support for O-235?

13brv3 · #1 01-19-2008, 08:40 AM

Greetings,

As I try to decide on an engine for the RV-3, I realize that I've been assuming the O-235 is a fully supported engine (mount, exhaust, baffle kit, etc). I took a look at Van's web store though, and I don't see exhaust listed for any O-235, not even for an RV-9. Is that because it's the same as the O-320, or because not enough people use the O-235 to make it worth building an exhaust?

How about mounts? I've been assuming (there's that word again) that the mounts are the same for all engines. In other words, a dynafocal 1 mount would fit the dynafocal 1 version of an O-235, O-320, or O-360. Is that true?

Thanks,
Rusty

Yukon · #2 01-19-2008, 11:43 AM

I am installing a 0-235 N2C in my RV-9. While Van did provide the motor mount,
everything else is up to the builder. Carb attach bracket is just a little bit different, so you will have to build one, and the hose and cable lengths are a little different too. Exhaust comes from Vetterman, and I believe it is the same as the O-320 with about 2 inches you cut from the crossover pipes.

Good luck. This is a terrific little engine and I look forward to it's small appetite for fuel.

13brv3 · #3 01-19-2008, 07:13 PM

Thanks for the comments John. If the exhaust is the same as an O-320 with just that small mod, that will be easy. Do you happen to know of the mount is the same between the O-320 and O-235?

At the moment, I'm still trying to decide between the O-235, and a single rotor Mazda (type) engine that I've got on a test stand. It's the best chance I'll ever have to actually use it, but I know from first hand experience how much work will be involved. I do like a challenge, at least up to a point

Cheers,
Rusty

elippse · #4 01-19-2008, 11:06 PM

I have the crossover exhaust system I took off my O-235L2-C that I bought from a friend who re-engined his Lancair with an O-320; it's for sale. It probably has about 400 hrs on it. I designed and built my own augmenter cooling/exhaust system which is why I didn't use it. I also have an O-235 pan available. Again, I made my own pan from carbon fiber with the carb attached on the back side rather than on the bottom to give me a flatter cowl bottom.

N941WR · #5 01-20-2008, 07:35 AM

Rusty,

You are going to go through the same thing I did for my O-290 installation. Although the O-235 is an approved engine, it really isn't supported, as you found out.

As was pointed out, you buy the O-320 exhaust, which is actually an O-360 exhaust and cut it down. I used the little chop saw Dan recommended on his site for this.

The throttle bracket is another thing. Check out the engine page on my web site for details. A lot of what I did applies to the O-235.

The throttle cable bracket was the most involved. However, I did send the dimensions off to Van's so they should be able to punch you one up. If not, just ask for one w/o the carb throat and bolt holes, like I did, and drill the holes yourself.

With the O-290, I had to make extensive modifications to the baffles. It took a bit longer to complete but the changes weren't that difficult to do.

Let me know if I can be of any help.

13brv3 · #6 01-20-2008, 09:57 AM

Hi Bill,

Thanks for the comments, and the outstanding documentation!

I don't mind fabrication, but my initial assumption was the that the O-235 was a bolt on solution, whereas I'd have to fabricate virtually everything for the single rotor.

It sounds like the O-235 isn't completely supported, but if all I have to do is chop off a couple inches of a cross over pipe to make exhaust fit, that's a trivial problem. It's still hard to believe that the same pipes bolt to the cylinders of an O-235 and an O-360. I might have to check with Vetterman on that.

I'm still not completely clear on the mounts. Will an O-235 conical fit the same mount as an O-320 or O-360 conical? How about dynafocal-1? I'm assuming they do, but Van's finishing kit asks for the displacement, as well as the type of mount (conical or dynafocal), so I wonder if there are differences.

I also enjoyed the picture of your conical mount. I've been looking for a picture of one without the engine, so that helps. I'd probably so with a conical mount if I use the single rotor engine.

Thanks,
Rusty

Tony Spicer · #7 01-20-2008, 10:22 AM

Quote:

Originally Posted by 13brv3

I also enjoyed the picture of your conical mount. I've been looking for a picture of one without the engine, so that helps. I'd probably so with a conical mount if I use the single rotor engine.

Thanks,
Rusty

Rusty,

Here's a shot of the conical mount with an O-320 on the -3

http://picasaweb.google.com/tonyboyt...08144078555090

Far as I know on the exhaust, the crossover won't fit on the -3, so you'll end up with this:

http://picasaweb.google.com/tonyboyt...57008877095026

Tony

13brv3 · #8 01-20-2008, 11:44 AM

Thanks Tony,

Now that you mention it, Van's doesn't offer a crossover system for the RV-3, only a 4 pipe system. I also verified that the same exhaust gaskets fit an O-235, O-320, and O-360, so they are indeed the same size pipes. If I understand correctly, the 4 pipe system should bolt right on to the O-235, with no modification, which is cool.

I also did some looking into mounts. From what I have found, all 4 cyl Lycoming mounts seem to be created equally. I found some info on converting the Grumman Yankee from O-235 to O-320, and found that it does not require a new mount, which is also good news.

All in all, it looks like I could buy the main items for an O-320, and they will all fit. Smaller things like throttle brackets and such will be different, but that's not a big problem.

Thanks for all the comments.

Rusty

Yukon · #9 01-20-2008, 12:12 PM

What were your impressions of the rotary powered RV-3b? Speed, fuel burn, reliability?

13brv3 · #10 01-20-2008, 12:33 PM

Quote:

Originally Posted by Yukon

What were your impressions of the rotary powered RV-3b? Speed, fuel burn, reliability?

The two rotor engine on the previous plane has close to 200 HP, but it does weight a bit more than an O-320 ship typically does. Top speed is more about drag reduction than HP, but it would cruise at 200 mph. The climb performance was "adequate", at about 3000 fpm

Fuel burn just depends on how fast you want to go. The 13B rotary will never quite meet the same fuel burn as a well optimized piston engine, but it comes closer than most people think.

Unless you're turbo/super charged, you can lean a rotary until it quits, and there's no harmful effects. Actually, the mixture can be used as a throttle. Just put the throttle to the firewall on takeoff, and leave it there. At altitude, dial the mixture down until the power falls to whatever level you want. Very odd effect...

The single rotor version is something I've played with on a test stand for a couple years, and it still has some problems. I am absolutely sure I "can" make it work, but I haven't decided if I "want" to.

Rusty