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Old 04-18-2017, 09:06 AM
BruceMe's Avatar
BruceMe BruceMe is offline
Join Date: Feb 2005
Location: Shawnee, Kansas
Posts: 531
Default RV-4 Efficiency Plan

I went on a rant and stole Axel's thread, I'm giving it back.

Here's the summary. I'll post here in the future as it progresses.

Dave Anders(most effient RV-4 ever) has some great info, search his name on here. From memory, the biggest improvements he found has getting air smoothly out of the cowl and under the belly. He made various ramps forward of the firewall and tweaked the exit geometry. So the exit air thing doesn't surprise me.

Here's a link to an old post I made here years ago.

I think these are notes from a talk, they're hard to follow, but appear to loosely diary the updates he made before for making his CAFE killer N230A.

I'd love to put together a site that was just dedicated to what he did and how. He doesn't post much to VAF or anywhere, what he has posted is astounding. 243mph top speeds with 2" of ram boost (perhaps exaggerate but not much). It seems he's made over 100 modifications over the years, I know I've seen lists of alterations and the delta.

Oh btw, I'm buying back the fastback RV-4 N254MM I built. If we ever meet we should take pictures together some time. I'd like to share ideas for getting it even more efficient.

I have a pretty well matched Catto prop, IO-320 (balanced injectors) that does 5.5gph at 140ktas @8,000 running lean-of-peak ~2300RPM. I'd like to focus on the air frame improvement next.

Cowl inlet/exit (James cowl?)
Exit ramp
Cleaner Fairings
The canopy is a mess in general, I need to rebuild it, when I do I'll lower it about 2"
EFII injection system

I home in combination this gives another 8-10 kts on that 5.5gph cruise or ~4.8 gph 140ktas.

Other than the fastback and the ubiquitous PR wheel pants, my engine/airframe are totally stock RV. The engine started life as an O-320 that I converted to injected and has new slick mags. I have the very stock 2:1 exhaust. I'd like to put together a thoughtful upgrade plan and execute one at a time and re-test after each and get numbers just as Dave did.
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Last edited by BruceMe : 04-18-2017 at 09:08 AM.
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Old 04-19-2017, 02:34 AM
Capt Capt is offline
Join Date: Feb 2017
Location: Australia
Posts: 5

Gee all that sounds flash:-) I'd love a 4 with 200hp & 200MPH but am dreamin' I now !
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Old 04-20-2017, 07:45 AM
BruceMe's Avatar
BruceMe BruceMe is offline
Join Date: Feb 2005
Location: Shawnee, Kansas
Posts: 531

My RV4's IO-320 will never do more than maybe 170hp in a 2900 RPM full throttle dive. My goal isn't to make the baddest RV ever... there's a long line for that title. I'm aiming for total performance optimized on efficiency. Cruise like a Mooney on 150 burn-rates all operating off 1500 turf and still able to flip it around for fun if I want.

Serial Builder
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Old 04-20-2017, 08:40 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
Join Date: Jul 2009
Location: Mojave
Posts: 3,423

Good idea for a thread/plan. I met Dave at Mojave this past weekend and share his enthusiasm for efficiency. I hope to follow a similar path with my Rocket. Though I'd like to eke out a little bit more speed, my primary goal is to get the fuel burn down as low as possible while still truing 200 Knots or better. I could do 201 @ 11.5GPH all day long with the Bendix FI, but I want to solidly plan for 200 @ 10 ("solidly" = I have some margin for less than ideal winds and temps). After speaking with Dave and hearing his overwhelming enthusiasm for the SDS fuel injection, I suspect I'll have that performance in the bag once I get it flying again. In addition to the SDS engine management, I have a fairly lengthy list of aero and cooling changes which will be detailed on this board once they are validated through a flight test series.
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
PA-20-inspired "family truckster" -in work

Last edited by Toobuilder : 04-20-2017 at 10:05 AM.
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Old 04-20-2017, 09:39 AM
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BruceMe BruceMe is offline
Join Date: Feb 2005
Location: Shawnee, Kansas
Posts: 531
Default EMS

I'm definitely interested in an engine management upgrade. I'm weighing the costs of the various package systems with a more "assemble/tune" yourself... When I get closer to that decision I'll make some posts. There's a pretty huge difference in cost.
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Last edited by BruceMe : 04-20-2017 at 10:03 AM.
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Old 04-20-2017, 02:50 PM
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AX-O AX-O is offline
Join Date: Jun 2005
Location: SoCal
Posts: 2,085

I will talk to Dave and see if I can pass you his phone number. He is always open to talking mods and discussing performance. Just to warn you... he is on a whole different level than most of us. His experience is worth the price of gold.
RV-4 fastback thread
RV-4 fastback Pics
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VAF 2017 paid VAF 704
The information that I post is just that; information and my own personal experiences. You need to weight out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk.
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