[jamaca85]

this is on a track only car, how much of a temperature change is there from connecting both heads in the rear water ports to plugging them and running them without being connected with no flow in the rear of the heads. Is there a big difference? thanks

[PAUL K]

Originally Posted by jamaca85

this is on a track only car, how much of a temperature change is there from connecting both heads in the rear water ports to plugging them and running them without being connected with no flow in the rear of the heads. Is there a big difference? thanks

One guy reported a noticeable difference, I'm guessing 5 degrees or less. Another guy I know used to bleed the air after redesigning the plug and adding it on the opposite side. He said a noticeable amount of air escaped.

With that being said I don't think this modification will fix a problem. I do feel it's an overall improvement.

[jamaca85]

I am thinking of plugging both sides. I would rather not have to worry about water lines back there if I don't need them. I feel like it might not make too much of a difference seeing I only idle the car for a few minutes at a time at the track.

[PAUL K]

I don't think there's an issue with that. Back in the day we always plugged both sides and never had an issue.

I'm assuming you don't have the heater core hooked up. If it was blasting the heater on high will definitely help cool the engine temperature down after a pass or between rounds.

[jamaca85]

No ...I run an electric pump and fan. I just turn them on between rounds with the car off. I figure having both sides plugged would even the temp on the rear of both heads too

[Tim Corcoran]

I have never considered doing that mod. My engine has no cooling problem. By the time I get back to my pit it's down to 170 or 180. If it ain't broke why fix it. I plug bot holes in the rear. I have the pump and the fan on different circuits on a thermostat too. I always run the water pump when the engine is running and the fan kicks on at 165. When I get back to the pit I just leave them both on and they shut off when they reach 160.

[Skip Fix]

I have the ones on my IA both connected to the front crossover.

[Tim Corcoran]

Skip, just curious why you did this mod. Does it make the engine run cooler or is it to make more uniform temperatures of the cylinders and/or cylinder head? Thanks

[Skip Fix]

Theory to make more even temps. And maybe cooler. Heads have the "421 hole" also. Some race SBC intake manifolds even have holes at the rear tapped for this. Some folks ,even some Pontiacs I have seen, have them tapped in the middle of the head.

In Texas we need all the help we can get to run cool Even if just in theory, why I am hesitant to run a filled block on the street.

[Mike Morgan]

Connecting the rear holes to the cross over will even out temperatures may make little more power.

[65madgoat]

This engineer and Pontiac enthusiast has actual data:


https://www.youtube.com/watch?v=9ou2GKZFf3Q

[PAUL K]

Originally Posted by 65madgoat

This engineer and Pontiac enthusiast has actual data:


https://www.youtube.com/watch?v=9ou2GKZFf3Q

Would mind giving is the short version please? ...... Hard to find sixteen minutes to watch a video. Like the Butler hat though.

[Tim Corcoran]

Paul, I'm retired I have a lot more free time than you. I just watched both of Monty's videos. It looks like if you tap into the rear of both heads then connect to the water cross over on the front of the intake manifold you have both improved cooling and more importantly more consistent temperatures in the cylinder heads. This way the coolant goes from the rear of the heads then through the radiator before returning back to the engine. I don't think I would bother doing this for my street car but for my drag car I can see some benefit. Would this modification also make more consistent temperatures of the cylinders?

[steve25]

I don't see how any of this much matters on a drag car unless your scratching to eek out the last 4 hp out of a motor. but a road race car is a far different deal.

That being said I think fuel distribution plays a far bigger roll in cylinder temps then coolant in a drag motor.
If your fighting a detonation issue that could be due to a few issue then I can't see how a mire 5 degree drop or so in engine temp is going to be much help.

Has anyone ever look for / calculated how much coolant gets moved thru a motor on a 11 second or faster pass?

Keep in mind that in terms of what takes place in the cylinders heat is power.

[Skip Fix]

Steve if you are "hot lapping" drag runs keeping it as cool as possible is important.

[PAUL K]

Originally Posted by Tim Corcoran

Paul, I'm retired I have a lot more free time than you. I just watched both of Monty's videos. It looks like if you tap into the rear of both heads then connect to the water cross over on the front of the intake manifold you have both improved cooling and more importantly more consistent temperatures in the cylinder heads. This way the coolant goes from the rear of the heads then through the radiator before returning back to the engine. I don't think I would bother doing this for my street car but for my drag car I can see some benefit. Would this modification also make more consistent temperatures of the cylinders?

Thanks Tim! You are a-ok!

Yes I think it helps all the way around. I take any improvement I can and eventually they start to add up. Obviously things will work as the factory set it up but sometimes improvements can be found.