Economy modding my Chevrolet Astro work van (diesel 5-speed conversion)

[JB3]

Hi, newbie to the forum! just wanted to start a thread on my ongoing project of maximum effeciency while still achieving maximum usability in my 1989 astro work van.

Some quick history is I use this van for property mantainence and am almost daily towing, or carrying items around, or traveling to a jobsite or back. I've had the van for 3 years, and absolutely love the early shorty vans, which are a few inches longer than a jetta, yet turn just as tight or tighter, and can tow a double axle uhaul flatbed.

For the last couple years I've been collecting parts and waiting out the epa for my eventual plan of a diesel powertrain swap. Previously the van would do at best, 19 to 22mpg, and 16 towing.

Earlier this year I got a final gas inspection sticker, and started work on the swap. The donor motor was to be a 1980 mercedes 616 4cyl diesel, which I would boost power with a 1983 turbo from a 617 motor on custom manifolds, and mate the powerplant to a 5-speed overdrive manual transmission.

I just recently completed work and am in the tweaking phase. First test run I was doing 29.4 mpg which while pleasing is unsustainable with the gearing I have, too much top end, not enough granny power for the low HP plant.
Ill be updating with periodic improvements to see what I can do for economy, but glad to join the forum! Any advice or opinions much appreciated!

[oil pan 4]

Do you have electric radiator fans or an intercooler?

[JB3]

Not yet, the year diesel motor I have actually uses a fixed fan as well, without even a viscous clutch.

I'm using the astro stock radiator. Intercooler is definitely a plan eventually, and perhaps electric fans as well! Right now its extremely simple

Also, unrelated question, how do you get the stats on the left side under your username? Not sure how to do that

[Sporty Modder]

I think you need to start a fuel log for your truck...

Consider this, the fixed fan takes horsepower to turn, the more rpms, the more horse power. On low horsepower engines, like yours and mineremovingthe fan and replacing with a electric can give you a +5% or more increase in power. I amrunning a cheapy ele fan in my car and def won't go back to a mech fam.
I also recomend reducing turbulance under the truck, easy as a lawn edging air dam, or as a belly pan. Again reducesthe amount of horsepower required tl move the van down the road.
Reducing weight, removing un needed seats, carpeting, speakers ect, is also good for city driving, + it alows an increase in payload.
Bumping your tires to max preasure will allow less roling resistance and also give you some more tire payload. Make sure the truck is mechanically sound esp in the steering dept, tierod ends ball joints ect... Tires wobbling and exessive corecting of steering will reduce fuel mpg's
Sounds fun, have fun, and let us know.

[MetroMPG]

Neat project. I assume the van was originally automatic?

(PS: hope you don't mind I added the diesel swap info to the thread title - more eyeballs.)

[JB3]

Originally Posted by Sporty Modder

I think you need to start a fuel log for your truck...

Consider this, the fixed fan takes horsepower to turn, the more rpms, the more horse power. On low horsepower engines, like yours and mineremovingthe fan and replacing with a electric can give you a +5% or more increase in power. I amrunning a cheapy ele fan in my car and def won't go back to a mech fam.
I also recomend reducing turbulance under the truck, easy as a lawn edging air dam, or as a belly pan. Again reducesthe amount of horsepower required tl move the van down the road.
Reducing weight, removing un needed seats, carpeting, speakers ect, is also good for city driving, + it alows an increase in payload.
Bumping your tires to max preasure will allow less roling resistance and also give you some more tire payload. Make sure the truck is mechanically sound esp in the steering dept, tierod ends ball joints ect... Tires wobbling and exessive corecting of steering will reduce fuel mpg's
Sounds fun, have fun, and let us know.

Electric fan is definitely an attractive idea. To do so ill have to rework how the radiator is held, as the fan shrouds actually hold it in in this application. I might cut them down or make something out of aluminum that does the same thing.

As far as underneath, I have a pretty bumpy skyline there, I relocated the battery to underneath, and in order to perform the engine swap, I did a suspension lower and a body lift to create up and down space, so I have a lot of large areas for wind capture from that modification.

The original 4.3 motor was wider and lower, and the diesel is tall and thin, so space was cramped in one dimension, and roomy in others

[JB3]

Originally Posted by MetroMPG

Neat project. I assume the van was originally automatic?

(PS: hope you don't mind I added the diesel swap info to the thread title - more eyeballs.)

sounds good to me!

Yes, the original drivetrain was a 4.3 V6 gas, and an automatic 4-speed with a 3.23 rear end.

what are the rules for pics here? EDIT- oh I see, 5 posts first

[JB3]

pic attempts-

Here is the van, obviously, the Astro platform is as far from aerodynamic as it can get.




here are the drivetrain comparisons-

diesel on the left (first pic)-




here is the diesel drivetrain installed-



I ended up doing a custom floor mount aftermarket clutch pedal for the van. There were factory 5-speed astro's, like 1500 of them total, but the clutch pedal for those was quite difficult to install properly



So currently the phase I am in is one of gearing. The mercedes diesel I have installed is a 70hp plant. I was confident it would work though as this same engine was used in the 207D series Mercedes TN vans, which are the same size as a sprinter, and move around well enough as NA motors based on gearing alone-



With the added turbocharger, im hoping for a bit better performance and power-



I haven't done a dyno run, but Im hoping the low PSI charger I installed will give me another 10-15 hp, to place this van between 80 and 90hp total.

the 3.23 rear end is far far too high for this plant though, I can't pull overdrive at all, and achieved my test run of 29mpg in 1-1 ratio 4th. Im going to a 4.56 rear end, which should allow a pull in the .86 OD gear, and improve torque in all gears. Ist takeoff is also too sluggish for my tastes, I would not be able to confidently tow with the first gear as it is.

(I hope these pics work!)

Once I nail the gearing, im hoping that the fact that I can pull the overdrive at that point should not overly impact my economy. My personal goal with this van is to just touch 35mpg. That may be impossible, but would be pretty good for a 15mpg over stock

[MetroMPG]

Pics worked! Neat project. Adding it to the front page...

[MetroMPG]

PS: your Beetle in the background of the first picture?