Gas Mileage Question

[miamibob]

Anybody translate the codes????

[johnunit]

assuming it's the same as with boxes, you have a 3.27 open (non trak-lock) rear.

[79lincolnlover]

Lots of junk in the trunk??

[SVT98t]

Axle codes
Open/Lock/Ratio #
-----------------------
G / H / 2.26
B / C / 2.47
8 / M / 2.73
7 / - / 3.07
Y / Z / 3.08
4 / D / 3.42
F / R / 3.45
5 / E / 3.27
6 / W / 3.73
2 / K / 3.55
A / - / 3.63
J / - / 3.85

The above information is available in the Drivetrain Section. Heeere--> http://www.grandmarq.net/vb/showthre...258-Axle-Codes



3.27.
And as i recall, the aeros were lighter than boxes and whales.
I get around 20 city and 28 highway.
I also have a host of mods that are specifically installed for fuel economy.
Tire pressure, I go 34 rear, 32 front.
When was the last time you did a tune up? I'd install a new air filter, fuel filter, and do fresh plugs and wires. Maybe even clean up the MAF and throttle body.
I run 2.73 gears. They suck for acceleration, but are awesome for crusing on the highway.


-ryan s.

[miamibob]

Thanks for the info!! How does the gear ratio affect gas mileage? For example, are the lower numbers better for mileage or higher. Sorry for the dumb question! Bobby

[SVT98t]

Lower numbers have a higher top end, but less acceleration. 2.73:1 gears mean that input pinion gear (Driveshaft/ power from the engine) rotates 2.73 times every time the ring gear (Rear axle/ tires) rotates once. It's not goood for acceleration, but great for top end.
A 4.10 gear means the driveshaft rotates 4.10 tiems to every rotation of the rear tires. They are much better for acceleration, as the engine/ drivetrain can more efficiently transfer power to the rear wheels, making the car take off quicker. The only down side is that you lose top end. I mean most people don't cruise the highway everyday at 120 mph.

In a bit simpler terms, think of it like a multi-speed bicycle:

If you use a first or second gear, you can acclerate very quickly, but you can't go fast.

But, if you start in like a sixth or seventh gear, you don't accelerate quickly, but you can go faster.

So, 2.73s (what I have) are great for cruising at highway speeds (50-75) but suck accelerating.
3.55s, 3.73s, and 4.10s are great for accelerating (like city driving and such) but don't have much top end. Granted, you can still do 140, but the car may not like being there for too long.

I hope this helps!!

-ryan s.

[miamibob]

Ryan, thanks for the "crash course" in gear ratios! So, with mine being in the middle of the range, what dioes that mean gas mileage wise??

[SVT98t]

Regular. Norm. Right in the middle.

http://www.fueleconomy.gov/feg/Find....n=sbs&id=12054

-ryan s.

[BigMerc96]

3.27s should actually do a touch better in the city/stop and go driving as the engine doesn't have to work as hard to get it moving from a stop as it does with say..2.73s. My buddy gets 1 mpg less than me in the city in an '05 with 3.55s, and he has a very heavy foot compared to me.

My car with 2.73s and dual exhaust regularly pulls down 19mpg city in the warmer months, AC on or not. Around here, city is 0-45mph mostly. I gained about 1/2 an MPG when I installed the dual exhaust.

Clean the MAF sensor, new air and fuel filters, clean up the throttle body, new PCV, oil change with a good quality oil (I've been running either Motorcraft semi-synthetic or Mobil 1). After all that, reset the PCM by disconnecting the battery for 10 minutes or more to let the car relearn its new parameters. Also, it doesn't quite make sense to me, but I saw significant MPG improvement when I replaced my worn out shocks with the good new KYBs.