External cooling lines?

[JeffG]

Has anyone plumbed their heads for external cooling lines? I am about to convert over the NPG+, and I was thinking about completely blocking off the bypass and running one line from the back of each head........then plumb them back into the top radiator hose. The more fluid I can get pumping through the heads the better I figure. I am running iron heads by the way.

Thanks in advance............................

On a secondary note, has anyone tried reverse cooling one of these 3.8's?

 

[bruce]

Originally posted by JeffG
Has anyone plumbed their heads for external cooling lines? I am about to convert over the NPG+, and I was thinking about completely blocking off the bypass and running one line from the back of each head........then plumb them back into the top radiator hose. The more fluid I can get pumping through the heads the better I figure. I am running iron heads by the way.

On a secondary note, has anyone tried reverse cooling one of these 3.8's?

Unlike alot of other GM engines, the Buicks have an excellent cooling system. At least IMO.

Have you seen a cooling problem with the 3.8?. making the HP they do, seems testimony to how good it is.

 

[JeffG]

Thanks Bruce. The external plumbing would be to aid detonation suppression more then anything else. My car run 160ish most of the time, but I am sure there are hot spots in the cylinder heads under load.....especially with the amount of power these little motors put out (as you said).
Talking to guys at NPG, they stated that anything you can do to the 3.8 that increases flow is benifical. They think lack of flow is the down fall of the 3.8 cooling system.

 

[KendallF]

I think Jason White has his heads set up this way. He seemed to think it was helping avoid detonation and keep the heads on; it's hard to really test thoroughly.

 

[JeffG]

Thx Kendall. I think I may give it a shot.

 

[Brian Mc]

I tried it by drilling the top rear edges of the intake, and then realized that the heads would not receive enough coolant flow so i filled the holes w jb weld

 

[JeffG]

Brian,
You were concerned that the flow would not be going across the cylinder head (back to front), but straight out the external lines?

 

[Crazi]

I did the intake mod to my car and have had NO adverse effects. I used really small lines (5/16 or 3/8 don't remember) and did it mostly to get some flow from the back of the heads. If you look at the angle of the heads and the way the intake fit on the block, there is room to trap either air or stagnant water at the back cooling ports.

I looked around at alot of four corner water systems on SB's to get the idea and like I said, I haven't had a problem.

 

[JeffG]

Crazi,
Did you tap into the intake or the backside of the cylinder heads? Where did you feed the lines to? Did you block off you bypass on the pump?

Thanks!

 

[Crazi]

I tapped a barb into the pad on the back of the intake on both sides. Then I ran both of these into a tee to provide crossflow. From that tee, it runs into another tee where I looped the TB coolant lines.

I painted the intake the last time I had it off so you can't tell it is not supposed to be there uness you are looking. Water pump bypass??? Where and what does that do?

That might be the next mod I do even though it is working fine now. You know us buick guys. Always making stuff better.

 

[JeffG]

Crazi,

The water pump bypass is the small outlet near the top of the pump. It loops back to the intake manifold. It's there to allow pressure bypass when the thermostat is closed. NPG recommends restricting this passage and running no thermostat......again, to increase flow.

 

[Crazi]

Hmmm... I cut three slits in my thermostat with my dremel to keep some coolant flow when it is closed. They are about 2mm wide and spaced evenly. Kinda like this

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Maybe I should block this bypass as well? I know what you are refering to and my reasoning says that it puts hot water back into the engine with out going through the radiator first. Correct?

 

[JeffG]

Yep..........

 

[Crazi]

Then I will try that too come spring time. The bypass keeps excess pressure from building up behind the thermostat? But with a 160 or even 180 thermostat, shouldn't the thermostat open if the pressure is that great? Pressure equals heat correct?

Either way, I am blocking mine off and will find out what happens... (famous last words )

 

[Brian Mc]

jeff, that's what i was thinking. It kept me from doing it.

 

[Crazi]

Brian,

What size hoe did you drill??? If you drilled a hole large enough to worry about the heads receiving enough water then you shoulda filled it.

Basicaly what I was trying to acheive was enough coolant from the back of the heads to prevent steam or hot spots from forming. I just got done running 30 psi with my alky injection and my O2's were in the mid 700's. Prior to that, I used to run down into the mid to high 600's at times without any detonation.

I tried it, it worked well for me using 5/16 or 3/8 hose. If yours was bigger then that then you might have had a problem.

 

[Brian Mc]

I did fill them. i drilled a 3/16 hole for the fluid and a 1/4 npt for the fittings.

 

[Silver 6]

With the bypass removed and the heater valve closed, how will water move inside the motor when the thermostat is closed? And with zero water movement wouldn't you get some serious hot spots in the heads?

 

[JeffG]

Sliver 6,
That is why I was going to run the lines out in front of the thermostat. Probably into the upper Rad hose somewhere. When running NPG (which I am switching to) you are suppose to remove the thermostat so none of this would really be an issue anyway. I do have some concerns with extended warm up times without a thermostat so I may just run one with some bypass holes drilled in it. We'll see..............

 

[Crazi]

Hmmm... Wouldn't some water be moving through the heater core? Well it is now cause it is cold but I see what you are saying. Ok my bypass is staying in then since I have not had cooling problems to date.

Brian, I seriously doubt a 3/16 or even 1/4 hole would affect cooling to them point where no flow would go through the heads. Think about the size of the radiator hose vs your two 1/4 lines. When the stat is closed, the coolant will go wherever those lines lead but when it is open or even partly open, your coolant is going to take the path of least resistance. I say do what makes you comfortable but I haven't had a problem with my setup so far.