Dont laugh, OK go ahead and laugh. But I made one for about $40 out of high-temp .25" thick silicone 60 durometer. The thing actually feels pretty dang quick and the plenum is ice cold from the thermal insulation. Should provide a pretty dense air charge. The stock bolts worked too. I think I'll keep it on there. Maybe try a 3/8" version next week.

 

Cool, and you said you can feel a power difference by just adding your home made 1/4" thick plenum spacer.

 

Lets try a little higher res.

 

Again, this is just a rainy weekend brainfart. No dyno yet. But as cool as the plenum is after some WOT runs, the aircharge must be pretty dense. If there are gains, its probably from the thermal isolation, not from the height of the spacer. Just my opinion. I also used the Nextgear thermal isolator between the lower plenum and the last runners into the heads. The silicone is just too thick to go down there.

 

I don't really understand the idea of cooling the plenum upper. I mean, if you can prevent the upper from absorbing heat, then the heat will just build up in the components before it, which may still have the same heating effect on the incoming air, no?

I'm thinking of it like this (hypothetical example):

a) Air travels through a 15' 200 degree tube.

b) Air travels through a 12' 250 degree tube.

Assuming that each tube has the same heat energy, won't each tube have pretty much the same effect on the temperature of the outgoing air? Someone please help edumucate me =)

 

I give you a week before you start having vacuum leak problems. I don't see how that stuff can seal correctly with all that compression.

 

Not only the upper is insulated. The upper and lower plenum, including the runners, are isolated from the heads. Seems to seal perfectly. Hitemp silicone is used in everything from caliper piston seals, to main bearing seals. Who knows. I'm just experimenting anyway. But it is on my car and I'm liking the results. If it starts to leak, I'll take it off and try something else.

 

Wow, nice piece of custom work! Can't beat the price