Oil Temps- Thinking out Loud

[turbophil]

Originally Posted by kverges

I constantly monitor my oil temp, in the pan, where it should theoretically be hottest after being spun out of the bearings and drained from the top end. On the street I never see over 180 and on track never see over 250. Not sure about transient oil pressure response, but it sure seems quick on my gauge - I never see under 40 psi and at higher revs never see under 75. If there is a thermostat, it is set too low, as IMO oil needs to get over 200 to properly purge absorbed combustion products , water, acids, etc.

As for water/oil heat exchangers, the concern I have is that eventually, you have to exchange heat to the air and if you limit yourself to the surface area of the radiator, it sure seems that less heat can be dissipated than if you have the extra surface area of the two oil coolers. Also, I have to believe that an oil cooler with 250 degree oil in it has to disspate heat better than a radiator with 200 deg water in it. If I saw real test data to the contrary, I could be persuaded, but I think the factory setup is pretty good.

Thanks K- That's exaclty what I'm looking for...So the question is if a good quality oil to liquid cooler can maintain proper oil temps, 200-220 or so, why wouldn't we dump the stock oil cooling system, plumbing, weight, etc... I don't think it's a matter of what cools *better*, it's a question of what cools *sufficiently* to maintain desired temps from a cooling aspect.

You guys should google the Laminar Mocal oil coolers. A lot of racers use them___ including Lotus 111 and Caterham race cars in the UK. They're very small (bigger than the TRD system though) and everyone raves about them. I'm not sure whether they cool as well as the OEM system, but they seem to cool *sufficiently*....

My desired goal is to get/keep the oil in an optimum operating range while losing the complexity and weight of the OEM oil cooling system and then use those two front scoops as part of a brake cooling system

That said, I realize I can tap into the main airflow trunk that directs air to the radiator for those brake ducts, I'd just prefer to do it this other way

Best,

Phil

[Jack]

Phil,

FWIW -- I also monitor my water and oil temp quite closely (track usage only as my car is never driven on the street). My oil temp sensor is located at the sandwich adapter just above the oil filter...don't know how that affects the accuracy of the readings...lower or higher than actual. You experts tell me.

On cool track days (ambient temps of 60 to 85 degrees F), oil temps maybe reach 190 max and it takes a good amount of time to get to 170. I never take the revs up until I reach a reasonable oil temp which can take a good 15 minutes of driving time. Water temp gets into the proper operating range rather quickly -- ~ 183 on cooler days and stays there (185-188) for the most part (no a/c condenser to block flow).

On HOT (ambient of 100+ degrees) track days, the highest coolant temps that I've seen are ~198-200. As for oil temps, never seen more than 220. Both drop very quickly once in clean air and the revs are reduced -- cool down lap.

[GregD]

Originally Posted by Conan

FWIW: My typical H2O (I know, you want oil, but I don't have an oil temp guage) temps from the OEM dash readout read 190-195 deg F on the highway @ 75-90 mph. On track, the temps go from 205 deg F in clean air to as high as 225 while consistently drafting. Not sure that helps, but data points are data points.

So to handle extreme conditions, which the Lotus engineers have to account for, the radiator is already at the minimum size. If you start using it to cool the oil as well, it sounds like you'd run into some serious overheating problems. I suspect that Lotus couldn't fit a larger and/or more effective radiator, so the separate air to oil coolers were the only option.

I think going to an oil to water cooler would probably be a bad idea unless you never run your car in extreme conditions, or you find some way to improve the radiator effectiveness. My guess is that improving the radiator effectiveness would be extremely difficult to impossible, otherwise I think Lotus would have done it, and gone with the oil to water cooler for its simplicity and reduced weight.

[turbophil]

Jack- As usual, you rock!

That's also the kind of info we need... Given those figures, one might argue that the oil should be running a little warmer than it is in our cars... Also, despite the thermostat, my suspicision about slow warming oil temps seems to have some validity to it...perhaps the t-stat doesn't shut down the oil flow competely??? Only way to tell is to try something different

Just for the record, I'm not poo-pooing Lotus engineering. There's no doubt that they know what they're doing. However, they make MANY MANY changes to their GT car from even the cup car, which simply goes to show that there are a good number of sacrafices that had to be made to not only keep the car somewhat civilized (something we're not talking about changing with this), but to also meet cost, production, and marketing demands...

Best,

Phil

Originally Posted by Jack

Phil,

FWIW -- I also monitor my water and oil temp quite closely (track usage only as my car is never driven on the street). My oil temp sensor is located at the sandwich adapter just above the oil filter...don't know how that affects the accuracy of the readings...lower or higher than actual. You experts tell me.

On cool track days (ambient temps of 60 to 85 degrees F), oil temps maybe reach 190 max and it takes a good amount of time to get to 170. I never take the revs up until I reach a reasonable oil temp which can take a good 15 minutes of driving time. Water temp gets into the proper operating range rather quickly -- ~ 183 on cooler days and stays there (185-188) for the most part (no a/c condenser to block flow).

On HOT (ambient of 100+ degrees) track days, the highest coolant temps that I've seen are ~198-200. As for oil temps, never seen more than 220. Both drop very quickly once in clean air and the revs are reduced -- cool down lap.

[GTsRasta]

Interesting read...

So what is the end all, most effective oil cooling mod route? Will you guys change things around like ronin?

[ace996]

Flush the coolant system and add one small bottle of water pump lube, distilled water, and a bottle of WaterWetter...that'll make the efficiency better if you're going to go with the water/oil cooler.

[kverges]

Oil temps of 250 deg F are perfectly fine - no cause for concern at all. I run that temp in my race cars regularly and have done endurance races with higher temps. Of all the things to mess with, oil temp and front brake cooling are not necessary in the Elise.

[turbophil]

Originally Posted by kverges

Of all the things to mess with, oil temp and front brake cooling are not necessary in the Elise.

I'm not so sure I agree with that...

Cheers,

Phil

[Tang0_au]

the elise S (aus and euro only) uses a 1zz engine, not quite as high revving as the 2zz, and doesnt have the oil coolers up front, it has the trd oil/coolant cooler ... but i have seen my water temps upto 108 degrees centigrage on a 35 degree c day on the track ...
oil cooling is next on my spend list ...

[Simba]

Originally Posted by TimMullen

I'm not sure that the Celica used the oil/water cooler.

I don't believe they used a cooler on the 2ZZ in the Celica. They did, however, use a very similar water to oil cooler setup for the 3S turbo engines in the previous Celica GT-Four and MR2 turbo. My experience with those horrid little pieces of metal is better left unsaid-- long story short: A sandwich plate with a good fin and plate cooler is a much, much better cooling setup while doing any sort of track duty. While WTO coolers have a more efficient heat transfer, they also have a lot of negatives such as the aforementioned additional load on the cooling system, and the fact that once your coolant is up to temperature, they're operating at significantly higher than ambient temperature for cooling.

The only way I'd do a WTO cooler would be a separate coolant system, perhaps using similar sized heat exchangers up front in place of the oil coolers, and running coolant through the hoses in the body. That would give you a significantly larger temperature differential between the average system water temp and the oil temp. Unfortunately, it would also be very complex, and if anything add a fair bit of weight to the back of the car by way of a cooler core, pump, header tank, plumbing, and a bunch of coolant.

I personally don't see my oil temps get much over ~210-215 degrees in my turbo Elise, even when giving in the beans in very hot weather. If one is concerned about oil pressure drops, I'd just add an accusump and call it a day.

[kverges]

All I can say is that those here in Texas who race or track drive with real pace do not fiddle with oil coolers or brake ducts and have no brake fade or engine longevity problems. In fact, the cooling and brakes are two of the most impressive things about this car when driven at race pace.

[Jack]

Originally Posted by kverges

All I can say is that those here in Texas who race or track drive with real pace do not fiddle with oil coolers or brake ducts and have no brake fade or engine longevity problems. In fact, the cooling and brakes are two of the most impressive things about this car when driven at race pace.

I think it depends on the track(s) that you run. One of our brethren (DMH) that runs back east has had some brake cooling issues... I believe at Watkins Glen.

I haven't had any oil temp or brake cooling issues at my local tracks When I run hard in 110 degree ambient temps, oil never gets above 220. I, personally, would not want to see 250+ oil temps in my car.

All the best,

[dmh]

Originally Posted by kverges

All I can say is that those here in Texas who race or track drive with real pace do not fiddle with oil coolers or brake ducts and have no brake fade or engine longevity problems. In fact, the cooling and brakes are two of the most impressive things about this car when driven at race pace.

As Jack wrote, brake cooling is an issue. And that is why Lotus runs brake ducts on their race cars just I do.

[turbophil]

I concur with Jack and Don. My brake get mighty toasty as well... granted I'm running stock sized rotors with sector's Giro discs and st-43 pads and those will get things warm There are soooooo many performance oriented parts that can still be improved on with this car and the GT cars are good examples of that.

Brake ducts are one of those.

Regarding the oiling system. I'm not questioning whether the stock system does a good enough job--> it obvously keeps the oil plenty cool (if not too cool). The question is can we keep the oil in an acceptable range with a lighter, smaller, less complicated system---> Like a WTO oil cooler??? There are a lot of *race* cars that run WTO oil coolers and piggyback off the stock cooling system with great success.

There are so many things about the stock oil system that just isn't cool (no pun intended): It adds more heat generation through our frame rails, it's heavy, the radiators take up good duct space for the brakes, the radiators are in harm's way in case of a front impact, 25 feet of oil hose, etc... Wouldn't you love to ditch the system for a simple, small, light weight alternative could keep the oil in an acceptable heat range? That's really the point of the discussion...

Best,


Phil

[kverges]

I have not driven an Elise at the Glen, but would be surprised to experience fade unless you have a power adder on the car. In fact, I can get away with a much less temperature resistant pad in an Elise than in other cars. But I suppose it is possible that a track has enough heavy braking zones to be a problem, although the Elise sure does not seem to have enough power to create the issue.

I am not really sure anyone really is getting brake fade or other problems caused by excessive brake heat - by definition the brakes get hot - they turn kinetic into thermal energy. But do they get so hot that they do not reliably and predictably stop the car? Mine do not.

As for brake ducts, any reason you could not draw air from behind the stock coolers? Remember that air is likely to be no hotter than 200-250 deg F and may still cool brake rotors that may see temps of 120 deg F.

And I stand by my opinion on 250 deg F oil temps with synthetics - I have done 25 hour races with those kind of temps and many years of sprint races with those temps, all without any engine wear or failure issues, even in race engines with generous bearing clearances.

Improved cooling never hurts, though. I'd still want to see data that actually shows a modified oil cooling system works better than stock before going to the effort to re-route plumbing and so on.

[Arno]

My K20A2 setup with some TODA goodies (cams, headgasket, etc.) in my Elise uses a BIG laminova water-oil heat exchanger (over a foot long) fitted on the coolant outlet of the engine. No T-stat on the oil cooler.

Sounds odd, but actually it works quite well as it helps to heat the oil in winter much more rapidly than normal.

Normally my car will run at a steady 84C (183F) coolant temperature on the road. Creeps up to about 88C (190F) on a hot trackday (hot here is between 25 to 30C, aka 77 to 86F). Won't go much higher if you keep the speed up. My car pre-dates A/C, so I have a single radiator up front (no A/C condenser)

Oil temperature measured in the sump gets close to 120 degrees C (248F) under those conditions, but not much more.

Works well IMHO and the oil hoses needed are only about 2 feet long.

I do get the feeling that the K20 is not a very 'hot' running engine to start with (oil and coolant temperature wise), so it may not be comparable to the 2ZZ in this respect.

Bye, Arno.