off to drive the before gear vendor mileage check. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mtdave2 · 09-13-2009, 10:42 AM

ok, i have burned one tank of gas doing normal driving, some high way some in town, putting my foot in it a bit. results 11.2 mpg.

now i have a full tank, and im goin to get on the high way and drive like an old man at 65 to austin.

ill repeat once in get the gear vendor in..

Sinister · 09-13-2009, 11:05 AM

Can you get some pics of the install?

BB72CHEVKT · 09-13-2009, 11:07 AM

Are you installing it or is it being done by a shop in Austin?

mtdave2 · 09-13-2009, 11:21 AM

ill be doing my self...and ill make a long detailed post on it... if anyone wants to help, ill buy the pizza and beer.. shouldnt take but 4 hours or so..

BB72CHEVKT · 09-13-2009, 11:28 AM

Quote:

Originally Posted by mtdave2

ill be doing my self...and ill make a long detailed post on it... if anyone wants to help, ill buy the pizza and beer.. shouldnt take but 4 hours or so..

4 hours depending on how much beer

Longhorn Man · 09-13-2009, 03:35 PM

dave, come on over, I'll help you out... you'll be able to get a good baseline on the way here, and a good idea of the improvement on the way home.
You buy the pizza, I'll buy the dew!
Bring your own cigars for the photo shoot though!

**70cst** · 09-13-2009, 03:40 PM

I too am interested in gas mpg improvements.

mtdave2 · 09-13-2009, 04:06 PM

results..65 mph for 149 miles, no a/c....13.45 mpg. those vorteh heads helped a bunch! i was at 10 or 11

Longhorn Man · 09-13-2009, 08:00 PM

wow... 65 MPG???

Like I have room to poke at typos!

mtdave2 · 09-13-2009, 08:49 PM

Quote:

Originally Posted by Longhorn Man

wow... 65 MPG???

Like I have room to poke at typos!

man i wish! lmao now i have to fix it..

**70cst** · 09-13-2009, 08:55 PM

Quote:

Originally Posted by Longhorn Man
wow... 65 MPG???
Like I have room to poke at typos!
==============================================
man i wish! lmao now i have to fix it.

==============================================

Bummer...I was hoping to get 65mpg.

mtdave2 · 09-14-2009, 09:30 AM

me too! im really going to start tweeking for milage once the gear vendor is in.. i wonder with the best one could hope for is....

95light · 09-14-2009, 10:23 AM

Quote:

Originally Posted by mtdave2

ok, i have burned one tank of gas doing normal driving, some high way some in town, putting my foot in it a bit. results 11.2 mpg.

now i have a full tank, and im goin to get on the high way and drive like an old man at 65 to austin.

ill repeat once in get the gear vendor in..

Quote:

results..65 mph for 149 miles, no a/c....13.45 mpg. those vorteh heads helped a bunch! i was at 10 or 11

I'll throw a guess out there. On the high side it could add as much as 20% so normal driving should be a little more than 13mpg but I would guess maybe 12.5 mpg. Highway would be close to 16.5 mpg and I would bet with everything tuned right you might see it.

ddp · 09-15-2009, 01:41 PM

I haven't been much of a poster so far, but I just went through the overdrive/mileage project over the last year. Now, I knew going in that it was never going to pay for itself. I just did it to do it and see what would happen.

I have a 71 1/2 ton longbed with a 350/quadrajet that started with a th350 trans and a 3:42 gear set. Next I went to a th350 + 3:08 gear. Then, a 2004r + 3:08. And now, the 2004r + 3:73 gear set. Through all of those combos, I was +/- only about 1 mpg highway. Right now, the overall driveability is the best with the 2004r/3:73 combo. Here's my unscientific results breakdown:

th350/3:42 - 12.5 city, 13.5 highway
th350/3:08 - 12.5 city, 14.5 highway
2004r/3:08 - 12.5 city, 14.5 highway (no lockup)
2004r/3:73 - 12.5 city, 15.5 highway (with lockup)

My city driving is in Chicago, so it's really stop and go, and my highway driving was 65-75 mph interstate over a couple of hundred miles. I always adjusted miles traveled for any error in my speedo/odometer. I'm guessing that I could pick up maybe another 0.5 to 1 mpg if I held the speed down to 65, but..

Anyway, that's been my experience. I guess that at some point it's the aerodynamics (or lack of) that really hold you back.

09-13-2009, 10:42 AM	#1
mtdave2 newly minted old timer Join Date: Dec 1999 Location: Hudson WI Posts: 3,511	off to drive the before gear vendor mileage check. ok, i have burned one tank of gas doing normal driving, some high way some in town, putting my foot in it a bit. results 11.2 mpg. now i have a full tank, and im goin to get on the high way and drive like an old man at 65 to austin. ill repeat once in get the gear vendor in.. __________________ ____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban

09-13-2009, 11:05 AM	#2
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: off to drive the before gear vendor mileage check. Can you get some pics of the install? __________________ Beat it to fit, Paint it to match...

09-13-2009, 11:07 AM	#3
BB72CHEVKT Junior Member Join Date: Mar 2007 Location: Hideaway, TX Posts: 4,950	Re: off to drive the before gear vendor mileage check. Are you installing it or is it being done by a shop in Austin? __________________ 71 Suburban 350/700R4 Project Trixie 72 CHEVY,Highlander,SWB,396,T400

09-13-2009, 11:21 AM	#4
mtdave2 newly minted old timer Join Date: Dec 1999 Location: Hudson WI Posts: 3,511	Re: off to drive the before gear vendor mileage check. ill be doing my self...and ill make a long detailed post on it... if anyone wants to help, ill buy the pizza and beer.. shouldnt take but 4 hours or so.. __________________ ____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban

09-13-2009, 03:35 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: off to drive the before gear vendor mileage check. dave, come on over, I'll help you out... you'll be able to get a good baseline on the way here, and a good idea of the improvement on the way home. You buy the pizza, I'll buy the dew! Bring your own cigars for the photo shoot though!

09-13-2009, 03:40 PM	#7
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,365	Re: off to drive the before gear vendor mileage check. I too am interested in gas mpg improvements. __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

09-13-2009, 04:06 PM	#8
mtdave2 newly minted old timer Join Date: Dec 1999 Location: Hudson WI Posts: 3,511	Re: off to drive the before gear vendor mileage check. results..65 mph for 149 miles, no a/c....13.45 mpg. those vorteh heads helped a bunch! i was at 10 or 11 __________________ ____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban Last edited by mtdave2; 09-13-2009 at 08:50 PM.

09-13-2009, 08:00 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: off to drive the before gear vendor mileage check. wow... 65 MPG??? Like I have room to poke at typos!

09-14-2009, 09:30 AM	#12
mtdave2 newly minted old timer Join Date: Dec 1999 Location: Hudson WI Posts: 3,511	Re: off to drive the before gear vendor mileage check. me too! im really going to start tweeking for milage once the gear vendor is in.. i wonder with the best one could hope for is.... __________________ ____________________________________________ 72 c20 longhorn 65k org miles and counting! 69 k10 Suburban

09-15-2009, 01:41 PM	#14
ddp Registered User Join Date: Nov 2006 Location: Chicago IL Posts: 114	Re: off to drive the before gear vendor mileage check. I haven't been much of a poster so far, but I just went through the overdrive/mileage project over the last year. Now, I knew going in that it was never going to pay for itself. I just did it to do it and see what would happen. I have a 71 1/2 ton longbed with a 350/quadrajet that started with a th350 trans and a 3:42 gear set. Next I went to a th350 + 3:08 gear. Then, a 2004r + 3:08. And now, the 2004r + 3:73 gear set. Through all of those combos, I was +/- only about 1 mpg highway. Right now, the overall driveability is the best with the 2004r/3:73 combo. Here's my unscientific results breakdown: th350/3:42 - 12.5 city, 13.5 highway th350/3:08 - 12.5 city, 14.5 highway 2004r/3:08 - 12.5 city, 14.5 highway (no lockup) 2004r/3:73 - 12.5 city, 15.5 highway (with lockup) My city driving is in Chicago, so it's really stop and go, and my highway driving was 65-75 mph interstate over a couple of hundred miles. I always adjusted miles traveled for any error in my speedo/odometer. I'm guessing that I could pick up maybe another 0.5 to 1 mpg if I held the speed down to 65, but.. Anyway, that's been my experience. I guess that at some point it's the aerodynamics (or lack of) that really hold you back.



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