94 Caprice Wagon 5.7L project--46 MPG so far

[jojogunn]

On powering the vent windows:
First generation chrysler minivans had rear quarter power windows. These came in manual or power. A teleflex cable was in the headliner from the the front of the car to the back to make it work.

[funkhoss]

Originally Posted by aardvarcus

Yes, this vehicle is very impressive, better MPG than would be expected for a vehicle with that engine and tow rating. Gives me hope for my Suburban project.

I'm very interested to see how your Suburban turns out, too!

I've thought that if I had to do this over again, I might start with a 2500 Suburban instead of another Caprice. The wide availability and compatibility of truck parts with that platform would have made this project much easier. And, there are times I've found myself wishing that I had four wheel drive (despite already having a selectable locker and mud tires).

-Funkhoss

[funkhoss]

Originally Posted by jojogunn

On powering the vent windows:
First generation chrysler minivans had rear quarter power windows. These came in manual or power. A teleflex cable was in the headliner from the the front of the car to the back to make it work.

I pulled some quarter window motors 6 or 7 years ago. I forget now exactly what they were from (probably a Nissan van).

I've still got them in storage somewhere--just haven't gotten around to doing it. Clearly, it isn't a pressing need.

-Funkhoss

[britttolbert]

Interesting given that most people would think to go the route of light duty/light weight parts to get better MPG that the route of super heavy duty parts can give similar results when chosen wisely! Awesome project!

[Planecrazy]

This thread has been a blast to read! I have always had a fondness for big wagons and, after owning a 2005 diesel Excursion, I've experienced owning the biggest wagon of all, lol!

What you've pulled off with the Caprice is truly impressive! Makes me much more confident with plans to "upgrade" any SUV's I find myself with in the future! Rock on!!!

[funkhoss]

Thanks, britttolbert and Planecrazy, for the encouraging comments!

We've just finished moving, to a different place in Virginia that's about 190 miles away. We moved almost all of our stuff with this wagon, in five loads--three using our 16' open trailer, and two borrowing a friend's 16' x 7' box (enclosed) trailer.

We drove faster than usual on each trip, averaging about 55 MPH, so that we could go up, unload, and drive back in one day. The open trailer averaged about 20 MPG round trip each time--probably ~18 there and ~21-22 back.

The box trailer averaged right at 16 MPG both trips. However...when you consider that a "normal" gas powered pickup or SUV would have probably averaged about 10 or 11 MPG with that trailer--that's still pretty good.

It was kind of unnerving seeing the average that low, for so many miles. However, once I unhooked the trailer the trip averages immediately went back up to the low 40's MPG, so all is well.

-Funkhoss

[Desert_Slim]

Funkhoss, got no clue how I ended up on this page.. but I want you to know that your build thread is the reason I joined ecomodder. Awesome work! I’m off to head down the rabbit hole of ecomodding which is completely foreign to me. I’ve got a project 2500 GMT800 suburban with the boat anchor Vortec 8100. I intend to swap it with something else, a diesel perhaps but my question to you is this.. what Top 5 mods could a newb make to such a platform to get better overall efficiency?

Keep up the good work! and thank you for sharing!

[funkhoss]

Originally Posted by Desert_Slim

Funkhoss, got no clue how I ended up on this page...

Ain't the internet great? It's good to have you here, and thanks for the kind words!

Originally Posted by Desert_Slim

...what Top 5 mods could a newb make to such a platform to get better overall efficiency?

Without doubt, the single most important "mod" you can make is to adjust the nut behind the wheel.

Driving technique trumps everything else. With this wagon, I can pretty much always get low to mid 40's MPG, with some tanks as high as 50 (as long as I'm not towing, of course). However, if a "normal" driver drove this car, they wouldn't get anywhere close to that. For some drivers, I'd be surprised if they even got half the mileage that I do...

Now, with that said, there are certain modifications that have to be made in order to even allow for such advanced driving techniques--pulse and glide with engine off coasting being the most important, and hands down the biggest fuel saver, especially for a large vehicle with a large displacement engine. If you haven't read up on how P&G with EOC works (maximizing an engine's BSFC, and eliminating all other fuel use) you should poke around on this site for a while until you have a thorough understanding of how it works. (While we're talking about technique, the other two things I'd strongly emphasize for your vehicle are (1) to slow down, and (2) to minimize your use of the brake pedal as much as possible. These two things, combined with P&G/EOC, are pretty much the "secret" to my success with regard to driving technique.)

With that said, to even attempt to do P&G with EOC in your vehicle you will need at minimum the following:

• A manual transmission
• An engine kill switch
• Either manual steering conversion or an electric power steering pump, so that you can still steer even with the engine off
• An electric vacuum pump for your brake reservoir, so that you don't lose your brake assist with the engine off

Then, just as importantly, I'd recommend that you purchase and install some sort of trip computer like a Scangauge. Pretty much everyone on this site has one, because nothing beats realtime feedback for teaching you how to drive more efficiently.

I guess that's five mods already! Just doing these things, combined with the right technique, could probably come close to doubling your mileage without doing anything else. Any other mods you do will have a much lower ROI. However, if I had to name a few more where I would start, they would be:

• Low rolling resistance tires--I've found that these can make a very measurable difference. The best LT tires that I've found are the Nokian Rotiiva HT. They're the only LT tires that I'm aware of that are specifically built and marketed as LRR.
• Gearing--keeping the RPM low, especially with the 8.1L engine, is really going to help, even with P&G
• Tuning--If you can tune out power enrichment at lower RPM (say, below 2500 RPM and 80% TPS), and keep it in closed loop, that will help maximize the effect of P&G.
• And of course...areo mods! Air dam, grill block, smooth wheel covers, skirts, and some sort of Kamm extension would be the basic things to try first.

Personally, I'd do all of these things before I even touch the 8.1. If you do all of these things, swapping to a diesel later might not even improve it all that much.

I hope this helps! Welcome to the world of ecomodding!

-Funkhoss

[funkhoss]

One more thing I forgot to mention: if you start doing a lot of EOC, you'll probably need to upgrade to a deep-cycle battery and perhaps LED lights. Especially in the winter, when you use the lights and heater fan a lot more, you can kill a normal lead-acid starting battery in short order. Ask me how I know...

And, if you like having heat in the winter, and electric pump in the heater core circuit is a must.

-Funkhoss

[MetroMPG]

Welcome to the forum, Desert_Slim.

Some good advice (no surprise!) from funkhoss.