I just recently picked up a new toy, a RV-4 with a O-320 160hp engine. I have a few questions and would like some input.
First off, the plane has a 3 blade Catto prop on it. To me, the RPM seems low. I will try to fly it today and take notes of the RPM it achieves static, and during the take off run and climb out, then again at full power in level flight... But till then, I just think its a bit low, almost as if it is over propped.
In the panel there is a manifold pressure gauge. Prop is fixed pitch thou.
Also in the panel is a fuel computer that I can see my fuel burn.
So I am using the fuel burn rate, and rpm and manifold pressure all together to try to set the throttle for cruise flight. As it is, I am setting the power for about 2300 rpm, and seeing 22-23 inches of pressure and a fuel burn of around 9 gallons per hour. airspeed is only around 160 mph at this setting.
At those settings, I have ALOT more throttle lever to go forward, but then fuel burn goes up quite a bit too. I had always been told to expect 7-9 GPH out of a 320, so to go with more throttle, ( I need to experiment with it some to be sure ) I believe I will be in a GPH range of 10.5-11.5 easily.
If the plane didn't have that fuel flow gauge I would just throw the throttle further forward and go faster, but seeing 10+ GPH makes me think I am either giving it too much throttle or something???
Perhaps the fuel computer isn't accurate? IDK
So the other thing I wanted to discuss, is would it be SAFE to run car gas in this engine? It is a 160hp version, and the logs on this plane kind of suck... It appears to have gotten new cylinders back in 2012 or so, but doesn't say what brand or what compression ratio. All I could find was some paperwork from ECI authorizing some type of paint color application onto the cylinders, with a log book entry saying new cylinders were installed in 2012.
I have access to 90 octane non ethanol fuel, and access to 93 octane pump gas ( pumps all say it could have up to 10 percent ethanol in it )
I know some will say fuel costs should be the least of my worries, but it does add up! Av gas is currently 4.50 a gallon at my place, where as 90 octane non ethanol is 2.25$ a gallon currently. In a plane that may be burning 9,10 or even 12 GPH, That could be a savings of 20-27$ per hour.
I used the 90 octane for 5 years in my old Piper Tri Pacer with a 150HP 320. And have used it in my Jabiru 3300 powered Sonex for the last year and a half with no problems.
Your thoughts? And any factual info to consider?
And I guess, if the auto gas is not totally ok, but not totally bad, perhaps a mix of AV gas and autogas would be ok? I have a large 120 gallon fuel cell / trailer in my hangar, so I could fill it with a ratio of say 50/50 av gas and auto gas and fill the plane that way. Wouldn't save me as much money as going 100 percent auto gas, but could still save me 10-15$ per hour.
First off, the plane has a 3 blade Catto prop on it. To me, the RPM seems low. I will try to fly it today and take notes of the RPM it achieves static, and during the take off run and climb out, then again at full power in level flight... But till then, I just think its a bit low, almost as if it is over propped.
In the panel there is a manifold pressure gauge. Prop is fixed pitch thou.
Also in the panel is a fuel computer that I can see my fuel burn.
So I am using the fuel burn rate, and rpm and manifold pressure all together to try to set the throttle for cruise flight. As it is, I am setting the power for about 2300 rpm, and seeing 22-23 inches of pressure and a fuel burn of around 9 gallons per hour. airspeed is only around 160 mph at this setting.
At those settings, I have ALOT more throttle lever to go forward, but then fuel burn goes up quite a bit too. I had always been told to expect 7-9 GPH out of a 320, so to go with more throttle, ( I need to experiment with it some to be sure ) I believe I will be in a GPH range of 10.5-11.5 easily.
If the plane didn't have that fuel flow gauge I would just throw the throttle further forward and go faster, but seeing 10+ GPH makes me think I am either giving it too much throttle or something???
Perhaps the fuel computer isn't accurate? IDK
So the other thing I wanted to discuss, is would it be SAFE to run car gas in this engine? It is a 160hp version, and the logs on this plane kind of suck... It appears to have gotten new cylinders back in 2012 or so, but doesn't say what brand or what compression ratio. All I could find was some paperwork from ECI authorizing some type of paint color application onto the cylinders, with a log book entry saying new cylinders were installed in 2012.
I have access to 90 octane non ethanol fuel, and access to 93 octane pump gas ( pumps all say it could have up to 10 percent ethanol in it )
I know some will say fuel costs should be the least of my worries, but it does add up! Av gas is currently 4.50 a gallon at my place, where as 90 octane non ethanol is 2.25$ a gallon currently. In a plane that may be burning 9,10 or even 12 GPH, That could be a savings of 20-27$ per hour.
I used the 90 octane for 5 years in my old Piper Tri Pacer with a 150HP 320. And have used it in my Jabiru 3300 powered Sonex for the last year and a half with no problems.
Your thoughts? And any factual info to consider?
And I guess, if the auto gas is not totally ok, but not totally bad, perhaps a mix of AV gas and autogas would be ok? I have a large 120 gallon fuel cell / trailer in my hangar, so I could fill it with a ratio of say 50/50 av gas and auto gas and fill the plane that way. Wouldn't save me as much money as going 100 percent auto gas, but could still save me 10-15$ per hour.