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> 914-6 runs HOT - solved?
gereed75
post Mar 1 2017, 03:08 PM
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Ok I can see that. Knew EGT would rise and that could certainly Raise CHT's.

With all of the other stress that can be caused by overly advanced timing and excessive high ICP, erring to the retarded side seems to be better than high as long as performance is good.

Think I would try for 32 max on OP's (and my) engine.

I have seen two degrees of retard drop CHT's 30 degrees on a fully instrumented (CHT, EGT, RPM, MAP, fuel flow) air cooled Lycoming with no perceptible drop in power.
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Justinp71
post Mar 3 2017, 04:35 PM
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If it only has 600 miles on the motor, maybe it still has a warranty? Will the engine builder shop help you out?
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Wdunster
post Mar 4 2017, 09:13 AM
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I am running a 2.4 e cams 9.5-1 compression mag cased 6 with scolex carbs. It ran hot as well with additional air through a GT Style engine lid. It would get to 212 to 230 in the summer. Added an oil cooler in the back with a fan and it definitely helped. I still keep a watchful eye on it.
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767driver
post Mar 21 2017, 05:42 PM
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UPDATE:

I might have found the answer today...

After I first posted this thread, I kept digging into forum searches and the interwebs... hoping for that golden nugget of knowledge. Talked with some very knowledgeable folks and bounced some ideas all around my group of gear-head buds. I was getting ready to send the car to a local Porsche shop and start the process of chasing the gremlin$.

One of the things I noticed about my car was that the PO had capped the ducts that take cooling air from the engine fan and duct it to the heat-exchangers. The black corrugated hoses were not installed either. It had occurred to me that this might just make the heat-exchangers (HE) hotter than they would normally be. When the hoses are installed there is always air moving through the HE when the engine is running. The air goes through the HE and a diverter valve where it either enters the cabin heating system or simply gets vented to the atmosphere. Without air cooling those HEs they get damn hot. And the driver's side HE is right under the oil cooler.

So I removed the 2 caps from the fan shroud, connected the black hoses, 1 to each HE, and went for a long drive.

Here are the results...before and after. The first pic was taken on a 60 degree day a few weeks ago. The second pic was taken March 21 on a 58 degree day. The gas level is reading the same only by coincidence.


Attached Image Attached Image

And some good info here, particularly posts 6 and 7...

http://forums.pelicanparts.com/porsche-911...exchangers.html

Lesson learned... heat-exchangers need air moving through them at all times!
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767driver
post Mar 21 2017, 05:44 PM
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A picture (not my car) of a heat-exchanger with the proper connections. You can see the hose come down into the HE from the fan shroud. The air goes through the HE and exits at the diverter valve. With the engine running and the heat OFF you can feel engine fan air coming out of the doughnut-shaped opening....thereby removing LOTS of heat from the HEs.

Attached Image
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Eric_Shea
post Mar 21 2017, 06:16 PM
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JmuRiz
post Mar 21 2017, 08:06 PM
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Excellent, glad you got it fixed!
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IronHillRestorations
post Mar 21 2017, 08:23 PM
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Always nice to see a problem resolved, especially when it doesn't involve lots of $$.
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Cairo94507
post Mar 21 2017, 10:03 PM
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Great work and investigative know-how. (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/beerchug.gif)
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gereed75
post Mar 21 2017, 11:43 PM
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Nice work. Isnt it amazing that Grady's voice still provides so much knowledge

All makes sense. The factory engineers were very good
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porschetub
post Mar 22 2017, 01:53 AM
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can't for a minute see how this sorted the issue,if the air supply to the HE's wasn't capped of I would say lack of cooling air to cylinders and oil cooler but they were capped !!!.
I run headers with block off covers on both sides of my engine runs great oil temps,this is known to provide better cooling besides.
Have worked with aircooled engines for 30 odd years this one has got me stumped (IMG:style_emoticons/default/WTF.gif)
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gereed75
post Mar 22 2017, 06:45 AM
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Tub, the heat exchangers on the stock headers effectively double wall the headers preventing cooling air from carrying heat away from the header and tubes. Then the exterior of the heat exchangers is also heated


I can see where this is a much bigger heated mass and a much bigger heat radiator than just the air flow cooled header tubes. The result would be more heat transferred into the heads

Would like to see an analysis by my thermo dynamics prof but That's my theory
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IronHillRestorations
post Mar 22 2017, 07:03 AM
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To take gereed75's theory a step further, if the heat exchangers can't allow the hot air to escape it's going to back up the positive air flow. As long as the hot air can get out, either to the cabin or out the vent in the flapper box, there's positive air flow and it won't be a problem.

The reason this isn't a problem in a car with headers is because there's no restriction of the cooling air flow.
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bretth
post Mar 22 2017, 07:14 AM
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Years ago I rigged an electric fan in the spare wheel well to blow heat through my 68 Bus heat exchangers in an effort to keep from blowing engine fumes into the cabin. I ended up having to run the fan all of the time because the exchangers would get hotter and overheat the flex hoses I was using and cause a burning smell. I can see how this could cause additional heat in your situation.
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rgalla9146
post Mar 22 2017, 07:56 AM
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QUOTE(gereed75 @ Mar 22 2017, 01:43 AM) *

Nice work. Isnt it amazing that Grady's voice still provides so much knowledge

All makes sense. The factory engineers were very good


That would be the esteemed Grady Clay of Denver Colorado.
Proud to say I met him long ago.
He left this world in 2014
RIP
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Justinp71
post Mar 22 2017, 11:26 AM
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Wow, what a difference. Nice find! Thanks for sharing.
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porschetub
post Mar 22 2017, 12:51 PM
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So they basically cease being a heatexchanger without the flow from the fanshroud,the heat builds up but has no where to go right ?? so it transfers back into the engine, hot heads = hot oil =high temp right ?.
Thanks for helping my clear this up Perry and gereed75,good I have that in my thick head know (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) .
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767driver
post Mar 22 2017, 01:12 PM
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QUOTE(porschetub @ Mar 22 2017, 02:51 PM) *

So they basically cease being a heatexchanger without the flow from the fanshroud,the heat builds up but has no where to go right ?? so it transfers back into the engine, hot heads = hot oil =high temp right ?.
Thanks for helping my clear this up Perry and gereed75,good I have that in my thick head know (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) .


When I pointed my IR thermometer at the backside of the oil cooler near the bottom I got readings near 300 degrees (after driving it) before I put the ducts to the heat exchangers on the car. After I installed the ducts (and driving again) that same area of the oil cooler read 235 degrees!!!!!!! The oil cooler is only a few inches above the exchanger. Imagine how much heat must have been radiating upwards onto the bottom of the cylinders..:-0
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gereed75
post Mar 22 2017, 01:41 PM
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That says a lot

Glad you got that worked out. I believe that that is Puffs old car I had faith that it was solid (looks right too!!)
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767driver
post Mar 22 2017, 03:23 PM
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QUOTE(gereed75 @ Mar 22 2017, 03:41 PM) *

That says a lot

Glad you got that worked out. I believe that that is Puffs old car I had faith that it was solid (looks right too!!)


It is Puffs old car. He was kind enough to pass along the needed ducts!
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