Hardcore

Anybody ever try running dry headers w/ thermal barrier coating w/ an enclosed engine compartment. My experience w/ HPC coated headers on race cars is that they keep engine room temps down quite a bit. I know it's apples and oranges but lots of race cars front fenders & hoods are made of fibreglass too.
I'm thinking of trying to fabricate some dry stepped headers and HPC coat them. My engine compartment will have a lot of ventilation and I'll probably run a Harwood Scoop as well.
Anybody think (or knows) whether it would be safe to do this and would there would be any power advantage (on a normally aspirated 509 cid)? Also, does anybody make dry headers for the Merc. Bravo 1 setup?
I can only imagine that if this could work, it would make the cost of construction of boat headers substantially cheaper (especially when it comes to large displacement engines which need large tubes w/ stepped primaries).

Gary Anderson

It will be a very well ventilated compartment once the hatch bursts into flames. I dont think it's even legal to run non-water jacketed exhausts in enclosed compartments.
Gary

puder

you need eth jackets. I ran non jacketed tailpipes once. Mind you they were attached to fully jacketed and colled CMI and the damn things still started glowing. You 100% need some cooling water.

if yu want dry just get dry tailpipe and dumop the h2o totally seperately from the exhuast gas through thru hulls dumps.

Dennis Moore

I say try it! Let me know how it works. I think it is possible, if your are careful.
Dennis Moore

paradigm shift

If you wrap them you can keep the heat in the pipe pretty well. Problem I see is getting them out through the transom. They will run HOT and remember your boat motor runs under a load for long periods of time compared to a car. Be very carefull if you try this!!!!!!!!!!

I assume your looking at cost compared to jacketed headers that run dry.

Bob280Silencer

Hardcore,I agree with PUDER ,get wet headers and dump the water before the pipes.Race cars have an open(bottom)engine bay,boats are completely enclosed(until the hatch bursts into flames like GARY said)You'll probably come out ahead(time vs money)just buying rather that building your own.BOB

mopower

Hate to be so negative , but....






fugettaboutit... hope you have an automatic halon system too

Dry headers in an open ski boat , yeah ok , but enclosed I'd say too much heat

puder

when i ran eth tailes it was dusk when i took it out for spin. IN 5 minutes of idling and maybe 3 minutes at 1/2 to 3/4 throllt i had them glowing. For the cost of making your own headers and tails and coating your better of buyign apari fo cmi and pipes. I happen to have a pair od lighlty used CMIs (fullpolish) and dry pipes. The water mixxes right at the very end of the pipes so they aren't FULLY dry. buts its enough. Reversion is't and issue. Th eabsolutle fully dry is way to damn loud. I like loud and it gave me a headache.

but if you wanted fully dry you coudl easily weld up eth wate rdump wher eth two walls meet and put a bung in for en external water dump. 0-mail me if your interested. I'll make ya a deal. I am running stellings (with CMI pipes i modified) cus they fit better.

Hardcore

Thanks for the responses guys - even the negative ones! However, what I'm trying to find out is, has anyone actually tried HPC (or other Thermal barrier coated) headers. I know the coating works. I would say it works as good as wrapping the header. I take the point about exiting the transom though. I was thinking of injecting a small amount of water - say through a AN-8 fitting, to cool the tailpipes. Loud is good. Louder is better. As far as legality goes, I live in the Cayman Islands (like Cayfomula) and we have very little in the nature of Coast Gaurd type certification of boat hardware down here. (Still wouldn't want to turn my newly painted and rigged A/O 2600 into a funeral pyre though!)
I am looking at the water-restricted Lightning Headers and for the cost of those it will probabaly be worth my while to buy those instead of piecing together a dry header and sending it away to get it coated.
BTW: there's a company called GGB that's advertising some really good looking headers in Powerboat. anybody know anything about those? They appear to have an inverted cone like collector (like what the Nascar boys use) and look like they might make power. Of course, looks don't necessarily win races...

puder

can't run lightenings in salt. the inner tubes rust out super quick as they aren't stainless.