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Fuel Flow O-360 RV-6

G

Geeman

Well Known Member
OK guys, I just joined the RV club. This will be the first of many questions I am sure.

I purchased a flying RV-6 last weekend and just flew it home 410 nm. It is carbuerated, and does not have a fuel flow computer. It also does not have CHT/EGT....I know, this will be my first mod. I flew it up to 10,500 and leaned it the old fashioned way, leaned till rough and turned it back in till it smoothed out. It burned a little over 10 gallons/hour on that trip. I pulled the plugs and they looked like I was running really rich. Plugs were cleaned before I left. Just completed the annual.

I have flown a friends RV-7A with a Dynon and we could lean it out and burn around 8 gph up high with wide open throttle keeping the CHT & EGT in check. His plane is fuel injected.

My question, is this typical with an O-360? What kind of fuel flow is average? I am looking at putting a Dynon in the plane with EGT/CHT/Fuel so in the future I can better monitor the engine.

Any thoughts?

My first attempt at posting a picture.

RV-6KTYR.jpg
 
I have a RV-6 with a carburated O-360. 50 Degrees rich of peak usually gives me around 9 to 9.5 gph. I don't think you're too far off the mark. Are the plugs black or is there a lot of lead build up on them? If they are just black you may want to keep an eye on your oil consumption as it my be oil fouling and not because it's too rich.
 
Fuel burn

Seems like alot of fuel at an altitude of 10.5K. Based upon other 360's I've flown I would expect about 9-10 gph down lower where you were making 65-75% power.

Not sure what the expected burn would be at 10.5K but I'm guessing 9 gph max (ROP).
 
Same as mine

Mine burns 10 Gal per hpur at 8-10K and WOT. Had 2 different carbs and they were both burning the same.
 
Around 10 GPH overall

Have flown 0-360 Constsant Speed for 10+ years, and overall average is between 9 & 10 gph. You can set your clock by it.;)
 
Nice looking RV. Congratulations on the purchase.

I have found that my carbureted O-360 is much more accommodating to leaning if I am not WOT. It stumbles on much higher fuel flow when WOT, so I always pull the throttle back in cruise, at least just a little. Others have theorized, on this board and other places, that the turbulent flow around a slightly displaced throttle plate may aid in evening out of fuel distribution to the various cylinders. Maybe your engine set-up is similar.

Since I have Pmags, this comparison may not be relevant, but at 10.5K I'd expect my Fuel Flow to be under 8 gph, probably right around 7.5. I have an EI Fuel Flow monitor and it pretty much matches what the gas pump tells me when I fill up. That isn't WOT though either.
 
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Unfortunately, 10 gph at 10.5K sounds pretty high to me Kyle. I'd probably be down around 7.5 with the throttle just off the wide-open stop (to get it out of th eenrichment zone and create a little throttle plate turbulence) with our carb'ed 360's.

Paul
 
You did not mention what RPM you were running at that altitude.

Since I can see you have the Sensenich fixed pitch prop., if you were running at full throttle, and you have the same prop pitch as is typical, your fuel flow was probably just a bit higher than I get with my airplane (I will typically get 9.5 or so at that alt. WOT, which will produce about 2650 RPM).
 
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If I strain my eyes with the little power charts in the O-360 Operators Manual -

It looks like at 10.5 press. alt. max. power is just about 70% of rated from the alt vs rpm vs power chart.

This 70% gives a Min. fuel flow of 9 gall/hr on the fuel flowchart.

Does anyone read it differently?
 
O-360 Fixed Pitch

A week ago I had a 550 NM leg and burned a tad less than 7 GPH at about 160 knots TAS and 11,500 MSL. Nice little 3.5 hour flight with a slight headwind. That is throttled back considerably at about 2500 to 2550 RPM but I didn't record the MP. For shorter hops I figure 7.5 GPH at that speed. For lots of local stuff down low and faster with short hops it can be 8.5 GPH. It has never been as much as 9 GPH except for very unusual racing type stuff down low (low for me would be 4,000 MSL). I lean just as the original poster stated he leans. I have a carb and my EGTs will be all over the place. Everywhere from well LOP to peak to ROP.

I have kept a fuel consumption record for the last 13 years. Average consumption to this point is 8.34 GPH and dropping steadily. I have had no engine problems during that time.
 
Hi Kyle,

Welcome to VAF---I think you will find the site enjoyable and hopefully informative.

Reference the 6a----sounds like your trip and the 10+ gph was based on block to block fuel usage -- ie it included the climb to altitude and the time still rich prior to reaching your lean setting. Was the lower burn in the friends plane calculated the same way or was it the ff from the instrumentation after the leaning process was completed??? You probably adjusted for this but if not it would account for a big difference--especially if you were climbing from a relatively low altitude.

Just for info, my 9a with a carbed 360 and a fp Catto prop usually burns around 8 gph at my normal 60-65% power setting while in the cruise phase. I do have a LS EI on one side and a mag on the other!!

Again, welcome to the world of RVs.

Cheers,

db
 
Ditto What Paul and Scott Said

rvbuilder2002 said:
You did not mention what RPM you were running at that altitude.

Since I can see you have the Sensenich fixed pitch prop., if you were running at full throttle, and you have the same prop pitch as is typical, your fuel flow was probably just a bit higher than I get with my airplane (I will typically get 9.5 or so at that alt. WOT, which will produce about 2650 RPM).
Click to expand...

Ditto What Paul and Scott Said.... I do not have my fuel flow monitor hooked up yet but I did measure mine twice at 8500'. I taxied, climbed and descended on one tank and flew exactly one hour on the other tank. Filled the tank upon landing to measure the burned amount. WOT throttle pulled back slightly below 2700 rpm prop limit. Cruise burn was 9.7 gallons both times. Speed was right around 200 mph. I believe I will try that at 10,500' and see what that brings but I think it will be just like Scott's experience (Trust that experience) O-360 A1A carb with a -85 pitch Sensenich prop.

ps GeeMan my call sign is G-Man.....:) Law Enforcement related or is that your last name?
 
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