Diesel Performance

FOURSOME-I hate to say it but you will have to "live with it"! I owned a used 1975 chevy dually once-had a 454 cid engine. The truck would pass everything on the road EXCEPT a gas station! Got 10 MPH -bed empty or full! There are some things you can do-but they will only make minor improvements on the mileage. Its the way these trucks are geared. James

RIGHT! Change the gearbox!

You might try the "Tri Before You Buy" option that www.bullydog.com has. They can load a temporary tune on your truck and you can see for yourself if it makes any difference before you spend any money. Just visit their website to find a dealer close to you and see if this helps. The link to their dealer locator is:

http://www.bullydog.org/locate_dealer/ds_tri.cgi

I'm not a car (or truck) enthusiast so my idea might not be feasible.

Could you try putting slightly larger tires? I mean, for the same rpm you'll cover a longer distance, right?. I don't know how that would affect your truck's performance though.

If you put bigger tires on the vehicle, it will help some in the gas mileage BUT the tradeoff might be LESS pulling power for that trailer! (more strain on the transmission) James

It's in the gearbox and the weight of the truck. They made it to haul a load and go on and on down the road. Fuel was cheap then and global warming a far off nightmare yet to raise its ugly head.

I don't remember fuel being that cheap 3 years ago. Are you saying that there has been NO improvement to the design since the seventies?

good luck with that as direct injection engines are nothing but diesel fuel vacuum cleaners-is it was indirect injected it would have better mileage perhaps when the warranty is gone you should ask a diesel mechanic to bypass two of the cylinders.

Welcome to the world of high torque, no horsepower and high weight to contain the peak firing pressures of a diesel engine (the knock you hear).

I'm a diesel engine consultant and I agree with all posts here that you are toast. You can get on the net and check for a performance chip or software download to boost mileage, but I'd guess it will only boost about 1-2 MPG (or should we say GPM).

Careful what you spend so run the math out to a payoff date. A $500 goodie pays for a lot of fuel at only 0.3 MPG boost, for example. But a $200 item that yields 3 MPG will pay out. And fuel will get more expense as the super low sulfur stuff costs $$$$$ to produce and it is mandatory soon.

That Cummins engine is based on the C model which is a work horse from the 70's (tons of torque, but no power, cement truck type application). Try short shifting it unless it is an automatic. This means lug it for a week and keep your foot out of it when doing so. Shift 300-500 RPM sooner even though you will pull your hair out. You are moving it back on the curve and efficiency may improve even though lugging. If you black smoke it, that is unburned fuel out the pipe. If fuel economy boosts, short shift more until economy drops and find the sweet spot. Don't rev it up . . . lug it.

Good news is that it is a 250,000 mile engine. Bad news is when it breaks, you'll need a credit line at a bank. To set the injection pump and clean the injectors every few years will shock you (check this now for fun).

Now, go do what my daughter did to her Ford Excursion (13 MPG on French fry oil). She built a filter bank and water separator and gets free veggie oil from restaurants and sucks it out of their vats with her filter bank, stores it in a bulk tank at home and has 50 cent fuel, getting cheaper as she pays out her investment with each batch. The kits to do this are on the net (you still need to start / stop on diesel) and might be $2k (don't know) and stuff to build your own filter bank is another $800 plus tanks and hassle and mess and ....... but it works.

George

Dear George,

Your reply to Petro-Power was "spot-on". I do like what you say about your daughters collection of vegetable oil .

This is somewhat what I suggested to the writer from Bali who complains about the condition of distillate as sold there. Use coconut oil its cheaper and would definitely run that Dinosaur Cummings more cheaply.

Well gentlemaen highfuel consumption the price you or any body pays for emission control.It appears that the world will come to an end if you operate a diesel engine due to its emissions and resulting greenhouse effect as if other source of emissions from diffrent sourses are forgoten and diesel engine has been made a scape goat for example has any body estimated how many tons of nox is produced per day other then diesel engines? similerly how about CO,Particulates,co2 it has been made out that only diesel engine is polluating the world.The new generation engines which are supposed to be emission complaient are not fuel efficent the research prooves it.even top of the line fuel injector manafacturers are not able to produce and replicate quality products. about emission testing equipments less said the better.we are forgetting basic engineering depending on stastical models and dumb advocates of clean energy and paying the price.

crm

Dear,

If you can try a 20% blend of biodiesel and conventional diesel fuel, u may get an mileage of atleast 10% more. I have tried one in our LCV and we could get 7% increase. Though the increase looks not so high, but it can pay-off immediately as cost per mile would come down to an average decrease of 20-30%. Try an approved biodiesel supplier only.

Give me a response as soon as you get some results, say in a month or so. Record daily mpg.

Try changing the rear end, or try a Ford. I own a 250 crew cab Lariat diesel. Average, empty no trailer, is 15.5 city and 20 hwy. According to my local dealership, this is above average for most Ford diesels, but it beats 9mpg.

Do you really expect good fuel consumption when there is a truck engine under the bonnet (hood)?

That engine was designed for one of these.

Add to that the automatic gearbox........

That's a good thing about a one-ton truck - same mileage whether it's idling or pulling your house at max speed (probably only about 50 mph). It's usually in the rear-end - a lot of 3/4 ton and one-ton trucks have the same engine and tranny, but the one-ton usually has the lower-geared rear-end. Good for torque, especially on the low end, but it sucks on mileage. A lot of towing types will tell you to buy the 3/4-ton - same engine and tranny, but a higher-geared rear-end - better mileage, higher speeds, almost as much towing capacity.

Be careful of the straight veg-oil - some will say it causes no damage, but some will tell you it will gum up your system pretty quick. If you have the inclination, you could make an inexpensive bio-diesel reactor and make your own bio-diesel - the learning isn't rocket science, the parts can be had for a few hundred dollars or less, and you should be able to get waste veg-oil for cheap or free for hauling it off. Look around Google, maybe head over to Journey to Forever (journeytoforever.org/biodiesel_make.html) and do some exploring.

I believe the "gumming" comes from veg oil that has a small quantity of water in it. I once watched an episode on National Geographic that showed how veg oil can be converted to fuel. The first batch they made resulted in "soap" due to the water content.

I guess the soap will clean your engine but it won't like it one bit. Sounds like my son when his mom tells him to take a bath.

We have both a 2004 and a 2006 3500 Laramie Dodge. Both trucks are loaded with every thing imaginable. These cummins engines get 17 plus mpg M/T and 14 mpg loaded. 24000 lb. GVW is the loaded weight with average road speeds of 75 MPH. The only difference is our trucks have the 6 speed manual overdrive gear boxes. We did have a 94 with automatic transmission and it was pretty constant at 14 MPG heavyl and 16 MT. Your truck will last many years with care as reports of these cummins engines at 500,000 mile and still performing reliably. My suggestion to you is to take the truck to a cummins engine dealer for a check up. At 9 MPG your truck should be passing black smoke from the exhaust excessively. If so this will indicate excessive fuel passing through the engine. At fault may be damaged injectors or turbo charger. Our experience with Dodge dealers is less than desirable so we rely on the Cummins dealer. Also after reading most of the replys you have recieved I have a strong feeling

you should ignore their remarks as I saw nothing constructive. Bottom line, Your 94 should get at least 15 MPG running around MT. Also don't trust the MPG digital read out when doing MPG tests. We completely fill our tank and drive to the next town and re-fill the tank. Using simple math will give you a close MPG rating for your truck. Have a nice day. Dick Wallen/Del Sol Engineering...

Del Sol,

A good positive reply - well done. Here in the UK the diesel vehicle sales ratio is rising fast as the latest common rail turbo diesels are so much better to drive, and so much cheaper to run than the petrols. And yes I always check that the speedo is reasonably accuracte - using a GPS, and that the trip computer gives a fair reading by several full to full tank fill ups - many trip computers are very inaccurate.

I think your comment about overdrive manual gearboxes is right to the point. Unless the truck auto is the latest lockup overdrive design with software controlled gearchanges which recognise driver style and vehicle weight factors, you will never get a good economy figure out of your auto box. We now have 6 speed auto boxes with lockup in the top gears.

I expect any European car to achieve 50 miles per Imperial Gallon, and my 3,5 tonne van ( truck to you) should exceed 30 mpg unless towing a 2 tonne boat!

I would always recommend a Cummins as I have really good experiences of them, but do talk to an expert driver about driving style as it does matter.

Good luck to you all

It's a hit and miss with some of these Dual wheel bases w/ .410 rear ends but you should be getting at least around 14-15 mpg dry. Do like this guy said and take it to a Cummings dealer not to Dodge.

Check with these people http://www.bullydog.com/

You did not mention if your truck has a turbo. Adding one will help if you don't already have one. Like another poster said skip the dealership and go to a cumming dealer for one.

even though you have just had a tune up, it sounds like your injection timing it a little late.

I agree with Del Sol, ignore most of those earlier comments, escpecially from the so-call Diesel Engine Consultant. I personally own a 2005 Chevy 2500HD Duramax with the Banks Power Big Hoss Bundles package. I have a good friend that has the same truck as yours that he purchased shortly after he saw the performance I was getting with mine. He gets on average around 17mpg. When it was purchased, the only modification was a Diablo Sport Puck, which added about 60hp. Since then he has added the Banks HiFlow Ram, a higher flow turbo housing by Banks that improves the flow through the stock Holset Turbocharger, & a high flow air filter. He get 21mpg on the freeway from his 1-ton dually vs. the 19mpg I get from my 3/4 Ton Durmax. Your Cummins is probably the most bulletproof & reliable motor of any of them. Banks put that same motor into a Dodge Dakota, towed a trailer with it to the Bonneville Salt Flats, ran a 221mph pass with a world record average of 216mph, and was capable of getting 21mpg on the road. That motor is very capable. You should first check to see that you are getting sufficient airflow to your motor. Unless someone has damaged something, you might just have a clogged air filter. You should only be getting that kind of mileage if you are doing some heavy towing.

I bought a 2004 5.7 with auto trans . pulled a trailer of 5ooo lbs plus milage was 12 to 13 until 70000 miles went to 16 13 with trailer 136000 now with trailer 15 to17 truck only 16 to 24 55mph is best 85 cost mpg . you have to break in the engine to get better milage aprox 70000.