Hi Everyone, heavy wagon / SUV 'project' Volvo V70 XC

[mcrews]

I went from 245/45/18 (26") to 245/50/18 (27.6"). but I run a V8. It dropped the rpms nicely on the freeway

[Sporty Modder]

I have had great success with front airdams. 5-10% increases typicaly on multiple cars, I used polycarbonate on the last one(for my Celica 8%)and garden edging for others.

[Nevyn]

Lowering would help, but an air dam would probably do about the same amount of good for a lot less cost.

Kind of funny, actually. One of the selling points of the XC over the regular V70 was the increased ground clearance...

I bet the easiest way to lower it would be to try and swap standard V70 suspension in to replace the XC parts.

[MetroMPG]

I'd also recommend removing the side bars of the roof rack system, provided they're not too difficult to reinstall when needed.

People sometimes mistakenly think the side bars don't affect aero very much, reasoning that they present such a small profile to the wind as seen directly from the front. But we rarely drive in windless conditions (or into wind which is directly ahead of or behind the car), so in real world cross-winds they actually present a much larger obstacle to airflow and significantly increase both frontal area (as seen by a cross-wind) and drag coefficient.

Roof racks for the vast majority of drivers are really wasteful. Drivers pay constantly for their rare usage.

[sikbrik]

Good call Nevyn. The xc can use v70 springs up front but need s60awd parts for the same effect in the rear due to the differences of the awd suspension. I agree that it's very ironic to lower an XC! Haha...but where I live and for where I drive, 11" of ground clearance is overkill until the meteors start hitting earth.

I'll try the airdam first but would like the lowering for added roll stiffness and better cornering, which should allow me to carry more speed safely through turns.

[sikbrik]

LOL @ James Martin. Nicely done! Thanks for fixing it for me.

[josh.chaos]

hey, sounds like a solid plan, I work for a suspension shop right below you in md, so if you need any suspension help just pm me... good luck.

[sikbrik]

Josh, thanks for checking in and offering assistance with the suspension!

After a few weeks of practicing driving technique, I've learned that I'm already a pretty economical driver. i didn't realize any real improvements in mpg with eco driving. Not to say a few of you couldn't put up better numbers in my car but I personally can't. I'm even logging a/f and a few other things with a monitor and my normal driving style seems to be as conservative as I can get, even with utmost concentration.

After that, I ran a few known trips back to back to back with roof rails off. No improvement at all. I guess I should clarify that maybe I'm looking for gains in the wrong way...I commute about 20 miles per day. I can increase my mpg by taking a different rural route which nets me between 10% and 15% better fuel economy. Problem is, that makes my commute 30 miles total and I end up burning more fuel even though my mpg is higher. I do very few highway trips but I'm sure the mild aero mods I'm planning will help there.

So my quest seems to have moved out of aero and into actual engine efficiency. Sure, going from 42 to 44psi has helped a bit on a full tank. Up next is engine block heater. Then you folks will likely think I'm crazy but I'm going to run a piggyback ecm and lean out the fuel maps, adding water injection to keep detonation at bay. Parts are already piling up.

Could it be that volvo already tuned this thing with an eye toward economy and 21 city stop-n-go is the best I'll ever achieve? Is 2mpg (10%) over epa ratings not as sad as I think it is?

[MetroMPG]

Originally Posted by sikbrik

After that, I ran a few known trips back to back to back with roof rails off. No improvement at all.

Correction: no ability to DETECT a small improvement.

We KNOW there is an improvement in efficiency from removing roof racks. However a single small change will be lost in the "noise" of normal variability of your fuel consumption even on known trips.

(FYI: http://ecomodder.com/forum/showthrea...ery-11445.html )

So it would be a mistake to discount small, well understood aero mods as a route to better fuel economy, just because individually they may not rise above the statistical noise. Cumulatively, they will eventually make a measurable difference.

[Nevyn]

Don't think "magic bullet" when it comes to MPG; it's much more like "magic birdshot."

To state it another way (has been quoted elsewhere): Don't look for 100 places to lose a pound. Look for 1600 places to lose an ounce.

I pulled the crossmembers, runners, and mounts for the roof rack off of our 2003 Mazda MPV. *I* noticed a definite decrease in noise (wife, not so much). If nothing else, less noise makes a nicer drive!