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Doug Rohrer 01-02-2018 07:01 PM

IO-360 in an RV-9A?
I have to make a decision soon on the engine I plan to use in my RV-9A build. I know the O-320 is the recommended engine, especially the 160 HP version. While looking for a used O-320, I ran across an IO-360 B1B rebuildable engine. It appears that the cost to rebuild this engine (sitting for years/probably rusted inside) would be similar to an O-320. Using the search function shows several -9 builders have successfully used the 360/180HP engine in their planes. Tracking through the Lycoming literature seems to indicate the B1B variant would work on a -9 with a -7 cowl and engine mount. Van's cannot confirm for sure this engine would fit with available factory components, so I am asking the experts. Has anyone used an IO-360 B1B in a -9 and what issues could I expect other than those listed above? Am I correct in my assumption about rebuild cost? Thanks.

Piper J3 01-02-2018 07:07 PM

Stupid question... if inside is rusted, then what components will you be keeping - maybe just the cases and chrome cylinders back to size?

sirlegin 01-02-2018 07:38 PM

Van's cannot confirm for sure this engine would fit with available factory components, so I am asking the experts.

I believe you have asked the experts. The only real difference between the 2 is climb speed from my experience. The 9 is a fast and economical machine with the designed engine designation by Van's although I'm pretty sure I will be dumped on by some with this view.

N941WR 01-02-2018 07:56 PM

One fit under my Sam James cowl.

Van's is very concerned that with the (I)O-360 up front, the -9 will go right past its Vne.

I would probably have to agree as in level flight at 75% power and 8,000' DA, mine will cruise right at 200 mph, 10 under Vne.

You will have to control the throttle, especially when going downhill.

This is not an endorsement of installing the large engine as the airplane does very well with an O-235 up front.

airguy 01-02-2018 09:35 PM

Vne can be exceeded at idle power too, that's a pilot problem, not an equipment problem.

I've got an IO360 under my James Cowl as well, and the performance is excellent, I've never thought for a moment that I made the wrong decision. You can always pull the throttle back and use less power if you want, but when you need it (that's spelled W A N T...) there is no replacement for displacement. You'll need to carefully look at your CG and move equipment around where possible to offset the noseweight, like the battery aft of the baggage compartment and some remote avionics as well.

Yes, it will cruise fast. Yes, you have to use the throttle just like any other control item to stay in the flight envelope. And yes, it will climb like a banshee and REALLY cruises well up in the mid-teens where the wing is happy.

And no, Vans is not happy about it and won't support it - but they'll still sell you parts.

rvbuilder2002 01-02-2018 10:51 PM

It has nothing to do with VNE!
Since it has been a while, I guess another clarification is appropriate...

I have posted numerous times in the past but the most recent I found is HERE

No sense writing out the same thing again...... look at the link if interested.

Vno (Maximum structural cruise speed) is the engineering design factor for max HP decision.

Not Vne

An RV-9 with more than 160 HP can easily fly above Vno in level flight at max continous power (or less).

You may not think that operating within the yellow arc range is a big deal...... well it is.

If you use a bigger engine, and fully understand and avoid operating above Vno then you will probably never have a problem.
If you own an RV-9 with an engine bigger than 160 HP and still think that Vne is your limiting factor, you may some day have one........

One thing to keep in mind is that Vno is a indicated derived airspeed. So regardless what HP you have, as long as your INDICATED speed is in the green arc you should be fine. So at higher altitudes it is not likely to be an issue (as long as you TAS remains below Vne). At lower altitudes, 180 HP engines at normal cruise power settings will easily push you above Vno.
The reason people get the idea that Van's doesn't like bigger engines is shown in this (and many other) threads.
If you incorrectly understand the issues related to using a bigger engine.... and spread that incorrect info to others, it clearly demonstrates the dangers involved with this sort of thing.

Please don't anyone follow up to this with "my wings haven't fallen off yet" (and get this thread derailed so that it gets closed).
Everyone can say that until it happens (God forbid) so it is not a valid response.

The important thing here in the forums is that correct information be provided, so that people don't make serious decisions based on incorrect info and then have someone get hurt (or worse).

rockwoodrv9 01-02-2018 11:22 PM

I am just about finished with my 9A. I had planned all along to put a O-360 in because my airport was at 8000' elevation. I flew with a friend out of Rifle CO (5540') on my first RV flight - at about full gross in his 9A and we had plenty of power. Vlad came to visit and we flew up near Aspen and had plenty of power. I still planed on the O-360, but a screaming deal came up on a O-320 I couldn't pass up so I decided because of experience, it would be fine.

I moved to Idaho and the elevation is only 2500' so Im sure it will be great. If I still lived in Aspen, I may want the additional hp, but I am happy how things worked out.

As mentioned, you can go too fast at idle. If you can't control the throttle, you probably should stick to a 172.

Scott -good reminder that it is VNo to be watched. Edit: my point is you can get yourself in trouble no matter what engine you have in your plane.

rvbuilder2002 01-02-2018 11:27 PM


Originally Posted by rockwoodrv9 (Post 1229440)
As mentioned, you can go too fast at idle. If you can't control the throttle, you probably should stick to a 172.

You are right, but isn't that the case with nearly every airplane that can fly.
So why is that regularly used as a reason for justifying using a larger engine?
Operating primarily out of a high altitude airport like you mentioned, would be a good reason..... saying that any airplane can go too fast at idle is not.

Plummit 01-03-2018 12:16 AM

If it fits, you must acquit
Wow a guy asks a simple question about the fit and cost of a certain engine and.... :mad:

There are times I wish my -10 had 50 more HP!


Fearless 01-03-2018 05:51 AM

The OP had a 9A with a 160 hp O-320 previously so he already knows the performance with that combo.

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