I live in quite a warm climate, and my car has the stock heat exchangers, but the heating system is not connected and I don't have the motor installed to pump warm air to the cabin anyway.

My question is whether I would benefit by blocking off the 2 vents from the fan housing, that blow air through the heat exchangers?
Would this help force more cooling air through the fins of the motor?

Here is a pic of one of the fan housing vents I am referring to...

Yes, blocking them off will force more air thru the cylinders.When I got mine, it had these capped off by some aluminum bits fabed from an old license plate and worm drive hose clamps.

excellent.
Thanks for the reply!

Air flow is tricky stuff. It doesn't always do what it looks like it should.

In this particular case, we have at least one person with instrumentation (Jake Raby) who tells us that blocking those off leads to increased head temperatures. I don't know the mechanism, but is seems like the setup wants to bleed air off through those.

--DD

oh.. now i am confused.. I too thought i read somewhere that blocking off is not good.
But even if the tubes and heater fan were all connected, if the heater was turned off and the air had nowhere to go, isnt that the same as blocking the exits?

No the air get dumped after going though the exchangers, so it bleeds a small amount of air at all times. Think of how hot the heat exchangers would get if the bleed air didn't flow through them.

The air does have somewhere to go. Have you ever looked at a flapper valve? When closed to the cabin, the air that's passed through the heat exchangers simply gets routed out to the ambient air under the car.

ok
I am convinced now, that I should NOT block off the vents to the fan housing and that they should be left to run through the heat exchangers...

If you have heat exchangers you should run the air through them. As mentioned, the airflow through the HE's never stops. For cabin heating, the air is directed to the interior by the flapper. If no cabin heat is required, the air is dump out under the engine at the heat flapper.