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RV-9A - Which Engine - Which Cowl

RV-9A - Which IO-320 - Which Cowl - Which flow

  • IO-320 D2A

    Votes: 8 40.0%
  • IO-320 other (specify)

    Votes: 9 45.0%
  • SJ Cowl Shorty

    Votes: 0 0.0%
  • SJ Cowl Extended forward facing

    Votes: 1 5.0%
  • SJ Cowl Extended updraft

    Votes: 3 15.0%
  • SJ Plenum

    Votes: 3 15.0%
  • VANS Baffles

    Votes: 11 55.0%

  • Total voters
    20
  • Poll closed .

1bigdog

Well Known Member
I can't think of a better way to do this other than a survey. I'm not looking for a debate. I'm no expert on the many varied engine variants of the IO-320 and I want to place my order for the finish kit next week. I'd like to use the SJ Cowl but between updraft, forward facing, sump position, prop extensions it's a bit cumbersome so I'd like to know what has actually worked in practice for others.

My 9a will have an IO-320 with a 3 blade Catto prop and I have no intentions of changing to constant speed.
I'll need a vacuum pad for a gear driven backup alternator (don't know if all engine variants have the vacuum pad).

So the questions whittle down to

Which specific IO-320 variant did you choose? D2A, D1A, other ?

Which Sam James Cowl? Shorty, extended updraft, forward facing?

Did you use the SJ plenum or VANS baffles ?


Greatly appreciate the input.
 
Cowl choices

O320 D3G converted to IO320, vans baffles with home brew plenum, James extended cowl, was carbed, so it's updraft. Used James air filter kit.
 
Titan IO-340, used the vans baffles/cowl but would happily try the SJ option next time.
 
Titan IO-340, used the vans baffles/cowl but would happily try the SJ option next time.
Same here, but using the O-340. Vans Cowl & Baffles.

Only hiccup was the Rotec TBI I used is slightly shorter than the traditional carb so I had to make my own FAB. If I were doing it again, I would go with EFI and the snorkle-less cowl, with a basic cone-type filter, but the Rotec starts easily and I'm quite happy with it!
 
Not that far along yet, but I think by OSH 18 I will be..

My guess IO320 with CS and 3 blade
My goal is economy and smoothness

Not sure of Cowl
Sam I see every pancake breakfast at our EAA66... I guess I should look into them
 
I have Titan IOX340 with normal Vans baffles and cowl.

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Thanks

So first, thanks for the responses and the inspirational photo.
What I really learned is that my learning curve was nowhere near complete. I thought I had asked an easy set of questions.

What I can extrapolate is that most purchased the VANs cowl and appear to be using vertical draft and and the VANS baffle. Given my home base and where/how I intend to fly it became clear the vertical sump gives what is needed for heat muffs (something I never considered when I first asked the question).

Cheers.

Michael B.
 
ECI Titan IO340 (now Continental Titan) with standard Vans IO360 cowl for RV7A. ECI forward facing cold air induction, vans snorkel (not to be confused with the "snout"). Vetterman 4-straight pipe exhaust.

Originally thought I would go with Sam James cowl but glad I went with Van's standard cowl and baffle. Everything was straight forward with the Vans. I know now that would not have been true had I gone with Sam James.

YMMV. Good luck with whatever you choose.
 
I have the O-320 D2A with a long James cowl. The cowl is great but fitting the FAB was a ton of work - mostly because of the exhaust with the heat muff up front. I had to take the muff, cut the piece for the supply and to the cabin heat off and get them re-positioned to work. If it were not such a PIA to post a picture, I would do it!

I have a plenum that was built by BillL and modified a bit by me. I will be doing some run ups and taxi work next week so I will see how it works.

I would have gone with the O-360, but I got a good price on a new engine - too good to pass up.
 
I have the SJ short cowl and an ECi O-360 spinning a two bladed Catto prop.

The SH cowl choice was simply for looks.

The O-360 was only 20 lbs heavier than an O-320 and maybe not even that much more. Ordering the tapered cylinders saves you about six pounds. P-mags save another three pounds and lightweight accessories saved even more.

I see no need for a back up alternator as most EFIS's have back up batteries with them. Even my backup artificial horizon has its own internal battery.

You are much better off keeping your options down and build lightness in.

For example, don't bother with a flap sensor, electric trim, and every other option you can think of. The planes fly so much better when kept light. (The tip-up taildraggers are lightest combination and everything after that is just weight.)

Remember, the "A" models tend to be tail heavy because the main gear is behind the CG, so plan accordingly. It would be a bummer to put a lightweight Catto on the fron only to have to add a weighted crush plate to it.

PS. Regardless of which cowl option you elect, you will need the Van's baffles.
 
A few rebuttals to Bill R's reply...

The O360 is 17 pounds heavier than the O320, and delivers 20 more horsepower per nameplate - a significant horsepower/weight improvement, there is no other single modification you can do to the airplane that will give you this much reward for so little weight gain. With a constant speed prop of standard design, the tail-heavy margin disappears quickly, especially if you choose to install some of the popular modifications such as the Anti-Splat nose-gear mod, an optional backup alternator, oil separator, etc etc.

Vans baffles are still needed as he points out, unless you want to go the plenum route - which is more efficient if done correctly, but adds about 1 pound up front over the baffles (my aircraft, I have not audited others).

And finally - the CG is entirely within your control. You have to carry all the items you select to install, but you get to choose where you carry them. My battery is aft of the baggage compartment as are all my remote avionics - because I am heavy up front with items I deemed "necessary or desirable". My CG works out just fine without ballast anywhere.

Lightness is always a good thing - but you can move equipment around to carry what you want where you want it.
 
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