RV6/6A - Best Engine/Prop For Speed

There was another thread on here about RV6 cruise speed which is of a similar nature to my question, but didn't hit it exactly on the head, so I figured I'd post my own.

I've finally decided on my first aircraft to purchase and want to go with an RV6 or 6A. I'm got my PPL in a Citabria and am about to finish my IFR, but the range and speed limits of the Cessnas in the club I fly with have driven me to become an owner. Now just finding the right one...

Speed and efficiency (gph) - but mostly speed - is obviously the primary driver in something for cross-country. I chose the 6 because one can tend to get more for the dollar than with a 7, I only need two seats, more bang for buck with an experimental, a proven design, and it will give me the opportunity to continue my limited aerobatic experience from when I flew the Citabria.

In my search for a good copy though, I do tend to come across a wide variety of results with regards to performance. Some folks say their O320 and FP gets them nearly the same cruise as others with an O360 and CS. Others disagree. But with so many different combinations, it's hard to parse out good from bad in my situation.

So here is my question: Are there some generalized standards when it comes to engine and prop combos for the RV6/6A? Well known winners? Losers? What should a prospective owner know going into this kind of decision?

I understand the increased expense of the CS prop and can accept that for the performance benefits, but I mainly wish to achieve the performance I'm looking for (book performance) without exotic options that lack support (either company or in the field).

Also, I know everyone has their opinions. I'm looking for yours, not looking to facilitate and argument, so avoiding tangents will be appreciated!

Thanks everyone!

The fastest RV-6 was Tracy Saylor. You will need to go look at race results for Sun-N-Fun race years back to see the speed he did.

Tracy had the 180 HP parallel valve with a Hartzell Constant speed prop and lots of mods.

When one compares engines, the 180 HP parallel valve engine uses less pounds of fuel per horsepower produced than the 160 HP engine.

The constant speed prop is a compromise over the fixed pitch. At one speed the fixed pitch will be more efficient than the fixed pitch but at all other speeds the constant speed prop will be better. The constant speed prop allows you to have the max power available at any speed or location that the aircraft is located. Push the blue know forward (high RPM) and the throttle forward (high MAP) and all the power the engine can produce will be available. Yes you may need to adjust the red knob to get peak horsepower. The constant speed prop will also allow you to get best efficiency out of the engine. Most miles per fuel used. You can pull the blue knob back lowering RPM to get best efficiency out of the engine where you burn the least fuel per horsepower produced.

The fixed pitch is like having a transmission on a car that only had one gear. You start out lugging the engine and as speed picks up, the engine RPM goes up to the point that you can either over speed the engine or get to maximum RPM. When taking off, the fixed pitch will prevent full power because the engine will not be able to get to maximum RPM. At some speed and altitude, the fixed pitch prop will allow the engine to overspeed.

From one old pilot to another OP. Check your messages. I hate to type.

I'm probably not the best qualified to respond, but just so you know, I've been looking at RV's for a while and have pretty much excluded the 6 from my search specifically because in my case, it doesn't fit my X/C mission.

My friend had a 6 and loved it, but it only had 38 gal fuel tanks and with a big engine + constant speed prop, the useful load is pretty small unless you get one where the builder has upped to max gross from what Van's recommended. That's what my friend had and he had no problems with it, but it's not for me.

Best speed, overall performance and value = 180hp c/s prop
Best mph per dollar = 160hp catto 2 blade prop

The only time you will ever want more performance than the 160hp fixed pitch prop offers is everytime you fly with your buddies with 180hp planes. The 160hp planes are great and perform wonderfully, but watching your buddies pull away by 10kts has cost me $30k to remedy.


I have an 0320, conical mount, in my rv6 with rv200 c/s prop. I overhauled the engine recently and did a bunch of internal mods. It is now putting out around 190hp. I am getting 172kts tas at 8000ft DA at 100 ROP on a pretty clean -6. Of course after flying to oshkosh with 200hp birds, i am again searching for 5 more kts. �������� It never ends if you are addicted to speed. The limiting factor is the 182kt VNE, if you care about such things.

Non-exhaustive list of advantages provided by a CSP:
- getting outta short fields, the more so with obstacles close by
- lo speed hi ROC when mountain flying.
- easier adjustments whilst formation flying
- showing off when you decide to pull away from your flying buddy...
- braking effect. Going from lo to hi RPM on approach will load my shoulder harness alright. Now add a sideslip and ya talkin' short field approach
- cruise flight might also be more relaxing noise wise, as you'll have the option of using lower RPM and still increase the boost some, depending on your favourite % setting...

My 2cts, if $$$$$ allow, buy the biggest more powerful engine available and a CS prop. And the sissy wheel at the rear end.

DeeCee 57 said:

Non-exhaustive list of advantages provided by a CSP:
- getting outta short fields, the more so with obstacles close by
- lo speed hi ROC when mountain flying.
- easier adjustments whilst formation flying
- showing off when you decide to pull away from your flying buddy...
- braking effect. Going from lo to hi RPM on approach will load my shoulder harness alright. Now add a sideslip and ya talkin' short field approach
- cruise flight might also be more relaxing noise wise, as you'll have the option of using lower RPM and still increase the boost some, depending on your favourite % setting...

My 2cts, if $$$$$ allow, buy the biggest more powerful engine available and a CS prop. And the sissy wheel at the rear end.

Click to expand...

What he said. Sometimes the truth hurts.

Normally I'd be all about more power, but there's an RV6 on one of the sales sites right now with a 200hp io360 and a whirlwind C/P prop. I inquired about it because it seemed like it would be a super fun plane to fly, but the empty weight is so high that with me (170 lbs), my wife (125 lbs) and no bags, there was only enough useful load left for 28 gal of fuel.

No doubt it's great fun for blasting around for a couple of hours, but if part of the mission is cross country flights, having to stop every 2 hours for gas would get old in a hurry.

He said part of his mission was cross country flights, which is the only reason I bring it up.

1994 RV6 Performance.

8,500 MSL
Winds light & variable.
WOT: 2400 RPM
160 HP Carb.
Hartzell Constant Speed.
LOP
171 knots GS
7.5 GPH
100 Octane Fuel

Tracer, Ground speed means nothing...did you mean TAS?

CS prop is more fun!

Bevan

We just completed a long cross country coast to coast and return and I kept track of our performance. We have an RV6A with a IO-320 and one PMag and a constant speed prop. At lower altitudes and 23 square we make around 150 knots. When we are between 8 and 9000 feet and 75% we get in the lower 160?s and when between 11 and 12000 feet we were getting between 165 and 168 knots in smooth air with autopilot driving burning 8.2 gallons per hour. We have an increased gross weight of 1800 lbs and we used all of it with fuel fuel and a hundred pounds of camping and baggage plus the two of us. When we departed Casper Wyoming the density altitude was 8500 feet and the amazing little RV still got off quite well and we cruise climbed at well over 500 FPM. You might get a bit more performance out of an O-360 but we are delighted with the IO-320 in every way.