Too much grill block

[winkosmosis]

Originally Posted by Frank Lee

If the fan is running more you are kind of defeating the purpose of blocking in the first place.

Why do you say that? How much power does a fan use? If you're getting the same cooling with a smaller grill block, you will still improve efficiency if the drag decrease offsets the fan wattage.

[Frank Lee]

Because I don't think the drag reduction offsets the wattage.

[fourfa]

Originally Posted by 3-Wheeler

Some of the university students who design, build, and race SAE formula cars, have mentioned something that would help in this situation.

Consider that 1/3 of the engine heat goes to the radiator at what ever throttle position the engine is running at.

If you are pulling a large load up a pass in Colorado, and the engine is putting out 200 hp, then the radiator will need to dissipate 1/3 of that load, or 67 hp!! AND the hole for the radiator block needs to be sized accordingly.

just want to clarify this:

generally, normally-aspirated spark-ignited gasoline engines take the chemical energy in the gasoline and can only turn about 1/3 to actual power. 1/3 is wasted in the radiator to prevent overheating. 1/3 is wasted out the tailpipe as unrecovered heat. So if the engine puts out 200bhp, the radiator also has to dissipate heat equivalent to 200hp. Not that this helps us visualize what size hole is needed for that much heat dissipation...

[aerohead]

Originally Posted by fourfa

just want to clarify this:

generally, normally-aspirated spark-ignited gasoline engines take the chemical energy in the gasoline and can only turn about 1/3 to actual power. 1/3 is wasted in the radiator to prevent overheating. 1/3 is wasted out the tailpipe as unrecovered heat. So if the engine puts out 200bhp, the radiator also has to dissipate heat equivalent to 200hp. Not that this helps us visualize what size hole is needed for that much heat dissipation...

Yep,that's pretty much the story.

[Dean in Milwaukee]

This is why airplanes have cabin adjustable vents. They only open them just enough for conditions which lowers drag increasing speed and economy.

Cabin adjustablity in a car should'nt be too hard to rig up with a cable setup and a simple damper type arrangement in front of the radiator.


Dean in Milwaukee