60 seires 515 hp

[terryweber]

getting 6.2 mpg told to drop hp to 435 could getup to 20% better ?????:

[AmeriStar]

1997 brought the introduction of the DDEC IV engine, and further improvements in the design of the engine, notably a wastegate turbocharger and engine management improvements provided increased horsepower ratings up to 500 hp and increased torque outputs to 1,650 foot-pounds force. Prior to 97 the rated power for most of the 12.7's were at 430 horse power. Setting the 12.7 above 475 significantly reduces fuel mileage.
Our fleet of MCI motorcoaches used the 12.7 DD exclusively until 2007. We set the horsepower level at 470 and the top speed at 73 mph. Our fleet average is 7.8 mph.
500 horsepower sounds great, but the additional cost for fuel, not to mention the increase in operating temperature, is a huge negative.

[Jon Wehrenberg]

If you want to increase mileage substantially, for free, lift your right foot a little.

You only pay for the HP you use. It is that simple.

There are things you cannot control. You cannot do anything about the drivetrain efficiency, hills, quality of fuel, or the amount of HP produced per pound of fuel. When Mother Nature decides to blow strong headwinds at you there is no way to get her to stop them and make them a tailwind.

But you can drive slower. You can choose a lighter weight toad, you can reduce the weight of the bus by leaving a lot of stuff behind and not always filling the water tank before you drive. Save a little more fuel by never turning on the AC.

Or you can drive slower.

If improving your fuel mileage seems to be an issue do some math. Determine how much your fuel costs will be at your current level and based on the miles you drive annually. Then recalculate the cost at your target mileage figure. Then just to put that cost savings annually in perspective, determine your depreciation and the lost earnings on the capital invested in your coach. Kind of puts a quest for better mileage in perspective.

[jack14r]

I agree with Jon but there is something that we cannot change,as the coaches have gotten more slides and more marble/granite etc. they have gained as much as 8,000 pounds in weight,we must pay for that in fuel mileage no matter how much or little we use our right foot.I don't think that my coach will ever get the fuel mileage that Jon's coach will just because of the difference in weight.

[merle&louise]

There is a guy in Lufkin, TX who drills out the return fuel line orfice and increases the size of the opening from .008 to .009

Supposedly, this increases the fuel economy by 1 to 1.5 mpg!

A fellow POGGER told me about this. He has done it on his coach and now gets the improved fuel economy.

I was going to do it but the tech couldn't reach my return fuel orfice.

[johnklopp]

I agree with Jon. The only method to increase fuel mileage without emptying your coach is to get your foot out of it and slow down. Playing around with the fuel metering orifices puts your engine at risk. If it was that easy, the engine manufactures would have done it. Consider the consequences, a ruined engine 20K? or the EPA knocking at your door.

[travelite]

I'm trying to find the specs but my wife is pushing me out the door. I wanted to give the fuel pressure specs for idle, no load max rpm, and full load max power. Detroit Diesel is very specific about these fuel pressures. Opening the return fuel line orifice will certainly drop the pressures. Remember fuel is a lubricant and a coolant.

[merle&louise]

Kind of glad I didn't do it! Sounds like a bad deal. Ouch!

The good Lord must have been watching out for me.

[phorner]

If you are concerned about fuel economy, buy a Prius, not a bus.

There is absolutely nothing that's going to get your 50,000 pound vehicle, that's shaped like a brick, to sip fuel.

Just drive the darn thing and enjoy the ride

[terryweber]

If you want to increase mileage substantially, for free, lift your right foot a little.

You only pay for the HP you use. It is that simple.

There are things you cannot control. You cannot do anything about the drivetrain efficiency, hills, quality of fuel, or the amount of HP produced per pound of fuel. When Mother Nature decides to blow strong headwinds at you there is no way to get her to stop them and make them a tailwind.

But you can drive slower. You can choose a lighter weight toad, you can reduce the weight of the bus by leaving a lot of stuff behind and not always filling the water tank before you drive. Save a little more fuel by never turning on the AC.

Or you can drive slower.

If improving your fuel mileage seems to be an issue do some math. Determine how much your fuel costs will be at your current level and based on the miles you drive annually. Then recalculate the cost at your target mileage figure. Then just to put that cost savings annually in perspective, determine your depreciation and the lost earnings on the capital invested in your coach. Kind of puts a quest for better mileage in perspective.

thanks terry