rear coolant passages

[dusterbd13]

so in the back of my heads are a pair of coolant passages that do not meet due to being blocked by the intake manifold. since im already modifying my victor jr for EFI, should i build a coolant crossover for those two ports? would it gain me anything, or just be another leak point? engine is a solid roller cammed, indy headed, forged piston, 390horse at the rear wheels, 9.5:` compression 360 with a tremec. and ac. and power steering. and power brakes. using an aluminum radiator and electric fans, and have had a few instances of heating up to over 210 since the AC install.

so what do y'all say? crossover worth it, or not?

 

[fishy68]

Just a cross over from one side to the other won't do anything IMO. I have read that installing fittings back there and routing lines to a modified thermostat spacer/adapter can yield benefits but I have not actually seen hard data to prove that. At one point I was gonna try it to see if it really worked as I had the adapter but every manifold I could come up with had gussets back there for support and I would have had to either cut them off or take it to a machine shop and paid to have it done. Never had a problem with my engine running hot so I decided not to do it. Another reason I decided against it was I did some thermal testing with a laser temp gun and the temps I read at the back of the head were within 2 degrees of what I read up front. To me that indicated nothing could be gained, but I am no expert in the area so that was just my guess.

Here's a picture I found of a manifold with the mod done to it.

 

[Norway-dart]

well, I guess the main reason for them being there is you being able to swap left and right head, and still there will be possible to mount intake and have working coolant system.

second, If you bypass some water direcly to the thermostat housing, you remove water from the heads, and then you up the temp in the head because there flow less water through them. I dont see any gains from that? hotter intake manifold and hotter exhaust ports. may be good for Nox fumes

 

[fishy68]

well, I guess the main reason for them being there is you being able to swap left and right head, and still there will be possible to mount intake and have working coolant system.

second, If you bypass some water direcly to the thermostat housing, you remove water from the heads, and then you up the temp in the head because there flow less water through them. I dont see any gains from that? hotter intake manifold and hotter exhaust ports. may be good for Nox fumes

Agreed

 

[moper]

The coolant flows from front of block to rear, and from water jackets up to the head. So by connecting the ports in the rear to the neck, you are eliminating possible air pockets and keeping the combustioin chambers more evenly cooled. Some more racey heads also have ports between the center and outboard exh ports, and blocks have ports out of the sides of the cooling jackets. The problem is unless you use the reverse flow system you're still only feeding coolant that has picked up heat from the cylinders up to the chambers. Reverse cooling is much more effective - but the lines will look cool..lol.

 

[jos51700]

I'm no fluid dynamicist, but it seems like if the coolant is free to flow across the ends of the heads, then it wouldn't be prone to flow through the head and cool the middle two cylinders very well.

But even beyond that...if it isn't broke, why people be fixing it?

 

[Norway-dart]

The coolant flows from front of block to rear, and from water jackets up to the head. So by connecting the ports in the rear to the neck, you are eliminating possible air pockets and keeping the combustioin chambers more evenly cooled. Some more racey heads also have ports between the center and outboard exh ports, and blocks have ports out of the sides of the cooling jackets. The problem is unless you use the reverse flow system you're still only feeding coolant that has picked up heat from the cylinders up to the chambers. Reverse cooling is much more effective - but the lines will look cool..lol.

Does the chrysler heads have problems with air trapping at the back of the cylinder head? I have never had any big output engine, so I have never experienced anything like that...

In my head, the waterpump push water into the block, then water moves to the rear of the block before it is pushed up in the head, and then turn to the front of the head and then against the thermostat. Some of the coolant goes directly to the waterpump via the small hose from thermostat housing to the coolantpump.

This way the coolant becomes hotter and hotter on its way to the termostat. There are/should be some small holes between block and head in the gasket where the coolant passages are on cyl 1,2,3. They are to be kept small because they are there to remove air pockets in block,and not transport water. I have seen people making this holes as big as the cooling passages, and those engines got cooling problems, getting to hot on the rear of the engine.

Race engines like you say often push water in to freeze-plugs via a delivery pipe. This way you get a more even temperature around each cylinder. In such systems you want to open all coolant passages between block and head, and then you may remove 50/50 of water from engine from the two coolant exits in the head. even tap more exits if you want. I believe this is extreme situations. personally I believe the Stock cooling system is enough for 1000hp+(turbo) , but in some aplications you may want to do some changes. I agree the lines look cool tho I hope this was readable.