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Old 05-14-2021, 08:51 AM   #128 (permalink)
funkhoss
EcoModding Lurker
 
Join Date: Jun 2010
Location: Edinburg, VA
Posts: 95

The Little Car - '00 Chevrolet Metro
90 day: 91.08 mpg (US)

The Big Car - '94 Chevrolet Caprice Wagon
90 day: 44.9 mpg (US)
Thanks: 11
Thanked 165 Times in 52 Posts
Quote:
Originally Posted by Desert_Slim View Post
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!

Quote:
Originally Posted by Desert_Slim View Post
...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
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