I recently installed a ZZ4 short block in my '89. It has reworked 113 heads, Hot Cam advanced 4 degrees, long tubes, etc. It's had a Ron Davis radiator for over a year. Before old engine spun bearing & died, temps ran about 180 w/o A/C on the highway & about 188 with the A/C on - even on 100+ days in Phoenix.

Now, it runs about 197 with the A/C on in 100 degrees - in 5th gear at 75 MPH. If I shift to 6th and let RPMs drop, the temp goes up about 15 degrees. Same thing happens at lower speeds - cooler in lower gears (higher engine speeds). Checked the 180 stat - works perfect & is full open at 180 on the stove. Oh, water pump is high flow and near new & the radiator is properly "packed" at 1800 RPM so no air in the system. 50/50 mix too. Also, no obstructions to air flow.

Any ideas today before I go home & pull the water pump because I can't think of anything else? Thanks, Paul


[Modified by NavyVet, 9:13 AM 9/22/2003]

 

Like I said - baffling. Say, how'd you get to "1 post?" I know I've read many of yours before :confused:


[Modified by NavyVet, 9:44 AM 9/22/2003]

 

I don't think you have a problem!!! A newer engine has more friction and makes more heat. Higher horsepower engines also make more heat. A 180 thermostat does NOT guarantee 180 coolant temps. In spite of the fact that you have an aftermarket radiator, your cooling system operating temperature is limited by its ability to get rid of heat and this is mainly affected by the radiator size, the air temp and mass flow rate through the radiator. You live in a location with high ambient temps and high density altitude air (thin air). Your cooling system follows the laws of thermodynamics, NOT how you think it should work. Most aftermarket radiator makers follow sound theory in making a radiator that has more heat transfer ability than a stock radiator, but they lack test equipment to measure the characteristics of their product so they can only point to the things that by common sense should make the radiator transfer heat at a higher rate. I think your radiator probably is better than stock, but by your temp readings, it still isn't sufficient to allow your 180 stat to control the coolant temps. Currently it is wide open! I doubt there is much you can do about your temp situation except for installing a radiator with the proper heat transfer numbers for your conditions. If I were you, I wouldn't worry, your C4 is operating where GM designed it to.

 

jfb - thanks for the observations. I've been thinking about the same things this morning - new motor, higher compression, more cam, etc., so it must be making more heat. Then I talked to a friend, Merle at Exotic Muscle, who's an engineer and he told me the same basic things you said. He also pointed out that my old motor was so loose it didn't have any friction :D

Probably why it didn't have hardly any oil pressure too! So, I guess I'll drive a while before throwing another high output water pump at it. As long as I can maintain it within reason on the track, I think I'll be OK. Thanks, Paul

 

What after market radiator did you install? I installed a Griffin Rad. About 3 years ago, and it made an unbelievable difference in cooling. I had em build me a 2 core 1.25in aluminum unit good for up to 600HP more than ill ever need.

http://griffinrad.com/blank_chart3.php

:cheers:

 

Ron Davis Racing - dual core aluminum.

 

you dont have a problem, that temp of 197 is really low for todays engines...the 180 stat does not gaurantee 180 but is designed to maintain that temp assuming other components are funtioning as designed, you are worrying for no reason.

 

Installed my new 383 and car was getting hot. Apparently there was enough excess silicon from the intake gaskets,waterpump, and t stat to clog up the radiator enough to get it hot. had Radiator cleaned out by shop and now it runs cool again. almost too cool because I intalled a 160. Freeway temps are 174 and stop and go traffic is 185. 197 is not hot at all. Just my two cents