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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 896
Originally Posted by copbait73 View Post
Yes yes yes but Porsche knows a location(s) they can place a sensor and based on controlled lab testing and racing of other 911/930 based engines, often to destruction, know when this particular engine is overheating or not. That's what we are after here.
I think that is not correct. We are not talking an average wall temp here, which is tough enough to measure. We are talking about transient temps during the 15 degrees or so of combustion.

Porsche probably learned that their hot spot is the exhaust valve, from trial and error. They might not know how hot it is. They just try to reduce it as best they can.

Here are my suggestions:

1. Weld up the combustion chambers so that they have squish areas like the current production Chrysler Hemi. This will improve the end gas detonation problem.

2. Twin plugs are a must.

3. If we could find a way to smooth the the fins, and I mean really smooth, like a mirror (some sort of external extrude hone?), that would help the cooling efficiency.

4. Flat fan. Cylinders 3 and 6 get screwed for airflow. A flat fan would help a lot.

5. Improved efficiency fan. You can tell our fan is crap because the blades are straight. Every engineer knows that the tips should be curved backward for better efficiency. It would be quieter too.

6. Air to water intercooler. Stop dumping the hot intercooler air into the engine. The air going into the tail should just be for the engine.

7. Direct injection. The vaporization of the fuel cools the combustion air. There are turbo motors out there running 10:1 compression and 1.5 Bar boost with direct injection!

Of course you can run on tolulene, spray liquid N2 into the fan, and all kinds of wild stuff, but these are things that are practical, and we would have them today if Porsche could have stuck with air cooling.
Old 08-03-2009, 07:59 PM
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