Originally Posted by Overdriv
I just read the thread on zero decking, very interesting, and entertaining also.
Anyway CNC Blocks NE showed some pictures of a circle track engine that had lines running from the front of the intake to the rear of the intake on each side.
Someone please enlighten me. I would have searched but didn't know what to search for.
Unless I'm running exterior lines from the water pump into the side of the block and curtailing the normal coolant entry at the front of the block, I don't do this at least to this extent. My reasoning is that the if the engine is plumbed the conventional way of the pump delivering cold coolant to the front most cylinders which then flows the length of the block gaining heat as it goes and then mostly moving up the rear to flow forward thru the head to the thermostat and radiator return. This system results in the front cylinders on each side running cooler than those behind and the rear combustion chamber running cooer than those ahead. So in a perverse way it evens out the thermal efficiency of the overall engine where colder cylinders have hotter combustion chambers and warmer cylinders the cooler combustion chambers. Works OK on the street but not as well in lengthy situations of high power output.
If the inlet coolant is put in at the side of block it tends to level out the operating temp variations between the cylinders. The coolant then flows up to the heads and is tappet off at both ends which also helps to balance out the combustion chamber temps. The new Chevy RO7 NASCAR engine is completely designed from the get-go to incorporate the concept of individual temperature control on each cylinder with every cylinder having its own source and the return for each combustion chamber cast into the block and heads.
When ever I build an engine where the coolant inlet to the block is conventional, I keep the coolant return ,also, close to the conventional return plan with the exception of using a small diameter return of 3/16s to 1/4 inch tube from the rear of the intake where it covers the back side head returns or from the vent location on the LT1/4 heads. The purpose of this is not so much to redirect coolant from its normal path as to provide a vent to keep vapors from forming bubbles over and around rear combustion chambers. The reasoning here includes the thoughts that with conventional coolant entry, the engine retains the usual thermodynamic problems and solutions the factory built into the engine so that tapping a large return from the rear of the head will tend to over-cool the rear combustion chambers costing power and will short the forward chambers of coolant unless other steps are done with the head and/or gasket to allow a greater amount of coolant to return via the head from the forward cylinders.
So I guess my message is before messing around with coolant routing, make sure you know the whole story some of which you may not see in engine photo's.