L

Launchpad larry

Member
I know I'm getting a little ahead of my self but just wanted to know if anyone has gone over the recommended hp limit and how did it work out
 
180 hp is more than plenty.

My RV-4 has an 0-360 180 hp Lyc. and can almost hit redline in level flight at sea level. At 10,000 ft, WOT, it is right at redline (TAS) in level flight. Any descent requires a big reduction in power to avoid over speeding. Of course, cruising that far into the yellow arc requires very smooth air. All in all, I think 180 hp is too much for the airframe. I'd opt for 150 hp if I was building one. Cheaper up front, cheaper to operate, and safer. Just like Van recommends.
 
high HP -4s

There are a few 200 hp -4s out there with some impressive #s, but I have never flown one. I have flow a 300hp F1 rocket that was also impressive. I personally have a 160hp -4,with fixed wood prop, and I find it to be a great balance of good performance, light weight and decent fuel burn...sure,I'd love the 200hp, but it isn't really needed for my kind of flying.
 
The high water mark in RV-4s

The high water mark in my mind is set be Dave Anders. Jack Cox write an article about his airplane years ago when it was polished aluminum with red trim. Extremely fast with the Ly-con logo painted on the fuselage. I have the complete collection of Sport Aviation through the Jack Cox era on CD as sold by EAA. I will try to remember to look it up and tell yo what I find.

Bob Axsom
 
Power for a 4

I'm on my second RV4. The first one had a carburated 0320 with a wood prop.
The new one has a cold-air inducted, fuel-injected IO360, Lycon ported and balanced, putting out 210 to 220 hp with a 74 inch Hartzell CS. I'm getting some spider cracks in the bondo work on the elevator and have to be very careful not to "over-speed" it, especially on descents and in turbulant air.

The advantage is better climb with a full load, especially in high density altitudes. There are tons of guys out there with IO360's in 4's, and I'm not sure it's been a problem. For economy, the 320 is more efficient, for sure.
 
Dave Anders article

I never found the article I was looking for (it was probably in Sportsman Pilot and not in Sport Aviation) but for your purposes I found an article on the Dave Anders RV-4 that is probably better:

Sport Aviation January 1998, starting on page 38:

RV-4 New CAFE Triaviathon Champion​

Completed building the plane in 1991 (as if we ever complete) improved ever since.

Engine: Lycoming IO-360 A1B6 Engine by Lycon of Visalia, CA dyno reading 236 HP
Prop: Hartzell M2YR + 76-66 [sic] blades 70.5" diameter by Johnson & Son Propeller, Bakersfield, CA

In the CAFE testing:

Dave Anders' RV-4, on September
27, 1997, achieved the following:
Top Speed 250.71 mph.
Rate of Climb 3308.39 fpm.
Stall Speed 44.78 mph.
Score: 2381.24.

His airplane is painted white now with the same red trim as far as I can tell. I spoke to him briefly in Mitchell South Dakota before the 2010 AirVenture Cup Race where he won the RV Gold Class at 240.58 with his wife in back in a race that required significant deviations to maintain the race required compliance with VFR. So it is still fast and it has been flying for more than 20 years.

Bob Axsom
 
Rocketeers...

Launchpad larry said:
I know I'm getting a little ahead of my self but just wanted to know if anyone has gone over the recommended hp limit and how did it work out
Click to expand...

LL,
It depends on your definition of RV4. Long answer: YES! 300+HP. In 1990 John Harmon (5 time RV3/4 builder) decided to modify an RV4 kit and install an IO-540C4B5. He called it the Harmon Rocket 2. (The HR-1 was an RV3 with an IO-360) There are nearly 200 of them or derivatives flying. Short answer: YES!: In the stock RV4 form Bob A. is correct, the IO-360 A1B6 angle valve is probably the biggest 4-banger you could shoehorn into a RV4 cowling. However comma, the IO-390 is out there...

V/R
Smokey

PS: My HR2 was a modified RV4 kit with stock RV4 tail and .020 elevator/rudder skins, shortened wing per the Harmon plans and .040 forward fuselage skins. It's LyCon IO-540 dynoed at 313HP at 3000RPM. 220 KIAS was no problem in level flight...It's data plate shows it as an RV-4 :)
www.harmonrocket.com
 
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