MPG Run--NA B6

[TominMO]

Today I did a run on my NA B6. I had taken the rear turbo off because it needs rebuilding.

Engine mods:
1. advanced the timing from 7 BTDC to 14. Stock is 10, but I had 7 for the sake of the motor's longevity when the turbo was installed. Using 93 octane of course.
2. cat-delete pipe.
3. cold air intake.
Aero mods:
1. Festiva rear wing.
2. covered the air intake on the pass. side of the grill and bumper.
3. created a simple air dam out of a garage-door bottom strip, and attached it to the bumper. Not overly cool-looking, but probably helpful.
Other factors:
1. 185/60x14 Kumho tires on AR Estrella aluminum rims; tires @ 30 PSI. (BTW, all previous MPG runs with this car were run on 13" Metro steelies with 155/80x13 tires, inflated to 35 PSI.)
2. windows closed, radio on, pass. mirror not folded in.
3. temp about 80 degrees, no wind.
4. made sure the rear brakes/bearings were not dragging.

I wanted a real-world test, so I didn't overinflate the tires, fold in the mirror or turn off the radio.

Speed was kept at an indicated 60 MPH, which I think is really 61 or 62. RPM @ 60 was 2400. For consistency, the odometer was calibrated on the same 20-mile stretch of hwy I always use for this; it is marked every .2 miles, so I think they made a good-faith effort at accuracy.

So I did my usual run around the city, with a different starting/ending point because I moved, but about the same miles. For 88 miles I used 2.1 gallons, giving 41.9 MPG. Acceptable, but I was hoping for better. (Man, are we spoiled! ) I think the biggest negatives were the 1.6 motor and the wider tires. I'm not sure the aero mods made any significant difference.

[Ace]

41 mpg..
I'm so jealous.
I don't have a festy but the best I manage with my BPT in my protege is like 26 or so.

[bhazard]

I still dont think a 2 gallon fillup can be accurate for mpg calculations. Unless you have a fuel cell or something, theres just too much room for error with a stock gas tank...filler neck, etc.

Also 30 psi is just too low. Thats soccer mom pressure. I run 35 psi minimum, and thats what we always inflated car tires to when I worked at a tire shop, unless the customer wanted something else. I run 40 psi in mine personally.

[iceracerdude]

That sounds pretty good, but I don't think the b6 it the limiting factor here, I would say the tires (width) hurt your mileage more. The difference between 30 psi and 40 would shock you as far as mile per gal would be, you might want to do a test with that just for laughs. The difference between 175-70 13" and 185-60 14" is the 14's are 0.44% slower.
Check out this tire calculator, I use it all the time. You can compare up to 5 tire sizes at once! http://www.1010tires.com/tiresizecalculator.asp

[Charlie1717]

I still dont think a 2 gallon fillup can be accurate for mpg calculations. Unless you have a fuel cell or something, theres just too much room for error with a stock gas tank...filler neck, etc.

Also 30 psi is just too low. Thats soccer mom pressure. I run 35 psi minimum, and thats what we always inflated car tires to when I worked at a tire shop, unless the customer wanted something else. I run 40 psi in mine personally.

I agree. I have done several MPG runs and have found anything below about 5 gallons is somewhat inaccurate. I did identical runs same speed distance and even roads.
1st run- I went one way 95 miles and got like 50mpg (which I can only get when I go under 100 miles)
2nd run- I went there and back 190 and I got 44 mpg (which I have been able to consistently get + or - 2 mpg)

[TominMO]

I still dont think a 2 gallon fillup can be accurate for mpg calculations. Unless you have a fuel cell or something, theres just too much room for error with a stock gas tank...filler neck, etc.

Also 30 psi is just too low. Thats soccer mom pressure. I run 35 psi minimum, and thats what we always inflated car tires to when I worked at a tire shop, unless the customer wanted something else. I run 40 psi in mine personally.

I agree on both points, up to a point. The short drive distance is the same I have used for all my tests, and I am getting consistent results. When I had the 1.3 motor in there, the only significant variable was speed, and it showed:
Speed....MPG
60.........41.9 (B6 motor, 185/60x14 tires)
60.........52.1 (B3 motor, 155/80x13 tires
55.........58.5 (same as above)
45.........62.5 (same as above)

Yeah, I coulda gone to 35 PSI, but it would have made a .1 MPG difference probably.

I make no claim this is perfect testing methodology, but at least it gives a baseline to work from, and gives people an idea of what results to expect and the variables involved. Naturally a full tank of gas would be better, but I don't have the patience to drive 60 MPH for 400 - 500 miles!

[blkfordsedan]

I would record the mileage over a 2-3 tank fill-up. Fill every time until you can see gas in the filler neck. Then calculate MPG based on cumulative miles & gallons.
Don't forget that if the speedo is off, then the odometer is off as well. If the speedo is slow, you're actually traveling farther than the odometer says (i.e. getting better MPG). It varies on a constant percentage, so you can use that to adjust your miles traveled and get reasonably close. Of coarse, a GPS is probably the best way.

[Safety Guy]

Aqua has been giving me the following mpgs for the past few fillups:

31
31
35
32

Aqua has a B6/5 speed and runs 175/70-13s kept at 33 to 35 psi. This is my every day driving to and from work, a mix of city and freeway.

My fillups are usually from 6 to 8 gallons.

Compare these results with my trip down south a few months ago when I was getting 41 mpg on my highway legs travelling at up to 70 mph.

Some day I need to do a trip and make myself keep to 55 to 60 mph.

Karl

[Darlo]

I am so glad we are talking MPG mods and not performance ones!

So far, I am totally stock except I removed the mirror, and the back seat. (But I have added a sub, so it all evens out, lol). I also run my tires at 44 psi (the rated pressure for the tire).

Thus far I am getting an average of 46mpg (yes US gallons) and have had as high as 51.0mpg and as low as 41.4mpg.

I am really wanting to try a couple of things to improve the mpg and my goal is 60mpg!

1. Kamback/boattail - Should give me 5%-10%
2. Alternator delete - between 7%-15% improvement

Click on my Fuelly badge to see my distribution of mpg on different times of the year. I get way better mpg in the summer in the warmer temps and the all season tires (I run studded winters)

[Charlie1717]

I've been averaging anywhere from 35-40 MPG with about 50/50 highway vs city. Pure intestate I was getting 44-46 mpg. Pure city 30-33 mpg.

This is with a BP Festiva E series trans. 35psi 175/70/r13. I don't try for good mpg besides driving the speed limit on the interstate.

[TominMO]

Talked to John today, and mentioned that my new aftermarket temp gauge sez I'm at 165 degrees cruising at 60. The motor has a new dual-core rad and a 180 thermostat. I have the pass. side grill and bumper opening blocked off. He mentioned blocking off the driver's side too (one or both openings), to see if it'll bring up operating temp significantly. This might give better mileage too. I will try that, and air up to 35 PSI. Maybe next weekend. If the thermostat keeps me from getting to 190 or so, I will switch to a 192 or 195.

Karl, I typically get in the low 30s too, driving it city/hwy in a sporty manner, as if I had obtained it illegally.

[blkfordsedan]

I think you're on the right track Tom. If it's only running 160* it will definitely burn more fuel.

[freshtiva]

I got 40 plus on Frankenstivas' (NA B6) maiden road trip to "cruise in the corn" meet in Iowa. 70 MPH w/o a/c. I got around 37 on the return trip with the a/c on.

[skimsucka]

I got 40 plus on Frankenstivas' (NA B6) maiden road trip to "cruise in the corn" meet in Iowa. 70 MPH w/o a/c. I got around 37 on the return trip with the a/c on.

very nice !

Tom is a master mathematician I don't doubt his test results

[TominMO]

Tom is a master mathematician....

You are perhaps confusing me with Nate, the keeper of Skeeter.