A good engine to select for my project?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

geosnooker2000

Well-Known Member
Joined
Mar 30, 2019
Messages
133
Location
Somerville, TN
Hello all.
I am considering building a CH640 sometime in the future, and am doing a lot of research FIRST. I have been through various discussions over on the Corvair board and the Subaru board. Now I have some questions for you dedicated aircraft engine guys.
Zenair recommends a powerplant between 150hp and 240hp. You need a "high performance endorsement" to operate an airplane with an engine above 200hp, and that's not something I'm interested in just yet.
What I'm looking for is 6 cylinders with the lowest GPH burn possible. I want a Ford Explorer, not a Jaguar F-Pace.
This has sort of led me to the Conti 0-300, or the G0-300. I really don't like the idea of any gearbox, and I'm not sure if the 5HP missing from the 0-300 would be that much of a big deal?
Are there any other ideas for that range of power y'all can come up with? BTW, I'm not wealthy, so I won't be buying any new or newly overhauled engines. This would be a used engine with some time left on it.
Thanks for any input!
George
 

Geraldc

Well-Known Member
Joined
Nov 12, 2011
Messages
313
Location
nz
I got my motor early in the build which was a mistake.Build to firewall forward and then make your choice.Engine options change all the time.
 

cdlwingnut

Well-Known Member
HBA Supporter
Log Member
Joined
May 25, 2015
Messages
493
Location
Iowa
the o-300 wouldn't be a bad engine, but do not fret the high performance endorsement, one flight with an instructor can get that.
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,321
Location
BJC
When one discovers experimental aviation it's exciting because it promises to be a less expensive way to fly, and in some ways that is true. Then if you're interested in alternative engines it appears to get even better, but remember: TANSTAAFL

Don't underpower your plane to save money. This isn't Corvair territory. There is lots of information about owning/operating the GO-300 out there, and it may be a great option. A mid time 360 could also be perfect (they're everywhere and every A&P will know what to do with it). Ask the Zenith guys how a 145 hp (O-300) 640 would be. They don't bite.

Low fuel burn is a nice thing but all aircraft engines have essentially similar specific fuel consumption. What you pay for with a bigger engine is the ability to burn fuel faster when you want to, and unfortunately, the necessity for burning fuel faster when you don't want to (because the engine is heavier, and the weight snowballs and ripples through every part of the airframe). This is why Billski always reminds us that weight is the enemy. It is the enemy of performance and economy.

I hope you'll keep thinking about what you want to build and about engines and such, but I would strongly encourage you to get flying while you're doing that because it will help shape your mission and give you perspective on things like how often you will need four seats and whether a high performance endorsement is any big beal. If money is a driver, you could consider building something smaller and renting a 172 when you want to take some kids in the back.

Also, if you like six-cylinder engines, one other worth looking into would be a Franklin.
 
Last edited:

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,059
Location
Memphis, TN
Continental O-300s are great engines. The parts supply for the big stuff like cases and crankshafts are drying up. That is making them expensive to fix right. They are heavy for the horsepower. The GO-300 is a whole other mess. I would fly behind one but there are no parts for the gearbox. 80% chance you fly with one, it will be the last one you see. It also requires a special flight management. You have to fly full power and only use low power to land. You can’t fly at part power because it tears the gearbox up. That bad management is what killed it. Management of the big G engines were understood. A lay 172 driver did not. A Lycoming O-290G Is cheaper and can be turned into a 320 with minor work cheaper than replacing a O-300 crankshaft.
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
6,787
Location
Saline Michigan
Mid-time boneyard engines can be great deals. O-320 for the low end, O-360 for 180 hp, IO-360 for 200 hp, and then the big sixes for more than 200 hp. You need the logs, you need to know it was pulled from a running airplane or one that was totaled for airframe damage, and you need to know that it was NOT a prop strike victim.
https://www.eaa.org/Shop/ProductCatalog/Product.aspx?ID=2681564&SubTopicID=941 covers the engines to look for an more importantly the ones to skip.

https://www.eaa.org/eaa/search?term=Busch On Engines&limit=90c6632f49004175b4e0c6acd7d471a1 is Mike Busch's book, and worth time and money on engine inspection.

If it was pulled in the last moth, OK, but if it is older, the boneyard had better have pickled it. Show up with tools and a borescope (there are good ones for a couple hundred bucks that display on a tablet or phone). You need to find out that the cylinder walls are not rusty, that the valves are all good (no crescent moon looks on any valves), and you need to know that the cam and lifters are good. Enter the crankcase through the oil drain hole to look at the cam.

You will be flying sooner and on about the same bucks with a lot less fuss in an "airplane" engine.

Play with auto conversions only if you really want to play with auto conversions. This is an experimentors topic of its own.

Billski
 

Toobuilder

Well-Known Member
Log Member
Joined
Jan 19, 2010
Messages
4,777
Location
Mojave, Ca
As said above, dont worry about the high perf endorsement. One flight with an instructor (or none, if you know one well) and that's done.

Also agreed that fuel burn is a function of the HP you select. There is no magic to the internal combustion process at the duty cycle of an aircraft engine. This is especially true of a high drag machine like the 640.

I do like the sixes for the sound, but there is more component cost associated with the extra cylinders. The 0-300 has been discussed as well as the Franklin, but the Lyc 0-435 is still plentiful. It shares the same rare/expensive cylinders as the 290, but like the smaller engine can be bored for 320 jugs - creating a 480 of 240 HP.

Best bet though is to wait it out and grab a gently used Lyc 320 or 360. Get the right one and you will save years of development time and money, and have years of trouble free flying.
 
Last edited:

geosnooker2000

Well-Known Member
Joined
Mar 30, 2019
Messages
133
Location
Somerville, TN
I appreciate all the responses. The 4 cylinders are ruled out. I want 6 cylinders for safety concerns. If it costs 50% more at overhaul, so be it.
 

Toobuilder

Well-Known Member
Log Member
Joined
Jan 19, 2010
Messages
4,777
Location
Mojave, Ca
Depends on the nature of the malfunction. Throw one rod on a 6 and you're a glider. Add to that, sixes generally eat cylinders faster than fours, even among the same architecture.

If safety is the primary concern, then I suspect you will find that the Lyc 320/360 series wins that contest by a huge margin -and they are 4 bangers.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,059
Location
Memphis, TN
I see no difference in safety 4 or 6 in airplane engines. 6 was just a way to add horsepower without much work. Will a Continental O-470 work for you?
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,059
Location
Memphis, TN
Skip Stewart just just lost the cylinder head on his 6. I hate when that happens. His is a high stressed engine being an air show plane but the part is common to 4 and 6. Mechanically except the timing order and extra parts to add the two cylinders , there is no difference in them. Parts bin manufacturing at its best.
 

mm4440

Well-Known Member
Joined
Jan 14, 2012
Messages
189
Location
LA area, CA
Sixs run smoother than fours. One to look at is the Continental IO-360. Not as popular as the Lyc so might be less used.
 

geosnooker2000

Well-Known Member
Joined
Mar 30, 2019
Messages
133
Location
Somerville, TN
And I suppose you could look at it from the standpoint of plug wires. You lose a plug wire on a 6 Cyl Corvair, you still have 5 cylinders left... You lose a plug wire on a Lyc 0-320, you still have 7 wires left, and all 4 cylinders.
 

geosnooker2000

Well-Known Member
Joined
Mar 30, 2019
Messages
133
Location
Somerville, TN
I was not aware that 6 cylinders are safer than 4. Do you have a source for this?
I infer that you are asking for proof. It's not about proof. It's about what my wife thinks is safer. Unless 4s are more reliable than 6s empirically, and I can point to some statistics.... no, no, it still wouldn't matter. Know what I mean?
 

Toobuilder

Well-Known Member
Log Member
Joined
Jan 19, 2010
Messages
4,777
Location
Mojave, Ca
Would your wife rather fly behind a Merlin?

Seriously, where did she get the idea that more cylinders is "safer"?

I'm not about to debate the irrational fears of wives (I've heard plenty), but that one is very technologically specific.
 
Top