My friend just picked up a 1991 Z28 with a Dart 400 with either AFR heads or Blownfield(??) heads but we are not sure cause someone is definitely lying about something. Steel 4340/3500 stroke crankshaft, forged internals, titanium valves, and so on. The compression is 13:1 and it has a TH400 with a 12 bolt rear with 3.73 gears.

Anyways, we were on our way to get it dynoed and the car overheated to lik 270 degrees. We pulled over and it smoked and blew all the antifreeze out of the overflow. I figured it was just cause the car was at like 4000 rpm the whole ride and there is no air dam so it wasnt cooling enough.

So, we got it towed home and i filled it up with antifreeze and let it idle for about 10 mins, and it got to about 230 degrees, so i turned it off and it went up to about 242 and we left the fans on to cool it down.

So, I am wondering what we can do to get it so it wont overheat at idle like that, and so that we can drive it on the highway without it overheating. I am going to go get a 3rd fan to put in front of the radiator ouching air in so the other 2 behind it can pull it through.

What do you guys suggest?

Thanks
-Scott

 

3rd fan as a pusher is a very bad idea, it does not work. Find a 4th gen dual fan shroud for an LS1 and get that along with the fans and the air dams. You might also run a manual fan switch so you can turn the fans on when you need them on. Start with that and see how it goes. Others will have to put their 2 cents worth in about the motor, I am not sure if you can run it on the street at the temps it needs to last.

 

230 isnt overheating, it went up because you turn the car off and the fans didnt come on. 270 is definity over heating.

thngs to check
thomostat (you can get a 180 stat)
fans coming on
lower fan shroud
air bubble in the system
radiotor clogged
you may have a reverse water pump
fans switch is a good idea

 

i have 2, 3000cfmpushers on my car, and they work great. Dont even have to use the second one. Im putting out 501 horse, though i would think you are putting down more than that. Is the block filled?

what fan switch does it have?
does it have one?
are the fans spinning the right way?
what radiator does it have?
what fans does it have?

 

I am not sure but if the dart 400 is still like the Chevy the heads need to have steam holes in them or they will over heat, but like i said i am not sure if they are the same or not.

 

You definately need an air dam before you can tell anything on the road. You may also need a bigger radiator for you combination.

 

We made an air dam for it and its fine when driving around, but every time we stop it heats up a few degrees, and doesnt come back down when you start going again... I'm not too sure what that could be

 

What temp does it run when driving around? When you stop, what is "a few degrees?" "...and doesn't come back down when you start going again." How far or how long do you drive when you start going again before you conclude that it isn't going to come back down?