A reverse flow cooling system picks up heat from the cylinder heads first
(this is the critical area) and then passes through the engine block (the
cylinders themselves being much cooler than the combustion chambers). The
temperature "map" in the engine becomes less varied, the CCs are cooler and
the chance for unwanted events to happen in the chambers is reduced....
The concept is relatively simple... but now we need to move the thermostat
and make additional changes to reduce an resistance to coolant flow. At one
point in time, it was expected that production engines would require reverse
flow systems. These may be fitted on some of the exotics, but I haven't seen
any north american production engines with this as yet (though the Ford 2.9
V6 has a goofy fill procedure and I haven't had the chance to srudy the
cooling system closely....).
If we look closely at nearly any head gasket, we can start to understand the
amount of technology involved..... Notice all the little holes and passages
that seem almost random. These can be steam vents or passages designed to
increase coolant flow over specific areas of the cylinder head. If we look
closely at some race bred, American V8 cylinder heads, we can often see
mysterious hoses sprouting from the middle of the intake face of the head
(particularly on the Chevy V8s with teo exhaust valves side by each at
Let's not forget that, many, many years ago, cylinder heads had metal
inserts to direct coolant flow to the exhaust valve bowls in many engines...
These would rot out and create some mysterious overheating ailments.