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Discussion Starter #1
Want to get some thoughts on this. Automatic Turbo coupe and am wanting to get better highway mileage. I hear the 5spd cars with 3.55 are getting around 28 mpg So I am contemplating 3.27 gears to try to get 30mpg. Anyone ever try this? I am thinking it will put 65 mph around 1400 rpms Right now with 373 it is about 2500. And I am around 20 mpg.
 

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first and foremost make sure everything is sound and in good working condition

but yes get rid of them gears, they are not helping fuel economy one bit

i know it sounds silly but make sure the tires are pumped up
be sure none of your pulleys are binding and all bearings are all greased well, p/s reservior has good and clean fluid too, a/c is not too discharged with sufficient lube
all plugs, wires, etc.. need to be in tip top shape
change the air and fuel filters if you hadnt lately
the tune has to be good enough that your not dumping excess fuel in it, if its still using the hegos to control fuel then be sure the hegos have a good ground and are fairly new and functioning correctly

other than that drive it like a normal human and you should be getting excellent fuel economy
 

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I would not go to the trouble of changing to a 3.27 for gas mileage. I would do all the things decipha mentioned instead.

3.27 is such a small change. Maybe 3.08's would help, but a 4 cyl needs some gear to get going or it won't be fun to drive.

You should be able to get 30 MPG no problem as it sits. If we can do it with a heavy MN12 with a 4.6 V8, you should be able to to get 32 at least with a 4-banger.

Al
 

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Discussion Starter #4
I know with the 3.27 I am not going to win any races ha ha But the engine is freshly rebuilt car has about 125k on it, rides smooth. I drive 55 miles one way to work and thought the 3.27 would help drop about 900 to 1000 rpms cruising. With the 3.55 with the Automatic was wondering if I would get the same numbers as the 5spd cars?
 

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Lol. You won't drop "1000rpms" from a 0.28 change in rear gear ratio. Besides, you' likely do worse if that happened because you'll lose out on EGR flow. What you would benefit the most from is keeping constant speed, tires inflated, allowing some deceleration on uphills and regaining speed on downhill so as to not unlock the torque converter.
 

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There's something else wrong. My auto Turbo Coupe got 28mpg, my 5 speed got 30-32 mpg. The 2.3 turbo is a picky motor. Mine wouldn't run worth a crap unless it had Motorcraft plugs and wires.
 

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Discussion Starter #7
Lol. You won't drop "1000rpms" from a 0.28 change in rear gear ratio. Besides, you' likely do worse if that happened because you'll lose out on EGR flow. What you would benefit the most from is keeping constant speed, tires inflated, allowing some deceleration on uphills and regaining speed on downhill so as to not unlock the torque converter.
Yeah I guess more like around 500 rpms going from 3.73 to 3.27.
EGR is not connected.
What is the cruising rpm on the 5 spd cars at 65?
 

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There's something else wrong. My auto Turbo Coupe got 28mpg, my 5 speed got 30-32 mpg. The 2.3 turbo is a picky motor. Mine wouldn't run worth a crap unless it had Motorcraft plugs and wires.
Your Auto still had the 3.73 gears in it? And maybe it is the hills I have to go through on my way to work that is eating it up?
 

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Yeah I guess more like around 500 rpms going from 3.73 to 3.27.
EGR is not connected.
What is the cruising rpm on the 5 spd cars at 65?
So it went from 4,000 RPM approx to 3,500 RPM? How fast were you GOING?

(3.08 is approx. 2000 RPM with 225/60R16's on my 1991 Cougar ... )

EGR disconnected will hurt gas mileage on a properly tuned system.

RwP
 

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As already been mentioned, makes sure it's tuned up well and the tires properly inflated (you can actually pump them up with an extra 5 lbs and that would help). Like Ralph said, I tried the disconnected EGR on my vehicle and it hurt mileage to the tune of about 2-3 MPG. Get the tires off the ground, spin them, and make sure nothing is binding like dry bearings or brakes.

After you are sure it's running good, here are a few more MPG tricks:

1) K&N filter or CAI
2) Free flowing exhaust
3) Underdrive pulleys
4) Advance the timing / economy tune
5) Lighten the vehicle

That's about all I'd do if it were my vehicle...
 

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Yeah I guess more like around 500 rpms going from 3.73 to 3.27.
EGR is not connected.
What is the cruising rpm on the 5 spd cars at 65?
FWIW if you're turning 2500 RPM at 65 MPH with a 3.73, you would be turning 2200 RPM with a 3.27. With a 2.73 you'd turn 1800 RPM.
 

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Reconnect your EGR. Regain gas mileage.
 

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Discussion Starter #14
I was more concerned about swapping out the gear. The engine has been rebuilt, 30 over pistons, bigger cam, bigger turbo. And this is why I was contemplating another gear. So looks like I will go ahead with the gear change and go from there. Thks for your thoughts.
 

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With a bigger cam you are likely to be really disappointed with that gear change.

And bigger cams usually hurt gas mileage a little too.

Al
 

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I just ordered a tune for an Explorer 5.0L I just bought to try and get better mileage.

Don @ Lasotaracing did the tune for me, and I had him double up on the EGR flow in hopes of improving on the mileage with this SUV. I've already test driven the new tune and it seems I did the right thing (of course, I haven't had a chance to log some real data, yet, but I'll let y'all know).

Just throwing that out there so you know how important the EGR is for gas mileage...
 

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Oh yes, a couple times I had a code for "excessive EGR flow", and I got the best gas mileage I have ever gotten for 2-3 tanks. I got a solid 31 MPG! Then the code went off on it's own, and mileage returned back to normal.

Al
 
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