How big a hole (come on, get your minds out of...)

You really want me to go out into a blinding blizzard and slog my way to the garage along a slippery, icy walkway, just to move my Webber gas grill and Big Green Egg out from behind the car into the (now snow covered - again!) driveway so I can get the engine compartment open, move the mice nests out of the way and measure the almost inaccessible hole in front of the fan inlet??

Really?

OK, fine.......I gotta put on my friggin boots, now......Be back in ten minutes.

On FF/CMC it's n 8" 3/4 moon cut out just above the flywheel.  It show cutting it out in the build manual.

Damn!  Wolfie beat me to it.

Got everything out of the way and opened it up and, sure enough, looked like a mouse condomiminum in there.  I was surprised at how much of a fight Reindeer mice can put up.  Had to blind the little buggers with my 36-LED shop light to hold them transfixed while I did the measuring.

Found out exactly what Wolfgang said:  8" diameter hole, right in line with the fan inlet opening.  Almost looks like those crafty CMC build manual guys had planned it that way!

Anyway, turned off the shop light and the remaining mice scrambled for me so I slammed the engine cover and headed back to the house.

Ya gotta love Winter in the great White North....

BTW:  CMC's have a collar molded into the firewall that stands up off the firewall surface by about an inch.  THAT is where we do the cut-out for the opening so the air has a bit of direction more closely to the fan inlet.

Now Gordon, it wasn't that bad! Sorry you had to disturb the mice, though.. All kidding aside, thanks for braving the elements. I hope I gave your day purpose. I drew an 8" circle and taped it to the firewall, using a block with the stand and the shroud on as a guide for positioning; it sits lower than I'd imagined. The paper circle comes a little close to the right deck hinge area so I'll probably give an inch and a half or 2" clearance around it. I'm thinking about making a venturi entry ring for the outside of the hole; maybe out of some 8" pvc pipe. If I glued 2 or 3 layers of pipe together (pieces 1/2 or 1" high) and then used a router for the curve... 

And Wolfie, thanks to you as well; although in Florida you probably didn't have to battle any Arctic winds...

PS- How close does this hole come to the right side hinge? Any problems with the firewall not being strong enough to hold the hinge rigidly?

Gordon , you went through all that, and you didn't even get a picture?

How about 2, 4 inch holes? I was in the building supply place today and they had aluminum louvered 4 inch vents that pop right into a 4 inch hole anywhere you drill it. They also had rectangular flush mounted ones of various sizes. All of them had insect screen to keep out the big chunks and they can be painted any color you want.

You want photos of holes? Not that this relates to your car, Al, but my mechanic for my original Type 4 install with the more traditional fan housing and oil cooler mounted on the back side of it recommended an intake hole. You'll notice it there where the C-clamp is. I know Beck's have a different layout in the engine bay...as I recall it was about 4-5" in diameter. I didn't even need to put my boots on for this.

You don't want to do that Al. One 4 inch hole is about 12.5 square inches, two would be about 25. An 8" hole is 50 square inches, so DOUBLE the surface area. You could make 4 4" holes though........then we could call you Padre!

Danny, I'll probably need much more air than that for those massive carbs.

Measured.  Vintage 6"

Al,

I see what you did there...

Ted