproof" oil in a synchro'd box. Its too slippery for synchro's and the EP additives attack the brass metal. MT-90 is the best.

ill look into nulon and penrite, got to support the Aussies!

what do you guys prefer as oil filters? been using K&N as I figure its better then ryco and hopefully OEM.

lastly have you ever heard of low oil temps causing condensation to form in oil? looking at adding an oil cooler was going to go a 25 row with thermostat but worried if I oversize the cooler (25 row for a 200kw 4 cylinder is overkill) ill introduce water to the oil?

I personally don't see it affecting it, as now matter how hot the oil gets once water is in the crank case its not able to easily escape. vapour through the catch can is about it.

mountains out of mole hills?

"I do run a thicker oil (20w50) as it really doesn't get cold in Australia,"

Maybe not in Queensland, although I've been in Towoomba and its been freezing, but let me assure you even in Northern NSW waking up to -12 degrees C (with snow on the mountains within site of my home on the north-western slopes and plains) is not an uncommon occurrence.

+1 for Penrite, used Nulon a couple of times but always go back to Penrite.

Oil filters, in Australia at least, are often made by the same manufacturer (or they were when I was doing my apprenticeship) so I tend to just go for the Ryco.

Ryco come with "new car warranty"... so you can't go wrong with them.


Get a thermostatic sandwich plate for your oil cooler so it only cools the oil once up to temp.

Mishimoto do a universal one.

instead of a new thread ill ask here:

what are my options for a temperature sensor that works with haltech (0-5v) and reads over 130'c?

Bosch do one, NTC M12H that reads upto150 accurately, you'll need a gm/bosch diesel injector plug for it

looks good and affordable. bosch sell the connector.

can someone give me an idea how to do a custom sensor calibration in haltech platinum software?

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