Generators used in high altitudes

Road runner wrote: "I didn't mean to say that one could get MSL power at altitude by leaning the mixture. I do feel like the amount of power gained with leaning the mixture is more than small. Taking off from Denver in a loaded 172 with the mixture full rich will leave you sweating bullets as the runway end approaches and you're still on the ground."

If I recall correctly, the Pilots Operating Handbooks I have read say not to take off full rich above +- 5000' MSL. Instead lean for best power on run up.

I hear ya about Denver. Try doing the same thing at Mamouth Lakes, CA on a hot day! Density altitudes are often over 11,000 feet in summer. I believe the field elevation is over 7000' MSL

Chum lee

Chum lee wrote:
Road runner wrote: "I didn't mean to say that one could get MSL power at altitude by leaning the mixture. I do feel like the amount of power gained with leaning the mixture is more than small. Taking off from Denver in a loaded 172 with the mixture full rich will leave you sweating bullets as the runway end approaches and you're still on the ground."

If I recall correctly, the Pilots Operating Handbooks I have read say not to take off full rich above +- 5000' MSL. Instead lean for best power on run up.

I hear ya about Denver. Try doing the same thing at Mamouth Lakes, CA on a hot day! Density altitudes are often over 11,000 feet in summer. I believe the field elevation is over 7000' MSL

Chum lee

Mammoth Lakes. 85 F on a July day is pretty thin air up there.Airport

Back to generators... the Honda EU7000i is fuel injected, not carbureted... self compensating for elevation, but a bit big for camping.

Now pay attention OP, never use an under powered generator when flying over the Rockies. :B

Well, I do often refer to my class C as a "flying brick", when it comes to fuel economy.

Boon Docker wrote:
Now pay attention OP, never use an under powered generator when flying over the Rockies. :B

pianotuna wrote:
Well, I do often refer to my class C as a "flying brick", when it comes to fuel economy.

Boon Docker wrote:
Now pay attention OP, never use an under powered generator when flying over the Rockies. :B

I'm curious, what average mpg do you get with your motorhome.

Living at 9,000 ft, I tuned an around-town service truck to run as best it could.

Like my LPG pickup it took 12.5 - 1 pistons, a Crower Camshaft with high lift rather short duration and little overlap. one and one half degrees ********. A modified HEI distributor, with 30 degrees mechanical advance and fourteen initial. I hate Holley carburetors, but I used a 390 CFM, re-jetted and with 4.5 power valve. Simply rejetting the original engine didn't do snot except gain a tiny fraction of gas mileage. The truck hauled a 6-7 Detroit prime mover and 60 Kw Lima generator and a filled 260 gallon diesel tank to 11,200 feet without complaint. The cooling system was filled and the engine had 6 gallons of oil in it. I did not dare take the truck to <4K ft altitude. I sold it, as a matter of fact, in Mammoth, to a local "rancher" as a farm utility truck.


*********censored. Oops I meant to write the camshaft as being installed timed at mentally developed challenged one and a half degrees. Ever play in Reno or Vegas at a "Mentally Developed Challenged" table? Whatever you do don't bet on "The Field"

As an FAA PMA my experiences occurred on the ground. I heard so many different pilot "opinions" about "tweaking" fuel mixtures I grew deaf to comments. I specialized in Continental and Lycoming electrical, engine starter motors, alternators, and OVL systems.

Re-jetting a low compression engine for high altitude is about as worthwhile as polishing the finish for better mileage. It just wasn't worth it not even close. I did shave the cylinder heads on a Witte diesel about .200" to raise compression at 9,800 ft and that worked -way- better than throwing a new pill in the injector system to lean it out. Sticking a turbo on works best.

If it won't work, buy a bigger gen or a brand known to work at the altitude you camp at, is my recommendation.

Hi Boon Docker,

I drive 48 mph and on the flat I get an honest 11 mpg US. If I drive 50, it costs me 1 mpg.

I do have air tabs, but they appear to just make the inside of the RV a lot quieter regarding wind noise. If I'm able to follow a big truck or have a tail wind then the air tabs appear to make a difference in mileage.

I do have taller than OEM tires because I wanted to improve weight capacity. The OEM driver's rear was right on the edge of the capacity so when they aged out I moved up. To do so required buying seven new rims.

Thanks pianotuna !
That is pretty impressive, that is about the same as I get pulling a 24' trailer with a 1/2 ton.

Boon Docker wrote:
Thanks pianotuna !
That is pretty impressive, that is about the same as I get pulling a 24' trailer with a 1/2 ton.

I drive a VW TDI with a 3.0L V6 diesel. Trailer is 21 feet long, about 4200 # wet. At 55-58 mph, I get 16.5 to 19.5 MPG every single trip. MPG's go up when I get on the 5500 foot plateau above St George, all the way up to Yellowstone NP.

Diesel has more calories, and doesn't suffer from elevation, in fact less wind resistance ups the MPG from sea level, significantly.

NinerBikes wrote:

Boon Docker wrote:
Thanks pianotuna !
That is pretty impressive, that is about the same as I get pulling a 24' trailer with a 1/2 ton.

I drive a VW TDI with a 3.0L V6 diesel. Trailer is 21 feet long, about 4200 # wet. At 55-58 mph, I get 16.5 to 19.5 MPG every single trip. MPG's go up when I get on the 5500 foot plateau above St George, all the way up to Yellowstone NP.

Diesel has more calories, and doesn't suffer from elevation, in fact less wind resistance ups the MPG from sea level, significantly.

Wow, diesel burners sure are a lot more efficient than gas guzzlers.