320 v 360 v 390

[mking275]

First time buyer looking for advice.

I'm looking at 3 RV-8's, each with different engines. My impression is the 180hp O360 is the 'standard' model (as much as there can be such a thing among Vans). I get that the 160hp O320 is going to burn less fuel, and the 215 hp O390 is going to climb faster.

I'm wondering if there are appreciable maintencence/cost of ownership differences beyond the fuel burn. Hows the W&B envelope and useful load work out?

Also wondering about the O390 and the 200kt Vne. Im an aerospace engineer by training, so have some understanding of the engineering limits. What I'm wondering is practically speaking how close to 200kts do other RV-8 pilots fly.

Thanks in advance,
Matt KIng

 

[Majorpayne317641]

Can’t go wrong with the 360. I’d pass on the 320 but that’s a personal choice. The 390 is heavier so be sure you are comfortable with your mission set for loading the plane. With an aluminum constant speed some have issues with even a 360 angle valve. I cruise with a fixed pitch at 75% power 8k ish at 165 true, I’m never near Vne unless doing something aerobatics wise, or climbing super high to service ceiling. Then the Vne starts reducing as you already know.

 

[Mikeyb]

The RV8 was designed for the 0320. The heavier the engine and prop get the heavier the pitch control forces get. It’s just so much more fun with the CG in the middle. I find the 180hp with a CS prop to be outrageously powerful (It does 0-60MPH in 4 seconds solo) but haven’t flown many planes.

 

[dmattmul]

Prop makes a big difference

For me RV’s just feel more nimble slightly aft heavy (but still within CG limits). If you find a 7 or 8 with a 390 a composite prop is almost a necessity. EarthX battery on the firewall also a good thing. 7’s and 8’s with a 390 and an aluminum prop just seem not as responsive to elevator control. Lots of others with more experience than me to comment I’m sure. Good luck with the search.

 

[bmellis11]

Just make sure you're comparing apples to apples when looking at forward weight and its effect on nose heaviness. An IO-390-EXP119 with composite prop weighs about the same as the IO-360-M1B with the standard aluminum Hartzell prop.

In fact, with those two equal weight setups, the heavier metal prop being farther forward from the center of gravity should make the IO-360-M1B/Hartzell combo more nose heavy than the IO-390-EXP119/composite setup, all other things being equal.

You also need to consider other things like battery location (forward or aft), battery type (heavy traditional battery or light weight lithium battery), and whether the plane has aluminum or steel landing gear.

 

[RV8JD]

The RV8 was designed for the 0320.

Not sure why you say that. Per Van's:

https://www.vansaircraft.com/rv-8/

"Like all RVs, the RV-8/8A climbs well, lands slow and goes fast. Unlike earlier RV models, the RV-8/8A was designed to accept the 200-horsepower IO-360 Lycoming. The prototype outfitted with this engine demonstrated truly remarkable performance. With a single occupant, it would take off in 250’ and climb out at 2600 fpm — performance that had tower controllers asking “what kind of airplane is that?!” In 2020, Van’s approved the 210 HP Lycoming IO-390A for use on the RV-8/8A aircraft as well.

However, the fact that the RV-8 can accept a large engine doesn’t mean that it needs it. Traditional engine options – 150-180 HP Lycomings – have been retained. Probably the majority of flying RV-8/8As are powered by a 180 HP engine, and with these lighter engines performance is still exciting – and handling is even better."​

 

[oaklandaviator]

Fuel burn

I also wouldn’t blanket say that a 320 will be any better on fuel. A carbureted 320 will probably burn more than an injected 390 running lean of peak. Also, it will take the same amount of fuel, roughly, to move the airplane at the same speed no matter the engine.

 

[Taltruda]

A light weight 320 with a wood prop is about the sweetest flying around .. however, the 180 hp 360 is a welcome boost in climb especially going higher altitudes. I would think a 360 with a composite CS prop probably is the best combo. Haven’t flown a 390 version yet, but I imagine it being stiff and nose heavy..
Whatever engine you use, as long as it’s not turbo, I don’t think you’ll exceed 200 KTAS in these planes straight and level. In a descent, you could exceed it with a O-235… so just manage power in your descent.

 

[RV8JD]

Also wondering about the O390 and the 200kt Vne. Im an aerospace engineer by training, so have some understanding of the engineering limits. What I'm wondering is practically speaking how close to 200kts do other RV-8 pilots fly.

I have an YIO-360-M1B (180 HP) and a Hartzell Blended Airfoil CS prop. The 200 KTAS/230 MTAS Vne does limit one at higher altitudes in the descent. But one must take care with any of the engine choices.

Some descent examples below (in MPH). Note that above about 10,000 feet, Vno (168 KIAS/193 MIAS) no longer applies since Vne is less than Vno at those altitudes.

In case you haven't seen it, here is a link to Van's RV-8/-8A performance specs: https://www.vansaircraft.com/rv-8/#aircraft-details-2

 

[rv8ch]

First time buyer looking for advice.

I'm looking at 3 RV-8's, each with different engines. My impression is the 180hp O360 is the 'standard' model (as much as there can be such a thing among Vans). I get that the 160hp O320 is going to burn less fuel, and the 215 hp O390 is going to climb faster.

I'm wondering if there are appreciable maintencence/cost of ownership differences beyond the fuel burn. Hows the W&B envelope and useful load work out?

Also wondering about the O390 and the 200kt Vne. Im an aerospace engineer by training, so have some understanding of the engineering limits. What I'm wondering is practically speaking how close to 200kts do other RV-8 pilots fly.

Thanks in advance,
Matt KIng

Matt, All three of those engines will work great, but as others have said, it depends a lot on your mission, and the other aspects of the aircraft. I would not reject any of the three engines out of hand. They can all be excellent in an RV-8, depending on your mission. The other factors will included prop, finish, build quality, hours, age, how much love the aircraft received, availability, and of course price.

 

[claycookiemonster]

You don't know yet what you don't know.

I am not finished with my -8, but faced the same questions. One fact of life with these is that you are unlikely to get a do-over. There will not be a test aircraft which will teach you lessons so you can get it right on the final production model.
I stayed in the middle of the bell curve with an IO-375 (weight wise, the same as an IO-360) and am planning on an aft battery. For looks I chose a Showplanes cowl which pushed the prop forward 2.5" so I went with a lightweight composite WW. I am a relatively small guy, weighing about 160.
You can't know everything early in the build, so I just hoped to not do anything to push me hard in any direction. The type of rear battery will be chosen later, and the option to move it forward remains. Time will tell.

 

[jclark]

What RV8ch said … +

Matt, All three of those engines will work great, but as others have said, it depends a lot on your mission, and the other aspects of the aircraft. I would not reject any of the three engines out of hand. They can all be excellent in an RV-8, depending on your mission. The other factors will included prop, finish, build quality, hours, age, how much love the aircraft received, availability, and of course price.

I fly an 8 that is rather “stock” with an O-360 (180 HP, carbureted) plus Hartzell Blended airfoil. I also fly my friend’s IO-390 119EXP RV8.

I do NOT notice a heaviness as much as smooth, extra power to be used (as needed) but not abused.

Near sea level throttle forward during testing was 180+ KTS, not 200+.

So, as rv8ch said, depending upon what your mission is, don’t be afraid of the higher performance choice.

 

[Carl Froehlich]

First time buyer looking for advice.

I'm looking at 3 RV-8's, each with different engines. My impression is the 180hp O360 is the 'standard' model (as much as there can be such a thing among Vans). SNIP….

Matt KIng

I suggest the reason the IO-360-M1B and Hartzell BA CS prop end up on a lot of builds is this combination is the biggest bag for the buck.

IO-390 engines are way pricey. Composite props are as well. The plane’s wide speed envelope calls for a CS prop - for me I’d go with a 320 engine with a CS prop before any engine with a FP prop. I built my first RV-8A with a FP prop and replaced it with the Hartzell BA CS prop at ~300 hours. It transformed the plane.

Get what you want but verify the battery is located such that the W&B meets your mission.

Carl

 

[Freemasm]

First off, the OP probably can't make a wrong decision here. That said, I'll add some more variables to cloud the decision process. If a someone disagrees, fine. Not looking for a debate

Resale: The O320 plane will have more limited resale options than the others. Of course that also works in the OPs favor during purchase so it's almost a wash.

Reliability: Straight valve Lycomings (including the 540) are the closest thing to a bullet proof PP as you'll find. Want more power out of one? They can be stroked/ported/better flowing sump/higher comp pistons/etc. at overhaul to put their power into the lower 200s of HP. Not enough long term data to see reliability effects of these mods IMO.

Enjoy the buying process. Don't let the PP alone decide your choice.

 

[Tim 8-A]

I’m Flying my second 8a the first had a 360 with constant speed Hartzell.
I’m currently flying a 390 with a whirlwind. The 390 weighs 1190 pnds right about 100 pnds heavier than the 360. The weight difference is not due to just engine and prop the 390 also has duel battery and alternator along with other add ons. I had to carry ballest in both aircraft to lighten the nose, the light aerobatics I do I feel no difference in the performance of the two aircraft.
Cruise speed of the 360 was about 165 to 172 knots at 8 gph. The cruise speed of the 390 is 178-185 knots at 8.6 to 8.9 gph. I do a lot of searching for aircraft I see the 320’s staying on the market a long time and when sell its for less then the other 2. When I purchased my 390 I had 2 days to decide then he was moving to another buyer said he never had so many calls.
The 360 and the 390 are both fun aircraft.

 

[DanH]

Early 390 adopter, with about 1150 hours now. All the previous comments are accurate. I think the #1 determiner is mission. If hauling a passenger and lots of baggage, an angle valve and a metal Hartzell is hard to beat. If the back seat won't be used much, I'd take the M1B and a composite Hartzell. Either will do either job, so it's just optimization.

The 390 shines in climb, and by extension, when operating at high DA.

An angle valve cylinder head is easier to cool, but requires more oil cooler.