cooling systems

[redrider044]

Here goes my two cents again. In the late 60's early 70's, my daily driver was a big block '69 Camaro 396 cu. in, 375 factory under rated hp. It had 11: 1 compression, I installed a rowdy 7000rpm cam, motor idled 1100-1200rpm in gear shaking all over the place, 4:56 gears, total timing was 38 degrees, intimal timing fell in at around 18 degrees. Needless to say, this car had major cooling system issues. I solved the cooling problem as follows, I don't know if this would work on a 928 but here goes. The BB Chevy had a thermostat by pass hose from the intake to the water pump. The theory was during warm up the coolant would circulate in the motor avoiding hot spots etc. When the thermostat opened, coolant would go from the motor thru the radiator. BUT, BUT, BUT, some hot coolant still circulated thru the motor making things even hotter. My solution was to block off the thermostat by pass & drill four 1/4inch holes around a 160 degree thermostat. Now, all the coolant was forced to circulate thru the radiator. Granted though, it took a little longer for the motor to warm up. I also used a flex-a lite fan, I know, I know. This set up worked too well. I had to go to a 170 or 180 thermostat. As I said, I don't know if this would work with a 928, but it may be food for thought.

[Danglerb]

No offense intended, but tinkering with a cooling system you don't really understand rarely has good results. The main if not only cooling problem the 928 has is that we are running around with 20 year old parts, which is a heck of a long time to expect a cooling system to keep functioning. Engines, heads, and radiators are well coated with junk and fans have one blade in the grave.

Cooling capacity comes from the size and type of radiator. Thermostats have no effect on cooling capacity they control the on and off, not the how much. Changing a thermostat is like using a new accelerator pedal with the same engine.

Increasing warm up time is very bad for a motor, the rich fuel condition washes oil off the cylinder walls and generally creates an extremely high wear condition.

[Barbapapa]

Actually, the 928 already has tricks like bypassing during warmup. There are some other features that make it a very well designed sytem, like the heater source coming from the rear of the head and the small line going to the WP inlet side. Both of these help to keep air pockets from forming. The high resevoir is another good thing.
A typical domestic hot rod is a cooling system nightmare. The biggest problem is air pockets forming from poor design, especially when changes are made by a typical owner who doesn't understand cooling sytems. If you go to your typical car show or track you'll find alot of cars that suffer from cooling issues and the owners think they need a bigger radiator when infact they really need to re sort their system to deal with air entrapment.

[yetibone]

If a 928 has a hard time keeping cool, there would be something likely causing the problem, which should be addressed. Something like a half-clogged radiator, half-opening thermostat, loose fan clutch, in-op condenser fan, or a timing belt that's not tight enough to turn the water pump at idle.

I've seen light duty diesels with less cooling capacity than a 928. Big block Chevy's as well.

[Normy]

As said before, the 928 thermostat does TWO things. It blocks coolant flow when the engine is cold, and then makes ALL the coolant flow through the radiator when it is warm.

-I don't know what to do with a 396 Chevy, but a 396 Porsche M28 engine [also known as a 6.4 liter Devek 104 mm bore~] is best off with at most...a low-temp thermostat and an original radiator. Mark Thomas took one of his 396 cubic inch 928 motors to a measured 211 mph on the Silver State Challenge.

[don't try going larger than 104 mm with a 928 block without sleeves]

Have fun!

N!