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support for O-235?

13brv3

13brv3

Well Known Member
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
 
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.
 
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 :p

Cheers,
Rusty
 
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.
 
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.
 
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
 
conical mount

13brv3 said:
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
Click to expand...

Rusty,

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

http://picasaweb.google.com/tonyboytoo/RV3BMiscellaneous/photo#5157608144078555090

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/tonyboytoo/RV3BMiscellaneous/photo#5137657008877095026

Tony
 
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 said:
What were your impressions of the rotary powered RV-3b? Speed, fuel burn, reliability?
Click to expand...

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 :p

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
 
13brv3 said:
...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...
Click to expand...
Rusty,

It sounds like you are getting the answers you need. I really don't know if all the mounts are the same, other than length, longer for lighter engines of course. The mount in my -9 is 2" longer than the O-320 mount, giving me a full 12" inches between the firewall and the engine.

I seem to remember the -7 engine mounts have some gussets at the tube joints and on my -9 engine mount, there are none. I suspect this to strengthen them for acro "work". Either that or these are unique to the -7A. (I don't recall what a -7 mount looks like.) Check with Van's.

Happy to help with the pictures. Let me know if you need any more, I've only posted a few select pictures and have "few" more on my hard drive.
 
N941WR said:
I really don't know if all the mounts are the same, other than length, longer for lighter engines of course. The mount in my -9 is 2" longer than the O-320 mount, giving me a full 12" inches between the firewall and the engine.
Click to expand...

Hi Bill,

I hadn't even considered the length, because I didn't think they made cowls in different lengths for different engines. Makes sense though...

For the RV-3, I think the cowl is a one-size-fits-all solution. The finishing kit asks the question "cowl type", and I haven't thought of an answer other than "fiberglass" :D

Rusty (working on an O-235 scheme)
 
13brv3 said:
I hadn't even considered the length, because I didn't think they made cowls in different lengths for different engines. Makes sense though...
Click to expand...
Yep, they do make different length cowls, at least for the -9. My cowling had O-235/O-290 written on it. For your plane, who knows what Van's has in their warehouse. I suggest you give them a call. Heck, you not the first to put an O-235 on a -3. I may just be that they have one size fits all and you just trim it. As you can imagine, that isn't a big deal.

Building it light, such as you are planning, will make for one nice flying plane!
 
A final note for anyone playing along. I talked to Van's today, and they confirmed that there is only one cowl for the RV-3. There is also only one mount, so an O-235 will end up having a more aft CG than an O-320. It seems the only real option is dynafocal or conical.

Thanks to all who replied :)

Rusty (still don't know what engine I'll use)
 
O-235

I am building an RV9a with an o-235. Vans supplied a dynafocal 1 mount which is perfect for my application. The mount is longer to compensate for the lighter engine. They also have a cowl that will fit. The exhaust can be ordered directly from Vetterman. He has one for my application. You will probably need to order you throttle linkage and I'm not sure about baffles but that's no big deal. The o-235 is more supported than most people think. Getting the mount and cowl are the most important.
 
Last edited by a moderator:
I am looking to buy rings for O-235 С1В for pistons PART N 73851 P20 anybody knows the source?
 
Vlad said:
I am looking to buy rings for O-235 С1В for pistons PART N 73851 P20 anybody knows the source?
Click to expand...

Check ECi. They might have them. Heck, they make rings for the O-290 so they just might have them for the O-235.
 
rings

The 0 235C is not very well supported by any certified parts. 20 years ago a ring set was over $1000. For a homebuilt its best to look for automotive rings that will work.
 
I just don't get it!

Why are you guys agonizing over the availability of parts and the lack of support for these little engines? The O-320 is a wonderful little engine with tremendous support and parts availability. Throttled back to 55 percent power it has virtually the same fuel flow as the smaller engines at the same power output and it will run just fine on mogas, so where is the cost savings?

And how in the world will you sell that plane with the little engine when you get tired of being passed by every other RV in the world?

I'm not trying the spoil your plans, but maybe this "little engine" idea needs to be thought out a bit more. Somebody please tell me why it's a good idea?
 
Somebody from far away asked me he has that little engine. I run new O-320 and I am very happy with it.
 
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