Fuel Burn 4 Cyl (200hp) vs 6 Cyl (300hp)

[GeneralT001]

Hi,

IIRC fuel burn for a Lycoming 200hp 4 cylinder in cruise is around ~8-12 gph? What would it be for a Continental IO-550A 300hp 6 cylinder? I'm guessing 10-14gph? Guess my question is how much more per hour does this add up too in operating cost?

[Bolter]

31 minutes ago, GeneralT001 said:

Hi,

IIRC fuel burn for a Lycoming 200hp 4 cylinder in cruise is around ~8-12 gph? What would it be for a Continental IO-550A 300hp 6 cylinder? I'm guessing 10-14gph? Guess my question is how much more per hour does this add up too in operating cost?

Operating LOP Cruise, I was typically 8-9 GPH with a Lyc IO 360 in a J model at 150 KTAS and I am typically 13 GPH with a Conti IO 550 at 170 KTAS. 

You cannot beat the J for economy because that is 45% more fuel for 13% more speed.  Sure you can throttle back even more and get the Ovation to J speeds, but that is not how you would typically fly a plane.  And you are still burning more fuel at the same 150 KTAS.  

[GeneralT001]

48 minutes ago, Bolter said:

Operating LOP Cruise, I was typically 8-9 GPH with a Lyc IO 360 in a J model at 150 KTAS and I am typically 13 GPH with a Conti IO 550 at 170 KTAS. 

You cannot beat the J for economy because that is 45% more fuel for 13% more speed.  Sure you can throttle back even more and get the Ovation to J speeds, but that is not how you would typically fly a plane.  And you are still burning more fuel at the same 150 KTAS.  

Thanks Dan.

[Hank]

Long term, my C runs ~9gph, less up high, less when shooting multiple approaches. But I have to run ROP due to I efficient distribution after the carburetor. 

[GeneralT001]

5 hours ago, GeneralT001 said:

Thanks Dan.

 

6 hours ago, Bolter said:

Operating LOP Cruise, I was typically 8-9 GPH with a Lyc IO 360 in a J model at 150 KTAS and I am typically 13 GPH with a Conti IO 550 at 170 KTAS. 

You cannot beat the J for economy because that is 45% more fuel for 13% more speed.  Sure you can throttle back even more and get the Ovation to J speeds, but that is not how you would typically fly a plane.  And you are still burning more fuel at the same 150 KTAS.  

I guess the upside would be better performance in high hot conditions and rate of climb?

[Bolter]

24 minutes ago, GeneralT001 said:

 

I guess the upside would be better performance in high hot conditions and rate of climb?

More practically, a lot more useful load and cargo space.  Plus, for my standard 600 nm family trip, shaving 30 minutes with the 20 knots speed increase brings more family harmony.  If fuel economy is your primary goal, the J (or cleaned up E or F) is the optimum.  If you need more speed and more cargo volume, you look to the long bodies at the expense of economy.    

[NickG]

4 minutes ago, Bolter said:

More practically, a lot more useful load and cargo space.  Plus, for my standard 600 nm family trip, shaving 30 minutes with the 20 knots speed increase brings more family harmony.  If fuel economy is your primary goal, the J (or cleaned up E or F) is the optimum.  If you need more speed and more cargo volume, you look to the long bodies at the expense of economy.    

Plus you get alot more performance from the O than the J. Even more with the STC and 310 HP. I can true 172-174 KTAS at 12-14k at 11.5 GPH or so. 

[Shadrach]

2 hours ago, GeneralT001 said:

 

I guess the upside would be better performance in high hot conditions and rate of climb?

It’s not so obvious. You need to run the numbers. The higher horsepower makes for a faster plane, but also quite a bit heavier. In terms of runway and climb performance, it’s not so black and white. My bird weighs 1681lbs. With 50gal, me, and 20lbs of bags, my op weight is around 2200lbs. At that weight on a standard day I can average >1000fpm from SL to 10,000’

Book numbers below. 

[Ragsf15e]

You’re looking at ~13mpg (Ovation) vs 15mpg (M20F) vs maybe 16mpg (M20J).  It’s different but not a ton and there’s maybe some higher altitude options with the bigger motors that could cut into the difference.

[Bolter]

6 minutes ago, Ragsf15e said:

You’re looking at ~13mpg (Ovation) vs 15mpg (M20F) vs maybe 16mpg (M20J).  It’s different but not a ton and there’s maybe some higher altitude options with the bigger motors that could cut into the difference.

Agreed.  For me, as a real-life cost, I use about 10 more gallons for my standard family trip (each way).  I do not consider that a a big cost for the 30 minute shorter trip, though the ROP "speed demon" could say the same for going 180 at 18 gph (or so).  

Like George Carlin said, everyone faster than you is an idiot, and everyone slower is a moron, so your preferences may vary. :-) 

(those economy values are nmpg, vs cars typically giving mpg in statute miles)

[1980Mooney]

4 hours ago, GeneralT001 said:

Hi,

IIRC fuel burn for a Lycoming 200hp 4 cylinder in cruise is around ~8-12 gph? What would it be for a Continental IO-550A 300hp 6 cylinder? I'm guessing 10-14gph? Guess my question is how much more per hour does this add up too in operating cost?

Since you reference an IO-550A, it sounds like you are considering a M20J with a Missile conversion by Rocket Engineering. Real world you will fly 20 kn faster than a stock J. But you will never see 10 gph unless you fly slower than the original J as @Bolter highlights. Remember that you are dragging around an extra 350 lbs over the original J not including the extra fuel that you need. It has 2 batteries in the tail plus more Charlie weights to offset the 550 and full feathering prop. 

The Missile is slightly less fast/efficient than an Ovation. At 13,500 you might see 11.5-12 gph at 170 kn. at MGW of 3,200 lbs if everything is perfect.  But I always plan trips for 15 gph. 

Operating cost firewall forward is probably 50% more. You have 50% more jugs, plugs, injectors, exhaust risers/joints, propeller blades. Oil fill on the IO-550A is 12 qts. The engine mount is complex, susceptible to corrosion due to proximity to high temp exhaust and expensive to repair. The starter adapter on Continentals is also expensive if it fails vs Lyc 4. - lightweight starters will kill it. The full feathering Scimitar prop is a beast - maintenance is key  - new replacement is over $30K now.  

The operating cost for the rest of the plane is about the same.  Exceptions. Double cost of batteries. You have 300 extra pounds on the nose gear vs a standard J - maintenance and lubrication of linkages is critical. 

[GeneralT001]

26 minutes ago, 1980Mooney said:

Since you reference an IO-550A, it sounds like you are considering a M20J with a Missile conversion by Rocket Engineering. Real world you will fly 20 kn faster than a stock J. But you will never see 10 gph unless you fly slower than the original J as @Bolter highlights. Remember that you are dragging around an extra 350 lbs over the original J not including the extra fuel that you need. It has 2 batteries in the tail plus more Charlie weights to offset the 550 and full feathering prop. 

The Missile is slightly less fast/efficient than an Ovation. At 13,500 you might see 11.5-12 gph at 170 kn. at MGW of 3,200 lbs if everything is perfect.  But I always plan trips for 15 gph. 

Operating cost firewall forward is probably 50% more. You have 50% more jugs, plugs, injectors, exhaust risers/joints, propeller blades. Oil fill on the IO-550A is 12 qts. The engine mount is complex, susceptible to corrosion due to proximity to high temp exhaust and expensive to repair. The starter adapter on Continentals is also expensive if it fails vs Lyc 4. - lightweight starters will kill it. The full feathering Scimitar prop is a beast - maintenance is key  - new replacement is over $30K now.  

The operating cost for the rest of the plane is about the same.  Exceptions. Double cost of batteries. You have 300 extra pounds on the nose gear vs a standard J - maintenance and lubrication of linkages is critical. 

Thanks for that...it sounds as though the J is more inline with my pocket book

[Pinecone]

Or go turbo.

My M20K 252 is 175 KTAS on 10.1 GPH, but you need to go high and use O2.