2nd Gen Non-Engine/Transmission Fuel economy mods - what do you think?

[WBusa]

Nobody needs me to tell them that the price of diesel is sky-high, and is only gonna get worse in the long run... judging from the number of recent threads dealing with fuel prices, this issue is on everyone's mind.



Myself, I've lately started to wonder what modifications I could make that would improve fuel economy, and I would enjoy hearing all your thoughts on this subject. But first off, let me list a few truths I already realize, and which don't require much further discussion:



* The cheapest, easiest, and best way to improve fuel economy is to keep your tires properly inflated, drive like an old lady (except, unlike an old lady, you should avoid lugging the engine), and don't carry around cargo that you don't absolutely need to (i. e. , no brush guard, no snowplow in June, get those old cinder blocks out of the bed, etc. )



* Very few, if any, modifications that promise improved fuel economy are clearly cost-effective in the short term. That is to say, if you spend $1000 on a mod that improves your fuel economy by 5% (say it takes you from 20 MPG to 21), you drive 10K miles per year, and fuel costs $2 per gallon (I wish!), it will take 20. 8 years for the fuel savings to pay for the mod. To me, this is not a problem for a number of reasons:

(a) This kind of analysis assumes that fuel prices stay level (or if you get a little bit fancy with an Excel spreadsheet you can factor in some constant annual inflation rate without too much difficulty). I'm of the opinion that we're going to be seeing exponential price increases from here on, in which case fuel-saving mods pay for themselves a lot faster.

(b) There are non-monetary benefits to take into account, as well: bragging rights, a nice warm fuzzy feeling (hey, I'm a tree-hugger and proud of it - so shoot me!), and another excuse to play around under the hood (i. e. , its a hobby, its not supposed to pay for itself). So I'm not real concerned about whether a mod will pay for itself or not... I'm more concerned that it will actually have a positive impact on fuel economy.



* Many mods that are advertised as improving fuel economy often don't. For example, a BHAF will improve mileage only if your CTD is starved for air; if not, you'll see no improvement. Tonneau covers are a controversial point... I've seen some folks swear they improve aerodynamics (and thus improve fuel economy at highway speeds), whereas others swear the opposite.



All that said, I'd welcome a discussion of practical mods (engine, transmission, body or otherwise) that you think would have positive impacts on fuel economy. Let your imagination soar... though I'm prolly not gonna go for a bullet-shaped carbon-fiber body :-laf

 

[Gary - K7GLD]

One frequently overlooked MPG inprover, especially when driving in traffic, is to look WAY ahead, and anticipate traffic flow, stops and starts, etc.



Dunno HOW many times I've been in traffic next to some jackrabbit driver who spurts from one stoplite or traffic bottleneck to another, taking off like a shot, then forced to slam on the brakes at the next stop - not only does his MPG suffer, but also his tires, brakes and nerves...



In traffic, I rarely use the brakes - I watch ahead, and let up un the throttle LONG before the actual need to stop, and let gravity and other natural forces slow me down. And little point in dragracing away from a stoplite, when I can clearly see traffic at a dead stop 1 or 2 blocks ahead of me... In fact, properly guaging traffic flow and stoplite timing can in many cases ELIMINATE the need to come to a complete stop...



Nothing like towing a trailer to teach you the smoothest and most economical ways to drive! :-laf

 

[Mark_Kendrick]

There are very few mods that are cheap enough to make buying them worth while. Propane in very small quatities helps but not enough to pay off in the lifetime most owners have a truck. injectors and boxes can help but only if driven properly.



The 12V guys can make big differences in tuning. 24v guys are at the mercy of the aftermarket.



The easiest and cheapest mod is taking a bit of weight off your right foot

FWIW,

Mark

 

[TMills]

I don't think there is many, if any, cost-effective fuel modifications. If you want to most for your money then follow the first bullet of your statement.

 

[WBusa]

Again, folks, please let me remind you that as I previously explained, "cost effective" or "cheap enough to make buying them worthwhile" isn't one of my main issues here...



I know, maybe this just sounds weird, but think of it a little bit like BOMBing... nobody says "man, that BOMB will never pay for itself. " Of course it won't. Who cares? Its a hobby, not a business.



Mark, can you perhaps point me to any solid info re: the mileage effects of propane, and the equipment required?

 

[Mark_Kendrick]

The propane should be 5% or less. . 7gal lasts 2000mi or so. In low quantities it acts as a catylist to the diesel process. It will give a very minor increase in performance due to consumption of available fuel, reduced particulate emissions and increased mileage (burning less fuel to do the same amount of work due to more complete combustion)



I have a friend in Ft Worth that uses it in his '94 2500 and a 40' pusher. the '94 gets 28mpg in town and weighs about 9500#. the bus gets 12mpg out of an 8. 3.



I'll talk to him and see if I can't find some sources and prices for an estimate.



Later,

Mark

 

[WBusa]

Thanks Mark... I'd definitely be interested to learn more. 28 MPG in city driving is certainly nothing to sneeze at for a '94 2500... on a good day with the wind at my back I'm lucky to see 20 MPG on the highway in my '95 2500, so that's gotta be like a 40% mileage improvement... that's HUGE.



That said, I'm old enough to suspect that there's gotta be a catch... but I still look forward to learning more.

 

[Gary - K7GLD]

I ran propane injection om my '91 - made a great improvement in power when towing or racing - and undoubtedly also delivered the MPG improvement it promised as well, but that was never my main purpose, so never really checked. Propane is easy to install and setup - just be sure to figure propane consumption into diesel consumption when calculating MPG...

 

[keimmmo]

My 01. 5 will consistently average over 22 mpg on trips with a light load... sometimes even into the 25-26 mpg range. When I replaced the VP-44 a while back it improved the economy over the factory pump. Gutting the muffler also made a noticeable difference! A straight pipe should do the same thing if you like the noise. Removing the silencer tube between the air box and the fender helped a little. Everything combined it is up about 4 mpg over stock.



I burn used motor oil in my fuel... it is free fuel.



Removing bug deflectors, mud flaps, etc. will reduce wind drag and improve the fuel economy.



My topper made little difference on the 01. 5... which is pretty good since it is about a foot taller than the cab of the truck! The cab high topper on the old 92 picked it up about 2 mpg. I think a good topper or bed cover will improve the fuel economy. A square poorly designed topper could very well hurt it.



Steve

 

[gonehuntingagain]

The size of the tires you run, as well as the type of tire will make a difference. I replaced my tires a few months ago with some that were the same size, but a step up in agressiveness. Mileage dropped 2mpg (figured by hand)

 

[bmoeller]

Before the flatbed, the fuel/air mods I have, gained me a solid 2+mpg. That was a nice surprise. Figured it would go down. With the flatbed, I really can't tell, since it is hard to fill up consistantly to the same level. Seemsto have dropped back down to where it was before.

 

[KVaughn]

A simple cheap MPG improver is to keep the air filter clean. I realize that a dirty filter picks up more particulates; however, a clean one improves MPG. Catch 22 maybe, but a good AFE Proguard7 seems to pick up everything clean or dirty.

 

[Mark_Kendrick]

Thanks Mark... I'd definitely be interested to learn more. 28 MPG in city driving is certainly nothing to sneeze at for a '94 2500... on a good day with the wind at my back I'm lucky to see 20 MPG on the highway in my '95 2500, so that's gotta be like a 40% mileage improvement... that's HUGE.



That said, I'm old enough to suspect that there's gotta be a catch... but I still look forward to learning more.

that '94 has a utility cap, aux tanks , solar panels, a fridge and tools. it weighs close to 10k#.

I am utterly amazed it's able to pass a gas station much less get the mileage it does.

the system Jim runs on his truck isn't what I/he are gonna put on mine. His has a servo actuated temp contrrol for the evaporaitor (20gal liquid draw tank).



the Pusher uses what I'm gonna have. it went from 8-10mpg to a solid 12.



I don't think i'll get those gains on a 24v(electronic) but the machanically injected trucks seem to see huge gains.



FWIW,

Mark

 

[dodge cummins]

can that be for real 28 mpgs out of a 94 12 valve.

 

[Mark_Kendrick]

can that be for real 28 mpgs out of a 94 12 valve.

I was with him when he was getting 23 pulling a 12' enclosed trailer at 70+mph.



I never cease to be amazed at the economy he squeezes out of that old 12v. I wish my CAR did as well

 

[WBusa]

OK, I've had a chance to do a little learnin' about propane injection. Not much, but a little -- most of the info that's immediately available to me is marketing flurp from the guys who sell these systems (mostly BullyDog and ATS), so there's not a lot of solid info there.



Anyway, they seem to downplay the mileage gain... typically suggesting a 2-3 MPG increase. Hey, more power to 'em for not promising outrageous increases, but at a (typical) 1:4 propane:diesel mix I think that doesn't add up to improved mileage... just burnin' more fuel (i. e. , the added propane), so mileage based on diesel-only increases. Both companies mention some gobbldeegook about the propane acting as a "catalyst", improving diesel combustion efficiency from its typical 75% to near 100%. I'm not sure I buy that, though. First off, a 'catalyst' increases the speed of a chemical reaction without itself being consumed in that reaction... but I'm quite sure the propane gets consumed in the combustion reaction, so it ain't a catalyst. Secondly, I find it hard to believe that normally only 75% of the diesel gets combusted... am I really shooting 9 gallons of #2 right out my tailpipe for every tank-full? I would need to crunch some numbers, but my sense is that propane isn't an actual fuel economy improvement, but instead is just an added fuel... more fuel, more power. I don't doubt that it increases HP, though.



For me, personally, I don't think I'd be comfortable with propane injection. You're putting a combustible propane:air mix in the charge air circuit, where the designers never expected an explosive atmosphere to be present, so I don't like the safety issue. And if you ever develop a leak in your charge air circuit (and who doesn't, sooner or later?) then you've got a propane leak under your hood...



I'm not trying to be a nay-sayer, Mark; I appreciate you pointing out propane injection to me. I'm just thinking out loud about the issues and unanswered questions.

 

[Mark_Kendrick]

The reason they downplay it is because the electronic motors tend to compensate somehow for the additive.

I'm not suggesting using the propane in comustable quatities (near stochiometric) because that would cause premature combustion. In SMALL quatities the propane merely has an effect on the current combustion cycle.



I am saying in a 1:20 or so quantity. once ~5% is reached it then takes a jump to 15% or so until there is enough extra fuel in the mix to 'feel' the hp gain. In the 5% range you have to watch the gauges to see the difference. you may hear a difference but probably won't get a 'seat of the pants' change.



Most propane kits are designed for power improvement not the marginal changes in mileage. The average consumer wouldn't 'feel' the difference and would be a bit perterbed at the expense.



FWIW,

Mark

 

[DKayser]

can that be for real 28 mpgs out of a 94 12 valve.

I think it is. My old truck, 95 std. cab long box auto did 27. 5 two different times on the same stretch of hiway BEFORE I changed over to shorter tires. New truck, 98 Quadcab shortbox auto, only pulls 23 on same trip. The biggest mpg killer I have found on either of my CTDs is a headwind. Just kills economy. And I too drive like an old lady. Truck has a sweet spot @ just under 75, so I try & keep it there. DK

 

[Mark_Kendrick]

I had the percentage off. it's 10%. right now propane is actually cheaper than diesel. a 5 gas grill bottle should run 750-800mi.

Jim says he's seen 10-30% mileage. You won't see more power till over 20%.

Sorry about the mixup.

 

[WBusa]

What about injectors and MPG?

OK, here's another question for the group: will upgrading the injectors yield a fuel economy improvement (if you keep your foot out of it, that is)? I'm guessing (but I sure could be wrong!) that bigger injectors deliver the fuel faster, so more of the combustion occurs at the sweet spot of the piston's cycle, so more of the combustion energy goes into useful work turning the crank. Eh?