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Old 09-04-2012, 01:28 PM   #1 (permalink)
EcoModding Lurker
Join Date: Sep 2012
Location: central pa
Posts: 16

Acadia - '12 GMC Acadia SLT FWD
90 day: 16.45 mpg (US)
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Hi Everyone, heavy wagon / SUV 'project' Volvo V70 XC


New to the board and I wanted to introduce my project (oh, and I'm Mike from central PA.)

It's a 2001 Volvo V70 XC, automatic (5-spd manu-matic), AWD, 2.4 liter inline 5 low-pressure turbo car. 150,000 miles but in well maintained condition. I currently average about 21mpg over a full tank - this rarely varies at all and my calculations always match the built-in computer almost exactly. Shorter trips can be as low as 16mpg. This is mostly my to-from work average. On a longer weekend trip to the beach, I can average somewhere in the 24 to 25mpg. Looking forward to tracking this more closely.

Also looking forward to learning about a few well-known and maybe a few fringe technologies to improve this. My end goal is hopefully somewhere in the 15% to 20% improvement range (I know, lofty goal!) and if this is more biased toward the local commute vs. highway, I'd be fine with that. I'd like to limit myself to a 3 or 4 year payoff for modifications and I'm very comfortable with advanced auto mechanics. Budget will likely be capped at about $3,000 usd.

Limits - the car must remain usable as a wagon to haul my kids (3 and 4) and my wife and our 2 dogs safely to a destination, possibly with a load of cargo or even the occasional trailer in tow. It can look funky doing it but I don't want to disturb the inherent safety of the car (not going to chop the roof and change pillar angles, for instance.) I'd like to retain the AWD if possible. I've gained what seems like 1 to 2 mpg avg. over a summer season with the center driveshaft removed but never did an A-B-A comparison in the same weather conditions. I may make that a seasonal maintenance item.

Things I'm most interested in:

* starting with lower viscosity synthetic lubricants at any maintenance intervals

* leaner AFR, increased static compression ratio (milled head) and supplemental water injection to keep things from knocking - I've read that water injection is really only effective on diesels but I wonder why trimming back fuel and advancing timing (reducing power) but cooling - I feel like big gains could be made here but nobody has really documented it very well for FE gains.

* possible stand-alone engine management to mess with fuel/timing rather than just trying to fool the fuel management

*lighter, narrower wheels and LRR tires (this falls outside the budget since I'll need tires in a year or two anyway and I'd wait until then.)

*lowering the vehicle approximately 1.5"

*airdams, undertrays, other aero mods (custom grill, etc.) possibly some of the rear hatch aero conversion stuff but only if it doesn't kill visibility.

*possible downsizing to Volvo 1.9T 4-cyl instead of 2.4T 5-cyl

*slight possibility of completely removing all AWD components and going to manual transmission but then why not start with a FWD car?!?

I've also always had a radical idea of supplementing with an electric drive for the rear drivetrain and decoupling it from the front. The cost/size/weight of batteries is the limiting factor on that one since payback would be closer to 10 years so I've never really seriously considered that one for very long.

I'd love to hear other feedback about similar 4,000lb vehicles with huge frontal areas and big hatchback dropoffs. Thanks everyone! Looking forward to the journey!

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