gas mileage survey

[100hraspen]

Just a quick question for anyone that might have a spare minute: what kind of gas mileage to you get on your different rigs?

Thanks

[lvwrench]

Not sure what you mean by gas mileage since everything we run is diesel powered. Since we have Detroit Diesel power I can hook up a MPSI reader system that will give me the data stored in the computer for the engine and give me mileage statistics as well as current fuel usage as I am driving. The driving condition would determine fuel consumption, amount of throttle applied. Anywhere from about .5 to 8 miles to the gallon.

[BirkenVogt]

I can't say exactly because some rigs go such a short distance but overall we generally get 4 to 12 MPG depending on the rig

Some of the old ones with big gas engines like the GMC 427 and the Ford 534 got worse than that

Birken

[Scottsfire]

lvwrench,
What are you getting for gas milage on 8V92's (Detroit). Of course your a wrench so you already know its a Detroit! Ha
Just curious......I know weight and apparatus style etc all play into the actual mileage but curious about the general mileage on those.
Also....what can I expect in loss at altitude. IFSTA says 3.5%/1000ft. on gasoline engines but Detroit 8V92's per 1000 of alt????
We are at 9500 feet.........yea....try drafting!!! But always curious about whats under the hood.

100hraspen....sorry to temperally hi-jack your thread but had to ask since its a fuel issue.

[lvwrench]

Haven't had an 8v92 since the early 90's. It's all 60 series now and for a long time before. The 8v92 was DDEC what? 1 or 2? Its 3, 4 and 5 now. Our 60's are 430HP for the pumper and 470 to 500 for the aerials. More fuel less mileage. I'm at 2300 ft. unless California breaks off and we wind up with ocean front property. Not exactly sure of the HP loss at elevations. We do have some units that run up to Mt. Charleston at about 10,000 ft but have not heard of any major HP problems. Drafting? Egads we are on City hydrants with anywhere from 70 to 100 PSI out the hydrant. Ain't city life wonderfull? I'm sure Detroit would have the HP loss figures. Have a great day and keep it safe. Us mechanics types are trying to make it right and safe for the good guys.

[Scottsfire]

LV Wrench,
Yes.......you guys keep us going and its greatly appreciated. I know we are hard on engines, especially the hose monkey types but without the wrenchs we would be answering calls in Toyota Tacoma and other POV's........ha!

[lvwrench]

Great chatting with you Scotsfire. Hey, I appreciate the good guys even if they are a little rough on the rigs sometimes. Everybody has a job to do and some of us just work behind the scenes like in Hollywood. I think that a good relationship between the heroes and the behind the scenes types makes for a better overall department and helps to keep it safe for all concerned. I know that when I came to work one day and did not look so good, not a hangover either, the paramedics checked me out and sent me on my way to the doctors for a thorough look. So far so good but won't get the final results till Monday the 13th. Hope its not unlucky. Have a great day and keep it safe.

[Dave1983]

Huh? You mean somebody actually wories about fuel mileage on the BRT's?

[Fire304]

Bear in mind that you "miles per gallon" include pump time, since the speedo reads when pumping. Typically a pump at idle is running the gear box at 15-25mph, so it makes it nearly impossible to read true milage.

We also tend to do a lot of cold running of our engines which ruins milage (and our engines). Even if the engine is in a warm house or has a block heater its "cold" compaired to the exhaust temp which is about 400F at idle (with coolant at 180F) and 1600F at full throttle, then we run at full throttle for 4-5 minutes getting to the scene, and finally we idle for 45 minutes while we investigate and do paper work. Diesels do not warm up at idle and some will actually cool off which (along with alternator output)is why you should always run your throttle up while sitting at the scene or use fast idle. The drive home (and of course working fires) is the only time the engine and gear box (which can take an hour to come up to temp) actually begin to warm up and get decent milage.

If you look at commercial trucks you'll see that city delivery trucks of comparable HP and weight will get 5-12gpm and a highway truck will get 9-15gpm. Kinda depressing to think that a 100,000lbs tractor trailer can get milage almost as good as my SUV and better than the Ford Excursion. YIKES

[Scottsfire]

lvwrench.......hope everything goes well with the Doc...you guys are our brothers too even though your "behind the scenes" as you call it!
Its a team effort..........no one goes home until we all go home.

Fire304.......thank you thank you......yes...you are correct 100% Some of the other engineers in my dept. fail to realize the importants of fast idle. If we are on scene not pumping and I see an engine running awhile at idle I'll raise the engineer and ask them why they aren't shutting down or high idling the engine...if they must keep it on. Damn those carbon deposits!!! Tough on an engine!!!

[Fire304]

Scottsfire, its worse than just carbon build up. When a diesel runs cold not all of the fuel injected is burned. Eventually enough fuel is left over that it pools on top of the pistons. On the comression stroke some of the fuel is driven down past the rings into the crankcase, dilluting the oil, causing premature wear on things like crank shaft bearings, rings, turbo bearings, etc,.

If enough oil builds up on top of the pistons it will make an effective seal increasing the compression enough to ignight that same fuel causing predetonation (pinging) which can lead to a bend push rod, (this is pretty rare on modern engines but it is possible).

Bad injectors can also cause fuel to not burn (poor pattern). When there is a lot of unburnt fuel you'll see white smoke from the exhaust pipe (as opposed to light blue smoke for oil).

[lvwrench]

Got my test results, heart okay and lungs okay just drained my system down and needed a recharge. The same thing happened twice too me in the Air Force. A little thing called enemia. Got to put back what I take out of the old body and hadn't done that. Back inthe swing and feeling good, except for the usual job stress and honeydoos. Thnaks Scotsfire for the thoughts.

[Murph64]

Originally posted by Fire304
If you look at commercial trucks you'll see that city delivery trucks of comparable HP and weight will get 5-12gpm and a highway truck will get 9-15gpm. YIKES

Rather appropriate units of measure...But is it -per mile, or minute


Andy

[Scottsfire]

Hey welcome back lvwrench to the front lines.........good news good news. We all have to care for our own in the brother and sisterhood.
Hey man...take care of yourself.

Fire304.....yep thats all true.....thought about those after I posted.
Stuff like this needs more attention than we often give it. Thanks for the great feedback too.......Dilution of the oil is a biggey.

[Fire304]

Luckily for us the life span of an engine is so much longer than the truck its self, so we rarely eat up engines. I used to work on boats where it can be days at 100% throttle followed by days at idle. Its much more importnant to take good care of the beast there.