Idleing 2 stroke

[robertglines1]

Started new thread>  ???I have been told by truck friends that a idleing 2 stroke on fast idle can use up to 5-6 gallon per hour. I thru that out in a recent discussion. I would like to know because I do not like to pass on false info. My friend told me this because he said with todays fuel prices it was cheaper to put his drivers in hotel rooms than let them sit with engines running. I used this figure in making power decisions during coach building. So what does your experience show. One member said 1 gallon.     That's a big spread.  The 5-6 maybe really high.    What figure is more correct??    Bob

[Oonrahnjay]

     Bob, I don't have any direct experience with idling engines but the guy who parks his tractor unit next to my bus in the storage lot has a generator that he has installed down at frame level.  It sits kinda where you'd expect air tanks to be, the top of the enclosure doesn't come above the chassis frame rails.   It's pretty quiet considering that the guy who installed it didn't really do anything to make it quieter -- it sits in a box made with a angle steel frame and aluminum "diamond-plate" floor, sides, and lid. (but it's still kinda noisy).
     He does special contracts and he's often on the road weeks at the time.  His wife usually travels with him, their sleeper unit a single room with comfortable bed, kitchen area, head/shower.  Except for the air conditioner, microwave, coffee maker and cook top, all his loads are 12V, these are taken off with a converter/charger. 
     He specifically installed the generator so that he wouldn't have to run the truck engine (it's a 2007 Somolebiggassthing with a Series 60) when he was parked.  He must think it's worth it; the cost was in the thousands of $$$. 

[Geoff]

If you hook up a container with exacly one gallon of diesel to your primary filter you can find out for yourself how long a gallon of fuel lasts at fast idle.  Of course, you also need to have the return line go into the container. 

[robertglines1]

Scotty just posted .8-1.5 in another thread acording to the goverment ideling per hour for semi. wonder if that is including 2 strokes.  if so boy am I wrong!   Been wrong before!!! Will be my new lesson for the day.    Bob

[luvrbus]

Your 8v92 will be in 3 gal range per hour my 4 strokes were a little less but not by much lot altitude plays a big part also

good luck

[TomC]

On our new DD15's, we have an optional mpg/fuel per hour gauge. At low idle, it burns .8 gal per hour.  At 900rpm fast idle your at 1.2 gal per hour.  When I had my 8V-92TA and fast idled it at 900rpm, it burned about the 1.5 gal per hour.  I don't know what my 3406B does since I had a generator on board for overnight heat/A-C.

It has never made sense to me to have a 12-15 liter engine idling to run a 5hp air conditioning compressor all night long.  The new APU's (Auxiliary Power Unit) uses many different ways of doing the same thing-being able to shut down the big engine and have a little 2 or 3 cylinder 14hp engine keep you comfortable in the cab.  Granted the California version with particulate trap is around $15,000.00 installed, but considering you save about 3/4 gallon an hour, at our fuel prices now, that would only take about 3 years of use to break even. 

Unless you're having problems with your genset, why would you want to idle the big engine? Good Luck, TomC

[Busted Knuckle]

Well I can't say I know any amounts from any scientific testing.
But I have been told over the yrs 4-6 gals/hr. (this was even before Detroit had the 60 Series)

Then when I bought my first 60 Series truck I was told by the salesman it would consume 4 gal/hr idling all night.

I was recently (last few yrs) told that the big 14 L in our '05 S417's burn up to 6 gallons per hr by Setra

Now this is only what I've been told and have no documentation or tests to prove or disprove any of this!

All that said I'd say (as usual) Clifford probably has the #'s down pretty much accurate.
 BK  

[Busted Knuckle]

I see that TomC who also is fairly knowledgeable with stuff like this has posted while I was typing. (& answering phones)

Again I just know what I'm told and always thought 6 GPH sounded high.


Now as far as APU's go the biggest reason many people started installing them was big cities like Chicago outlawing trucks idling.

While they do save fuel, & wear / tear on the main engines many operators did not jump on the APU band wagon until Chicago successfully outlawed truck idling and they feared many more cities, states and even the country of California would be following suit soon.

Once some of the larger outfits put on APU's and reported the results then many of the others followed.
  BK 

[buswarrior]

Remember that there are those in the communication chain that would be motivated to overstate the fuel consumption when idling in order to avoid/place blame for running out of fuel.

And those that over estimate in order to avoid being wrong, rather than say to a customer "I don't know, I'll have to check."

In the commercial side of things, at ground level, you can't go wrong having everyone thinking it burns more than it really does.


Having an APU on a highway truck just makes good economic sense, and has for many years.

There's more cost than fuel to running an engine.

The trade publications have stated for years that it is safe to consider that a minute running is a minute running, whether down the highway or idling.

We only have to look at the mileage to overhaul between the coach and highway tractor segments of the industry.

Highway tractor has a higher ratio of miles to hours idling.

Coach has higher idling, and less mileage.

Added up, it comes out much the same in total hours of operation and overhaul is required.

So, how do you want to use up the prime mover?

I know fellows that ran small gensets on their trucks way back into the 80's. Saved a ton of money, and you'd be amazed at the life some of them got out of gasoline generators. Regular oil changes and they just kept on going. strapped down to the gangway behind the cab. Honda in particular were known for outstanding longevity.

happy coaching!
buswarrior

[Busted Knuckle]

Having an APU on a highway truck just makes good economic sense, and has for many years.

There's more cost than fuel to running an engine.

The trade publications have stated for years that it is safe to consider that a minute running is a minute running, whether down the highway or idling.

We only have to look at the mileage to overhaul between the coach and highway tractor segments of the industry.

Highway tractor has a higher ratio of miles to hours idling.

Coach has higher idling, and less mileage.

Added up, it comes out much the same in total hours of operation and overhaul is required.

So, how do you want to use up the prime mover?

I know fellows that ran small gensets on their trucks way back into the 80's. Saved a ton of money, and you'd be amazed at the life some of them got out of gasoline generators. Regular oil changes and they just kept on going. strapped down to the gangway behind the cab. Honda in particular were known for outstanding longevity.

happy coaching!
buswarrior

Yes your right but I know back when I was trucking there where very few trucks or truckers that had, used or favored APU's and most of them were "Bed Bugger's" who sat for days in on area putting together multiple household loads to haul cross country, or unloading them.
Back then many just saw them as another expense and something else to break down or get stolen. (myself included)

It wasn't until the late '90's that APU's took off in popularity mostly do to the fear of multiple anti-idling laws

Hey I think I met most of those guys back in the '80's when I was still driving Cabover Mack tow trucks w/o working A/C an I used to pull into truckstops late at night and find a quite spot to nose into (parking away from their running engines) and leaving my sleeper door an windows open for a breeze to get some sleep! Only to 9 times out of 10 wake up to some cow truck, OLD noisy thermoking reefer unit, or "thrifty O/O" with a contractors generator mounted on his catwalk and a window unit A/C in the back wall of the sleeper who parked after I did, or waited until then to start it.
 BK  

[TomC]

On a bus running the A/C at high idle-I could believe 4-6 gallons per hour.  Round figures, one gallon of Diesel per hour will produce about 18hp.  Good Luck, TomC