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  #1  
Old 02-03-2021, 05:01 AM
GyroRon GyroRon is offline
 
Join Date: Oct 2005
Location: Fort Mill South Carolina
Posts: 40
Default Got some questions about power, fuel burn, fuel type O320

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.
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Ron Awad
Fort Mill S.C.
Current fleet...
Jabiru 3300 Waiex
RV-4 160hp
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  #2  
Old 02-03-2021, 06:11 AM
rv8ch's Avatar
rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGY
Posts: 3,661
Default

What are you doing with the mixture? That's a big component. What kind of magnetos do you have? How are they timed? Another thing that can help/hurt a lot. How are your CHTs? Do you have an engine logging device that could provide data for a service like savvyaviation.com?
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  #3  
Old 02-03-2021, 06:15 AM
D Weisgerber's Avatar
D Weisgerber D Weisgerber is offline
 
Join Date: Sep 2019
Location: Ionia Michigan
Posts: 230
Default

I'm also curious what altitude you're at, when you say 160 mph is that true or indicated airspeed?
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first flight May 2, 1997
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  #4  
Old 02-03-2021, 06:18 AM
WA85 WA85 is offline
 
Join Date: Apr 2010
Location: Royse City, TX
Posts: 151
Default IO-320 data

I have an IO-320 with a FP W-W GA200L prop on my RV-8. When I built my fuel system, I made sure it was going to tolerant of 93E10. I have run about 2000 thousand of gallons of 93E10 through it in 585 hrs with no ill effects. There is a big WARNING about using STRAIGHT auto fuel - it will vapor lock / boil in the fuel lines on a hot day / hot engine scenario. At low power / RPM, this can lead to the engine stumbling or it just quits. Running the boost pump helps, but I typically run 70 /30 100LL to auto fuel during the hot summer months and 50 / 50 in the winter.
As far as power settings, using the Dynon SV engine power percent as a gage, at 65% power, 158 ktas at 7.6 GPH, 70% power, 161 ktas at 8.0 GPH, 75% power, 165 ktas - 8.5 GPH, WFO 178 ktas at 11 to 13 GPF.

All of these numbers are at around 5000 to 8000 ft MSL and vary based upon density altitude.

I do not pay attention to MP and RPM, with a FP prop, you get what you get by running at percent power settings.

At WFO, my prop is turning 2750 RPM, which is right at its limit.

A three blade prop on an O-320 may not give you the best speed, but might give you better climb. I have found that the W-W 200GL is the best 2 blade prop for my configuration.
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  #5  
Old 02-03-2021, 07:24 AM
edclee edclee is online now
 
Join Date: Aug 2008
Location: Lancaster, SC
Posts: 152
Default O-320

Quote:
...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.
I live just south of you at SC76 (Unity Aerodrome) and have a fuel tank in the hangar. I have an IO-320,160hp, 8.5:1 compression ratio engine in my RV-9A. The engine needs 91 Octane and running straight 90 non eth is just not going to cut it. It is not worth the risk in our hot weather here where your CHTs are going to be up. I run 4 parts 90 non ethanol to 1 part 100LL and get good results. That mixture should give you 92 octane. Even in the hottest August days I never had any issues with either detonation or vapor lock. I have run 93 ethanol in my 9:1 CR Sonex and had issues with both vapor lock and with detonation so I cant recommend it. It also has substantial storage issues, both turning bad in a short time and in absorbing water from the environment.

As for your power settings and fuel burn, there is not enough information to give any useful advice. The 9 gph consumption is about right for 75% power if you run rich. I never run rich, always lean of peak. In the 9A I get about 150 mph indicated, 155 TAS at 3000 ft at 6.7 gph. The 9 loves altitude and at 12000 ft full throttle (fixed pitch prop), 50% power lean of peak fuel burn is less than 6 gph with TAS of about 155-160 mph. LOP will always reduce the power (and speed) available of course, but does wonders for your fuel burn and the engine is happier with lower CHT, lower EGT, lower BMEP, what's not to like?. Power = fuel burned just no way around it. Best power is fast, but fuel burn is the cost. Fly down and see us sometime at Unity. We have another guy here from Fort Mill with a Just Highlander.
Ed
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  #6  
Old 02-03-2021, 07:34 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,865
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As mentioned, you don't describe how you are leaning. If you are running mixture full rich at cruise altitude, your results are not overly surprising. My 6 with a 320 does 185 MPH TAS at 8K' on 8.1 GPH while LOP. Expect a 4 to better that by at least 5-7 MPH. I do have EI that nets about a .5 GPH fuel efficiency over mags and a balanced injection system that also drives efficiency.

You need to do some searching on how to lean your engine at cruise. I also would not trust your fuel reading. Suggest you get the manual and run the calibration to ensure it is accurate.

Larry
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  #7  
Old 02-03-2021, 08:01 AM
BH1166 BH1166 is offline
 
Join Date: Nov 2017
Location: Eatonton Georgia
Posts: 373
Default Call Catto

with serial number off prop hub and they can likely tell who when and what the prop was built to do. Cruise, climb, or in the middle, or customers custom length/ pitch.

I run 93 octane non alcohol fuel in my 0320 D1A without issue. Lots of others do too, especially outside USA.

Good luck
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RV6A Purchased N72TX
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  #8  
Old 02-03-2021, 03:20 PM
edclee edclee is online now
 
Join Date: Aug 2008
Location: Lancaster, SC
Posts: 152
Default 93 non ethanol

Quote:
Originally Posted by BH1166 View Post
with serial number off prop hub and they can likely tell who when and what the prop was built to do. Cruise, climb, or in the middle, or customers custom length/ pitch.

I run 93 octane non alcohol fuel in my 0320 D1A without issue. Lots of others do too, especially outside USA.

Good luck
Wow, I wish we could get 93 non ethanol in South Carolina. We can only get 90 with no ethanol.
Ed
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Sonex/Corvair 2016 Finished, Sold 2020
RV-9A 2005 Purchased
IO-320 160 hp
Exempt but happily paid for 2021
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  #9  
Old 02-03-2021, 06:17 PM
GyroRon GyroRon is offline
 
Join Date: Oct 2005
Location: Fort Mill South Carolina
Posts: 40
Default

Quote:
Originally Posted by rv8ch View Post
What are you doing with the mixture? That's a big component. What kind of magnetos do you have? How are they timed? Another thing that can help/hurt a lot. How are your CHTs? Do you have an engine logging device that could provide data for a service like savvyaviation.com?
I have leaned it, but probably not far enough. I need to play with it some and watch the EGT while leaning to see where it a good spot mixture wise

The plane has a slick mag and a Pmag. The slick is supposedly set at 25 degrees.

Haven't paid a ton of attention to the CHT's. What would be good target numbers?

The plane has a ilevel device on it, I need to check and see if it data logs
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Ron Awad
Fort Mill S.C.
Current fleet...
Jabiru 3300 Waiex
RV-4 160hp
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  #10  
Old 02-03-2021, 06:18 PM
GyroRon GyroRon is offline
 
Join Date: Oct 2005
Location: Fort Mill South Carolina
Posts: 40
Default

Quote:
Originally Posted by D Weisgerber View Post
I'm also curious what altitude you're at, when you say 160 mph is that true or indicated airspeed?
indicated, at around 4000-4500 MSL, outside temps on the ground vary from 38-50 degrees F on the few flights I have made with it so far
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Fort Mill S.C.
Current fleet...
Jabiru 3300 Waiex
RV-4 160hp
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