Heater Block Off Plate Question.
 

Hey again all, just had a quick question about heater block off plates.
I have a 1980 911 SC and I am in the process of fabricating the block off plate for the left side out of sheet metal. I wanted to save the money and needed something to do for the day. My question that just went off in my mind as I am Mid-project was that since I am blocking off the air escape rather than backdating, won't I have overheating issues? Unless I am having a total blockhead moment, I was under the impression that the fan in the rear pulled air into the engine. Thanks in advance, and apologies for such silly questions. =P

~Harrison


=D

Block off plate
 

you are blocking of the opening that air is diverted through on its way to the heat exchangers. Without heat, you want to block this off. The large fan blows cooling
air over the heads and cylinders and some goes over the oil cooler. If you do not block off this opening, much cooling air will exhaust to the atmosphere and the engine might even over heat.

Harrison, Welcome to the forum some people say that routing the air to the heat exchangers like the factory did heated the cabin but also made the engine run cooler. Don't quote me but I did read it somewhere on tech forum, how? I don't know but if you use common sense blocking off air that is diverted to X and using all of the air over the cylinders will make for a cooler engine. To me anyway.

Yes, there is some debate as to air flow required through the heat exchangers. Without air flowing through them (via a block-off plate vs. diverter) you have two big heat accumulators/storage tanks attached to your engine.

I would use a block-off plate with headers only and diverters with heat exchangers.