plenum kit?
 

Greetings,

I've noticed that some folks are using plenums on their engines now, rather than the traditional baffles that seal to the top canopy. Does anyone make a pre-made plenum for the RV-8, with a stock cowl? I know Sam James makes one, but I think it's only for their cowl.

Thanks,
Rusty (emp kit just arrived, QB coming in Jan)

Plenum Options
 

Jon Johannsen makes one, but most of the web sites I've seen use Vans baffling and put a top on it. ?he guys at Showplanes.com are said to be close to a better version of the James Holy Cowl, but I've yet to see it.

On my next 8, I plan to mold my plenum out of foam and lay it up with glass and vinyl ester resin.

Robby

Make your own
 

The JJ unit is too much money ($800?). You can make your own from aluminum off of Vans basic baffle kit. You can also use Vans baffle kit and make a fiberglass cover. Robby suggest vinyl ester resin. I am not a Fiberglass guy but (I THINK?) the Vinyl ester stuff shrinks and is not good with heat. I think epoxy resin is better? Check it out first. Look at builder sites for ideas. G

http://home.mindspring.com/~rv6/RV6site/index.htm
http://rv8a.tripod.com/engine.html
The following is for Rockets, but you get an idea
http://www.vincesrocket.com/Engine%20and%20Prop.htm

Vinyl Ester
 

G:

The reason I mentioned Vinyl Ester is because James' plenum is manufactured using that material. To me it is all nasty stuff.

Robby

Thanks for the info, particularly the links to custom plenums. I've seen at least one of those in searches through the archives, but it's clear there's most than one way to do this. Unfortunately, my hope was that someone would have a reasonably priced plenum available, or at least plans to modify the Van's baffle kit.

On my first RV-8, I spent almost a whole vacation week working on nothing but baffles. I just couldn't believe how long it took, but they came out fine, and worked fine. I do think there are advantages to putting a lid on the baffles, rather than trying to seal it to the cowl, but I'm not sure "time to build" is going to be one of those advantages unless someone sells one ready made :p

I'll take a look when I get to that point, and decide if it seems easier to make them stock, or put a lid on it.

Thanks,
Rusty

Thanks for the links. Has anyone come up with a decent way to seal the cowl inlets to the plenum, assuming you are using the standard Van's inlet shape? I'd love to see some pictures of that. That's the one thing that still baffles me about making a plenum.

If you just need a decent (not perfect way) do what I did- use airseal fabric riveted to the top cowl to seal the top of the plenum, in the same way that the bottom cowl is sealed to the standard baffles. It's not as tight as, say, a Sam James, but it works, as you say, decently.

http://home.mindspring.com/~rv6/RV6site/plenum.htm

Custom Plenum
 

I plan on fabricating my own plenum using epoxy resin. I'm also going to use the inlet rings from Sam James to reduce the cooling drag. The plenum will be screwed to the standard vans baffle kit.

Philip Mercier, RV-4
Abbostford BC.
http://members.toast.net/pmercier/project2/index.html

Here's how I did mine on my Rocket.

Have you seen this?
 

Have you seen this?
http://rvbits.mybigcommerce.com/prod...er-Plenum.html