6V92T fuel consumption at idle and fast idle?

[BG6]

Does anyone know what the 9V92T drinks at idle and fast idle?

The discussion about generators and inverters reminded me that the factory alternator on my coach puts out over 5500 WATTS, and at fast idle will not only drive the alternator at pretty close to full output, but also enough to drive an AC generator head that I can mount where the factory aircon compressor went.

My idea is that I can use the engine for an hour or so to recharge my deep-cycles and at the same time run my high-current AC appliances for cooking, etc., while at the same time keeping the engine in good shape.

[Len Silva]

Running a generator head off the engine is problematic because you must maintain a constant, specific speed.

[BG6]

Running a generator head off the engine is problematic because you must maintain a constant, specific speed.

That depends on the generator.  The better ones can handle a fairly wide speed range, as long as it's above the minimum and as long as there is sufficient cooling airflow.  Pick a pulley diameter that is a little over the shaft RPM at fast idle and it should be good at highway speed.

If the range is TOO wide, simply get a smaller pulley for fast idle and a larger one for highway time.

[rwc]

There was discussion of this quite some time ago and I don't remember the particulars but there is a generator made for that purpose of running off engine. It was very pricey as I remember and also rare.  Seems like it was made somewhere on the east coast.

[Lin]

I believe there is general agreement among the 2-stroke mechanics here that you should avoid idling if possible.  Therefore, you would not be keeping your engine in good shape, but rather doing the opposite.

[BG6]

I believe there is general agreement among the 2-stroke mechanics here that you should avoid idling if possible.  Therefore, you would not be keeping your engine in good shape, but rather doing the opposite.

With any diesel engine, you want to avoid a low-speed idle.

I believe the fast idle is fast enough to prevent the problems.  I've seen coaches on fast idle for hours at a time outside repair shops, but that may just be idiot mechanics who don't know about 2-strokes.  If anyone knows any different, please let me know.

[Len Silva]

Running a generator head off the engine is problematic because you must maintain a constant, specific speed.

That depends on the generator.  The better ones can handle a fairly wide speed range, as long as it's above the minimum and as long as there is sufficient cooling airflow.  Pick a pulley diameter that is a little over the shaft RPM at fast idle and it should be good at highway speed.

If the range is TOO wide, simply get a smaller pulley for fast idle and a larger one for highway time.

Any generator that will operate at variable speeds must be a generator/inverter combo. The Auragen http://www.aurasystems.com/index.htm may be what you are thinking of. Very pricey indeed.

Any generator head you may find must be operated at 1800 for a four pole unit or 3600 RPM for a two pole.
Frequency = RPM * poles/120

The quality of the unit has nothing to do with it.  The Onan Quiet Diesel and some of the quiet Hondas are generator/inverter units.

[BG6]

The quality of the unit has nothing to do with it.  The Onan Quiet Diesel and some of the quiet Hondas are generator/inverter units.

I meant "better" as in "better design."

I've sent emails to some of the wrecking yards to see if they have a broken up Onan (nobody ever got fired for buying Onan) with a good head.

It just seems to me that there isn't a lot of load in a generator, if the engine is running already . . .

[TomC]

Although I'm an advocate of not running a 350hp engine to do the work of a 15hp engine, since the fast idle on the engine is usually around 900rpm, it wouldn't take much to just set up the pulley system to double the rpm to 1800rpm for the generator you want to use.  Then when you don't want to use it, just have a similar electro mechanical clutch like the original A/C had so when you do not want to use the generator, it is not turning.  Good Luck, TomC

[cody]

http://www.northerntool.com/shop/tools/product_8795_8795

[robertglines1]

up to 6 gal per hr at fast idle.. that is 6 times 3 is 18$per hr plus ..heat and noise generated...noise not a good neighbor! my 7.5 kohler runs under a gallon per hr running power efficient AC (3)and elect hot water and rest of bus...and is much quieter....also recharges my batt bank....the 3$fuel  cost does not consider oil and wear and tear on engine .( I figure a minimum of 3.50$per hr for wear and tear)I think that is a low figure..

[TomC]

The difference between a cheap alternator head and a quality alternator head- Years ago I went to Apollo generators (not sure if they are still in business) to look at a lite weight 6kw genset using a 2 cylinder Kubota (running at 2,800rpm) and a similar generator head like at Northern Tool running at 3,600rpm.  He loaded it with 30amps and after a couple of minutes I felt the cooling air coming off the generator head-it was almost hot enough to burn me!  As compared to my 1800rpm Powertech 10kw with a Seiman's big diameter brushless alternator head.  I've loaded it up to its' 10kw limit and felt the cooling air coming off the alternator head-a bit on the warm side, but no where close to the nearly burning that came off the el cheapo alternator.  The more heat that is produced, the less efficient it is making for more horsepower to turn it.  Once again- yous gets whats yous pays for.  Good Luck, TomC

P.S.- fast idling a truck- in general 1-1.5 gal per hour is the accepted rule of thumb.  We figure that 8 hours of idling will burn 10-12 gallons.  At $3.00/gal, that's almost enough just to get a hotel room.  Most Diesel gensets will burn in 1/2 to 3/4 gallon per hour when powering the A/C's.  Good Luck, TomC

[Len Silva]

That's why commercial trucks today have APU's.  Lot's of places have no idling laws in effect.

[James77MCI8]

Maintaining the constant speed is mostly to provide a steady frequency. I can atest to the the problems of idling (FAST OR OTHERWISE) a DD. Personally I think this set up will cost you more than you will gain in the long run.