Heat-coating

[moyest]

More questions folks -

In an effort to cool underbonnet temperatures, has anyone ever heat-coated their INTAKE MANIFOLD as well as their exhaust headers??

Is it possible to heatcoat the intake manifold, or is there some reason I should avoid it like the plague?? Seemed like a good idea to me to further cool my fuel flow and carbies.

Cheers :classic:

[2ManyZs]

Depends on what you are referring to as a heat coating. Jet Hot or something like that or the brush on types you can get at speed shops?

I've seen a few racers that have taken the time and money to have their intake manifolds and cross over Jet Hot coated on the outside. Due to the rules they can only do the outside and not the inside.

Does it make a big difference? Not one that could be felt in the seat according to the one who I know.

It does however look darn good.

If it were done inside and out, I think the benefit of doing it would increase as it would reduce the heat transfer in and out of the manifold by somewhat isolating the manifold material from all heat sources.

In other words, I doubt it would be worth the time and money unless it's done inside and out, where you will reap the largest benefit.

Same with the headers. If it is done only on the outside, the metal is still in contact with the hot exhaust gases, which will end up causing the metal to act as a heat sink which will hold the heat, while if it is coated on the inside, the more of the heat will escape thru the exhaust and not have the chance to heat up the metal.

[hls30.com]

I considered doing just that on my turbo project, but then I though about it some, and realized that could make a bigger difference with less money by getting the heat out of the engine compartment with fans and ductwork! The Jethot coating drops temperatures about 60 degrees under ideal conditions. If I coated the exhaust manifold, the "J" tube, wrapped the turbo and used a water cooled core, I would be limiting the heat introduced into the engine compartment substantially, now if I add thermostat controlled high powered fan under the cowl, and place a duct to pull air from the area sectioned off by the heatshield between the exhaust and intake manifolds, I would be cycling the air out of the engine compartment very quickly, and thereby lowering the temperature of and already insulated engine compartment even more! A Spal fan sized to fit runs $50-$75 the duct work would be made from a roll of aluminum sheathing-$10 at Home Depot.

In your situation, I would try a couple of the injector cooling fan assemblies from a 280ZX-cheep, available, and a stock Datsun part that just happens to fit your block like it was made for it-even draw air from the cool side of the engine-but extending the intake with a dryer duct woud be a cheep way of pulling cool air from under the car!

Will