Engine rebuild cooling idea...

[Adam]

I've been thinking about this as a modification that could be done when the motor is disassembled for a rebuild. So I thought I'd invite comment on what could be a good idea or a bonehead scheme.

I know that 993 (and possibly 959) cylinder heads have machined cooling fins rather than the cast type that all other 911 cylinder heads feature. Is it possible that prior to re-assembly, you could lightly machine or resurface the inner portion of the cooling fins to further facilitate heat dissapation? Over time, I can imagine the freshly machined surface would tarnish or even oxidize, but surely the smooth finish, rather than the factory cast-finish would aid in heat transfer.

I'm sure the differences would be minimal, but when most motors are now being rebuilt with higher hp in mind, I would think that achieving better efficiency all round would help in the long run.

Would smoothing the rough finish aid cooling without compromising the current setup by making the fins too thin? I'm sure that the thickness they are set at has been carefully researched, but I'm hoping you get my drift.

Ok, Metallurgists and Engineers: Educate me!

[RoninLB]

not a pro...
but, I don't think it's not worth the time for the itty bitty possible results.. carbs run an engune cooler than fuel injection, IMO.. after that I think 2 front fender coolers would be cool for big desert runs/ 90+ mph/ 110+ deg F.. and I assume your old pistons rings allowed combustion heat blow-by to add big heat to your oil.. I think if you break-in new rings to about 1 quart per 1,000 miles it'll be good piston lube. and tight combustion.. and cooler than worn rings because the top ring heat will be transfered to the jugs better.................Ron

[HawgRyder]

If you are looking for more cooling....perhaps you could paint the heads black using the type of paint I use for motorcyle cylinders.
It is special...very thin...soaks into the material and has to be baked in using several thin coats.
It makes a lot of difference in the cylinder temp ....so it should work for the heads as well.
However....do you want to cool the heads more?
I would think that would effect volumetric efficiency of the engine.
The factory designed for a certain amout of cooling/heat in the head area....perhaps to aid in combustion?
Bob

[Jim Sims]

Far more important is keeping the dirt and oil from clogging the slots between the fins; smooth may help keep things cleaner but I suspect the change is "in the noise". Jim

[Adam]

Originally posted by Jim Sims:
but I suspect the change is "in the noise"

I thought so.

My cooling woes are far behind me, now that I've got a Carrera cooler and electric fan. It's just a theory I was tossing around for a while. My 2.7 is only 10k kms old, so it'll be a while before I am expecting a rebuild.

Just trying to think outside the square.

[john70t]

Couldn't the engine be cooled better by a large intake scoop facing forward in a pure air stream instead of in a swirl/vacuum area behind the car?

What about a reverse fan that takes cool air near the ground and sends it upwards in the natural direction of heat travel? Isn't vacuum more efficient than pressure?
Get rid of the small outlet's of the air flow at the heat exchangers and internal vent.

[David Ceruti]

Wouldn't machining the roughness in the casting off reduce the surface area and harm cooling? the little bit of roughness could also increase turbulence and help cooling a little.
Note - these are only my musings. I don't have any direct experience here