Composite rocker/cam covers.

[Autodidact]

I've seen them amateur built and I think it's common on production engines nowadays, but how to do it? A certain type of resin, or reinforcement at the mating surface like an aluminum plate? Cut the top off of stock composite covers and bond a new top on? Why not use the stock shape? Maybe you might want something a little cleaner looking that looks airplane specific, or even mimics a classic engine from the past.

 

[mcrae0104]

How many grams per hour of fabrication time would composite rocker covers save?

 

[TFF]

Aircooled might be a little much. Watercooled engines are running cooler.

 

[Marc Bourget]

OEMs have been using engineering plastics for engine parts for years.

Ford (and others) used plastics for intake manifolds and other significant parts. It can be done for Lyc and Cont valve covers but I would speculate that it's cost effective only if you're running up against a CAFE regulation and are exposed to fines rather than simple performance advantage.

 

[Autodidact]

Aircooled might be a little much. Watercooled engines are running cooler.

I should have been clearer. The above is what I meant, primarily liquid cooled auto conversions; I see no reason to do this for any of the air cooled engines that I know of. The guy who put the aluminum block DD Ford in his Vari-Eze had what looked like fiberglass valve covers, and I was just wondering if it takes a special resin or something. And it wouldn't be for weight saving either, really, but mainly for looks, which wouldn't matter much unless the top end was exposed like some of the old aircraft. For example, you could take some of the modern DOHC engines with very fussy looking cam covers and make them look much nicer.

 

[autoreply]

PEAK (prepreg) or polyimide.

 

[Autodidact]

Thanks. The polyimides can withstand very high temperatures like 700F or so. Aircraft Spruce sells an HTR-212 epoxy that can withstand up to 325F which might work on liquid cooled heads, especially aluminum I hope.

The polyimide resin looks like it might be difficult to work with (for an amateur) and/or difficult to obtain...

 

[wsimpso1]

OEMs have been using engineering plastics for engine parts for years.

Ford (and others) used plastics for intake manifolds and other significant parts. It can be done for Lyc and Cont valve covers but I would speculate that it's cost effective only if you're running up against a CAFE regulation and are exposed to fines rather than simple performance advantage.

Working for Ford and Chrysler, they each had some basic guidelines for how much something could cost per 1% improvement in fuel economy. If it cost more than that, it was an uphill fight, if it was less, there was huge pressure to implement it on the next program year. Weight savings like plastic covers and pans and manifolds were a done deal many years ago. Many were glass reinforced high temp plastics with metal inserts molded in and gasket containment grooves, so they were putting leak warranty away at the same time.

Yeah, if a program was in weight trouble - the EPA blocked you into weight intervals, come in one pound above the one you were looking for, and the dyno was set 250 pounds heavier for your FE/emissions runs - they could get crazy about what they would spend to shave some pounds. Silly thing was that they let the car get bigger and put in heavy stuff to late to fix NVH issues like they don't have to pay the piper some time, then the want all of the carefully tested stuff to find ways to take out weight after the launch, forgetting the whole time that weight is hellish to take out once the concept is fixed...

Fines are levied on the whole corporation's composite fuel economy. The fuss there could be intense too.

Glad to be retired from that mess.

Billski