Wow A Best ever MPG!

collegekid01 · 11-26-2008, 06:43 PM

So Driving home to Ohio from MI, I got the best gas mileage I've ever had even with my girlfriend in the car and some luggage (around 80 lbs of extra stuff + extra person) plus I just got snow tires put on! I had just installed a WAI and it seems to be working like a charm (plus my driving habits are improving). I got 29.28 mpg!!! that's 1 mpg above my personal best before this (which I think was a fluke from a faulty gas pump). And on this fill I over filled a little. It's a thanksgiving miracle! lol

101mpg · 11-26-2008, 08:40 PM

Congrats! With winter you'll see lower mileage than in the summer. However, you'll also notice that better driving habits trump nearly all modifications. Keep up the good work - keep with your gaslog, and keep us all posted.

brucepick · 11-28-2008, 05:03 PM

I saw your grill block pic on your car's page - nice job! I made a grill block for the Volvo 240 wagon that was my dd before I got the Civic (still have it).

Anyway, anything around 30 mpg is good going in one of these with an automatic. Good job.

collegekid01 · 11-29-2008, 09:26 AM

I have to ask. how did you get above thirty without a WAI? Was it the rear roof spoiler thing, or maybe the electric fan swap? I haven't gotten to that yet because it's expensive but I have a feeling that it would save me a lot on gas.

brucepick · 11-29-2008, 10:35 AM

Well, I barely got above 30, and only for a short while. But it was good while it lasted!!

I did a bunch of things. However my commute ended in Nov. '07 and the new route that started in Feb. '08 was different - I think it was the cause of worse overall FE.

I extended the front air dam downwards so it ended 7" above pavement. Then I made a flat pan going from air dam's new lower edge to meet the oem belly pan. All that was done in plywood, eventually primered in oil base house paint. I recommend 2.7 mm. lauan plywood but take your pick. I think the belly pan was a big part of my gains.

I got the car a tach. It's not what you call typical FE instrumentation but at least its something. I don't know what the deal is for tachs for your year 740. If you'd like pointers on that, go to the forums at brickboard.com and ask away. They are the BEST for rear drive Volvo stuff. I do recommend a tach if you don't have one, even for an auto trans Volvo.

I restored the 240's preheated air intake system with a new replacement thermostat in the air box. I used pipe insulation over the hot air tubing to preserve the heat. I got an interior-exterior thermometer from AutoZone for $10 which reads the intake air temp from the air box. This is important since when the t'stat fails (and they do!) it will kill your air mass meter. I think this airbox restore + upgrade really helped last winter.

The earlier commute had lots of major hills. I went up around 50-54 mph in OD and then coasted downhill in neutral. The new commute had much gentler hills so I couldn't do that.

Synthetic 10W-30 oil from WalMart (SuperTech store brand). Synthetic Mobil 1 ATF in the tranny and same in the power steering.

And ya gotta keep the speeds down, you probably already learned that. These things are rolling boxes so any increase in speed really hurts FE. 50-55 is probably best for FE. Lower than that, I had the feeling that the engine was spinning and the tranny output was slipping.

groar · 11-30-2008, 11:43 AM

collegekid01, you seam to have already a lot of mods. You may think about rear wheel skirts. On my megane I had to improve my driving during 3 tanks to achieve my result with carboard rear wheel skirts : rear wheel skirt.

What about your driving habits ? With over-inflated tires, coasting in neutral permit to save a lot. Think about driving without brakes, so you have to anticipate a lot the slow downs. In city around 25-50% can be done by coasting.

Denis.

collegekid01 · 12-02-2008, 08:25 AM

wow thanks guys that's a lot of information. I do currently have a tach and I have been using the shift to neutral trick on everything from downhill to stopped at lights. I hope to do a belly pan and possibly some wheel skirts some time in the future. I already have an air dam installed too. I t had about 6" of clearance with my summer tires and now with winter tires my whole car sits about and inch or so higher lol. I am also considering doing some sort of rear roof extension as well. I notices the chunky triangular "spoilers" on the rear of minivans and thought they couldn't really be for "looks" alone, they curve downwards probably helping ease the air back into the airstream behind the rest of the car. Mine is so boxy it might help a little. Thanks for all the great ideas guys!

theholycow · 12-02-2008, 08:33 AM

Quote:

Originally Posted by collegekid01

I t had about 6" of clearance with my summer tires and now with winter tires my whole car sits about and inch or so higher lol.

Your current tires are taller than your old ones? Did you adjust your speedometer/odometer or calculate that in to your odometer reading?

groar · 12-02-2008, 09:12 AM

Quote:

Originally Posted by collegekid01

I am also considering doing some sort of rear roof extension as well. I notices the chunky triangular "spoilers" on the rear of minivans and thought they couldn't really be for "looks" alone, they curve downwards probably helping ease the air back into the airstream behind the rest of the car. Mine is so boxy it might help a little.

These small roof extensions are made to make the airflow cleaner behind the car, but the better is the Kammback :
Project: making a permanent Metro Kammback extension
And it even works with a minivan :
Minivan Kardboard Kammback boosts MPG +3.7% (6.6%, counting roof rack delete)
(sorry, some pictures may not be viewable for non members of ecomodder)

Quote:

Thanks for all the great ideas guys!

Have fun,

Denis.

theholycow · 12-02-2008, 09:21 AM

The Kammback is not intuitive, but it is backed up by well-executed professional studies. In fact, it appears counterintuitive.

A picture of a kammback from the link provided above:

Another interesting picture from that thread:

The minivan kammback:

A professionally studied kammback on a truck:
http://permanent.access.gpo.gov/webs...00-01-2209.pdf

Additional studies and kammback data:
http://www.nasa.gov/centers/dryden/p...ain_H-2283.pdf
http://www.greencarcongress.com/2005...at_tail_d.html