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Can I put a IO-390 in a RV-6A?

rv6ehguy

Well Known Member
I need some advice for an engine installation in a RV6A. I can get my hands on a new Barrett IO-390 for a song. I am not sure if this engine will fit on my kit. I understand this engine is identical in size to an IO-360 Angle valve 200hp Lycoming. However Van's states that an angle valve will nor fit in a RV6A but will fit in an RV7A. Yet I have a RV7A cowling which I have been told by Van's does fit on the RV6A fuselage. I am a bit confused here. One obvious difference I can see between the IO-390 and a IO-360 parrallel valve is the position of the prop governor. On the 390 it is located at the front and might interfere with the left air inlet scoop. Any advice from those more expereinced would be fantastic.
John Van L.
Toronto, Ontario
 
Suggestion

In addition to the fit issue it sounds like you will install a CS prop. Get the weights for the engine and prop and do a preliminary weight and balance. I know of a 9A where they installed an O-360 and CS prop and the forward CG is a problem.
 
Well, there are a few things that need to be considered with this pairing.

First of all, I recall the -6 to have a 180hp limitation. This, in and of itself is not really too important. People have installed 200 hp IO-360's in the past and they are holding together fine. I understand they have cooling issues to contend with.

Compounding this, the 390 has a propensity to run hot to begin with.

The weight of the 200hp angle valve 360 is already heavy on the -6. The 390 is about 8 - 10 pounds heavier than that!

Soooooo, do your W&B calcs conservatively.

You can go fixed pitch and save some weight and complexity.

Question, how much will you pay for the engine? It would have to be less than $25,000 for me to even consider it if I were you, because that is what a new IO-360 Para valve, injected would cost.

...and that is the engine that belongs in there to begin with!

If you end up not wanting the engine after all this deliberation, shoot me a message. I would be interested in using it for my -7.

:) CJ
 
I don't know what the CG would be like for a -6A, but for my -7A with a 390, getting the CG within range is not a problem. Empty, I am at the forward CG limit. The extra weight on the nose is noticable - not really in cruise, but on landing, with a light load you may find yourself looking out the side of the canopy to see the runway. There are some other things to consider that have been mentioned.

- With the prop governor being up front, you are going to have to design a bracket along with new baffles to fit. Most engine setups with front mounted governors route the control cable down through the baffles, but with the FAB being there, it's not possible. The cylinder barrels are also larger, so there may be other issues with the stock baffles.

- Heat is another issue. CHTs have never been a problem. I rarely see anything close to 400. LOP in cruise is around 280. Oil temps have been an issue though. Go for a large SW cooler and don't mount it on the baffles and it won't be a problem. I climb at 225 on a really hot day and cruise at 195.

Other than that, the engine is an awesome performer - not to mention it sounds great, too.

Scott
IO-390 RV-7A
180 hours
 
rv6ehguy said:
I need some advice for an engine installation in a RV6A. I can get my hands on a new Barrett IO-390 for a song. I am not sure if this engine will fit on my kit. I understand this engine is identical in size to an IO-360 Angle valve 200hp Lycoming. However Van's states that an angle valve will nor fit in a RV6A but will fit in an RV7A. Yet I have a RV7A cowling which I have been told by Van's does fit on the RV6A fuselage. I am a bit confused here. One obvious difference I can see between the IO-390 and a IO-360 parrallel valve is the position of the prop governor. On the 390 it is located at the front and might interfere with the left air inlet scoop. Any advice from those more expereinced would be fantastic.
John Van L.
Toronto, Ontario

John,

A difference from the 6A to 7A is the 7A engine front and cowling was dropped about an inch to provide better over the nose visibility. Perhaps that is why the factory says the engine won't fit.
 
See also page 177 of the "24 years of the RVator" from Vans for more information.

If you don't have this book, you really need it!

They pretty much say the 200hp engine in the -6 isn't worth the hassle, unless you really, REALLY want it.

:) CJ
 
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