O-360 derated to 160hp

[Oldgeezer]

Any RV9's out there currently flying with an O-360 derated to 160hp? I'm considering an XP-360 with builder option and would like to know if anyone has had problems with this set up, ie. cowling size due to the wider cylinders,tail cracking problems, ect..Plan on using mogas with lower compression cylinders. Any advise would be appreciated.
Thanks
Ron
Qb Fuse

 

[gmcjetpilot]

Derated O-360 for Autogas

Yea it is called an O-340-B1A or B2A (c/s-fixed prop) with 7.15:1 compression and is rated at 160 hp. It was designed for missionary work by Lycoming for places where high oct fuel is hard to get. A 150hp O-320 is 7.0:1 comp ratio and autogas approved. It is also 30lbs lighter than a O-360(340). The O-360(340) is not a bored or O-320. It is a completly differnt engine with a heavier crank, rods, heads, case etc..

My opinion is 150 hp is plenty of go for a RV9. It is lighter and cheaper and can use autogas. Using a 160hp de-rated O-360 (340), gets only 10 more HP than an O-320 at much higher weight. With a 150hp O-320, you will have a fast plane with good climb rate and Mo gas capable. All the extra weight of an O-340 (30lbs?) for 10 hp and autogas is not a good trade in my opinion. Not to mention you will pay more for an O-360 based engine than an O-320.

The issue you must remember is you will still have all the Mo gas system issues leading up to the engine and carb, ie vapor lock and possible problems with some seals and gaskets.

Also you are not following Van's guidelines for engine weight. An O-340 and a constant speed prop and you might be 30-60 lbs heavier than Van's recommended engine/prop weight. Which may or may not cause issues. I can tell you weight will affect the handling and performance of RV's. The motto of keep it light, is a good one.

Good Luck George

 

[az_gila]

George.... the O-340 has less displacement than the O-360, but the same bore.
It has a stroke in-between the O-320 and O-360 of 4.125 (O-320=3.875, O-360=4.375)

The weight appears to be much nearer the O-320 than the O-360 at 250 pounds, and, I'm guessing, given the weight, not quite as wide as the O-360.

More info is here... lots of engine info... gil in Tucson

http://home.adelphia.net/~aeroengine/Lycoming.html

------------------- from the web site ----------

O-340 -- {5.125 / 4.125 / 340.4} / {130.2 / 104.8 / 5578}

Same bore as O-160, O-320, O-360, O-480, O-540, O-541, O-720.

4cyl; O-340; 160-170hp@2700rpm; 1954-1977; Wt = 247-250#; TC = 277 on 7/20/54.
AY60; J56-57toJ76-77; S; W56toW62-63.
Applications: (US) Peterson Super V (Beech 35 Conversion to twin); Riley Twin-Navion; Thalman T-4.

4cyl; VO-340; 162hp@N/Arpm; 1954-1965; Wt = N/A; TC = none.
J57-58; S.
Applications: (US) Brantly B-2 (second prototype).
-----------------------------------------------