[RS Barn]

Adding more suface area and volume doesn't mean it will lower temps. It should but may not happen.

Track testing is the only way to determine if cooler setup actually lowers temps. After 15 minutes on track the thermal loads rise really quickly.

Before Dual Coolers i would make Pablo turn on Heater and fans to bring down coolant and oil temps.

BTW-the oil filter housing acts as a heat exchange between coolant and oil

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[Cloud9...68]

"BTW-the oil filter housing acts as a heat exchange between coolant and oil"



Thanks; what does this heat exchanger accomplish? In other words, is its intent for the coolant to heat the oil (and if so, why?), or for the oil to cool the coolant? Do the two fluids flow against each other in this piece at all times, or only during warm-up? Thanks.

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[Lear35A]

There is a thermostat in the unit, but while mine was apart I did not pay attention. I'm not sure if it is in a water or oil passage. You should tell us. Probably helps oil to get up to temp faster on cold starts. Makes little sense to use oil to cool water.

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[Cloud9...68]

Yes, that's exactly how I pictured it after I thought about it. I'd never heard of a unit like this, but that doesn't mean anything. I wonder if other cars have something like it. Thanks; I'll take a look at it when I'm putting my engine back together.

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[flash]

yup - sets the oil temp at about 205. been thinking about playing with that when i take the engine apart. no need to have the oil that hot where i am. 190 would be just fine.



not sure about the heat exchange properties between oil and coolant, but then i haven't had that section apart, so i suppose it's possible. probably has to do with emissions and warming things up quickly enough to pass the cold start test. having just gone through the CARB certification process on the supercharger, i can tell you that the cold start test is the most critical, and getting things to pass that are very difficult

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[Cloud9...68]

Flash - Good point about the cold start test - I've also heard it's pretty stringent.

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[Lear35A]

They had these from the beginning in the 944s. Could be for the emissions, but it's better for any engine to get the oil up to temp ASAP, especially when it's cold.

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[mrmister]

Pete, how hard is the install on your unit? With my supercharger, this is no longer an option for me. Doing track days I can't finish a session without getting in to redline coolant levels.

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[Cloud9...68]

mrmister,



Do you have an oil temperature gauge? You refer to coolant levels (plural) in your post, which makes it sound like both your water and oil are getting too hot. And you live in San Francisco; wow; something doesn't sound right...

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[Cloud9...68]

I'd like to have a show of hands - of those owners who track their cars, how many have problems with the coolant getting too hot on track days or in races (by hot, I mean hitting the top line)? Just trying to understand if this is a chronic problem with these cars that requires modifications to correct, or is running too hot an indication that something needs to be fixed.

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[flash]

there are a number of things that can lead to high coolant temps



i spoke to mrmister and his fans are cycling. that is an indicator of faulty resistors. likely corrosded connections. very common. after starting there, he may find that the temps are fine.



the radiators clog VERY easily. this will lead to higher temps too.



the OEM fan switch is not great if you are going to track the car. by the time the high temp fan kicks in, it's already on its way to redline, and because the capacity of the system is so small, it quickly gets up there and doesn't come back down. the lower temp switch engages the fans earlier, reducing this likelihood



drilling the thermostat is an old racer trick that can help too



if all of that is not enough, and the temps are still too high, then additional oil cooling would be indicated.

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[mrmister]

Thanks for the info and the phone call Flash. I will give the low temp switch a shot and clean my resistors. Is it the 75 degree switch I should get here? http://www.pelicanparts.com/catalog/shop....htm#item1



Cloud968 - I don't have an oil temp gauge. I am just assuming my oil temp is high at this point. From speaking with Pete, he seemed to think overheating with the stock cooling was normal on track days. He said around 20 minutes in to a session he would need to take a cool down lap and then hit it hard again.



To be clear, my levels are completely normal during regular driving, even sprited driving. Once coming off the track the car cools down very quick as well.

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[Cloud9...68]

So, for those of us who live in very hot climates who want to track our cars, is something like this something we need to seriously consider?



http://www.lindseyra.../944RADBIL.html



It doesn't say how much it increases the cooling capacity, but it does have a built-in oil cooler, which looks very slick. Not sure if it does anything to address the fitting issue, which I haven't researched yet, so I don't understand it. Is the problem that the 968 oil radiator uses different fittings than the 951, making the available oversized coolers designed for the 951 unworkable on the 968? Thanks.

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[Lear35A]

I suggest getting very specific with these guys about how to handle the oil cooler fittings on a 968 before buying this. What is their concept, that this oil cooler is in series with the factory cooler? The hoses, fittings and hose routing is going to be a real challenge.

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[flash]

mrmister - NO! you need the dual temp switch. it's 3 down from there. 85/93 vs the OEM of 92/102



part number 951.606.481.00.85.M2

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[Cloud9...68]

I agree; I definitely wouldn't plunk down $900 until I knew if this thing would work in a 968, and if it is even the best choice for keeping the engine cool on hot track days.



Not to get into a whole long discussion about the 968's mysterious cooling system, but my car for some reason took a step function up in operating temperature about three years ago. It used to never get about the 8 oclock line, no matter how brutally hot the day, and/or how hard I drove it (I'm taking about street driving). It never even got terribly hot on the track, although most of my track days tended to be during cooler parts of the year, and I've only driven on shorter, more technical tracks. Then suddenly, 9 oclock has become the "new normal", even though it has a new (drilled, from RS Barn) thermostat, a new (also fro RS Barn) radiator cap, I've had the radiator flushed (it turns out that it wasn't clogged in the least), the fans blow up a storm, it has a low temperature fan switch, which seems to be doing its job, and the water pump is new (I've even taken it out to make sure it's spinning freely, and the the impeller is secure on its shaft - I even put it in a large pot of boiling water to make sure the impeller wasn't coming loose at high temperature).



I'm holding out some hope that part of the problem is that practically every seal on the engine was leaking, resulting in both sides of the block being heavily caked in oil and heavy black grease (oil mixed with dirt, I assume), which can't be helping the heat dissipation characteristics. And I think I'm going to go ahead and have the piston tops, combustion chambers, valve faces, and exhaust ports ceramic coated, as long as I have it all apart.

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[flash]

ignore the gauge!!! it's a piece of crap that changes reading based on things like the ground potential. mine did the same thing, but my temps NEVER CHANGED. i even changed the sender. it was all the gauge, so i reset it



get a laser thermometer and check your REAL temps. you may be fine. at the hose near the bleeder screw, you should read 10-15 degrees over the thermostat, or 100 degrees over ambient temp, whichever is higher.

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[Cloud9...68]

That sounds like good advice; I'll get a laser thermometer and check the temps when I get the engine put back together. I was trusting the gauge because it did respond correctly when an earlier thermostat failed, so I assumed it was working reasonably well. But you're right - I may be putting too much faith in it. Thanks for the recommendation, and the information.



It still seems to make sense to take prudent and reasonable measures to ensure the engine will stay in a safe temperature range under the worst-case conditions in the climate in which it runs. That's why I think the ceramic coatings, putting all the pans on (mine only has the "bat wing"), and possibly an auxiliary/larger oil cooler strike me as things I should do while I have everything apart. Not sure about a larger radiator, though.

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[RS Barn]

I use live Digital temp gauges in cars. This way you know when your oil temp is 280F

Yes all 968's run high coolant temp when track driven as explained before. Has little to do with radiator

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[Cloud9...68]

Pete,



Just curious - why the preference for digital temp gauges over analog? Thanks.

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