Phil,
The oil pressure response issue during transient throttle was the reason we stopped using the factory coolers 3 years ago.
Here are a few alternatives.
Mocal liquid to oil

Pass side scoop

 

I knew you guys were doing that. I know Frank has relocated his after he used the front coolers for heat exchangers as well... I was thinknig of just putting the TRD oil cooler on the car, which is a sandwich plate between the block and the filter. It would be nice to have some documented figures before and after the change- specifically at the track since that's where things tend to get the hottest...

Do you guys have any figures? I'd like to know both oil pressure (post coolers) and oil temps (before and after coolers would be nice)....

I had read about a fella with a Celica who actually tracks his GT-S was maintaining temps no higher than 220, but averaged 210 with the TRD cooler and had temps in the 250+ range w/o the cooler. I suspect 220 in our cars would be pretty ideal. Particularly, if we could maintain better oil pressure while doing so... Of course, if this sandwich cooler is so great, why didn't the Lotus engineers take that approach? Tim M would be PO'ed if a guy deviated from Lotus's excellent engineering without good reason I presume it's possible that Lotus took the approach they did due to cost and availability, as they often were forced to do with other parts on the car.

Best,

Phil

 

Of course, if this sandwich cooler is so great, why didn't the Lotus engineers take that approach? Tim M would be PO'ed if a guy deviated from Lotus's excellent engineering without good reason I presume it's possible that Lotus took the approach they did due to cost and availability, as they often were forced to do with other parts on the car.

Everything in life is a compromise (usually involving cost). From stuff I've read, people with oil temperature guages are seeing oil temps around 220 or so while doing track days in the middle of the desert. I suspect that the coolers are actually doing a very good job - at least for most people.

As for the pressure drop, the lines are fairly good size and probably more than handle the oil flow. It's not like there is a huge volume of oil flowing through the system. As the volume/velocity of floe goes up, the pressure drop would be significant, but again for our engines, the flow isn't really that high and it's probably sized about right (putting a bigger sized hose wouldn't have been a big deal for the factory if had been necessary).

And everything can be improved upon. It's all a matter of what an improvement in one area causes what effects in another (i.e. more cooling = more weight: etc.). And cost is always a trade off - it's one of the reasons that we drive Elises instead of Enzos...

 

our oil takes "forever" to warm up, and perhaps our oil doesn't get hot enough to do its job effectively (recall that cold oil puts excess pressure on parts and does not lubricate as well as hot oil.... to a point anyway...).

The oil adapter that the oil lines connect to is a thermostat controlled adapter. It only sends the oil to the coolers as it heats up and gets warm enough to start to open the thermostat (just like the one in the cooling system). A cold engine is not sending the oil through the coolers. A hot engine is sending some (or all) of it's oil through the coolers. It's part of why the oil temperatures in the engine don't get as high as they do in most cars.

 

Good call Tim. I didn't see a thermostat type valve when I had the engine out, but I didn't look 'that' close either. I'm still curious why they didn't use a sandwich type cooler on the car and use the coolant to cool the oil. The water lines are already on the car for the TRD type sandwich cooler. They're the ones that are simply U'ed right above the filter that are known for leaking The U turn essentially goes nowhere and loops back around. I cut that section of coolant line out and replace with about a 4" piece of heater hose, which wa much cleaner and remove a place for leaks... It's almost like it was thought about and then abandoned. I wonder if TRD couldn't deliver enough sandwich coolers for the production run or something like that...???...???

Cheers,

Phil

 

Wasn't Lotus really concerned with oil temps destroying early 2ZZ engines on the Celica? Thought I read about that somewhere. I thought that was why they went with the coolers and the insistence on 5w40.

Take that FWIW - its simply my recollection of what I've read on this board and other sources.

 

Here's the TRD cooler, BTW

 

I found this excerpt from a guy who post the 986 forum. There' no telling where he got this information from. I think he's a bit off as evidenced in his first statement about lotus tuning the head and intake.....



>>Lotus has always massaged existing engines rather than produce their own from scratch. The Elan and Europa had Ford/Kent blocks w/ Lotus designed and produced heads. The Seven had a BMC inline 4, again massaged by Lotus. The Esprit had it's 2.2L 910 4-cyl. drawn from a Vauxhall Delivery Lorry engine, again, all new internals and heads.

Even the Elise uses a Kent engine (ROW) and the Yamaha-designed Toyota 2ZZ-GE engine, again with thorough tuning, intake, exhaust and head by Lotus for the US Market.

The 2ZZ-GE features a stroke of 85 mm (3.35 in) to an 82-mm (3.23-in) bore to attain a redline of 7800 rpm. The block is made of fine-ceramic-fiber- and grain-reinforced aluminum-silicon alloy. The piston's rubbing surface is iron-plated, and the pistons are internally cooled by oil jets. The 2ZZ-GE's cylinders are tightly packed, with only 5.5 mm (0.22 in) of metal between the adjoining bores. The cylinder block is split at the crankshaft centerline, and the cast aluminum lower block carries five main bearing caps. The 2ZZ-GE's Lotus designed cylinder head is unique to this engine. Valves are inclined at a wider angle of 43° for freer breathing through the upright intake ports. Valves are 34.0 mm (1.34 in) in diameter - intake and 29.0 mm (1.14 in) - exhaust. The 2ZZ-GE combines the VVT-i continuously variable intake-valve-timing device with the new VVT-L, a Honda VTEC-like variable-lift and variable-timing system, employing two sets of cam profiles for both intake and exhaust. Below 6000 rpm, the VVT-L employs the low and mid-speed cam profiles, and above 6000 rpm, the high-speed profiles. The high-revving 2ZZ-GE's camshafts are sprayed with lubricant oil.

In fact, Toyota had been having problems with this engine siezing and warping the heads in the Celica. They went to Lotus Engineering, who redesigned the Oiling system, added an Oil Cooler for higher capacity and flow and the problem was solved. This is why Lotus chose this engine for the Elise, though they massaged it even further. The Kent ROW engine could not be made to meet US EPA requirements, so Lotus went with the 2ZZ-GE which was already certified and being sold here. Toyota's 2ZZ-GE versions found in their own cars in the U.S. make ten fewer hp at 180 hp than the same engine in the rest of the world which has 190 hp.

However Lotus retuned the 2ZZ-GE for use in Elise, smoothing out the torque dip at the 6000 rpm cam changeover point and strengthening the torque in the other rpm ranges. In addition to the improved torque Lotus brought the peak horsepower back up to 190 in their U.S. version of the engine.
<<<

Best,

Phil

 

Geez phil.

Just put a bunch of monkeys in your engine bay with fans and call it a day.

What about the TRD thermostat? Ronin says he used it with great success.

 

I'm not all that worried about the engine temps, and I'm aiming on ditching the stock oil cooler system... I just need a good reason to do so other than my gut feeling... Like many things with these cars, it could be that nobody has taken the time to actually test the theories out there and we're all promulgating wives tales...:shrug:

The T-stat is a fine idea and I'm well aware of it... However, define great success for me? I haven't checked with Frank to see if his car can maintain the 160 temps and he may not know for sure yet since he's still tuning the turbo.. I dunno...

Our cars cool well, but I'm pretty certain my car can't hold 160 with the stock radiator on the track so it's a bit moot for a track rat like me... I've lost track of what Frank has for cooling, he may be able to hold 160- I'm quite confident that I can't hold that temp with my setup though...

Best,

Phil

 

Phil,
It may be a worthwhile move to mount an oil-temp gauge before you do anything to your oil-cooler. Most cars that find their way to the track, even stock, require additonal oil-coolers...and now that your car is well modded, you're thermal requirements are quite different. I also cannot believe that Lotus would mount oil coolers in the front clam (my car has the twin coolers) for cost savings, as the parts are certainly more expensive than the sandwich adapter. As with some things, overbuilt is a good thing...especially when it comes to thermal capacity...more so when applied to oil, as long as proper operating temps can be reached (oil t-stat).

We are actually blessed when it comes to cooling...ever try to keep a Vette cool on the track?...not fun...

Be good,
TomK

 

I also cannot believe that Lotus would mount oil coolers in the front clam (my car has the twin coolers) for cost savings, as the parts are certainly more expensive than the sandwich adapter. As with some things, overbuilt is a good thing...especially when it comes to thermal capacity...more so when applied to oil, as long as proper operating temps can be reached (oil t-stat).

Yep.

I'm not sure that the Celica used the oil/water cooler. But the reason that it's in the manuals is that Lotus uses it - on the Elise-R in some markets. They upgraded the oil cooling system with the dual oil coolers for the US market to cope with the added heat that we were liable to experience. Later they discovered that two oil coolers weren't necessary (and to save costs), and changed it to a single front mounted oil cooler for the Elise, with the Sport Pack adding the second oil cooler back for the expected track use.

Bottom line is that the oil/air coolers should do a better job of cooling the oil and maintaining the proper temperatures than the oil/water cooler does. The oil/water coolers are usually used where space is a premium and/or for cost savings consideration. I believe that we got the better system.

 

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

 

as to the oil to air cooling vs. the oil to water cooling, it all depends on the cooling surface coupling capabilities of the heat exchanger.
yes, the delta t is important but the transfer capability is not shown.

the liquid to liquid transfer path is more efficient on an area-to-area case, but is there THAT much more area to make the front cooler more efficient?...
there just isn't enough data to decide.
so i expect the measure and cut and try method is most practical for us.
thermocouples are cheap, the fluke 152 (i think) is a dual channel device i've used when curious about the efficiency of my dodge diesel aftercooler.
it'll record mins and maxes as well as T1-T2.
if someone is seriously interested, i could loan mine....
sam

 

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. :shrug:

 

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.

 

Bottom line, in a car where owners routinely spend hundreds (or thousands) of dollars to save a few pounds, it certainly seems like overkill to have two heat exchangers and 25 feet of hose to cool oil that doesn't need to get that cool. Ronin has had good luck with one heat exchanger behind the rear passenger wheel well. I think that, the Mocal system, or the TRD mod would be a good one if only for the weight savings alone.

 

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.

 

Jack- As usual, you rock!:up:

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

 

Interesting read...

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

 

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.

 

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.

 

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

 

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 ...

 

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. :crazyeyes

All the best,

 

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

 

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.

 

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.