Not to instigate here, but this requires an opposing data point to put it in perspective:

In my turbo car - with an oil cooled turbo - with a cheapo Trucool 24-row heat exchanger for the oil, BUT with ideal airflow (NOT behind the radiator, sitting in front right corner of car behind bumper, dedicated ducting in and out independent of radiator/intercooler air path) in similar ambient temperatures (~100* F) I see 230* F oil temp.

Naturally aspirated (much less heat), with a better heat exchanger (your Canton is same style as mine but double the surface area), you're seeing more oil temp. That doesn't paint a very supportive picture for the oil cooler behind the radiator config.

It will certainly work - as in, it will cool the oil more than if you didn't have an oil cooler - but it's not ideal and I think that is what Andrew was getting at.

-Ryan

Same temp sender location?

Good catch, that's misleading. Edited post for temp at sandwich plate. 230* F there.

-Ryan

Is that an actual temp reading? Or your oil pan temp+25?

Actual at sandwich plate.

Coolant is absurdly low for a turbo car too - 195-205 with 100* F ambient. With a cheap CXRacing radiator core. Ideal airflow FTW.

-Ryan

This raises some good points.

Nothing is ever ideal. Everything is a compromise. Your compromise was doing more work to the car + being more succeptible to debris + more oil pressure drop from longer hoses with more bends and a smaller oil cooler. Your car also has V-mounted radiator and intercooler. You did a heck of a lot more work to optimize the mounting locations to see the coolest possible air temps (highest possible DeltaT) than I did.

My compromise was to knowingly accept hotter air into the oil cooler -- which I remedied by increasing the oil cooler area (Q ~ DeltaT x Area). BTW, the Canton oil cooler IS a TruCool that's been marked up . . . grrrrrr.

Not sure if you are measuring at the pan or at the sandwich plate. If you are measuring at your oil pan, then our performances are pretty much the same. No matter what, we are both far away from the 300F we need to be worried about.

You are putting more heat into the oil than I am due to turbo cooling and increased bearing pressure, but not nearly as much as you think. You do have much greater water cooling needs though. Aside from going out the exhaust, almost all of the waste heat from combustion goes into the water jackets in the block and head. Oil temperature increase is mostly a product of bearing friction -- spin any Miata engine between 5000 and 7500RPM continually (even at part-throttle like we do when fuel tuning) and you'll see the oil temperature shoot up. Oil temperature is much more linked to RPM than power. This comes as a surprise to a lot of people out at the track -- they don't expect they need oil cooling unless they have made power mods, when in fact they need oil cooling as soon as they start continuously operating at RPMs that are much higher than normal street use.

If the air is cooler then the exchanger can be smaller and lighter with the same net effect, fwiw.

Let's also not forget the risk that if I crunch the front right corner of the car, it's almost a certainty that the motor will bleed-out :bang: :noes:

Absolutely agree, everything has it's own set of compromises.

-Ryan

What is the temperature of the air coming out of the radiator at 60mph? Anyone have equations or data?

Yes, that's what I meant by "Q ~ DeltaT x A." Q is heat transfer and A is basically how big the exchanger is. It's a simple and direct relationship, makes for easy calculations. In fact, I'm going to use Ryan's data compared to mine to calculate my approximate post-radiator air temperature since I've never measured it.

Using my data vs. Ryan's:

Let's assume Ryan needs 20% more oil cooling due to cooling the turbo and increased bearing pressures (this is a complete swag, BTW, would be great if someone had real data). So, if I'm rejecting 1Q to the air, Ryan is rejecting 1.2Q.

Ryan runs a 24-row Tru-Cool (A). I run a 48-row Tru-Cool (2A). Ryan had 100F ambient and 230F oil going to the oil cooler. I have 245F oil going to the oil cooler. Filling these into the equations:

Ryan: 1.2Q ~ A x (230 - 100)
Hornet: 1Q ~ 2A x (245 - ?)

Work the simple algebra and we have:

2 x (245 - ?) = 1.2 x (230 - 100)
245 - ? = 1.2 x 130 / 2
? = 245 - 1.2 x 130 / 2
? = 167F post-radiator air temperature

If the assumption is Ryan only needs 10% more cooling, we get 173.5F. If he needs 30% more, 160.5F.

My radiator in this instance is rejecting the heat from a 140HP engine. Given similar air flow, more HP means the radiator will increase the air temperature more if the engine is able to run at the same temperature.

Seems high to me. Assuming 200 degree water isn't that a 75 percent efficiency? Or is that not how it works.

I have the FM oil cooler kit and it isn't enough. Can I keep the FM thermostat plate and just buy different adapters to go from 8AN to 10AN hoses with a new bigger cooler?

Thanks!

<p>Looks like that is the standard mocal thermostat plate. So you would need a set&nbsp;of these:</p><p>Sandwich and Take-Off Plates - Mocal Sandwich Plates</p><p>Part #:&nbsp;$15.99</p><p>And then new 10an hosing.</p>

You're better off removing the FM kit, selling it complete, and buying our DIY kit. The only thing from the FM kit you'll keep is the adapter plate itself.

Trackspeed Oil Cooler Kit

Your right. It is now for sale. I'm just not sure where I'm gonna put your kit. I can't help but wonder about putting it behind the radiator. That's one of the few open places I have....just don't want my coolant temp going up

This link was posted in the cooling thread but belongs here:

Project S2000: Part 23. Testing Air Temps Through Coolers and Vents

Just keep in mind, mounting the oil cooler post radiator is a compromised location as you are sacrificing air flow and delta T vs. having a dedicated fresh-air feed. So size accordingly. Also, in the link, the author placed his oil cooler directly against the radiator -- but it is recommended practice to have at least 1/2" of air space between heat exchangers to allow the air to adjust to different fin configurations.

Another lesson learned for me, if you are using the less-expensive Tru-Cool type cooler, make sure to use vibration isolation (like this install with wellnuts -- https://www.miataturbo.net/build-thr...8/). I experienced a split core due to vibration. I don't think this is an issue with the more robust Sertrab type coolers, although Andrew's kit includes rubber isolated brackets, so . . . . Good idea regardless?

Dang, how have I never seen those wellnuts before? I think I just figured out how I'm mounting my megasquirt. :party:

I have my 25row setrab mounted behind the radiator. It'll do for now but my big concern is there's maybe 1/4" between the cooler and the sway bar, any collision could spell a lethal strike. I'll have to figure something else out for a location down the line with better placement..

Oil temp question.<br />
<br /><br />At the track today, I'm seeing 250 indicated in my sandwich plate. I know 250 is getting hot when its in the pan but my sensor is in the plate. What temp should I start doing cool down laps?

Oil cooler tech
 

Is that measured on the pre or post cooler part of the sandwich?

It would have to be pre, because the post cooler route goes through the filter and then into the block through the central pipe.

250 pre-cooler is nothing to worry about.

https://www.miataturbo.net/attachmen...ine=1441934897

Depending on the design of the plate, and its orientation, it's possible to take a measurement either pre or post-cooler.

This one, for instance, has ports on both sides:

https://www.miataturbo.net/attachmen...ine=1441934897

Brainfart.

Oil cooler tech
 

Yep, that's like mine and why I asked.

Mine is just a sandwich plate. Just for gauges/spacing.<br />
<br /><br />What temp should I be worried?
<br />Rotella T6

I'd start thinking of pulling off or doing cool down laps at like 240... running a boosted Miata with no oil cooler is kind of asking for trouble.

<br />
<br /><br />
<br />I have a 25 row setrab.
<br />I was refering to where the temp was taken.

Oh. I'm assuming that temp is before the oil cooler so then that means I have no clue for your scenario.

Not miata obviously, but a lot of high performance german cars go into limp mode in the 270's *F (dropped rev limit to about 1/2 of normal, HP down to ~25% of normal_ and stays there until oil is in the 250ish range. My C63 shuts the party down at 275, drops revs to 3,500 max, upshifts to highest gear, will remove your control to manually downshift it, power drops to about 100hp.

Given the fact that many of them shut it down around 270, I would think beating on it all the time near say 250 is probably a bad idea. If you did it, I'd swap the oil afterwards.

Isn't oil at the filter 10-20* hotter than the oan?

The question remains, is this oil temp prior to the oil cooler? If yes, and the oil is then being dropped to 220-230 in the cooler then it is in the acceptable operating range for T6 synthetic on the track. I would back off at about 260-265F. Racers often run higher in the heat of battle if they must, but they rebuild engines more often.

It typically gets slightly more difficult to get hotter as the temp increases (unless you have real shortcomings in the cooling system) because as the difference between ambient and the oil temp continues to grow the cooler actually cools a little better, all things considered. Don't cook your engine.

Is pre cooler.
<br />I will be changing the oil and sending a bit to Blackstone.

Dunno. The main source of heat into the oil is from being sheared in the bearings, then it gravity drains into the pan. If you could measure the oil temperature going into the oil pump, whatever temp the oil is once it's in the pickup tube, it's not going to get any cooler unless there's an oil cooler it's pumped through. Oil pump will heat it some, resistance flowing through oil passages, filter restriction, heat from surround engine components/block, etc.

I read online that the "normal" spot to measure oil temps is in the oil pan sump, so that's where I put my sensor. I wonder where the germans put theirs? I'll look for it on my mercedes next time I change the oil.

I would think the hottest oil would be coming from the bottom sides of the pistons and the oil control rings since that's where the fire is.

iMO you are correct, but then you take that hot oil and compress it, compressing anything makes it hotter.

<p>Wouldn't the best place for a temp sensor to be post cooler, so you know the actual temp of the oil going into your bearings?</p><p>Then you can look at the properties of your oil and see when you should shut down.</p><p>I also have the issue of not trusting my oil temp gauge, because my coolant gauge wasn't exact out of the box.</p><p>Oh well. Good thing its a 1.6</p>

Hottest oil and "most heat added" are not the same. I agree hottest oil is probably the oil stuck to the cylinder walls and pistons.

Best depends on what you want to know. If you want to know how well your cooler works, then a sensor after the cooler is probably best. If you want to know how hot the oil is right after it just cooled the bearings, then short of having a thermocouple installed on the crankshaft, the sump is the next best place to measure it.

<p>But why do I care how hot the oil that just cooled my bearings is? Don't I want to know how hot the oil that is about to cool my bearings is?</p>

Oil is a liquid, not a gas, you're not compressing it.

Oil will get a bit warmer when pumped due to friction, but that's pretty low (low friction is, after all, the main point to having oil).

I suspect it doesn't really matter all that much where you measure it. Personally I change the oil before every track day, because the cost just isn't significant compared to everything else.

--Ian

Oil degrades due to heat, so in theory you want to know the max temperature the oil has seen so you can decide if you need to change it or not.

The problem with this is that measuring the temperature of the sump doesn't actually tell you the max temperature, because the sump is a large volume of oil, and the oil that's going into it from the bearings is mixed with the cooler oil that went to the head.

--Ian

This. Also oil's viscosity drops with heat, so if your oil is getting too hot it's also going to get to thin and not protect the components it's designed to protect.

Your idea of measuring oil temp post cooler is the same as measuring engine coolant temp post-radiator instead of after exiting the engine.

you are correct, let me rephrase that, when you pressurize it.
when you pressurize a liquid it will raise the temperature, I see it all the time using aircraft hydraulic test equipment. they have very large coolers to cool the fluid after it has been "pressurized" to 3000 psi.
Have you seen the large heat exchangers on excavation equipment?

you want to know if you have heated the oil past it's thermal threshold and it will no longer do it's job. the sump is as good as any place, but I plan to put my sensor pre cooler.

what good does knowing what the temp is going to the bearings? If you put a kick ass cooler on and it lowers the oil temp from 350deg to 200deg, you have already smoked the oil. but think everything's great.

<p>Ok, so we want to measure the hottest bit? Hasn't it been reported that temps are hotter right before the filter, than in the pan?</p><p>Going to send this oil change to blackstone and see how it looks.</p><p>What temp does rotella t6 die at, saw a mention of 300, but that sounds high.</p><p>My temps held very stable at 245-255, and oil pressure was still around 60 indicated at full throttle, so I was not too worried. Also my water was 185-190 the whole time.</p>

This debate as to whether the largest contributor to heating of oil is friction in the main and rod bearings vs. transfer from the pistons and cylinder walls is an interesting one.

I've always subscribed to the former theory, albeit without any substantial scientific evidence. Anecdotally, we know that a 100 HP engine operated at sustained high RPM on the track will cook its oil, whereas a 250 HP engine on the street will typically not.

On the other hand, there's a lot of oil, and it acts as a thermal damping mechanism. Thus, the measured oil temperature reflects heat over time. And that 100 HP engine on the track is going to be making 100 HP pretty much continuously, whereas the 250 HP engine on the street is going to be making far less than 100 HP when averaged over a duration of several minutes





That's the conventional wisdom.

It's never made much sense to me. The oil going into the filter was sitting in the oil pan about one second earlier, and it isn't passing through any especially hot areas on its way between the two locations.

I'm not saying it isn't true, merely that I can't see any reason why it wouldn't be false.




SCIENCE!

https://www.miataturbo.net/attachmen...ine=1442025133

Anyone have data showing temps in oil pan and sandwich

From personal experience, the aha moment for me was when I was doing high RPM/low MAP fuel tuning on the interstate. In that condition, you're making maybe 20HP to maintain 70mph or so. The oil temperature skyrocketed. Based upon that, bearing friction seems the largest contributor by far.

Our oil pans are finned and oil pan sensors are typically mounted in the periphery where there can be stagnant oil and a temperature gradient. I don't have personal experience measuring in both locations, but I have seen posts to that effect (Mobius provided a link to such a post here: https://www.miataturbo.net/race-prep...4/). The typical delta was ~20F. Of course, if you could manage to place your oil pan sensor right by the oil pickup, I would expect that delta to disappear.

Yeap, it is by far.

Oil doesn't live at one temp and die at another. Its properties vary with temperature.

<p>Can't you &quot;cook&quot; oil. Where you get it so hot it basically &quot;dies&quot;</p>

What hes is saying is its not a hard line. It depends on your exact definition of "die", the oil type, and more. Its also a time @ a given temp. relationship. For example 1 moment at 280 may not "cook" the oil as much as 5 minutes @ 260 (just made up numbers for example, dont shoot me).

But yes, there is a temp at which an oil will die immediately, probably its flash point or just below, but thats up around 400*. Thats the mechanism that causes turbo "coking".

This makes sense. (Both parts.)

One can speculate all day long but it is just that until one has some real data, I have an 8 channel can egt box that i will use to log the oil temps at various points in the system when i get my car running again. That should give us some good info on what the oil is doing.
The only draw back is that it will be on the street or dyno and not in the track.

I'm not convinced about that stagnant oil part. Especially on the track. I'd imagine that all the sloshing around from the car being tossed around corners should provide some adequate mixing. I do buy the cooling part. That oil pan is a big heat sink and does provide a lot of surface area. So the oil in there would have to be cooler. But as to location of a temp sensor in the pan, I don't think it's crucial.

Cooler than when it came out of the bearings / cylinder walls? Absolutely.

But unless there's a permanent boundary-layer a half-inch thick all around the inner surface of the oil pan, I can't see why it would be significantly cooler than the oil which has just been sucked up out of the pan and pumped to the filter.

That's the part that bugs me.

Would love to see data from an engine with oil temp sensors installed both in a filter sandwich-plate and in the side of the oil pan.

I like data too.

But seriously, even if the oil temp difference was 20 degrees either way (one location cooler than the other) what decision would one make knowing this? I would think oil pan temperature is more important since that's the closest you can measure the oil temp after it exits the bearings. Even if the oil (same/hotter/colder) after another location before you cool it, what would you change?

I want to know the hottest my oil gets. Because at a point it stops lubricating correctly and you kill bearings. I want to know if that is happening in my engine.

This. The oil pan is the best representation of the temperature of the oil in the motor. It's the average of the oil that has been sitting in the sump longest (coldest oil in the system) and the oil that's dripping down off the bottoms of the pistons/cylinder walls (hottest). I think the only reason to measure a delta between the pan and the sandwich plate would be to subtract that delta from temps measured at the plate.

We all drill our pans for turbo drains - drill the other side (as low as possible) for a temp sensor. :party:

If the pan is out then adding a sensor is a no brainer. If you are doing it in the car a sandwich plate is easiest. Knowing the delta between plate and pan would be helpful for those of us with sandwich plates.

I will put a tc on the pan, on the oil pump outlet hex plug, on the oil cooler inlet and outlet lines, rad water inlet, ambient air temp.
That should cover all the bases, regarding the oil temp difference in the pan itself i doubt that there is any significant
temperature difference in the pan regardless of where you measure the tempreature; i have not cc'd the pump gears but would expect the pump to move 5gpm or more at 5k rpm that means that the pan oil cycles through every 10 seconds or so and there are g forces splashing the oil around on top of that so the oil is not just sitting there.


https://www.miataturbo.net/attachmen...ine=1442195562
https://www.miataturbo.net/attachmen...ine=1442195562
https://www.miataturbo.net/attachmen...ine=1442195562
https://www.miataturbo.net/attachmen...ine=1442195562