I have just about decided to put a O-235 on the RV-9 I am starting to build. I would like to hear from anyone who owns, operates or has any experience with this airplane/engine combination. I would like to know what your opinion is of this set up. Do you have any tips, thoughts or ideas from your experience.
Van's Air Force
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O-235 RV-9 Owners Experience Wanted
- Thread starter slykins
- Start date
lots of experience....
I have flown behind the 0-235 in the Bellanca 7ECA. In my opinion, you would do much better and be much happier with the 0-320. Consider a high altitude takeoff. Your 115 hp 0-235 with a fixed pitch prop might only put out 100 hp at sea level on takeoff. Now take it into a 4000 ft elev strip and you might get 80 to 85 hp out of it. That is not enough. Even with an RV-4 equipped with a fixed pitch 0-320, takeoff at these altitudes is a slow, dreamlike affair. (relatively speaking) Don't limit the capabilities of this plane with a low powered engine.
Cheers, Pete
I have flown behind the 0-235 in the Bellanca 7ECA. In my opinion, you would do much better and be much happier with the 0-320. Consider a high altitude takeoff. Your 115 hp 0-235 with a fixed pitch prop might only put out 100 hp at sea level on takeoff. Now take it into a 4000 ft elev strip and you might get 80 to 85 hp out of it. That is not enough. Even with an RV-4 equipped with a fixed pitch 0-320, takeoff at these altitudes is a slow, dreamlike affair. (relatively speaking) Don't limit the capabilities of this plane with a low powered engine.
Cheers, Pete
gmcjetpilot
Well Known Member
Nix the 235
http://generalaviationnews.com/edit...so?-token.key=8626&-token.src=column&-nothing
http://www.sacskyranch.com/combustionClean.htm
There was a O-235 with 9.70 to 1 compression (125 HP). Although Lycoming certified it on one or two planes, they took the 125HP O235's off the market due to detonation problems in the field from the higher compression; you can get aftermarket STC'ed kits to bump them back to 125HP. I would not fly that. The early 235's where 115HP, 7.00to1 versions.
Lyc article talks about the compression history in O235's (about 5 paragraphs down)
http://www.lycoming.textron.com/mai...cations/keyReprints/general/lookWhatThey.html
Nothing wrong with the any of the 235's overall, but the O-320 is more plentiful, so I believe parts are cheaper (supply and demand). O-320's just have way more supply. I am all for keeping is simple, light and not being a slave to HP, but the economics don't favor the smaller engine, parts, resale and gas. Yes Gas. You can throttle a O320 back and get the same fuel burn as a 235 running harder to make the same HP.
As far as 150/160HP O320's, either is fine. You should look for a Dynafocal mount and wide deck O320's (later models) if possible. I think most O320-A and -B models are conical mount. G
NOTE: Van's data is wrong. They advertise a O-235 N2C as 118 HP. It is 116 HP, has 8.10 to 1 compression and is rated at 2,800 RPM. Also the cost is $21,900. You can get a clone O320, brand new for less than $20K.
Agree a friend and I owned a mighty Tomahawk with a O-235-L2C long ago (118 HP/8.50to1). Put a lot of hours on it. That model 235 was subject to lower plug lead fowling for some reason. (This was before the "deep reach" BY plugs came out that supposedly fix the problem..)Mustang said:
http://generalaviationnews.com/edit...so?-token.key=8626&-token.src=column&-nothing
http://www.sacskyranch.com/combustionClean.htm
There was a O-235 with 9.70 to 1 compression (125 HP). Although Lycoming certified it on one or two planes, they took the 125HP O235's off the market due to detonation problems in the field from the higher compression; you can get aftermarket STC'ed kits to bump them back to 125HP. I would not fly that. The early 235's where 115HP, 7.00to1 versions.
Lyc article talks about the compression history in O235's (about 5 paragraphs down)
http://www.lycoming.textron.com/mai...cations/keyReprints/general/lookWhatThey.html
Nothing wrong with the any of the 235's overall, but the O-320 is more plentiful, so I believe parts are cheaper (supply and demand). O-320's just have way more supply. I am all for keeping is simple, light and not being a slave to HP, but the economics don't favor the smaller engine, parts, resale and gas. Yes Gas. You can throttle a O320 back and get the same fuel burn as a 235 running harder to make the same HP.
As far as 150/160HP O320's, either is fine. You should look for a Dynafocal mount and wide deck O320's (later models) if possible. I think most O320-A and -B models are conical mount. G
NOTE: Van's data is wrong. They advertise a O-235 N2C as 118 HP. It is 116 HP, has 8.10 to 1 compression and is rated at 2,800 RPM. Also the cost is $21,900. You can get a clone O320, brand new for less than $20K.
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Kyle Boatright
Well Known Member
A few things to consider:
- You can throttle an 0-320 back to the fuel flows and performance you'd get with the 0-235, but you'll never be able to throttle up the 0-235 to get 0-320 performance. Even if you don't need the additional speed of the 0-320, there will be a day when you'd like better climb, load carrying, or short field performance.
- You can probably get a mid-time 0-235 cheaper than an equivalent 0-320, but the resale difference will be overwhelmingly in favor of the 0-320.
- As stated elsewhere, if you're going with a new or rebuilt engine, there really isn't any cost advantage with the 0-235.
- You can throttle an 0-320 back to the fuel flows and performance you'd get with the 0-235, but you'll never be able to throttle up the 0-235 to get 0-320 performance. Even if you don't need the additional speed of the 0-320, there will be a day when you'd like better climb, load carrying, or short field performance.
- You can probably get a mid-time 0-235 cheaper than an equivalent 0-320, but the resale difference will be overwhelmingly in favor of the 0-320.
- As stated elsewhere, if you're going with a new or rebuilt engine, there really isn't any cost advantage with the 0-235.
N941WR
Legacy Member
Skykins,
There is an O-235 (108hp version) RV-9A flying in Hickory, NC. I have spoken to him but Don't have his email.
His RV cruises at 150 mph and he loves the little engine. He had originally planed on an O-320 but that fell through at the last minute and he bought the 235 and installed it.
No complaints from him. Enough power, climb, etc.
There is an O-235 (108hp version) RV-9A flying in Hickory, NC. I have spoken to him but Don't have his email.
His RV cruises at 150 mph and he loves the little engine. He had originally planed on an O-320 but that fell through at the last minute and he bought the 235 and installed it.
No complaints from him. Enough power, climb, etc.
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n2prise
Well Known Member
Get the O-320 and you won't regret it!
I have been flying my RV-9A with an ECI Titan O-320 since June 9, 2005. The constant speed prop lets it go to max power on takeoff. I do most of my cruising up high from 10,500 to 12,500 MSL. At that altitude, it sips gas in the 5.5 to 6 gallons-per-hour rate cruising at 160 MPH true airspeed. The wing on the RV-9/9A is a Roncz airfoil and is happy up there, and efficient.
Like the man said, you can always pull the throttle back when you don't need the power. I went to LOE5 at in New Mexico last year. That airport is over 4000 feet MSL. The takeoff from there was not an issue. I did not notice much in the performance loss from my home area where the airports are all in the 700-900 MSL elevation range.
Jerry K. Thorne
RV-9A N2PZ, 171.7 hours
www.n2prise.org
I have been flying my RV-9A with an ECI Titan O-320 since June 9, 2005. The constant speed prop lets it go to max power on takeoff. I do most of my cruising up high from 10,500 to 12,500 MSL. At that altitude, it sips gas in the 5.5 to 6 gallons-per-hour rate cruising at 160 MPH true airspeed. The wing on the RV-9/9A is a Roncz airfoil and is happy up there, and efficient.
Like the man said, you can always pull the throttle back when you don't need the power. I went to LOE5 at in New Mexico last year. That airport is over 4000 feet MSL. The takeoff from there was not an issue. I did not notice much in the performance loss from my home area where the airports are all in the 700-900 MSL elevation range.
Jerry K. Thorne
RV-9A N2PZ, 171.7 hours
www.n2prise.org
Overhaul cost on the 235 is supposed to be equal to or greater than the O-320. Similar number of part all have to be dealt with in a similar manner. Only the initial purchase price is lower.
I see no advantage to the O-235 except in initial purchase price, and some careful shopping might negate that saving.
I see no advantage to the O-235 except in initial purchase price, and some careful shopping might negate that saving.
gmcjetpilot
Well Known Member
Fly higher
There are electric props but, I am not for that expensive option. More HP with a fixed prop is a much easier and cheaper solution to get both good takeoff/climb and cruise performance with a fixed prop.
I don't think there is any doubt 118 HP is plenty. However your point about the excellent high altitude cruise capabilities of the RV-9 wing remindes me it would be enhanced with more HP. With "excess" sea level HP, you could fly even higher improving economy. I am not a fan of sucking O2 thru a mask, but I am really talking about flying at altitudes say between 8,500 and 12,500 feet at gross with some "authority". RV's (or any plane including a B737/B757/B767) at service ceiling is a mushy uncomfortable affair.
If you LOOK at 118 HP RV-9A ceiling at gross it is only 14,500 feet. You need to know that is not a good efficient altitude. That's an altitude you can make 100 ft/min climb, may be. It is kind of marginal. You need to subtract about 6,000 feet or more off the MAX service ceiling to get a "reasonable" cruise ceiling. Looking at 118HP at gross weight you will be really maxed out at 8,500 feet. What if its real HOT and you're in mountainous areas. Any one flying distance in and around the west cost should consider the higher HP. For most a cruise of 8,500 feet is OK, but it would be nice to have climb capability to easily go to 12,500, even at gross. If flying solo over the mid west, the 118HP is plenty.
That is what the extra 42 HP gets you, high altitude climb and cruise capacity. If you are going to be doing fully loaded coast to coast flying or flying around the western side of the US, I think most builders are better service by the O320. It's not for speed it's for payload hauling capacity.
Sometimes HP can be a safety assist. Allowing you to fly over weather, terrain and takeoff and climb faster, even with high density altitude. With that said a O235 is a fine engine and a RV-9 with either either engine is a fine airplane. If I was into the -9 and found a O235 cheap, heck yea I would consider buying and installing it. G
Sure 115HP, 116Hp or 118HP is plenty. No doubt. I think the point everyone is making is the higher HP solves the fixed pitch prop dilemma. With a cruise prop and greater HP, you will have as good or better takeoff and climb as a 118HP RV-9 with a climb prop. As you point out there are no fixed props with two positions. There are ground adjustable props, but I am opinionated, the ones out there now look like they are made for ultra lights. However ground adjustable props does not solve the in flight problem.vanplane said:
There are electric props but, I am not for that expensive option. More HP with a fixed prop is a much easier and cheaper solution to get both good takeoff/climb and cruise performance with a fixed prop.
I don't think there is any doubt 118 HP is plenty. However your point about the excellent high altitude cruise capabilities of the RV-9 wing remindes me it would be enhanced with more HP. With "excess" sea level HP, you could fly even higher improving economy. I am not a fan of sucking O2 thru a mask, but I am really talking about flying at altitudes say between 8,500 and 12,500 feet at gross with some "authority". RV's (or any plane including a B737/B757/B767) at service ceiling is a mushy uncomfortable affair.
If you LOOK at 118 HP RV-9A ceiling at gross it is only 14,500 feet. You need to know that is not a good efficient altitude. That's an altitude you can make 100 ft/min climb, may be. It is kind of marginal. You need to subtract about 6,000 feet or more off the MAX service ceiling to get a "reasonable" cruise ceiling. Looking at 118HP at gross weight you will be really maxed out at 8,500 feet. What if its real HOT and you're in mountainous areas. Any one flying distance in and around the west cost should consider the higher HP. For most a cruise of 8,500 feet is OK, but it would be nice to have climb capability to easily go to 12,500, even at gross. If flying solo over the mid west, the 118HP is plenty.
That is what the extra 42 HP gets you, high altitude climb and cruise capacity. If you are going to be doing fully loaded coast to coast flying or flying around the western side of the US, I think most builders are better service by the O320. It's not for speed it's for payload hauling capacity.
Sometimes HP can be a safety assist. Allowing you to fly over weather, terrain and takeoff and climb faster, even with high density altitude. With that said a O235 is a fine engine and a RV-9 with either either engine is a fine airplane. If I was into the -9 and found a O235 cheap, heck yea I would consider buying and installing it. G
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0-235
I am installing an 0-235 on my -9 for the following reasons:
1) The airplane was designed for and the prototype was built with this engine.
2) Better fuel economy. It is not true that a larger engine will get the same economy when throttled. If that were true, we'd all be installing IO-540's.
3) Lower empty weight. More useful load. More range.
4) 2400 hr TBO
The only reason I can see not to would be frequent high and hot conditions. You also have the option of the MT electric propeller, if you want more takeoff performance. I am giving this serious consideration, but will be starting out with a fixed pitch metal prop.
I had trouble making the decision until I talked to Stan Shannon. He has built 3 RV-9s and has powered them all with the 0-235. Van's will give you his number.
John
I am installing an 0-235 on my -9 for the following reasons:
1) The airplane was designed for and the prototype was built with this engine.
2) Better fuel economy. It is not true that a larger engine will get the same economy when throttled. If that were true, we'd all be installing IO-540's.
3) Lower empty weight. More useful load. More range.
4) 2400 hr TBO
The only reason I can see not to would be frequent high and hot conditions. You also have the option of the MT electric propeller, if you want more takeoff performance. I am giving this serious consideration, but will be starting out with a fixed pitch metal prop.
I had trouble making the decision until I talked to Stan Shannon. He has built 3 RV-9s and has powered them all with the 0-235. Van's will give you his number.
John
As a general statement, it's true enough. It takes X amount of power to go Y speed. You can usually produce that power more efficiently with a larger engine. We don't all have IO-540s because they are too large, too heavy, and more expensive.Yukon said:
Engines will run hundreds or thousands of hours past TBO when properly cared for. Don't buy an O-235 thinking that you will get an extra 400 hours before overhaul. It's too dependent on other factors.
Small engine efficiencies
Study up, Joey. It's a well-known fact that an engine is most efficient when performing at it's rated horsepower. Van used it for a reason. It costs money to drag 30% more air through an engine, not to mention the friction of larger components.
2400 hr TBO is a statement of fact, not opinion or conjecture. I just disassembled a second-run 0-235 I'm overhauling for my -9 and it was perfect inside. Still has full bore hone marks in the cylinders and a standard crank. The logs show nothing more than accessory maintenance and oil changes for 4800 hours. Try that with a big-bore Lycoming.
The O-320 is a great engine too, but it is 30 lbs heavier and won't push a -9 170 mph on 5.5 gph. It's going to take 7.5 gallons to do the same speed with the 0-320. At $4 to $5 per gallon, that's real money in the lifetime of an engine.
John
Study up, Joey. It's a well-known fact that an engine is most efficient when performing at it's rated horsepower. Van used it for a reason. It costs money to drag 30% more air through an engine, not to mention the friction of larger components.
2400 hr TBO is a statement of fact, not opinion or conjecture. I just disassembled a second-run 0-235 I'm overhauling for my -9 and it was perfect inside. Still has full bore hone marks in the cylinders and a standard crank. The logs show nothing more than accessory maintenance and oil changes for 4800 hours. Try that with a big-bore Lycoming.
The O-320 is a great engine too, but it is 30 lbs heavier and won't push a -9 170 mph on 5.5 gph. It's going to take 7.5 gallons to do the same speed with the 0-320. At $4 to $5 per gallon, that's real money in the lifetime of an engine.
John
You are arguing a point I did not make, as what I said doesn't contradict that.Yukon said:
What I said was that it takes a certain amount of power to move an aircraft through the air at a certain speed. You can often generate that power more efficiently with a larger engine as opposed to a small one, even if the larger engine has to be throttled back to where it's not at its most efficient.
I never said it wasn't a statement of fact. It's just that it is an irrelevant statement of fact. The manufacturer's stated TBO is in no way a reliable indicator of how long the engine will actually last. To make a statement to the effect of "The O-235 has a greater TBO and thus will last longer than an O-320" is not accurate.
I used to work at a facility that maintained a fleet of thirty recip-powered aircraft. I have "tried it", and I have no doubt that a big-bore lycoming will match an O-235 for longetivity when they are both cared for and used in the same manner. There are no characteristics inherent to the O-235 that will make it last longer.
This is simply not true, as Van's factory -9A will do 177.2 smph on 5.9 gph. If the extra .4 gph bothers you, throttle back until you get 5.5gph, it'll still be doing 170mph or better. It will also do 193mph at max cruise, which an O-235 version can't do at any fuel burn.
I was thinking about the O-235
I was thinking about an O-235 when I first started building my 9'er, but with my Aero Sport O-320, 160HP with a 79 pitch fixed pitch prop, I can set the power back at 2200 RPM and run 140 knots indicated. I can climb at 1500 FPM any day, and I have been getting 5 to 6 GPH fuel burn typically. So, why did you want that O-235 now given the overhaul cost being the same? Also, remember, "power can be your friend when you are in trouble", and maybe that might have helped the original ill fated prototype climb out of trouble, but we will never know.
John
I was thinking about an O-235 when I first started building my 9'er, but with my Aero Sport O-320, 160HP with a 79 pitch fixed pitch prop, I can set the power back at 2200 RPM and run 140 knots indicated. I can climb at 1500 FPM any day, and I have been getting 5 to 6 GPH fuel burn typically. So, why did you want that O-235 now given the overhaul cost being the same? Also, remember, "power can be your friend when you are in trouble", and maybe that might have helped the original ill fated prototype climb out of trouble, but we will never know.
John
L.Adamson
Well Known Member
Yukon said:
I don't believe so. My 1520 c.c. motorcycle engine, and the DuraMax diesel in my Chevy Silverado, are a lot more efficient (fuel wise) when throttled back. 50-60 mph highway speeds save a lot of fuel versus freeway speeds of 75 mph.
And then of course, Cessna derated the 172's such as the R model from 180HP to 160 HP by limiting RPM. Which was the most efficient?
But......... I'd personally pick the 320 simply because I hate high density altitude problems. I want the most horse power available when a density altitude takeoff poses a risk to my health.
mlw450802
Well Known Member
Use appropriate comparisons
Come on guys. At least try to use apples to apples when you argue these things.
First, a diesel has no throttle so should not be in the mix here.
The contention is that an engine operating at full open throttle is more efficient than an engine operating at partial throttle. This is surely true and most will see the light if the playing field is leveled.
Using the automobile analogy let's pick a speed of 70 mph. Using the same chassis in both cases let's install an engine say 1200 cc that at full throttle just makes it to 70 mph. It gets X mpg. Now let's install one of the 8 liter monster crate engines and motor down the freeway at 70 mph even though we could go 160 at full throttle. Our fuel mileage will be something less than X because of several reasons, not the least of which are the huge pumping losses due to sucking air past the nearly closed throttle plate.
In each case the horsepower (to achieve 70 mph) is identical but the smaller engine is operating at a much higher efficiency even though the large engine is operating much more easily and at lower stress.
-mike
PS the issue works the same in aircraft although the differences are smaller since the engines argued are closer in power and displacement.
Come on guys. At least try to use apples to apples when you argue these things.
First, a diesel has no throttle so should not be in the mix here.
The contention is that an engine operating at full open throttle is more efficient than an engine operating at partial throttle. This is surely true and most will see the light if the playing field is leveled.
Using the automobile analogy let's pick a speed of 70 mph. Using the same chassis in both cases let's install an engine say 1200 cc that at full throttle just makes it to 70 mph. It gets X mpg. Now let's install one of the 8 liter monster crate engines and motor down the freeway at 70 mph even though we could go 160 at full throttle. Our fuel mileage will be something less than X because of several reasons, not the least of which are the huge pumping losses due to sucking air past the nearly closed throttle plate.
In each case the horsepower (to achieve 70 mph) is identical but the smaller engine is operating at a much higher efficiency even though the large engine is operating much more easily and at lower stress.
-mike
PS the issue works the same in aircraft although the differences are smaller since the engines argued are closer in power and displacement.
Here's something else that's very important to note while we are on the subject. Just because an O-320 isn't being operated at full power doesn't necessarily mean that it's being throttled back. You could have the throttle wide open at 50% power. We are talking about aircraft, after all.mlw450802 said:
Dan has posted here that he was getting 170 smph at 4.8 gph with the angle valve IO-360 in his RV-7. Does anyone here think an O-235 (or 320) in the same aircraft would beat that?
Efficiency
So Joey, where does this theory stop? I had a guy try to convince me the other day that I should install an O-360 and derate it. Will it throttle back to 0-235 numbers too? How about an H-6 Subaru? Should we be installing a 350 lb system on an airplane designed for a 200 lb engine? What does Van say about that? Rocket guys favor the 0-540. Just how far will it throttle back? Does empty weight not figure at all into an efficiency equation?
170 is top speed for the 0-235 -9. I believe best economy was at 55% power and yielded 35 MPG. I can't remember the speeds, but they are in an extensive Sport Pilot article about the prototype back in 2000. If you want to run around with your hair on fire, buy a big engine. If you don't, the 0-235 is an economical alternative.
The crash of the prototype was in no way related to horsepower, it was a weather accident in Arkansas, and the airplane had no gyros.
John
John
So Joey, where does this theory stop? I had a guy try to convince me the other day that I should install an O-360 and derate it. Will it throttle back to 0-235 numbers too? How about an H-6 Subaru? Should we be installing a 350 lb system on an airplane designed for a 200 lb engine? What does Van say about that? Rocket guys favor the 0-540. Just how far will it throttle back? Does empty weight not figure at all into an efficiency equation?
170 is top speed for the 0-235 -9. I believe best economy was at 55% power and yielded 35 MPG. I can't remember the speeds, but they are in an extensive Sport Pilot article about the prototype back in 2000. If you want to run around with your hair on fire, buy a big engine. If you don't, the 0-235 is an economical alternative.
The crash of the prototype was in no way related to horsepower, it was a weather accident in Arkansas, and the airplane had no gyros.
John
John
Wherever you want it to. Look, I'm not trying to convince you not to use an O-235 in your -9. That's your choice. Other people reading this forum haven't yet made that choice. If you're going to post the O-235's advantages over the O-320, make sure what you post are really advantages. You posted that an O-320 powered RV-9 would burn at least 7.5gph at 170mph. Why should bad information not be corrected?Yukon said:
It probably will, as evidenced by Dan's post about his IO-360 that I linked above. It's not recommended in the RV-9, of course.
Once again you are arguing a point that I haven't made. Van's supports the use of an O-320. Where have I advocated the use of an engine in an RV-9 that wasn't endorsed by Van's Aircraft? Didn't I post earlier that some larger engines shouldn't be used because they were too big and too heavy?
me said:
rv9aviator
Well Known Member
The difference in resale value of an RV-9A with an 0-320 verses an 0-235 will buy a lot of fuel even if it did use a tad more. Not trying to start anything, just an observation.
O-235 for RV9-A
We are finishing up a RV9-A which will be powered by the O-235 Lycoming. I will be surprised if the numbers vary much from those posted by Van's. Craig Catto pitched the Catto prop for good climb with very little off cruise performance. Once flying (June 2006) I will post numbers using Catto's formula for this prop.
With fuel prices heading higher, I think this will be a dandy little plane. Since this plane is in the Plains (Kansas), it fits the mission well.
I feel that Van's has developed an incredible airframe that cannot be compared performance wise to using this engine out of a less effecient production airframe. (Apples vs. Lemons?)
I think this will fly better than a C-152 (or whatever other production brand)with the same engine.
Just a thought.
Determine the mission and build to suit. (I am also building a RV9-A with the O-320 150hp Lycoming........different mission.)
Maybe we can fly these head to head for comparison.
We are finishing up a RV9-A which will be powered by the O-235 Lycoming. I will be surprised if the numbers vary much from those posted by Van's. Craig Catto pitched the Catto prop for good climb with very little off cruise performance. Once flying (June 2006) I will post numbers using Catto's formula for this prop.
With fuel prices heading higher, I think this will be a dandy little plane. Since this plane is in the Plains (Kansas), it fits the mission well.
I feel that Van's has developed an incredible airframe that cannot be compared performance wise to using this engine out of a less effecient production airframe. (Apples vs. Lemons?)
I think this will fly better than a C-152 (or whatever other production brand)with the same engine.
Just a thought.
Determine the mission and build to suit. (I am also building a RV9-A with the O-320 150hp Lycoming........different mission.)
Maybe we can fly these head to head for comparison.
