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RV 4 Engine selection ?

Larry DeCamp

Well Known Member
I need to decide what engine for my 4 project. I am not a horsepower / ROC / Speed seeker. I am relatively anal about smoothness and am convinced a big engine loafing is more desirable than a small engine working harder to fly the same speed.SO, there are three options for me:
* 340 from stroke increase
* 340 from bore increase
* 360 pretty much stock with maybe 15lb weight penalty
Your comments from EXPERIENCE would be appreciated...Larry
 
The 340 is not the smoothes motor and depending on the prop combination there are harmonic issues. Not sure how you came up with the 340 as being smooth compared to others. But i can tell you my 0-320 on my previous rv-4 was way smoother than my IOX-340 in my new rv-4. To the point that i thought something was wrong. Both engines/props were dynamically balanced.

I have had issues with the spinner bulkheads and the prop wearing on each other due to the vibrations. Craig Catto gave me some bevel (spelling?) washers and told me to keep a close eye on it because it is a major problem if it keeps happening. He then told me about the harmonic issues a certain rpms (from test data collected) and cautioned me to stay away from those at continuous rpm operations.

In 100 hrs i have had broken 3 exhaust hangers and found a crack on the exhaust flange on #4.

Hope that helps.
 
I had a 160HP O-320 with a metal Sensenich prop in my -4. It was reasonably smooth, but could be better. I did not have it dynamically balanced. I ran a 3 blade Catto on it for a while and that was very smooth.
 
No question for me- Lyc O-360A1A

Hi Larry,

I have owned four -4s. The first three I bought flying and three had O-320s two with wood props (Sterba and Demuth) and one with a metal Sensenich. I finally built my own -4 after a venture with an RV-8, RV-6 and a Rocket. With those hours and experiences under my belt I went with an RV-4 with an O-360 A1A, carbureted, and Hartzell 74 inch Blended Airfoil. I've had it balanced and LOVE the combination. And now with my EMags it's even smoother. At cruise I run 2350 RPM which keeps the vibration and noise down and can routinely see 200+ mph at 8gph. Flying formation with my O-320 neighbors I can see 6-7 gph at 170-180 mph TAS. I do not fly 'hard' aerobatics in my -4, usually limited to 3-4 Gs and do not have an inverted system. With the energy my airplane maintains I can do a vertical maneuver (loop, Immelmann) from level flight and gain energy! I also LOVE the combination for formation flight and pattern energy control. I'd venture to say once you've gone constant speed in an RV, it's hard to go back to fixed. I used to fly my -4 800 miles a week from TX to KS and back and used to look forwArd to the flight (good seats help) and consider the -4 my perfect all around best airplane......for me. The O-360 'fits' well and gives you a 'no excuses' airplane when built for YOU! Enjoy the adventure!
 
I have RV 4 with STOCK rebuilt Subaru 2.5 Legacy ,with SDS control for fuel injection,ignition, (sto?k) along with stock starter,alternator.I used 0-320 mt that came for RV and made own adapters from Suby to mount so a 0-320 could be reinstalled with standard mounts.we have our air worthiness and are currently taxi -testing.However hard to find calm days this time of year in Northeast for first flight.Using PSRU from Air Trikes in Canada,along with their 3 blade ground adjustable 3 blade prop.Using rad underneath,similar to Ross at SDS, my ductwork aluminum,his made neater with fiberglass..Give me e mail an would photos.Tom (have not had time to figure posting photos here)
 
Look at the UL power engine

O.320 with Sensenich FP on mine and TVs not bad.

However, as I will need another engine for my 9 I am considering a UL power engine. Much lighter than a lycosaurus, and more power, plus 6 cylinder which should make it smoother. One has just been fitted to a 4 in the states.
 
Hi Larry,

I have owned four -4s. The first three I bought flying and three had O-320s two with wood props (Sterba and Demuth) and one with a metal Sensenich. I finally built my own -4 after a venture with an RV-8, RV-6 and a Rocket. With those hours and experiences under my belt I went with an RV-4 with an O-360 A1A, carbureted, and Hartzell 74 inch Blended Airfoil. ......he O-360 'fits' well and gives you a 'no excuses' airplane when built for YOU! Enjoy the adventure!

I have heard that having a CS on a -4 moves the CG quite far forward, enough to increase the pitch forces so that you no longer have the nice light handling. But you seem to be very happy. Do you notice a big difference between the wood prop airplanes and the 360/CS in terms of pitch forces? Or do you always fly with a fat guy in the back seat? :p
 
O-360-A1A with Warnke FP on my -4. 1 mag 1 LSE. Very smooth and significantly out performed my O-320 -4 flying partner.
 
IO-360A1A pumped
Up to 200 HP. With the whirlwind prop, my empty weight cg is within 1/2" of where Van recommends. So I still get the light handling, with the added vertical performance. Plus, I had the prop balanced so it is turbine smooth with the 3 blades.
 
ive got a 360, with a hartzell C/S on my 4. with the battery in the stock location I am out of cg forward unless i have 212lbs in the pilots seat. my friend has a 320 with wood prop and its smooth as silk and is only about 3 MPH slower than mine. he cannot catch me in a climb, though. he goes out of CG aft with a big person in the back. solo his is lighter on the controls, mine is a lot better with two persons on board. If i were to do it again, i would go with a 320 with a wood or composite prop.

bob burns
RV-4 N82RB
 
Larry
I have built 5 RV-4s. The first one had a wood prop 0-320. The next 4 had 0-360s and C/S props. I would never go back to a wood prop or 0-320.
Flying in rain would damage the wood even though it had leading edge protection.

I moved the battery back behind the baggage compartment bulkhead. This kept the CG in range. I also moved the elevator bell crank behind the bulkhead, giving more room for baggage.

I know the 0-360 C/S is more expensive but, if you think you might want to sell it later as I did, that's the way to go.

2 cents please.

Carr
 
No prob with the 360

Scott,

Flying my RV-4 with the O-360 and CS DOES get heavier on the control at higher speeds. I mitigate this 'problem' by enjoying starting acro maneuvers around 160-170 mph indicated. Much less control and trim force. I also trim thru the maneuver to minimize stick force. Lots of power available to motor over the top. Furthermore, I CAN carry fat palooka's in the back. My record, out of necessity, was a 280 lbs, 6'4" man that NEEDED to be moved. Anyway, I see no downside to my configuration. I get 215 mph TAS at cruise (9.5- 10.5 MSL, WOT and 2350 rpm) and yet still stalls at 49. Every time I see Richard V I thank him for the -4. Regardless of your engine selection, you can't go wrong. BTW, personal preference only, and I DO admire all the true 'experimenters' out there, but I like what Van used to say about engine 'conversions' for the RV series of aircraft. He said the BEST conversion he recommended for the RV was take $XXXX and convert it to a Lycoming engine. ������

BTW Carr, I endorse your comments. Flying in rain was/is destructive to wood/glass/composite props. Furthermore, I was always shocked by the NECESSITY to torque and retorque the wood prop bolts with temperature and humidity changes. I hope people realize that. Very important for safety. No problemo with metal.
 
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Thanks for the help !

OK I get it. A 320 with light prop elegant. A 360 is probably the best investment for resale. A 360 CS is the ultimate performer if you don't mind managing CG. AX-O had the only comment on 340 variants. I will study archives and start a different thread if needed.
 
thanks for the reply. I flew a friend's 7 with CS 360 and it left me with a sore neck after every takeoff. It just pulled like crazy. Alas, my airplane came with an engine and its crank won't accept a CS prop, nor will my pocket book. Oh well. But I am interested to hear that you don't mind the handling at the forward CG.

I do see a disadvantage in being able to fly a 260 lb person in the back. I want to put a max passenger weight of 130 lbs placard there, for purely sexist reasons.
 
If I had it to do over , I would go with a dynofocal Mount engine. Much stronger than a conical mount and the engine is much smoother running. It is easier to get at the back of the engine to work on it as well..
 
I have a friend with a 4 powered by an 0360 and the light Whirlwing CS prop. We pull up side by side with me in a 200hp 8. He would run off and leave me. The Whirlwind also reduces the weight on the nose. If you are looking for a fun, fast and aerobatic RV I believe this is the best combination and aircraft in the Vans stable. That RV 4, Way Cool.
 
No excuse for HP?

I need to decide what engine for my 4 project. I am not a horsepower / ROC / Speed seeker. I am relatively anal about smoothness and am convinced a big engine loafing is more desirable than a small engine working harder to fly the same speed.SO, there are three options for me:
* 340 from stroke increase
* 340 from bore increase
* 360 pretty much stock with maybe 15lb weight penalty
Your comments from EXPERIENCE would be appreciated...Larry

Hi Larry,
I bought my RV4 tail kit when Reagan was our President and Vans aircraft was still in a garage. At that time RVers were very cost conscious "tinkerers" with budget and low weight as high priorities. Which is the best engine for the RV4? it depends...on your mission.

Being on my Uncles fixed salary (Uncle Sam) I chose a 0-320 narrow deck and Sterba prop for a total investment of $3K and all said and done tipped the scales at 925lbs and $21K invested (1995 bucks) The first flight confirmed the designers wishes, light, responsive, relatively fast (compared to the F16) and inexpensive. I would fly it in that configuration for over 1000 hours, 11 trans-cons, a foray to 21,000 feet and lots of adventures. I never flew big fat dudes in the back seat as Scott quoted above for the same sexist reasons. My RV4 filled the bill for what I originally intended, a 180mph aerobatic Super Cub.

When the original 0-320A started burning oil I removed it, traded another RV 4 builder for his dynafocal mount and built up a blueprinted 0-320E2D with 9.0:1 compression, flow matching and a balanced crank. Craig Catto created my third prop from his deft hand having tested his first RV prop 8 years prior. I also used my original Electroair ignition and one mag.
Performance improvement? Amen brother, I hit the lottery. The nose remained light (something I despise in Hartzell equipped RVs) cool temps in the climb in summer (something 0-360 dudes are always watching) and faster. It still gets off the ground quick and with practice is easy to fly formation, land on short strips and my favorite, dog fighting! (1V1)
Over the next 20 years I would assist over 200 new RVers experience what I truly know is the best flyer of the breed. I also flew all the others in just about every configuration. Despite all that I still hold true to my original mission statement, and engine/prop combo.

I've flown RV4's with 0-360's, IO360 angle valves and even one with an IO540 (my Rocket) yet the 0-320 is hard to beat for bullet proof smoothness and a FP Catto prop gives what I believe the best bang for buck. :)
V/R
Smokey
 
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Smokyray is correct !!

I have flown several -4s fix and C/S props,320 and 360. they all preform well but my light fix pitch O320 -4 is my favorite.
 
I'll second Twister and Smokyray and add a few, but they mostly covered it.

27 years on 160 hp with composite prop, very light and simple still extracts big smiles and satisfaction.

Cheers, Hans
 
propeller

Don?t have the experience of SmokeyRay (wish I did), and for a fixed prop, the overwhelming RV consensus would be the Catto. When I bought my RV-4, it had a Sterba prop. I replaced it with a 60-layered maple Performance Propeller, which I had seen on several small Pitts and a One Design at aerobatic contests. The airspeed vs rpm seems to be a little different than most props. I received it after giving details of desired airspeeds and max rpms to the designer, without the final hard coatings. After some flight tests, I asked the designer to increase the rpm by 50. The airspeeds versus rpm tests were started with takeoff at full throttle and airspeed controlled with pitch. Some or maybe all of the rpm dip could be the increased in drag with increased angle of attack during the climbs to control airspeed at full throttle? Here?s the graph of the airspeed versus rpm before and after the slight modification.
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For what I do with my RV-4, O-320, 160 hp, the Performance Prop has been very satisfactory with very good takeoff and midrange accelerations.
Bill McLean
RV-4 slider
Lower Alabama
 
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