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  #1  
Old 10-31-2006, 09:33 AM
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henriquerv9 henriquerv9 is offline
 
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Default IO390 FUEL CONSUPTION

HI ALL,

JUST WONDERING IF ANYBODY IS USING A IO390 (210HP ENGINE). I WOULD LIKE TO KNOW HOW THIS ENGINE IS PERFORMING FUEL CONSUPTION LET'S SAY, AT 8000' AND 75% AND 55% POWER. IS THE CONSUPTION CONSIDERABLY HIGHER THAN A TRADICIONAL IO360 180HP ENGINE?


THANKS ALL


HENRIQUE CASTRO
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  #2  
Old 10-31-2006, 09:54 AM
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mark manda mark manda is offline
 
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Location: Bakersfield ,Calyfornia
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Scott Farner is in Phase one at Chino with his IO-390x-- I'll check with him. Or if any of the Chino guys read this they see him regularly.
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  #3  
Old 10-31-2006, 10:49 AM
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gmcjetpilot gmcjetpilot is offline
 
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Default Horses Eat

Quote:
Originally Posted by henriquerv9
HI ALL,

JUST WONDERING IF ANYBODY IS USING A IO390 (210HP ENGINE). I WOULD LIKE TO KNOW HOW THIS ENGINE IS PERFORMING FUEL CONSUPTION LET'S SAY, AT 8000' AND 75% AND 55% POWER. IS THE CONSUPTION CONSIDERABLY HIGHER THAN A TRADICIONAL IO360 180HP ENGINE?

THANKS ALL HENRIQUE CASTRO
For a guess you can ratio the HP 210/180=1.16 to get an approximate fuel burn. Horse power: Horses eat. The more ponies the more fuel. It is basically a function of HP.

You could throttle back and burn the same fuel as a 180 HP, e.g. same airspeed, but apples to apple 100%, 75% and 55% power you will make 16% more power and burn 16% more fuel. Yes?

Compression ratio is higher with the IO390 and should be more efficient. So the HP ratio may be off a little in favor of the IO390. Also since the IO390 is really closer to a IO360 angle valve it would be better to compare those two engines.

Dan has a IO360 angle valve and flys w/ LOP operations often and gets great reported fuel econ. However if you are putting a XIO390 you probably can afford the fuel. Its only money you can't take it with you, why make the kids rich when you die.
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Last edited by gmcjetpilot : 10-31-2006 at 11:55 AM.
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  #4  
Old 10-31-2006, 11:19 AM
scott7A scott7A is offline
 
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Location: Anaheim, CA
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I don't have any good numbers yet as I have been pretty conservative with the mixture. I haven't ventured down to 55% yet; still breaking in the engine, but at 75% and 8000 DA, I'm around 12gph.

Scott
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  #5  
Old 10-31-2006, 01:57 PM
Red Red is offline
 
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Default IO-390 compression ratio

The compression ratio I was quoted by Barrett for an IO390 was 8.7:1. This is a LOWER compression ratio than most IO360s I've seen in RVs.
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  #6  
Old 10-31-2006, 02:47 PM
Allen Barrett Allen Barrett is offline
 
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Location: tulsa, Oklahoma
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The IO-390 compression ratio is 8.9:1 Don't know what the actual fuel consumption really is, but at 75% leaned to BSFC of .52-.53, you should see right around 13 GPH, 10 @ 55%.

Allen
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  #7  
Old 10-31-2006, 04:18 PM
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hevansrv7a hevansrv7a is offline
 
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Default Picking a Nit

If you take two engines, identical except for displacement (same CR, prop, etc) and run them at the same HP, the larger one will have greater pumping losses and therefore, all other things being equal, will be less efficient. This is pretty much the same as the observation that the same RPM and MAP will give more HP at a higher density altitude, assuming the same RPM and MAP can be reached at the higher altitude. The reason is the resistance offered by the throttle plate. I don't know if this is a big deal, but it's fun to think about these things.
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  #8  
Old 10-31-2006, 08:04 PM
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MCA MCA is offline
 
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Default Fuel burn

I have about 96 hours on my RV-7 with an IO-390 and a 72" whirlwind prop (new 74" Hartzel arrived today). I usually cruise at 11k-12k ft (airport here is at 5,800 ft) and burn 7.4 GPH at 53% power, 50deg LOP.

At sea level takeoff (everything forward) it burns about 20GPH, and at lower altitudes it's something around 10-13GPH depending on the power. I haven't flown much at lower altittudes so it's not documented.

Hope that helps.
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  #9  
Old 11-01-2006, 07:04 AM
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mgomez mgomez is offline
 
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Quote:
Originally Posted by MCA
I have about 96 hours on my RV-7 with an IO-390 and a 72" whirlwind prop (new 74" Hartzel arrived today). I usually cruise at 11k-12k ft (airport here is at 5,800 ft) and burn 7.4 GPH at 53% power, 50deg LOP.
And how fast is your RV-7 under those conditions?

Thanks,
Martin
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  #10  
Old 11-01-2006, 08:52 AM
Walter Atkinson Walter Atkinson is offline
 
Join Date: May 2006
Location: Baton Rouge, Louisiana
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**If you take two engines, identical except for displacement (same CR, prop, etc) and run them at the same HP, the larger one will have greater pumping losses and therefore, all other things being equal, will be less efficient. This is pretty much the same as the observation that the same RPM and MAP will give more HP at a higher density altitude, assuming the same RPM and MAP can be reached at the higher altitude. The reason is the resistance offered by the throttle plate. I don't know if this is a big deal, but it's fun to think about these things.**


Since we're picking nits... Uhh, no. The reason it makes more HP at the higher DA is that there is less exhaust back-pressure and the cylinders have a better volumetric efficiency.
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