Tumper

Tumper

Well Known Member
I apologize if this issue has been discussed and beat to death, but I couldn?t find a lot on the subject. Here is my dilemma, I am building a RV-9 because I think that is the best plane for me, however I own a low time 180 hp 360. I have read where several people have installed 360?s in the 9 and it runs great. Here are some of the comments I have run across;

(1) I have had people tell me you don?t have to run the engine wide open, you can ease back on the throttle a little. And on heat/altitude issue days it is great to have a 360 in front of you.
(2) If you look at the weight the 360 is only maybe 20 lbs heaver than the 320. If you add a heavy prop out on the end of a 320 you may have gained part of the 20 lbs back.
(3) Comparing the 160 hp 320 and my 180 hp 360 we are talking only 13% more hp. Is that so much? With a little work you could get 180 hp out of a 320.
(4) It is my life that is sitting behind the engine, is 20 hp worth the risk?

If I understand correctly Van?s greatest concern is speed (see point 1 above).

I?d be interested in any additional thoughts.

All the best,
Dean Eiland
RV-9
 
My thoughts on this.

I am building a 9A. It is my belief that the 360 will work fine especially since you already own it. That can be a great savings for your build.

You are correct concerning the speed. The 180 hp will allow this plane to creep closer to the danger zone of the flight speed where you can see a structural failure. However, if you are any kind of pilot at all you will be aware of what your airplane's limitations are and stay away from that edge. The RV9 is not unique in this respect. In fact, I was just having a conversation with an Alon Ercoupe owner yesterday about his maneuvering speed, cruise speed and Vne speed. He has a narrow window from cruise to maneuvering speeds to deal with. He is aware of this and flies his plane accordingly. That is true in this scenario. It will be up to you the pilot to fly your plane with the awareness that speed can become an issue.

In my opinion the weight is just as much an issue as the speed if you are building a 9A. The nose gear has come under great scrutiny lately due to several failures. Adding extra weight on that nose gear can be an important issue. You stated you are building a 9 and not a 9A so I am assuming you are not building a nose gear airplane. If that is true then the weight may not be that much of an issue for you. Only you can determine that.

The 20 lbs is probably a good estimate but as I have discovered in talking with various engine manufacturers, no one will give you a straight cut and dried answer on what a 320 or 360 weighs or how they compare one to the other in weight. I personally find this unacceptable considering how important weight issues are for airplanes that the very people who construct these engines will not admit to a specific weight for their engines. And lest someone go down the road of explaining this with the idea that there are many variations one can put on an engine, sorry, I don't buy that. Build an engine, list what components are in it, set it on the scales and tell me what it weighs. Then the other guy does the same thing. Give me the results and let me compare the two. Why is that difficult? Or better yet, if they are so concerned that one component will be compared to another inappropriately then tell me the weight of these components and let me determine from the sum of all the parts what the engine will weigh. But I digress.

Anyway, in my opinion, the important issues with the 360 are going to boil down to airspeed the engine will push the airframe and the weight of the engine on a nose gear airplane.

Good luck with your decision.
 
Steve said it well. I'm building a 9A as well, and fully intend to put an IO360 on it. I would prefer to put a 160hp turbodiesel up front, but it appears there will be no serious contenders anytime soon.

There is basically only the one major issue with running 180hp in the 9/9A, which is encroaching on Vne (and flutter) at altitude and during descent, which can be done much more easily with more power. This is where the PILOT comes in - as in PILOT IN COMMAND - you have the authority to make the airplane do what you want, or not do what you don't want. Exercise that authority and you'll be fine. You could exceed Vne in a 9 with an O-235 in it by diving - it's not the evil engine that will kill you - it's the actions of an inattentive pilot allowing the machine to exceed its limits.

Slightly more minor issues involved with this engine choice include CG placement, total weight, cooling airflow and fuel burn. All can be dealt with by making smart decisions throughout the build process with regard to what other equipment is installed, and where it is placed. In my case, I'm building a nosegear 9A, and with an IO360 and heavy prop up front, I know I will need to put my battery far back in the tail to keep the nose light and reduce weight on the fragile nosegear. I will also have an oxygen system on board with the tank in the tail, so between those two I should have no problem keeping the nosegear weight low enough to be reasonable for paved runway operations. I don't intend to operate on grass strips.
 
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Dean,

If you go with the O-360, put a wood prop on the front, such as a Catto. Other than that, build it as light as you can and you should be fine.

My two blade Catto prop is only 9 lbs. A metal prop is much more, around 40 lbs. A constant speed prop is much more.
 
I opted for the 360 engine and FP prop. My calculations were that there would be less weight on the front wheel (9A) with this combination than with the 320 and a CS prop. So I don't believe that weight is a major issue. That said, shifting things like the battery rearward may reduce nosewheel weight. I think there is no loss of fuel economy, as one can throttle back the 360 to get the same fuel burn as the 320 (for the same speed). However, having the extra power if necessary is a good thing (I fly out of Reno at 5000 ft with density altitudes often at 8 or 9000 in the summer). And since you already have the 360, seems like an easy decision to me. The usual disclaimers apply....

greg
 
Guys

Just a smart *** from Oz :D.......but look here;
http://www.vansaircraft.com/public/rv-9per.htm

The right hand column looks pretty good to me so why try to redesign what Vans have done for you?

Sure you can use a wood prop and save weight, but think of it this way.....do that with an 0-320 and save even more!

If you become too experimental and then have a prang, not only is it pretty bad for you, it gives the whole Experimental thing a bad name.

Vans have a price list of XIO engines and props with a discount, why not make the most of it.

Cheers
DB:cool:
 
PCHunt said:
bhassel said:
Is it possible to run with RV7 nose gear?
Click to expand...
Just curious, what's the difference between the two :confused:
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I don't know the answer as I built a -9 but aren't the -9A & -7A nose gear the same?

For those of you building a -9A, what does your part number start with? If the part number on your nose gear leg starts with a "9" than that part is unique to the -9A. If it starts with a "7" than it is a common part shared between the 7 and 9A.

(FYI, the main gear legs on the -9 are unique to that airplane are not shared by any other model. They are longer than the others.)
 
Dear VAF Users,

Once again I think you guys have done a fantastic job of covering this subject. As I summarize speed and weight are the issues. Speed can and should be controlled by the PIC. Same as with any engine.

As far as weight is concerned let me add to my post I am building a conventional so the extra wheel is in the rear. Does the gear configuration change the CG?

I own a composite c/s prop so I am about 20 lbs lighter than the aluminum f/p.

I think the combination should work well on a RV-9.

Many many thanks to Doug and the rest of you guys with your heads in the clouds and feet on the ground (and that is intended to be a compliment). Hope to join you soon.

Dean Eiland
RV-9
 
Dean,

It is my pleasure to welcome another -9 builder!

The CG remains in the same place for both the -9A and the -9. This is based on the wing, not the landing gear.

Check out Dan's Weight and Balance page to get an idea how they are coming out. Unfortunately there are only two -9's on there. Mine doesn't really count as I went the other way and installed an O-290 up front, which helped me come out VERY light.
 
180 vs 160

Hi Dean - welcome to the forum.....

My 2 cents.......

Vans suggests no more than 160 hp and they have their reasons. I have yet to see a solid, legitimate reason to go with 180 hp in an RV-9/A. If any pilot is looking for more speed than what a -9 is capable of (without exceeding Vne) - well, should have gone with a -7. It can carry more horses and go a good bit faster. I've heard people legitimize the 180 hp engines with reasons such as "short field performance" or "high density altitudes". The -9 can handle all that with the 160 hp. I believe that is nothing more than the "Tim Allen" syndrome - "Oh, oh, oh, More Power! .....and for that I'm gonna get my head chewed off.

The climb in an RV-9 is outstanding as well. All planes perform at a lesser degree when they are warm and high.

Dean, the fact that you chose a -9, ("as the best plane for you"), I'm guessing that indicates that you were looking for a slower airplane to begin with. Yes, others have put 160 hp (and more) up front on a -9 but the -9 is pretty darned quick without that much hp.

Van's has put a special note on the "Performance" page of the RV-9 explaining "Why can't I use a larger engine?". It is the only plane they do that for.

If you do decide to stick with the 180 hp engine, keep an eye on your airspeed and try not to let that take the fun out of your flying. The bottom line is this - it's your plane - build it the way YOU want it.
 
Its all F.U.D.

Fear, uncertainty, and doubt.

A 360 with a catto will probably weight less than a 320 with an aluminum prop.

Just use a fixed pitch prop, pitched to limit the speed to whatever is safe for the 9.
 
Steve,

What HP do you think you are getting with your 320? What is the weight of your Catto Prop.

Thanks,
Dean
 
I am in the "160 is enough" camp, but you may have the best reason to go with the O-360 I have heard yet. Unless you find someone with a 320 that really wants a 360, you are going to have to shell out some serious bucks. Good reason!

Just keep everything else light (starter, battery, prop, etc.) You might want to stick with a two blade vs. a three. Having a relatively light nose wheel is a good thing. And as far as speed, hey, that's why you have that big black knob. Have fun and build on! Just my $.02.

Bob Kelly
 
I'm in the 160 HP is over kill camp.

With all of 135 HP up front, I'm continually stunned at how quickly my -9 gets off the ground and climbs.

Robert has flown in my plane as has his wife out of 28A which is 2300' long with trees at both ends. Never has getting out of there even been an issue. Even on 90+ degree days with a full load.

Granted, "there is no replacement for displacement" but there is some real value in keeping it light.

Why not sell the 360 and buy a 320? You will probably have money left over to buy some other goodies for your -9.

Remember, Van designed this plane to fly well with an O-235.

PS. A few weeks back I gave a ride to another member of this forum who is building a -9A. He commented that he thought we were off the ground before the O-320 powered -9A he had ridden in two weeks prior. Again, keep it light, leave all the options for your car.
 
I'm guessing 170 hp

Tumper said:
Steve,

What HP do you think you are getting with your 320? What is the weight of your Catto Prop.

Thanks,
Dean
Click to expand...

But that's just a guess. More accurately I'm guessing I might be +10 over the stock engine, whatever that actually produces. I don't know exactly what the prop weighs, but I thought I read 14 pounds.

At about 8500 DA, I get about 164+ kts TAS firewalled. I don't have fairings between the legs fairing and wheel pants. I'm guessing that might cost me a kt. Most of the time now I'm pulled back a bit running LOP to save fuel + keeps the engine cooler.

If I were building, I would build a 7 or 8 for the higher speed capability, but if I wanted to build a 9, I would not hesitate to put a 360 in with Catto prop. If the problem is weight and speed, that solves the problem. Just have it pitched for 2700 RPM at vans published 75% cruise.

I wish I had more power. I have a 300hp Subaru WRX Sti and I wish that had more power as well. I offer no explanation as to why. My wife has tried, unsuccessfully, to get that answer for years.

I read what some wrote about letting the pilot manage speed. That is a reasonable premise with a FP prop, because there is obvious audiable feedback if the speed increases. IMO, trying to do that with CS prop is risky because there is no feedback. A few moments of inattention can really build up some speed. AND the margin is not that big in the 9. Using TAS as the red line I have pushed near the limit several times during power on descents. I suspect with a CS prop I would have exceeded them. Like most pilots I have always been totally focused on IAS so managing TAS is not natural.
 
I had planned on a cloan IO-360 as the cost and weight difference over an IO-320 wasn't much. But, the Sun n Fun engine deal that Van's had with a Lycoming IO-320 and prop was too good to pass up. If you have a -360 already, that is what I would use, though.
 
I'm still researching...

Currently about a year from having to make a decision. Plan of record is an IO-320. I've read the Van's article on the subject and I don't need any convincing on the subject of Vne and flutter.
I haven't ruled out the 360. Not after the extra speed, it just seems like the improved climb and density altitude capability might come in handy.

But I have another twist to bring up, to be shot down in flames if necessary.

I expect to be getting ready to fly in 2-3 years. What's going to happen to our 100LL supply? It's probably safe then, but how about 5 years? 10 years?
I've read that a 320 can use a lower compression ratio to burn auto gas. And with the right seals, it can even tolerate some alchohol. But these are at the cost of power.
My thinking is that you ought to be able to do the same with a 360, and the derated power gets you back to where the 100LL fueled 320 is.

Am I completely off base on this?
 
N941WR said:
I'm in the 160 HP is over kill camp.

With all of 135 HP up front, I'm continually stunned at how quickly my -9 gets off the ground and climbs.

Robert has flown in my plane as has his wife out of 28A which is 2300' long with trees at both ends. Never has getting out of there even been an issue. Even on 90+ degree days with a full load.

Granted, "there is no replacement for displacement" but there is some real value in keeping it light.

Why not sell the 360 and buy a 320? You will probably have money left over to buy some other goodies for your -9.

Remember, Van designed this plane to fly well with an O-235.

PS. A few weeks back I gave a ride to another member of this forum who is building a -9A. He commented that he thought we were off the ground before the O-320 powered -9A he had ridden in two weeks prior. Again, keep it light, leave all the options for your car.
Click to expand...

Now, I must admit...................that my two friends flying 9A's are a bit jealous, 'cause my newly flying 6A will just dissapear out of site, on our 100 mile breakfast runs. I just have to keep that engine rev'd for the breakin! :D And I do believe in the luxuary of two axis A/P's too; even though it's a bit heavier. And.............I don't even have the main wheel pants or fairings installed yet.. :) The nose gear pant and fairing is on.

I really don't know if I'd go 180 horses for a 9 either, because I've flown both 150 & 160 HP 9A's around lot's of mountain country, and they do very well. However, I do believe in "there is no replacement for displacement" ; and enjoy the extra power.

L.Adamson
 
Chip, as has been noted in some other threads, the 0360s can eat auto fuel as well, provided they are not high-compression (9:1 or 10:1). That was a consideration when I built my Superior, which is 8.5:1 and can use autogas. It is my understanding (again from various threads on VAF) that the higher-compression engines have a shorter TBO as well.

greg
 
Another possibility is to limit the take off rpm on a 360 to 2400 RPM. This changes the take off rating for the 180 hp 360 to 160HP. There are certified 360 engines that have a TO RPM rating of 2400RPM at 160HP. The IO-360-L2A, in the later model Cessna 172's is one of these. So if you pitch your fixed pitch prop for 2400 RPM or set you governor for 2400 RPM you are changing your take off rating on a parallel valve 360 from 180 HP at 2700RPM to 160HP at 2400 RPM. So from a HP standpoint, at 2400RPM, you are not exceeding Vans recommendations.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
mahlon_r said:
Another possibility is to limit the take off rpm on a 360 to 2400 RPM. This changes the take off rating for the 180 hp 360 to 160HP. There are certified 360 engines that have a TO RPM rating of 2400RPM at 160HP. The IO-360-L2A, in the later model Cessna 172's is one of these. So if you pitch your fixed pitch prop for 2400 RPM or set you governor for 2400 RPM you are changing your take off rating on a parallel valve 360 from 180 HP at 2700RPM to 160HP at 2400 RPM. So from a HP standpoint, at 2400RPM, you are not exceeding Vans recommendations.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
Click to expand...

I don't believe absolute horsepower on takeoff was the spirit of the O-320 recommendation. Unless you're having a problem with keeping the airplane on the runway due to engine torque, you don't have too much takeoff power. The issue comes in letting the aircraft approach flutter TAS at altitude or descent, and as I've pointed out before, this is a PIC issue, not an engine issue. It is ultimately up to the PIC to fly the airplane within its envelope regardless of installed equipment.
 
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Thanks for all the responses. I think I would like to run with an IO-320 w/ 160 hp and c/s prop in my RV-9. I’ll bet that combination will be hard to beat. Is anybody interested in trading a 180 hp IOF-360 with 60+ hours for a 160 hp IO-320?

Thanks again,
Dean Eiland
[email protected]
 
L.Adamson said:
Now, I must admit...................that my two friends flying 9A's are a bit jealous, 'cause my newly flying 6A will just dissapear out of site, on our 100 mile breakfast runs. I just have to keep that engine rev'd for the breakin! :D And I do believe in the luxuary of two axis A/P's too; even though it's a bit heavier. And.............I don't even have the main wheel pants or fairings installed yet.. :) The nose gear pant and fairing is on.

I really don't know if I'd go 180 horses for a 9 either, because I've flown both 150 & 160 HP 9A's around lot's of mountain country, and they do very well. However, I do believe in "there is no replacement for displacement" ; and enjoy the extra power.

L.Adamson
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Different airplanes, different missions. BTW, I suspect your -6A doesn't have a 760 lb useful load like my -9 does, and that is w/o inflating the GW.

As for the AP thing, my -9 has a two axis Dynon AP installed. GREAT AP BTW!

I agree, more power would be nice but keeping it light is the key to good performance. Performance is much more than just HP, handling quality is very important to me. The lighter it is, the better it flies. The heavier it is, the more it feels like a truck/SUV/minivan

Back to the question, for comparison, my 135 HP RV-9 will climb at 1800 FPM on a hot day. I suspect it could do better with an O-320 and CS prop but why? Unfortunately Craig Catto didn't pitch my prop right so I'm limited to 165 MPH TAS at 64% power at the 2600 RPM continuous power RPM limit. Craig and I have talked about cutting a new prop and we both think could get 15 to 20 MPH more speed without sacrificing climb (Longer prop with a finer pitch.) but I'm not ready to open my wallet just yet.
 
N941WR said:
I agree, more power would be nice but keeping it light is the key to good performance. Performance is much more than just HP, handling quality is very important to me. The lighter it is, the better it flies. The heavier it is, the more it feels like a truck/SUV/minivan
Click to expand...

For the last four years, I've flown "lighter" 9A's. Quite frankly, it's my 6A that feels and handles more like a sports car! :D Actually, more like a fighter! I noticed this on day one. I think I'd have to go with a 3,4, or Rocket...............to be even more fighter like. Besides, I've been in a P-51D for a bit of the feel. :) Nope, my six isn't even close to a truck/SUV/ minivan. I drive a 4 door diesel Chevy Silverado... :D

L.Adamson ---- RV6A

edit............. 184 HP TIO-290-D2, Catto 4 blade prop, duel JATO bottles. ------ Now I'm jealous! :)
 
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Bill R wrote: "184 HP TIO-290-D2, Catto 4 blade prop..."

Bill can you clarify the above? All the pictures on web site show a two blade prop...have you switched and not posted new pictures or is this a future wish / tongue in cheek? Also you list "184 hp" but in your post you state "135 HP", so is this tongue in cheed again? Your climb performance is really awesome so wondering if you did any engine tricks to get to 184 hp maybe?

Thanks for the info...

Doug Lomheim
90116 / Mazda 13B "only" 160 hp hopefully
 
JATO bottles

N941WR said:
Different airplanes, different missions. BTW, I suspect your -6A doesn't have a 760 lb useful load like my -9 does, and that is w/o inflating the GW.

As for the AP thing, my -9 has a two axis Dynon AP installed. GREAT AP BTW!

I agree, more power would be nice but keeping it light is the key to good performance. Performance is much more than just HP, handling quality is very important to me. The lighter it is, the better it flies. The heavier it is, the more it feels like a truck/SUV/minivan

Back to the question, for comparison, my 135 HP RV-9 will climb at 1800 FPM on a hot day. I suspect it could do better with an O-320 and CS prop but why? Unfortunately Craig Catto didn't pitch my prop right so I'm limited to 165 MPH TAS at 64% power at the 2600 RPM continuous power RPM limit. Craig and I have talked about cutting a new prop and we both think could get 15 to 20 MPH more speed without sacrificing climb (Longer prop with a finer pitch.) but I'm not ready to open my wallet just yet.
Click to expand...

Bill,

Do you fish-tail a lot on takeoff being a TW RV-9 with your 'dueling JATO Bottles' vs dual JATO Bottles. Now you have them going. Excellent.
Mike H 9A/8a
 
dlomheim said:
Bill R wrote: "184 HP TIO-290-D2, Catto 4 blade prop..."

Bill can you clarify the above? All the pictures on web site show a two blade prop...have you switched and not posted new pictures or is this a future wish / tongue in cheek? Also you list "184 hp" but in your post you state "135 HP", so is this tongue in cheed again? Your climb performance is really awesome so wondering if you did any engine tricks to get to 184 hp maybe?

Thanks for the info...

Doug Lomheim
90116 / Mazda 13B "only" 160 hp hopefully
Click to expand...
No tricks to my engine, just a stock O-290-D2 w/ duel P-mags. Electronic ignition, any electronic ignition, really helps an engine realize its full potential.

I think the RV-9 wing coupled with the Veterman exhaust and Van’s FAB really help this (all) engine breathe better, thus I suspect the combination produces more power than when it was mounted in a PA-18 back in the 50’s. I will not go as far to toss out a HP number as I’ve never dynoned it and have no clue. In addition, the climb prop I have really helps it go up but limits my top speed to 165 MPH TAS. :(

The picture on my signature was taken by my sister-in-law on a cold morning from a standing start with two on board and baggage in the back. It was a normal take-off at Vx, not a zoom climb or any other tricks such as holding it down to gain speed. I simply roated to Vx and climbed out.

mike109g6 said:
Bill,

Do you fish-tail a lot on takeoff being a TW RV-9 with your 'dueling JATO Bottles' vs dual JATO Bottles. Now you have them going. Excellent.
Mike H 9A/8a
Click to expand...

No problem as all, as long as they both light off at the same time. When one ignites before the other, it is anyone's guess as to which way I'm going. ;)

Seriously, I just put that signature on there to see if anyone caught it. You two are second and third. Time to change it again.
me said:
Bill R.
RV-9 Flying
184 HP TIO-290-D2, Catto 4 blade prop, duel JATO bottles.
Watching wife build her own 9mth quick build
Build the plane you want, not the plane others want you to build!
Huntersville, NC
www.repucci.com/bill/baf.html
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O-360

My 9A that I purchased built has an 0-360 with a FP prop. The CG is good, the performance is great. Gets off the ground quickly. At 2500 RPM I indicate 174 mph and 8.4 gph lop. When I descend from altitude, I just control my RPM and speed. I usually descend at 190 mph if I am in a rush.

I just know the airframe limitations and fly within those limitations. This little airplane is a great cross country aircraft. The other day I went from Atlanta (20GA to Myrtle Beach (KCRE) in 2:14 minutes. It just doesn't get any better than that.

Just one 9A's owners experience.
 
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