Originally Posted by KA67_72
I'm putting together the cooling system on a turbocharged BBC project. I'm using a remote electric pump. My goal is to keep the chamber temps as even as possible. I will be casting my intake so I can make the coolant cross over the front, back, or both. The heads also have plugs into the jackets between the center chambers. From what I've found, reverse cooling isn't a good idea and I haven't found much on running extra coolant lines to the middle or back of the motor. I know this is common on a SBC. Is it not needed on big blocks? What do you guys recommend?
SBCs put additional cooling into the center of the head because of the paired exhausts creating a hot spot there. The BBC does't have the same problem.
Typically the way Detroit cools engines is to put cool coolant against the front cylinders and flowing it toward the rear picking up heat as it goes. Then introducing it at the back of the head to flow forward. This results in the situation of the coolest cylinders having the hottest combustion chambers and the hottest cylinders having the coolest combustion chambers. Surprisingly this evens out the work accomplished by each cylinder pretty well.
To change this pattern would require a lot of work to the head gaskets as their holes are the ones that really are managing coolant flow, not the casting holes which all tend to be rather large.
Tricks I've seen and some I've used are to obstruct the flow into the front of the block, feed the coolant thru the side soft plug holes, (yes this gets to tapping and making adapters) then flow the coolant up and out collecting it at both the front and rear of the heads for return to the radiator. I've seen this done in reverse but haven't done that myself. It's been 5 decades since Pontiac first put reverse coolant flow on a production GM V8, they removed it in a couple years seeing the problems exceed the benefit. We saw it again on the LT1/4 with the same old issues of problems versus benefits. While the benefit looks so good on paper, the engineering is just to quirky to take constant and consistent advantage of reverse flow at least in a production to general user situation.