IO-390 vs IO-360

[N546RV]

Originally Posted by Walt

http://www.continental.aero/titan/ex...tent=150x120px

About 44k last I heard but suggest you contact JB BALL for specifics.

Yowza...I knew prices had gone up but that's roughly 50% more than when I ordered my -370 about two years ago.



In any case, I'll +1 getting with JB - great to deal with and very responsive.

[gear1]

Another Data Point:
When I was searching for my RV8, the chaps at RV specialists Hotel Whiskey Aviation (Chuck Wilson and Jeff Hansen) strongly advised that I stick with a parallel valve engine with a constant speed prop for all around best performance. After flying 2600 hours on my parallel valve IO 360 powered RV8, and having done the acrobatic maneuvers fly-off for [u]two[u] RV8 aircraft with angle valve engines I am absolutely convinced of the correctness of their advice. The angle valve powered aircraft, because of the additional nose weight, are very heavy and slow reacting in pitch. On one aircraft we added 16 pounds of lead at the tail to get the aircraft within CG. however, it did not help with the heavy pitch stick forces required. It would be interesting to get Steve Smith's input here, as I expected the stick forces to be less. A possible cause might be the increase in polar moment of inertia with the weight at both ends of the aircraft.

[Freemasm]

Probably offsetting phenomena. (Intent of) Adding the weight would be to improve concentricity of the CG and pitch axis; would certainly lower the stick force in pitch. The integral contribution of the added weight to the polar moment of Inertia is proportional to the the square of the distance from said axis, thus increasing it. I believe these are probably off-setting each other for the most part. Would be interesting to plot the results of both lines and see where they intersect. Hopefully some smart people will weigh-in.

[rv8ch]

To steal Paul's quote with a slight modification:

"I wish I had more weight on the nose!" ...said no RV-8 pilot, ever!

[bkervaski]

Plus, when people say they have a 360 you can put your nose slightly up in the air and say "Oh <pause for effect> I have a 390" in a way that sounds like they made a terrible decision and should feel bad about their purchase.

[chaskuss]

Originally Posted by cjjohns79

I’m new to the group and looking to buy an 8 in the near future. Can anyone give insight about whether there is a noticeable difference between these two engines in performance.
Thanks for the help!

Check your private messages.

[DanH]

Originally Posted by cjjohns79

I’m new to the group and looking to buy an 8 in the near future. Can anyone give insight about whether there is a noticeable difference between these two engines in performance.

I built a 390 powered -8 back when 390s were rare, kit only packages, mostly because my friend Monty was very proud of his creation and I had some spare money. No regrets. Yes, it has high stick forces, but in fairness, it also has a heavy metal Hartzell. I could make it better with $19,000 worth of carbon.

It's a fastback, so it has a larger rear baggage compartment. Ms. Patti does not travel light, but here the rule is simple...if it fits, it goes. CG is the best and the worst reason to install an angle valve.

Typical cruise is 180+ KTAS with burn in the low 9's. Climb rate is proportional to excess power, so if you have 20% more excess, you get 20% more rate. Density altitude should never be ignored, but it's mostly a non-issue for an -8 with a 390. Here's 800 ft or so of roll at Johnson Creek on a warm June afternoon: https://youtu.be/yJeYto8dHYc

Yeah, 12 years now and I still like it.

[Tim 8-A]

I’ve owned both, the 360 flies lighter to the touch and has better glide, but it’s hard to argue these #’s in cruise.

[Carl Froehlich]

One consideration not mentioned, fuel options.

The 180hp IO-360 allows use of 93 octane auto fuel or when available Swift 94. The angle head options require 100LL or the new (and at an unknown price) 100UL.

This is the driving reason I declined Thunderbolt’s free option to put 9 to 1 pistons in my new Cold Air Sump IO-540. The extra 10-15 ponies would have been nice, but not enough to accept this pending fuel cost risk. Perhaps as we gain some visibly on 100UL cost this can be revisited.

Carl

[DanH]

Originally Posted by Carl Froehlich

One consideration not mentioned, fuel options.

The 180hp IO-360 allows use of 93 octane auto fuel or when available Swift 94. The angle head options require 100LL or the new (and at an unknown price) 100UL.

Let's remember Lycoming's current non-approval of mogas for the 390 is based on certification criteria. We're not limited to a particular configuration (ignition timing and exhaust pressure being two examples), nor is there any good reason to run near limit temperatures.

https://www.faa.gov/documentLibrary/...AC_33_47-1.pdf