high-temperature epoxy for hood?

[Michael]

Recently I built a custom nose-piece for my '78 280Z, integrating the headlights and radiator upper-support. I used polyester resin and cheap fiberglass cloth, both available from home improvement or generic autoparts stores; also, plywood ribs and foam between the ribs, with aluminum glassed-in here and there for hard-points. In functionality it's similar to a G-nose, but it's much shorter and follows a different philosophy.

 

From that experience, for my next trick I'd like to build a custom hood. It has a slight bulge to accommodate a standard 14â€-diameter, 3"-high air cleaner atop the big-block. [with a Performer RPM intake, BBC’s are too tall to use the stock Z hood]. Again I'm using plywood ribs and wood stringers. The framing is coming out pleasingly, but I am concerned about underhood heat. The fiberglass cloth should be OK, but conventional polyester resin, as well as similar 2-part epoxies, would soften and possibly melt.

 

So here's my question: any advice on brands/methods/retailers for high-temperature epoxy or polyester resin? I'm not expecting something that would survive a direct flame, but good stability at 250 deg F would be nice.

 

I also plan to use a heat-insulating glue-on blanket, of the type used to wrap starters to prevent heat-soak.

 

BTW, a search such as http://forums.hybridz.org/showthread.php?t=83659&highlight=epoxy+high+temperature is pretty much a dead end, but I vaguely recall discussions on this topic some years ago.

[Here comes trouble]

i am working on a 250 GTO project and have similar concerns about it's fiberglass hood. which is conprised of polyester resin and fiberglass strand as most other after market fiberglass products. I plan to incorporate a backward scoop to let the air out and use some type of insulation shield attached to the underside of the hood. The fiberglass hood has some built in webbing underneath for strength. I have found direct sunlight can generate incredible pressure in the enclosed webbing to pop a seam. I drilled some holes to let out the air pessure. I will also drill holes in the steel door to relieve pressure under the enclosed fiberglass door skins. I am not too concerned with an undeneath paint barrier to shield against engine heat because it may act to retain heat generated from the sun on the top side. I plan to use silver as the car color for better heat reduction from sun light. One of the problems with polyester resin is it may take years to cure if ever completely and excess heat makes it pliable which causes surface paint problems over time.

[280Zone]

Fiberglass hoods have been used for years on both race and street cars. If you are interested I have these hoods available.

 

http://forums.hybridz.org/showthread.php?t=101130

[dot]

I laid the glass for my hood in the eighties and it is still holding its shape. It was built with standard glass and resins.

Owen and Terry are probably the glass masters on this board. Seek them out for more info.

[blueovalz]

I went to the extreme. Unable to find an adaquate air filter holder for my K&N filter to fit under the hood AND within the strut tower reinforcing, I fabricated a fiberglass filter holder that allows the filter to fit under the hood. I've pushed and pulled on it after the engine bay was up to normal operating temperatures, and the part did not soften any appreciable amount. Underhood temperatures concerned me at the time of the build, but after 4 years it has held up well. This photo does not show it, but I finally refinished it and then painted it to match the exterior paint color. So in short, the fiberglass hood will not have any problems with typical underhood temperatures.

[Michael]

Terry, what would you recommend for a brand of epoxy or polyester resin?

 

BTW, I've had good luck with generic Bondo polyester resin (comes in a blue can), except that it eats away white foam. It works OK with pink (household insulation) foam.

[blueovalz]

I've no recommendation. Potatoe/Potawtoe, who knows?