I have just posted re: installing a diesel engine in a Caravan. I am interested in learning if there are other ways to improve mileage.

What I have hard anecdotally the Caravan with 4 cylinder/5spd gets 30 mpg on the freeway and 22 in city driving. Have you found mods to do to the engine/transmission/vehicle to get more?

I will be rebuilding the engine so have room to play around with machining, pistons, headers, exhaust systems, etc. I have seen several systems advertised as "running your car on water", which seems to be a simple little hydrogen generator to put in the engine compartment. Do these things work?

What works? What have you done? Changing 5th gear? What are my chances of making mods to get 40 mpg on the freeway?

 

Raising the compression ratio will increase fuel efficiency but you don't want to raise it so much that you need to use premium gas.
Advancing the timing a few degree's will do the same thing.
If you can find a reputable company that actually knows what they are doing,you could have a custom camshaft ground to optimize low RPM fuel economy.

Keeping the van's tires inflated and engine tuned will do the most for fuel economy.
Unless you just want to experiment,spending extra money on diesel engines and specialty rebuilds is a false economy.The money would be better spent on a newer,more economical vehicle.

Hydrogen generators do nothing except lighten your billfold.

 

There's the usual stuff (which some stuff has already been touched on) but let's face it..... the biggest factors are weight of the vehicle, aerodynamics and that thing at the end of your right leg.....

Caravans are heavy. I'm impressed by anyone who can get 30 mpg out of a caravan. I don't see my caravan using less fuel going up some of the hills around my neighborhood as my little car at half the weight. There's just no way. Mass is mass. It takes fuel to move it. Displacement of engine is another key factor. Smaller engines like the four-banger caravans are going to get better gas mileage, but the catch is giving up HP, especially for any of us who use it to tow or haul.

Aerodynamically, the newer models aren't that bad, but you're still pushing a lot of air. Let's face it, it's no Honda Civic when it comes to drag coefficiency.

Properly inflated tires help a lot. So does driving the speed limit. People who live in an area where the terrain is flatter have an advantage over those of us that have to drive up and down a lot of hills.

Okay,here are some of my tricks....

When sitting in a drive-in line (which I really don't do much) I shut the engine off when I predict that I'm going to be sitting in one spot for more than about 30 seconds. No, I'm not so cheap that I get out and push until I'm at the window.....

When sitting at a light, I stick it in neutral (yes, I have an auto) so that the engine doesn't have to work as hard since the tranny is basically disengaged. This is one advantage of manual trannies over autos when it comes to fuel economy.

I also get off the gas earlier when coming up to a light or stop sign. I've learned that my rig rolls farther than I thought even when I'm not on the gas pedal. No sense in driving fast up to the light only to wear out my brake lining faster. In other words, trying to drive more "smoothly" helps.

Of course, keep the tires properly inflated. I also changed the intake to a dual cone filter such that the engine doesn't have to work as hard to get air in. I also changed the exhaust system so the the engine is breathing better and doesn't lose power by having to work harder to push exhaust gases out.

I try to keep as many seats out of the van and extra junk such that I'm not carrying around any unnecessary weight (the van's heavy enough when empty).

The biggest thing is just driving less. Consolidate what trips you can. Move closer to your job. Move your job closer to you..... I have a four mile commute (one-way). I'm planning on riding my bike to work when I can.

Get a small daily commuter. For me, there's no sense in driving my biggest vehicle that I've ever own all over God's green earth....

Avoid traffic jams. Be as careful as possible about when you drive (within reason) such that you sit less in slow traffic.

Use a little thinner oil, not too thin. Most vehicles can stand one step thinner oil than what is in the owner's manual. Thinner oil means less work for the engine. I'm sure I might get a few people who don't agree with this one, but.... tough.

Use Gumout once in a while down the throat of your throttle body. Rev the engine a little so that it doesn't die when you do this, but it reall cleans off the injectors for pennies and helps to get rid of carbon build up.

Good luck.

 

I agree with LN323

I own a 1996 Dodge Grand Caravan SE Sport 7 passenger with the 3.3L V6. I'm actually impressed with my 4400lbsvan getting the 26 to 28 mpg on the highway. I've done the exhaust change, put in a K&N Filter, and some other li'l tricks to get it tho. I do one thing (and some might argue this point) when I change my oil most will over look. I put Slick 50 engine treatment in my motor oil and the Slick 50 Gas Treatment duringevery oil change. I've noticed a great changehow the van starts, idles, and accelerates. I run Castrol GTX High Mileage 5w30 motor oil and that seems to help as well. I run Regular 87 octane gas when driving around townand to help clean things up I will run the Mid Grade on road trips and have noticed that I can get as high as 30 mpg! I do use the cruise control alot to let the van pace itself when on the highways and interstates.

I've noticed driving in Kansas City that if you drive the speed limit and not go racing from red light to red light you can catch most traffic lights on green which helps tremendously cause you aren't stopping and starting all the time. I as well put my van in neutral at certain traffic lights cause they are longer than others and I avoid drive throughs all together. LoL I hope this helps anyone lookin' to improve their gas mileage.