Dynodonnymac talks about cooling systems

I love to talk about cooling, because nothing will ruin your race day faster than an overheated engine. Now, keep in mind that different engines need different things from the cooling system. A Ford has different requirements than a Chevy, of course, and different divisions have different rules. Today I’m focused on Chevy Sprint car engines.

Ron Shaver and plenty of other engine builders figured out quite a while ago that the standard cooling system was inadequate to keep a 700-900 HP engine cool. And since then, engines have become even bigger, up to 960 horsepower. That means that now the cooling needs have become amplified. One problem with the Chevrolet is that the hottest part of the engine is right between the two exhaust valves on the cylinder head. We had to address this issue because when it gets too hot then there is a tendency for it to lift the cylinder head and blow the gasket in between those two cylinders.

Resolve valve heating with reverse cooling

What we have done to fix this is what I call reverse cooling. On the Sprint car engine, the water pump is driven by the crank shaft. With reverse cooling we are not taking the water in from the water pump directly to the block. Instead. We direct the water from the water pump with a dash-16 hose directly into the cylinder head right in between the two exhaust valves. Remember, that’s the part that heats up the fastest on this particular engine.

With the water directed straight to the spot between the valves, this part of the engine gets cooled down quicker. The temperature inside the head is more uniform and that means there is less likelihood of blowing the gasket. The water goes into the middle of the head, then down into the block and then comes out two openings on the bottom of the block.
To do this we use two Dash 16 lines going in and two Dash 10 lines coming out at the bottom. We also have two small hoses on top of cylinder head—these are bleeds that keep air out of system. These small bleeds don’t flow a lot of water through, but it helps.

Bleed hoses reduce hot spots

One reason why the bleed hoses on top are important is because a tremendous issue with cooling is hot spots in the cylinder head. Every cylinder head when it’s running will have boiling spots. We need to get that boiling air out of system as soon as possible while we keep the air cool in there. These bleed lines help with that by taking the boiling air back to the radiator. As the water temp goes up and starts to boil, we get the air out as soon as possible.

Also, there’s something connected to this topic that I have been talking about with Russ O’Blenes, who is Head Engineer at GM Powertrain. One of the biggest issues with overheating is the amount of water flow going into the engine. Shaver Specialties is one of the few shops that can measure the amount of water flow going into an engine. We all agree that more water flow is better. There are a couple of reasons why I say that:

First, the water pump is capable pushing of 70-80 gallons per minute. The standard rule is that you need 10 gallons per minute for every 100 horsepower. So, for example if you have an 800 horsepower motor and you can flow 80 gallons per minute you should be ok.

Second, when the pump is flowing more water than the engine can take, the pressure inside the engine will go up. For example, this motor with two Dash-16 lines going in and two Dash-10 lines coming out will flow about 70 gallons per minute. The pressure inside the engine will go to 60 or 70 PSI.  When an engine gets to 60 or 70 PSI, that increases the boiling point for the coolant, which in turn decreases the air bubbles forming inside the engine, and that then creates more space for the water to take the heat out of the engine and transfer it back to the radiator.

Shaver’s redesign of the water system on the Sprint car Chevrolet 410 engine has become the industry standard. Because of these changes, we have been able to progress from 800 horsepower to almost 950 without destroying the engines.