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

http://i1217.photobucket.com/albums/...ps57913167.jpg

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!

Do you have electric radiator fans or an intercooler?

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

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.

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.)

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

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

pic attempts-

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

http://i1217.photobucket.com/albums/...ps57913167.jpg
http://i1217.photobucket.com/albums/...psa2b3d30b.jpg

here are the drivetrain comparisons-

diesel on the left (first pic)-
http://i1217.photobucket.com/albums/...n/616vs433.jpg
http://i1217.photobucket.com/albums/...n/616vs432.jpg
http://i1217.photobucket.com/albums/...n/616vs431.jpg

here is the diesel drivetrain installed-

http://i1217.photobucket.com/albums/...ps01f91295.jpg

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

http://i1217.photobucket.com/albums/...ps80cce332.jpg

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-

http://i1217.photobucket.com/albums/...psfc60021c.jpg

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

http://i1217.photobucket.com/albums/...ps7fca9236.jpg

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. :D:p That may be impossible, but would be pretty good for a 15mpg over stock

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

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

next door neighbor is a VW restoration guy. Thats his 1974 beetle DD, has one of those autostick contraptions for a transmission, making it of little value I guess to VW heads.
crazy setup, a clutchless stick shift with an electrically actuated solenoid that operates a torque converter for an automatic 3 speed transmission

I have one of those- it's a head-scratcher for sure with all the disadvantages of manual and automatic transmissions combined into one super complex unit. :confused:

Awesome project. Clean work. You should have no problem achieving 35. Check out diesel Dave on this site. He can get tanks up into the high 40s low 50s. Utilizing engine off coasting (EOC) good luck with it!!

Awesome
 

Hi, and welcome.

I see you now have stats under your username. I think MetroMPG may have helped you out, I think he's the site owner/mod.

I know the aero on an Astro isn't great, but there's plenty of room for improvement. You could add a bellypan underneath, skirt those rear wheels, add an airdam up front, etc.

Go look at Aerohead's assorted posts, the guy is an aerodynamics whiz. And for inspiration, read up on Basjoos, who takes aerodynamic optimization to its ludicrous ideal...ludicrous, but profitable.

Subbed, if I can figure out which button to push.

Very neat! I'll bet you get some interesting looks from folks who are like..."Um, why does that Astro van sound like a diesel?"

Needless to say that I like this project, altough I'd rather use some Asian engine instead.


That transmission from Volkswagen was just a regular 3-speed non-synchronized manual, but had both a viscous torque converter and a dry clutch for the gear shifts. The clutch was only engaged when the driver touched the lever, with a photoelectric sensor like the one used in cars adapted to disabled drivers. There were also some versions which used the electric actuator similar to the one used in the cars fitted with the Saxomat automatic clutch, which had a centrifugal plate to keep the clutch depressed when idling and a vacuum-activated setup for the gear shifting, with an electric contact assembled at the shifter lever to release a vacuum solenoid.

thanks for the tip! lots of amazing achievements on this forum, the engine off coasting is very interesting concept

thanks! good ideas, definitely a belly pan, and rear wheel skirts will do nothing to the daily usability of the van, while maybe improving economy

One thing id like to try and rig up long term is a ladder rack that either folds out, or is in some way aero. i only occasionally need to carry a ladder, but the bulky and exceedingly useful heavy racks on most work vans kill economy. If I can build something that can duplicate it but fold down behind some kind of wind fairing, that would be the best of both worlds for me

so far ive had one guy jump when I fired it next to him, then come back and say "diesel?" Most people just think I have a major engine problem though.

I took it to get exhaust welding done at a hot rod place, and the consensus was "why would you do that?" :D

its amazing how many people equate added HP with positive, and lowered HP with negative.

I find it conceptually fascinating how they designed the transmission personally, thanks for this added description! Though it does seem to be a major piece of complexity. My neighbor has already rebuilt the think early this year, and its having problems again, requires constant attention.

Decided on the MB engine as I am very familiar with them, less so with asian plants, but there is a guy who put I believe a nissan 6cyl diesel and 5-speed in his astro as well. He reports excellent service.

Here is his thread on his build-
NissanDiesel :: View topic - Astro Van with LD28

and here is my build thread as well-
http://astrosafarivans.org/bb2/viewt...hp?f=72&t=8941

I would really love to compare the two eventually. His has been in service for years I believe, he's put a lot of miles on it

Why create when you can contrapt? I mean, you're driving a minivan based on a pickup optimized for economy powered by a diesel which was never offered in the vehicle, provided by a manufacturer never associated with the vehicle, and considering adding a turbo that the engine never had before. When you're going over the edge, make it a swan dive. Go over with style.

I think a couple of manufacturers offer ladder racks that fold down - maybe. But even if they don't I don't see a reason why you couldn't fab a low profile one. You're obviously not afraid of your tools or of making changes to your vehicle. It won't be completely clean but you wouldn't have to assemble it when you needed it either, just pop a pin out, unfold, and pop the pin back in. Bob's your mother's brother and up goes the ladder. Add a little airfoil ramp ahead and behind the rack bits so that when folded it presents as clean a profile as possible.

Makes me remember the reactions of a few dumb schoolboys when I told them about a Suzuki Vitara repowered by an uncle of mine with a 50hp Volkswagen 1.6IDI engine.

wow this is an awesome website. Been reading up on some of the amazing projects people have completed.

so ive got a list of tradeoffs and things I could do and things I shouldn't too keep this as a usable work vehicle.

Things I have to keep-

1. Rear doors must open completely and not be interfered with
2. Sliding door must open completely and not be interfered with
3. Current length should remain the same (parking and maneuvering advantages of this particular van I don't want to lose
4. Have to keep the rear bumper (work van necessity)
5. Huge mirrors I must keep for towing and maneuvering, (though smaller side mirrors and strap on tow mirrors are a possibility)

Things I can do-

1. Baby moon hubcaps
2. Rear wheel covers (though passenger side might be an issue with sliding door)
3. Encapsulate the underneath
4. fairing for the wipers
5. Chin spoiler of some type
6. fold down utility rack that I hope to have drop beneath some kind of fairing

Thats just on aerodynamic mods, then I can can turn to the efficiency of engine components and such.

Id also like to preserve a reasonable ground clearance for job sites in rough areas, the rear of this van will actually be lifted approximately 1.5 inches once i get around to swapping out the rear spings.

If I am reading correctly, when doing a chin spoiler, it should come down to the lowest point of the underside and things should be flat from there?

A fresh set of rear springs will help a lot.
My suburban was sitting so low that the trailer hitch would scrape on some of the steeper curb ramps. It was also riding really rough even with new shocks, wish I had replaced the rear springs years ago.

I put a set of used C20 (3/4 ton 2wd) leaf springs on the rear of my suburban, it rides so much better now. The springs were not factory original to the truck they came out of, they had fresh paint.

With a chin spoiler or air dam the lower the better. Put it as low as possible with out tearing it off.

If you have 15 inch steel wheels you could throw on a set of these:
http://ecomodder.com/forum/showthrea...eel-22003.html

I think you could go to full moon wheel covers. A lot of guys have done that here and gotten great results. Or just whip out some coroplast and fab up something quick-n-dirty, it doesn't have to be gorgeous just to prove whether it helps. (NOTE: I don't think anyone has ever come back to say it had a negative effect).

The chin spoiler, ideally, should be as low as the lowest projection on the van's underside. There are proponents here who say a full belly pan almost eliminates the need for an airdam, and a good airdam almost eliminates the need for a bellypan. Almost. With so many other things on the vehicle non-negotiable, I think if the bellypan and airdam combine for better results, go for it. Besides, looking under there you can see it's an aerodynamic hell. You almost can't make it worse.

Rear fender skirts shouldn't be a problem at all.

Good work, JB3.

What transmission did you use for your van?

There are a lot of old 80s Benzes out there starting to lose the battle with rust but their engines are still the same old bullet-proof design. Since your Astro is a S-10 pickup chassis with a van body, a small pickup project would seem to be feasible.

New rear springs are in the works. This van has original fiberglass rear leaf springs, which as the years go by, I get increasingly alarmed that one day they will crack. A company called overland vans carries a replacement upgrade steel leaf set that is bolt on I've been saving towards. Shocks are shot too, definitely looking forward to a new rear suspenion

I agree, I don't see how doing both could hurt in any way, especially with the other tradeoffs

I'm using a T5, with non wc S-10 gearing and an astro specific shifter adapter. (Design of the van has th engine over on the passenger side a few inches so there is a special shifter t bring the stick over to the driver side). The engine and tranny are mated using a 4x4labs adapter kit, which is a pretty slick product

Interestingly the astro van chassis are a hodge podge of gm stuff. The van is actually a unibody with the front subframe from things like the caprice wagon, and the drivetrain frm the s10, k1500, ect. The 4.3 came in everything it seems

Yeah I have seen those fiberglass leaf springs plenty of time, I don't know of any problems with them.
But even steel springs sag over time, so I don't see why fiberglass would be any different.

My understanding is that fiberglass loses its resin over time and becomes brittle. The ones on this van are comin up on 24 years old of constant flexing and weather, time to beat the inevitable cracking to the punch is my plan. :D

Update on economy, a second test run the van did 27mpg loaded up. I don't have an odometer or speedo hooked up yet, so the way I'm calculating this is going to a diesel pump, filling up, making my work run and writing down exactly where I went, then returning to the exact same pump and filling back up. Then later google mapping the route.
I think I can get closer to 30 when its aligned as well before any aero mods. Its doing high 20s and I've cooked the RF tire in under 1000 miles. Basically I'm trying to establish a baseline for the current drivetrain I can compare against, especially when I go to a much lower diff ratio soon

High 20s while pigeon-toed and loaded, I think you're going to be very pleasantly surprised when you get those tires pointed the same direction.

Have you never considered to upgrade everything for an air suspension? That would be good, allowing you to ride lower in good pavement for a reduced drag or increasing the riding height in rougher roads.

so, swapped over to 4.56 from the 3.23

here are the two rear ends, 4.56 built into a 97 diff on the left-

http://i1217.photobucket.com/albums/...psa277704f.jpg

also put in steel leaf springs with a higher load capacity. I did make the van heavier doing this, Id estimate each leaf was 3 times heavier than the fiberglass monoleaf. However, the fiberglass had to go, not so much the springs themselves as the hangars were close to failure

http://i1217.photobucket.com/albums/...ps5ab08995.jpg

4.56 diff installed-

http://i1217.photobucket.com/albums/...ps00a6c418.jpg

The immediate difference is no sluggishness in first, and I can pull overdrive on the highway now! very excited to see what new MPG numbers this might present for me.
I can also do hill starts, which was a hit or miss thing with the 3.23.

had it aligned, it took them 2 hours to get the camber within spec, and they demanded I bring it back for another session in a month. :D

much safer now though

not a bad idea for down the line! Since i installed a lot of new components, it may be some time before Im ready to get back into the suspension

Great news on the axle/gear swap!!

Can't remember if tires were discussed. Truck-spec closed-shoulder highway rib tires would be my choice for another "major" change. Or, what is best suited to climate/terrain and truck use in a premium brand of tire if time/miles anticipated warrant it (MICHELIN, not BFG; Bridgestone, not Firestone. Etc). Tires are not the place to go cheap. They'll more than pay for themselves on a work truck. Same with shocks: Bilstein over Monroe, etc.

Has brake drag been looked over, front and rear axles? Same for steering slop, from column out through end links . . big truck manufacturers note this as a measurable FE problem.

The precise steering and "feel" of a tight front end, well-adjusted brakes/bearings and no-slop steering system coupled to premium tires/shocks is the feedback needed for low fuel burn tactics on a truck. The pieces needed to fit within a "smart use" strategy.

.

JB3,

Just started reading your thread and I thought I would give some tips for your OM616 engine. If you can find 82 or newer head for it you can take the Cam, Cam towers, etc... and put them on your other head. Of course you can just swap the heads too but it may be hard to do that with the engine in the van already. This will give you a couple extra horses and a little better efficiency because the later model years had greater lift on the cam to help the engine breath better.

Also you can adjust the boost on the turbo charger too. (its a pain in the butt but it can be done).

Edit: it may be 1983 where the camshaft changed.

oops I was off on the year. It was 81

further discussion can be found here

Any reasonable way to get more power from a 240D? - PeachParts Mercedes ShopForum

Edit: Okay with out a shop manual I can't nail the year down but the later 616 Camshaft code 10 is the one you want.

http://www.superturbodiesel.com/std/...light=camshaft

great info thanks! im going to check out these threads. I do happen to have a 240 head sitting here that someone gave me. It might be a later head, do you know how to identify the castings? Will the cam itself have a code 10 on it?