R

rrnixonjr

Active Member
I currently have an RV-4 with a 160hp 0-320 and a fixed pitch prop. It runs great but I want more thrust and speed control as I often fly formation and aerobatics with an Extra 300, a Rocket and a 0-360 equipped RV-4 with a constant speed prop. My plan is to install an IO-375 with a constant speed prop and recowl the plane while I am at it as the old cowl is getting pretty worn and I want Cam Locks. On the other hand I could stroke the 320 into a 340 and use a light constant speed prop.

I would appreciate any input. Thanks.
 
Stick with the Fixed.

If you want fine speed control (vs. fast top speed) you should stick with the fixed pitch--and if you have a metal prop, try a light composite. A heavy constant speed will only reduce the responsiveness as you wait for the prop to spin up or slow down whenever you adjust power. A light fixed pitch will instantly spin up.

Try the Catto.

-Matt
402BD
 
Ahhhh!...... The good ole Never Ending Debate, again!:rolleyes: And I believe top speed is not materially affected by whether the prop is FP or CS.
 
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Have you considered just the CS prop??

I fly an RV6 with a 160 HP O-320.

And, I fly formation with friends (Team RV) who have 160 (one other RV6), 180 (the majority), 200 (I think there is one) and 260 HP.

This has included RV4's, RV6's, RV7's, an RV7A, RV8's, an RV8A and a "Super 8". So there is a bit of (RV) variety.

Far more critical than horsepower for precision formation is the constant speed prop with NO vernier throttle. These two items are requirements in Team RV.

See: http://www.youtube.com/watch?v=j1BkSph-Kj0
-or-

http://www.facebook.com/pages/Team-RV-Airshows-Inc/127001924010418
 
Had a Warnke FP prop and it was difficult to hold position. Too much throttle work needed. Especially in rough air. Replaced it with MT FP prop and no problems at all now. This thing is like having a manual transmission car. Ease off power, it slows right now...push it up, it moves right now. Love it. Lighter prop than the warnke too. (both wood, go figure!) Had to add the Landoll ring to move the C/G back fwd a bit too...
Consider it...

Dennis

rrnixonjr said:
I currently have an RV-4 with a 160hp 0-320 and a fixed pitch prop. It runs great but I want more thrust and speed control as I often fly formation and aerobatics with an Extra 300, a Rocket and a 0-360 equipped RV-4 with a constant speed prop. My plan is to install an IO-375 with a constant speed prop and recowl the plane while I am at it as the old cowl is getting pretty worn and I want Cam Locks. On the other hand I could stroke the 320 into a 340 and use a light constant speed prop.

I would appreciate any input. Thanks.
Click to expand...
 
We do a lot of Formation, including Aeros and running a Formation School for RVs.

As above, CS prop is probably 1st on your shopping list. FP props all seem to "sing" at different speeds, and clearly lose thrust at low speed (over the top of a loop etc.). They also at high speed lose power as you pull the throttle back to avoid overspeeding. Effect is that even 2 FP props in Formation (Aeros) can be challenging, FP + CS far more difficult.

I am not saying FP is unsuitable... if budget / cruising / weight / complexity mean a FP prop is for you, then you can live with it in Formation (Aeros). But if you are going for a change, CS will be the biggest gainer.

Am sure you have considered CG. By altering 320/FP to 360/CS CG will go forward, which in a solo 4 could seriously damage it's "fun factor" :eek:

HTH
Andy
RV-8 G-HILZ
 
Thank you all for your informative comments. My current prop is a carbon Prince and it works fine for cruise, just out ran a friend's angle valve 360 going down the beach over the water. What I need is a better climb to stay with everyone, especially going vertical and as Andy said to improve performance in acro. So, which prop? Whirlwind, MT, Variprop? I need light so the Hartzell is out, I don't want to change my 4's sweet handling. Should I make the wide deck 320 I have into a 340 or sell it and buy the 375? The 375 should weigh very little more. I agree that balance is important, that's why I don't want to buy a Rocket, it just doesn't handle as sweet. I can afford the 375 but is it worth the premium over the 340? Thanks again to everyone for replying.
 
rrnixonjr said:
Thank you all for your informative comments. My current prop is a carbon Prince and it works fine for cruise, just out ran a friend's angle valve 360 going down the beach over the water. What I need is a better climb to stay with everyone, especially going vertical and as Andy said to improve performance in acro. So, which prop? Whirlwind, MT, Variprop? I need light so the Hartzell is out, I don't want to change my 4's sweet handling. Should I make the wide deck 320 I have into a 340 or sell it and buy the 375? The 375 should weigh very little more. I agree that balance is important, that's why I don't want to buy a Rocket, it just doesn't handle as sweet. I can afford the 375 but is it worth the premium over the 340? Thanks again to everyone for replying.
Click to expand...
Which "dash" number O-320 do you have? Can you even install a CS prop on it?

Add dual electronic ignition to your O-320/340 and you should add around 6% percent more power, which will get you close to 180 HP.
 
Yes, I can put a constant speed prop on my 320, can't remember the dash number but will look at my engine log. The engine has three main bearings, big front one, I think that was necessary for 160hp. I starting to think about the stroker, and choosing a constant speed.
 
You will get lots of opions on this subject.

To QUOTE an early RV-3 builder and Warbird restorer:
"There is NO subistue for cubic inches."

I fly a lot of formation with an RV-6 320 Constant Speed Hartzell. The RV-4 in the same setup is a lot faster. The RV-4 160 Constant Speed Hartzell will keep up with other RVs in formation when they fly per the RV Supplement to the T-34 manual and still have some reserve power.

If you go with the 340, you will have two choices on the crank flange. (320 flange or 360 flange) My opion is get the one with that is same flange as the 360. IMHO, the Hartzell constant speed prop for the 320 would be better if it had more twist. In other words, it is not as effecent converting horsepower to thrust at high speeds and would be faster with more twist or the same blades at the 360.

I do not know a lot about the 375. I do know that Bart is a good guy to work with. Why not just stick with the 360 that everyone else uses if the Constant Speed Prop on the 320 is not enough? Since you are thinking that you need a bigger engine, you will more than likely not be happy till you get the bigger engine.
 
Turbo...

Rebuild the 320 with 8:1 pistons and go turbo with a Whirlwind! You will have power galore and will have added little weight.

Hans
 
My Understanding is..

The MT constant speed composite props are much lighter and more responsive. If you get the right one it is supposed to be hard to over speed.

I ordered mine from a hardware customer of mine.

Jim from Less Drag Inc. 805-795-5377

I will let you know how it works once its installed 1+yrs from now.

Best Wishes,
 
not constant speed prop but. . .

I cannot comment on the constant speed prop as I have not run behind one before. I really cannot comment on the performance in formation flying as I have not done that either. I know the constant speed prop was your original issue but you also alluded to a debate over a 340 stroker vs 375. I can comment on that.

I am running the ECI IO-340 in an RV9A with a 3 blade Catto. ECI is rating this engine at 185 HP. During my build I made every effort to measure the weight of this engine with all of its components so I could get a true idea of what my Firewall Forward weight was going to be. In other words its "ALL UP" weight.

Here are the numbers I have on my installation. I did not rely on any manufacturer supplied information on weight. I weighed each individual component myself:

  • ECI IO-340 Dry Engine (includes 1 Slick Mag, 1 Lightspeed Plasma III EI) 250
  • Sky Tech Starter 7.9
  • Plane Power Alternator 8.5
  • Odyssey PC680 Battery 15
  • Flywheel 7
  • Ignition Coils & Spark Plug Wires 1.5
  • Misc. Hoses & Cables 1.5
  • Sabre Prop Extension 8.5
  • Catto 3 blade 68" X 72" Prop 12
  • Engine Accessories Sub Total 311.91

In my opinion you could not go wrong with the 340 Stroker. It is proving to be a great engine for me so far. Of course, by all means, you should take my statements in context. I only have about 41 hours total on this engine as I have just been running it since July 20th. However, it is proving to be a very strong work horse.

My .02 on your engine choices. Good luck with your changes whatever you chose.
 
Thanks for all the comments. I think I will go with a Whirlwind prop to start and add more if I need to. Pete Hunt, I hope you are well. It was great seeing you in Reno.
 
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