Intake Manifold Question

[dlomheim]

On my Mazda 13B installation I am using the original Mazda manifold but I want to take a 3" fiberglass pipe about 12 inches long and run it to the Throttle body that will be mounted about mid engine on the right side (looking forward from the firewall). Anyway, I wondered if anyone had any experience with doing this as to what kind of epoxy / glass would work the best; should carbon fiber be used, etc.

Thanks for any information.

Doug Lomheim
OK City, OK RV-9A, 13B FWF

[DanH]

Doug, be cautious about this plan. Operating temperature is the wildcard. Plenty of guys have built composite intake manifolds, but you must be sure it doesn't get warm. All epoxies designed to cure at room temperature get quite weak at elevated temperatures. Alternate approach would be to make sure the manifold is not structural, just an unstressed tube, with the throttle body entirely supported on a separate structural mount. That way the tube might live even if things get warm.

[AllanC]

Doug,

Talk with an epoxy specialist - there are epoxies designed to work in high temp environments, and maybe you need to measure temps first and then see what's available and suitable. I've used normal epoxy and CF in making air intake duct tubes for my oil cooler shroud and its worked very well so far. In fact my CF shroud is bolted to the oil cooler and seems to be standing up well. I concur with Dan's opinion on ensuring sound structural attachment.

Allan

[dlomheim]

Thanks for the replies...I'll try and apply your lessons learned!

dl

[airguy]

Originally Posted by DanH

Doug, be cautious about this plan. Operating temperature is the wildcard. Plenty of guys have built composite intake manifolds, but you must be sure it doesn't get warm. All epoxies designed to cure at room temperature get quite weak at elevated temperatures. Alternate approach would be to make sure the manifold is not structural, just an unstressed tube, with the throttle body entirely supported on a separate structural mount. That way the tube might live even if things get warm.

And vice versa - for my day job, I'm a corrosion consultant for the oilfield. My main product that I push is fiberglass, and the epoxy cures at 350F under oil bath for 1 hour, then in hot air at 250F for 4 hours. In actual use we see thermal degradation occur at sustained temperatures above 265F. It's all about the chemistry of the resin and hardener, there are literally thousands of possible mixes that can do whatever you desire. It's not the curing conditions that dictate usage - it's more like usage conditions that dictates the chemistry, which dictates the curing conditions.