Max oil temp ?

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acarlson
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Max oil temp ?

Unread post by acarlson » Fri Dec 01, 2017 8:02 pm

I just rebuilt my Corsa engine and installed a new cam, cylinders, rings, bearings, pistons, etc... I’m running 10-30 convential oil plus some ZDDP during the break-in. My turbo engine gets head temps above 400 degrees. This can’t be good for the oil. I’m concerned about the oil breaking down if the oil temp gets too high. It sounds like the oil in the pan is boiling when I shut the engine down. What kind of temp can this oil take before I run into trouble ?
1965 Regal Red Corsa 4 Speed Turbo Convertible

Jerry Whitt
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Re: Max oil temp ?

Unread post by Jerry Whitt » Fri Dec 01, 2017 10:18 pm

Normal engine temperature is 350 to 400 degrees. Couple things come to mind if the engine runs much hotter.

1. Timing is set wrong. Initial timing, vac advance, vac retard and centrifical advance are all important to check.
2. Fuel mixture is too lean. A smog machine is ideal to check air fuel ratio.
3. Temp gauge is not correct. Check actual temperature with alternate source.
4. Oil cooler is not flowing oil. Pull the cooler, and make sure fluid can flow through properly.
5. Thermostatic valves that allow air to flow out bottom area of engine are not fully opening. Visual inspection to see if both valve open.

The oil itself will be ok to about 500 but would not advise running that very long until proper operating temperatures are attained.
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acarlson
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Re: Max oil temp ?

Unread post by acarlson » Sat Dec 02, 2017 8:12 am

Jerry, tooling around town my head temps are in the 350 to 400 range. On the highway (with the turbo boosting) I'm seeing 425 or so. I thought these were fairly normal temps for the turbo engine.

1. I believe the timing is correct but that is an easy thing to double check.

2. Clarks rebuilt and tested my Carter carb so I believe the mix is OK. However, I have an Innovate MTX-L Plus Wideband air/fuel system installed, I just don't have the gauge hooked up yet. I guess I'll have to get that install completed and see what that shows.

3. Temp gauge and thermister are original '65 parts. They seem to be accurate, but I can double check that.

4. Oil cooler was cleaned out during my rebuild. It's working correctly but I've seen posts that even the oversize coooler on the Corsa's may not be enough for the turbo engine.

5. Damper doors are working correctly.

Alec
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66vairguy
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Re: Max oil temp ?

Unread post by 66vairguy » Sat Dec 02, 2017 9:49 am

First - a mistake adding ZDDP. Richard on the other forum answered well on these additives --- impossible to determine what is the proper amount to add and how it affects a motor oils chemistry. Too much ZDDP can do damage. Besides it's only effective when oil starts to fail due to high mileage. If you're worried about low ZDDP oils, just change the oil before 2,000 miles or once a year, whatever comes first. ZDDP was increased in the 60's to allow extended oil change intervals, and oil back then was not as good as today's blends.

Second - engine temperatures vary depending on where you measure them. Head temperatures can reach 450F depending on the sender location on a long hill climb. The oil will NOT get that hot. I've never seen oil break down in the head area if the OIL WAS CHANGED at proper intervals.

With a good functional oil cooler (clean passages for air flow) you should not have an issue. Folks in Arizona in the summer have no problems with high oil temperatures.

Third - yes oil failure at the turbo bearing is possible if you shut down the engine after a "hard" run - not just a Corvair issue. If you have been on a hard, or long, run just let the engine idle for a few minutes to cool down the turbo housing before shutting down. Synthetic oil blends tolerate higher oil temperatures.

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Re: Max oil temp ?

Unread post by bbodie52 » Sat Dec 02, 2017 1:12 pm

:goodpost:
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Pennzoil wrote:High or low, extreme temperatures can directly impact the performance of your motor oil. Pennzoil Platinum® and Pennzoil Ultra Platinum™ Full Synthetic motor oils rely on PurePlus® Technology, a process that creates base oil from natural gas instead of crude oil. PurePlus® base oil won't "gel" in extreme low temperatures, so your engine can still pump oil even on extremely cold days. It also won't evaporate or break down when exposed to extreme high temperatures inside your engine. The oxidation stability of Pennzoil Platinum® and Pennzoil Ultra Platinum™ Full Synthetic motor oils make them ideal for today's direct injection and turbocharged engines that run hotter.
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Machinery Lubrication Magazine wrote:Petroleum Base Oil vs Fully Synthetic Oil

A construction equipment contractor was experiencing premature turbocharger failures when certain engines were operated under full load conditions and used around the clock. Investigation through oil analysis and diagnosis of the failed components revealed that the failures were caused by coking of the petroleum base oil within the turbocharger oil passages, thus restricting oil flow and resulting in bearing failure.

The initial cause of the oil coking condition was excessive temperatures within the turbocharger housing.

A fully synthetic diesel engine oil was selected of the same viscosity as the original conventional oil and installed. Premature turbocharger failures did not reoccur and oil operating temperatures dropped by about 8°.
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Mobil 1 resists high-temperature deposits

The motor oil industry uses the Honda Hot Tube test, which is a proprietary Honda high-temperature deposit test that measures an oil’s resistance to deposit formation in turbochargers. In the severe-service test with turbochargers, Mobil 1™ 5W-30 advanced full synthetic oil displayed superior protection compared to a competitive full synthetic oil as well as our own conventional oil (which met industry-standard GF-5/API SN requirements).

Mobil 1 helps turbochargers withstand high heat

:angry: Today’s turbocharger-equipped engines operate under extremely high temperatures. See how Mobil 1 advanced synthetic motor oil performs in our lab, where we can replicate extreme operating conditions and create turbo temperatures that exceed 1,600°F. Watch what happens.



:torch:
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acarlson
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Re: Max oil temp ?

Unread post by acarlson » Sat Dec 02, 2017 1:18 pm

I added the ZDDP because Clarks included it for free with my OTTO cam and recommended that I add it during the break-in period with the new cam installation. Since this is a Corsa turbocharged engine, the temp sensor (thermister) is located in the bottom/front of the left cylinder head - that's the stock location. I'm running Valvoline 10-30 Conventional oil (not synthetic) and it only has about 70 miles on it. Since I am also running new piston rings, I can't use synthetic till the rings seat - at least for another 500 miles or so...
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Re: Max oil temp ?

Unread post by miniman82 » Wed Dec 06, 2017 1:55 pm

Some thoughts:


If you have chrome rings it's gonna take a whole lot longer than 500 miles to bed them in, standard rings around 1000 and you're probably good to go. The ZDDP additives are supposed to protect flat tappets from scuffing, since modern oils lack the additive packages older oils used to contain. They went away mainly because of emissions reasons, but also because modern engines have roller valvetrains so they don't need the anti abrasion additives to function.

The stock thermistor should not be relied on as a quantitative device, it merely shows you when something has gone terribly wrong. For example if your belt snaps and the gen light/buzzer fails for some reason, super high temps above what you normally would see should alert you that something is wrong and you need to stop to investigate. If you really want to know what your head temps are, you need a thermocouple based gauge with ice point compensation like Dakota Digital or a datalogger. The stock gauge is mainly there for the sake of appearance, the reality is head temps will vary widely based on driving conditions, state of tune, and even outside air temps. I personally am more aware of the sound of detonation, long as I don't hear the rattle can I drive it how I want. Having said that turbo engine temps generally will be higher than a 140, because the turbo adds heat to the engine bay.

If you drive aggressively like I tend to, the stock oil cooler isn't enough period. I don't care what anyone else on this forum says, I've taken my own measurements and have the data to back it up. On hot days oil temps can skyrocket past 300* just through normal driving, I'm not even talking about getting into boost yet. If you plan on using the turbo, replace the stock cooler with the Clark's external adapter and get a large transmission cooler. Place it in the air stream under the car or if you can't do that, put a fan on it in the engine bay. Does anyone here really think the dinky stock cooler has enough capacity to service a 6 cylinder turbocharger engine just simply based on its size? If you don't believe me, instrument your own engine and see for yourself.

Head temperature is NOT oil temperature, though prolonged high head temps CAN increase oil temps. Again, it all boils down to the heat shedding ability of your oil cooler. If you never use the turbo the stock cooler is fine. If you use it regularly, you're cooking your oil point blank.



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acarlson
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Re: Max oil temp ?

Unread post by acarlson » Wed Dec 06, 2017 2:34 pm

Nick, Thanks for your insight...

I do have chrome rings so I guess I'm looking at 1000+ miles to get them seated. No problem there...

I'm not terribly concerned about head temps, at least not so much that I need to know exactly what they are. I was only concerned about how high head temps affected oil temps and whether conventional oil could take very high temps without breaking down.

Right now my turbo isn't boosting like it should (you and I are working on a fix for that). So boosting isn't currently an issue.

I have an Innovate O2 wideband sensor bung installed. I haven't installed the gauge yet although I have all the wiring in place. I ordered some Thermo Tec exhaust wrap, a VDO vacuum/boost gauge and a mounting bracket for my new gauges. I've also got my speedometer out to a speedometer repair shop to get it recalibrated. I'm hoping to have everything installed by early next week. It will be interesting to see what the O2 sensor says about the air/fuel mix. I'll let you know.

Alec
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notched
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Re: Max oil temp ?

Unread post by notched » Wed Dec 06, 2017 3:12 pm

I have a turbo. I also have a Dakota Digital oil temp gauge with the sensor mounted in the pan. With the stock 12 plate cooler the hottest I have seen was 240 degrees. Most of the time it hovers around 210-220 at warmer outside temperatures and driving on the highway.
I run Brad Penn 10W30 which already has the additives needed for the older flat tappet engines.
I rarely look at the head temperature gauge but mine rarely gets near 350 degrees on the highway. But then again I run a lot of part throttle advance at steady cruise which helps lower the head temperatures. I also run 140 exhaust tubes, manifolds and matching oversized crossover which also helped bring the temperatures down.
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Re: Max oil temp ?

Unread post by miniman82 » Thu Dec 07, 2017 7:37 am

But you know what to look for and know what you’re doing, unfortunately this is one of those engines with sort of a steep learning curve. If you aren’t well versed in tuning, it’s real easy to get into trouble when the hammer drops.

That’s why I’m so adamant about having instrumented feedback, so you know what you’re looking at. Wideband O2 is a bare minimum requirement here, knowing your AFR and timing are invaluable. You can’t hope to get the best possible performance without them.
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Re: Max oil temp ?

Unread post by 66vairguy » Thu Dec 07, 2017 9:16 am

Wow a lot of "opinions" here. Amazing that GM built all those turbo Corvairs and they all ran just fine on 60's motor oil - which as Richard1, the oil guru on the other site, said was inferior to today's motor oils even with their lower ZDDP.

It is a fact that the turbo Corvair engine will overheat if you keep it wide open throttle for extended periods, but as GM Corvair engineer Benzinger told a crowd at a Corvair convention - Running full throttle for more than a few minutes would exceed the cooling capacity of the Corvair engine, but of course you can reach maximum top speed in under a minute and extended full throttle operation was not considered normal, and it would be illegal on public roads.

Now if your going racing that's a whole different scenario.

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Re: Max oil temp ?

Unread post by miniman82 » Thu Dec 07, 2017 5:56 pm

Define ‘just fine’?

My experience has been they run ‘just barely’, there’s so much room for improvement it’s hysterical.
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