Jake Raby

All the cars are slow to cool... Without coolant circulating through the engine and cooling system the heat soak issue creates a spike just after the engine is shut down.

We have a way to combat this and it isn't that expensive, finding a place to mount it in a street car is a challenge, but we are working on it.

When I datalog these engines I find they can still have coolant temps over 180F for 3 hours after being shut down with hotter ambient temps. The oil can stay hotter than that for longer.

The Boxster is the worst as the heat can't escape from the engine bay very well at all, but we have a solution for those as well, thats a bit more simple and uses a turbo timer from a Diesel truck..

SH || NC

+1

Marlon

My thought is that an automatic circulator motor that comes on kind of like a post-shutdown oil circulator for a turbo engine would work great. I just don't know enough about the coolant flow and temp activated/actuated valve arrangement in the 996 to draw it in my mind. The odd thing is that the Tip cars come with the 'third' radiator and it still stays hot. My .02 cts worth for now...

Doug Donsbach

That has to be some of the best M96 satire ever posted here.

ArneeA

https://rennlist.com/forums/6690641-post5.html

Jake Raby

A post circulation system is what I have been referring to. One of our test cars already has one installed, but the killer is where to mount it and the fact that it can kill the battery in less than 7 minutes of run time.. Ultimately the engine needs to run to help keep the battery charged while the post cooling occurs, as the the stock water pump won't move enough volume by it's self.

1999Porsche911

The solution is to keep your engine from getting so hot to begin with, which is easily accomplished. Cool down after a run is very quick if you run your engine compartment and radiator fans for a few minutes while pulling the car into the garage.

CosmosC4S

That cracked me up Tim! Are you fantasizing again!?

Ahmet

The 996's temperature fluctuates more than some cars, but the ultimate cooling capacity is just fine (I even run AC on track, and still doesn't over heat, I don't have a third radiator either), I don't think it stays hot any more than some other car either. I've very seldom had the engine compartment fan come on when it's a 90+ degree day and just got off track with a short cool down lap.

You want an engine compartment that stays warm for a while, try an iron block M3... You're not only worrying too much, you're worrying about the wrong thing for "engine" longevity, engine compartment temp is not going to effect bearings or other internal engine parts, that's strictly a function of oil temperatures. Again, from what I've seen a 996 is just fine in this regard also, again unlike a lot of other cars...

Tippy

Your engine would last far longer if it always stayed at operating temp, then the parts wouldnt go through cycles of expansion/normalizing.

I think the longer the parts stay hot and slowly cool, the better.

Of course spikes create rapid expansion which isnt good.

This of course is nothing to leave sleep over, ALL engines suffer from heat soak to some degree.

Jake Raby

I agree that slower changes in engine temperature at cool down is optimum. What I do not like is the fact that the engines can rise in temperature after shut down as much as 30 degrees.

1999Porsche911

There is absolutely no risk to the engine of cooling down too fast even in sub zero temperatures. The only way you could cool it down too fast is to submerge it in a cool liquid,. Although there are a few areas of a water cooled engine that MAY increase in temperature after shutdown, these are few and experience minimal increase in temperature which is very short lived. These componants are primarily external to the engine or do not put your engine at risk.

ArneeA

Hm. I guess you've never heard of temperature coefficient of materials and delta Temp.

Try pulling a spark plug out of a hot motor and see what happens to the motor.

On the other opposite extreme example, put a very hot cup of coffee/tea in the freezer and see what happens.

Material change is directly proportional to delta temp and temp. coefficient of material.

gota911

I called her "Amazing Grace" even though her name was Susan.

1999Porsche911

My guess is that there is no one on this board that had the years of experience in thermal testing as I have.

BTW. No damage will occur to a hot cup of coffee or tea that is placed into a freezer that has a temperature of ZERO.

Like I said, air temperature in areas that cars can be driven cannot cool down an engine fast enough to cause any damage due to thermal contraction or expansion of any componant.