T

TShort

Well Known Member
Well, I'm back from OSH and altho it will be a few more months before I need to decide for sure I'm looking for some input on engine choices for the -8.
I like the idea of a larger displacement / low compression engine that is "loafing" more than a high output tuned engine. I talked with Allen Barrett at length about the IO-390; he is putting one in his -8. My main concern is W&B. I have read all the previous posts about building light, forward CG, etc and really don't want a heavy / nose heavy plane. There doesn't seem to be any info on Checkoway's W&B site for the 390; additionally, there are parallel valve engine setups that are heavier and nose heavier than some of the angle valve setups on the list.
I think if I go with the IO-390 I will almost be obligated to get a composite prop.
If money were not a concern (I wish!) what would you guys pick as the "ultimate" combo for the -8? I'm thinking maybe the IO-390 and the Aerocomposites prop. The 340 stroker is an interesting engine, but leaves little alternative if 100LL becomes a problem in the future. Allen Barrett said the 390 could burn ethanol (anyone see the ethanol powered fleet of RV-3's and -8 from SD at OSH - pretty cool!!)
 
There will always be the urge to shoot for upper HP limits by many, but at least sit down and seriously consider a standard 180hp '360 at 8.5:1.

If you look at the numbers you get by hanging good prop on it (constant speed OR fixed), you'll meet or exceed Van's posted numbers all day long.

Low compression, balance of intended design, simple, economical... Just Do It. Fly more, tinker less. ;)
 
Yes......0-360

Vern is right on the money. The -8 with an 0- or IO 360 is the way to go. A friend built one and used a composite MT and is really happy with the result. As it stands right now, the 390 doesn't have the history that the 360's do and your resale is good since that seems to be the engine of choice,
 
I agree wholeheartedly with Pierre and Vern.
It's hard to beat the parallel valve O-360 with the Catto 3-blade.
If you don't mind the extra cost and weight, then the c/s prop is ok also.
 
Anyone know the full (ballpark) price for those engine kits. I see all they have on the website is individual prices listed. I realize thats probably so you can pick and choose on everything but I just want to know the cost for the basics with carb and mags.
 
I'm building an '8 and have a new IO-390 and an Hartzell extended prop. I looked at Checkoway's weight and balance spreadsheet

http://www.rvproject.com/wab/

and looks like several have IO-360's (200hp) and Hartzell's. The 390 is almost the same weight as a angle valve 360 when configured the same (308 vs 304). My prop is about 12 lbs heavier and is located about 3" forward compared to a standard hub. BTW, Dan's site also has the type certificates for most of the lycoming's and Hartzell's, so you can do your own analysis.

I ran the following on one example that has a IO-360 and a Harzell. Looks like myself, a 180lb pass, full fuel, and 80lbs of baggage is still within limits.

The only change I'm considering is to put my aux battery in the very rear of the fuselage depending on how things work out. I may also bump the gross weight up a little depending on the empty weight.

--- One particular RV8 -----
Engine: Lycoming IO-360 (200 hp)
Propeller: 74" Hartzell 2-blade Aluminum Constant Speed
Number of Seats: 2
Fuel Capacity: 42 gallons
Empty Weight: 1125 pounds
Empty CG: 76.86" aft of the datum
Max Gross Weight: 1952 pounds
Useful Load: 827 pounds
Full Fuel Payload: 575 pounds
CG Range: 78.7" to 86.82" aft of the datum
Aerobatic Gross Weight: 1600 pounds
Aerobatic CG Range: 78.7" to 85.3" aft of the datum
Owner's Comments: No vacuum system, GRT EFIS, Stab Camera, not painted, all fairings on, Todd's 1/4inch canopy

--- Fully loaded ----
Custom Loading Scenario
Fuel: gallons (max 42)
Pilot: pounds
Passenger: pounds
Baggage: pounds (max 50)
forward baggage: pounds (max 50)
Rear baggage floor: pounds (max 50)
Rear baggage shelf: pounds (max 25)

--- Resulting W&B ---

Your Custom Loading Scenario:
Weight Arm/CG Moment
Aircraft 1125 76.86 86472
Fuel 252 80 20160
Pilot 210 91.78 19273.8
Passenger 180 119.12 21441.6
Baggage 0 138 0
forward baggage 30 58.81 1764.3
Rear baggage floor 50 138 6900
Rear baggage shelf 0 152.91 0
Total 1847 84.47 156011.7

Like they say in the country..."you makes your choices and pays your moneys". (YMMV).

Deene
RV8 QB, IO-390X, Hartzell BA, SJ cowl and plenum
 
I'm also in the Vern/Pierre/Mel camp. Until proven otherwise, the 340/390's need some time on them to see how they're going to fare. I really like the 340 concept but then there is that nagging fuel issue. For angle valve or 390 motors, more weight on the nose than an O-360/Hartzell and you're asking for weight issues. Then, it all boils down to where to put the battery, gross weight adjustment (up), acro loadings, typical pax weights, etc. There is no single right answer. I like to remind folks in this decision making dilemma of my friend Jeff Ludwig's former RV8 in which he checked me out for five hours for insurance requirements: He won the Airventure Cup race a coupla times as I recall, with O-360/Hartzell and solid piloting skills. Hauling around 30 or so extra pounds on the nose when you're just out to get a hamburger on most of your flights is kinda silly. LIGHTWEIGHT RV's are AWESOME. When heavy, much less so. Short, stubby wings don't like flying heavy.

When my RV8 is flown solo, with half tanks, it's a total blast and feels light and nimble. When dual with a big bubba in the pax seat and full fuel, it almost feels ponderous and anemic. Still, it blows the doors off most spam, but is remarkably different in character

Horsepower is nice, VERY nice, but at what price?
 
Well put...

Well said, Brian,
I went out at early sunup last Saturday, solo, 1/3 tanks and tried a few loops and rolls....what a difference! I've also had 270 lb pax and full fuel....yes, a different airplane and we only weighed 1046 empty, :)
 
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