What kind of MPG increase did you get from adding OD?
#2125647
08/05/16 12:47 PM
08/05/16 12:47 PM
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Joined: Jan 2003
Posts: 28,067 Irving, TX
feets
OP
Senior Management
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OP
Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I'm looking at dropping my 518 in the Imp and wondered what kind of mpg increase you guys have seen.
The primary concern is to drop the engine rpm because I've become accustomed to the lower engine speeds in newer vehicles. Any mpg increase would be a bonus.
My old beast tips the scales at 5100 lbs empty and runs a 29" tire on a 3.23 rear gear. The 518 would drop the rpm nicely and make for a better driving experience. The 440 should have ample torque to pull the car at the new rpm.
I've had the transmission and Ultrabell sitting around for the better part of 10 years. Might as well do something with them.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126059
08/05/16 08:32 PM
08/05/16 08:32 PM
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Joined: Jan 2003
Posts: 5,791 Hamilton, Ontario Canada
Magnum
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master
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Posts: 5,791
Hamilton, Ontario Canada
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I had no change but I did it backwards. Went from OD to no Od.
87 Ram D100 reg cab shortie. Swapped in a 5.9L Magnum and a 518. With 3.55 gear and a 28" tire.
I did not drive for mileage. I did much of my driving at a comfortable 120km/hr.
I lost overdrive but continued to drive the truck in 3rd gear. Except now 120 km/hr was too much rpm so I cruised the right lane at 105 which was a little high in the rpm but with the reduced speed I was still getting 18-19mpg.
After losing all confidence in the 518, I swapped in a NV3500 5 speed. Then I was finally had a mileage improvement.
69 Super Bee, 93 Mustang LX, 04 Allure Super
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Re: What kind of MPG increase did you get from adding OD?
[Re: dezduster]
#2126081
08/05/16 09:11 PM
08/05/16 09:11 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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Milage increase I don't know. However in my 422 ci duster 3500#with manual 5 speed od it would get up to 22 23 mpg on the highyway at 70 75 mph. This is with 34 ° maechanical and 12° vacuum for total of 46° Total timing. This all being very conscious of milage! But even when driving spirited and careful of the law 18 19mpg was the norm. Gears are same as yours and tires are very close 275 60 15 BFG drag T/As. Rpms at 70 is 1700 in OD I can't give any prior results, as I stuff an OD into the build from the start, but my Daytona 440/6 pack with a Keisler TKO 600 5spd .064 OD, 4:10 Dana 60, 27" tires, will do 20-22 MPG highway on long cross country cruises at 70-75 MPH, on the street where I have a hard time keeping my foot out of the throttle, it'll suck it down to 8-10 MPG On the HEMI cars with a Keisler TKO 5 spd .64 OD, 3:54 and 4:10 rear gears, avg highway at 70-80 MPH cruising would be 16-18 MPG, again on the street blasting it, mileage could get sucked down to 5-8 MPG Played around in the past with various OD's in the .80- .70 range, results were often minimal for the effort, you really need to step into the .64-.50 range for the cost of adding an OD to "pay off"
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Re: What kind of MPG increase did you get from adding OD?
[Re: DAYCLONA]
#2126278
08/06/16 01:09 AM
08/06/16 01:09 AM
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Joined: Mar 2011
Posts: 1,655 Cut and Shoot, TX
kentj340
top fuel
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top fuel
Joined: Mar 2011
Posts: 1,655
Cut and Shoot, TX
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Played around in the past with various OD's in the .80- .70 range, results were often minimal for the effort, you really need to step into the .64-.50 range for the cost of adding an OD to "pay off" Exactly. I have a Tremec 6-speed in a 2005 GTO, 400 hp, 3.90 rear, 25" dia tires. Sixth gear 0.50:1 is super - runs about 1800 rpm at highway speeds. But 5th gear 0.75:1 pretty much never gets used - it's a waste, not enough reduction. You really need the 0.50:1.
If you don't see two dolphins, you need a vacation.
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126279
08/06/16 01:12 AM
08/06/16 01:12 AM
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Joined: Jan 2003
Posts: 104,346 Garden Grove, CA
OzHemi
Penguin-hating Ginger
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Penguin-hating Ginger
Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
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I'm looking at dropping my 518 in the Imp and wondered what kind of mpg increase you guys have seen.
The primary concern is to drop the engine rpm because I've become accustomed to the lower engine speeds in newer vehicles. Any mpg increase would be a bonus.
My old beast tips the scales at 5100 lbs empty and runs a 29" tire on a 3.23 rear gear. The 518 would drop the rpm nicely and make for a better driving experience. The 440 should have ample torque to pull the car at the new rpm.
I've had the transmission and Ultrabell sitting around for the better part of 10 years. Might as well do something with them. If he doesn't see this thread, ask Stu...he has an OD (4L60E I think) in his Road Runner...and it gets driven a bunch of course..
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126332
08/06/16 03:25 AM
08/06/16 03:25 AM
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Joined: Aug 2011
Posts: 2,860 Pattison Texas
CSK
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master
Joined: Aug 2011
Posts: 2,860
Pattison Texas
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I can't speak for mileage improvement, but I get 15 average in my 68 Charger 512cid,a518 w/lock up & 3.23 gear 28" tire.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126370
08/06/16 08:50 AM
08/06/16 08:50 AM
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Joined: Jan 2003
Posts: 3,575 The Netherlands
BigBlockMopar
master
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master
Joined: Jan 2003
Posts: 3,575
The Netherlands
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2-bbl 318 / 904 & 7-1/4" 3.23 rear axle. lousy, neglected engine tune / very lean @ highway speeds / worn timing chain; 6-7mpg daily / 17mpg highway
4-bbl 318 / A518 & 8-3/4" 3.55 rear axle. AFR tuned engine / new timingchain / recurved distributor / better ignition ; 11-12mpg daily / 15mpg highway
65mph = 2200 rpm @ 20" engine vacuum A518 = OD only, no lockup Fuel = LPG
IMO, the heavier internals and friction of the A518, and the absense of convertor lockup and lack of cr and strong torque in the engine, dampened my highway mileage, compared to the 904 at least.
But, over the years the car has become much more fun to drive with the 4-speed auto.
At one time I had a 518 with OD and LU installed, which was even more fun, where the Lockup pretty much felt as a short 5th gear.
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Re: What kind of MPG increase did you get from adding OD?
[Re: Jwilli500]
#2126446
08/06/16 11:44 AM
08/06/16 11:44 AM
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Joined: Jan 2003
Posts: 28,067 Irving, TX
feets
OP
Senior Management
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OP
Senior Management
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Posts: 28,067
Irving, TX
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I've wondered the same thing, so I'll be watching this one. Are you going with a lockup or non-lockup converter? My transmission is set up for a lock up converter.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: What kind of MPG increase did you get from adding OD?
[Re: moparx]
#2126493
08/06/16 12:34 PM
08/06/16 12:34 PM
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Joined: Jan 2003
Posts: 28,067 Irving, TX
feets
OP
Senior Management
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OP
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Irving, TX
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feets, what carb are you using ? have you tailored your distributor curve, including vacuum advance, for mileage now, or will you be doing that once you get the o.d. installed ? are you going to something deeper than 3.23 gears to get the mass rolling easier, then using the o.d. to lower the highway rpm's to acceptable levels ? Right now the engine is in pieces. I plan on dropping a FiTech system on the car and setting the distributor for best torque/mpg. A proper Imperial is not a performance car.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126555
08/06/16 02:33 PM
08/06/16 02:33 PM
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Joined: Jan 2006
Posts: 704 USA
rftroy
super stock
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super stock
Joined: Jan 2006
Posts: 704
USA
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I have done this twice.
First was with a 69 Barracuda fastback. 318 with 360 1.88 heads; hyd cam w/specs midway between stock 318 and 340 cams. 3.23 axle. With standard 4 speed: 17-18 mpg highway With OD4: 24 mpg highway.
Second was 69 Barracuda conv. Slant 6, stock cam, Holley Economaster 1920 1 bbl. 2.76 axle With standard 4 speed: 19-20 mpg highway With OD4: 27.5-29 mpg highway.
Now have 2.94 axle (2.76 was just too low with OD). Haven't done a long range highway test yet, but around town stayed about the same at 22-23 mpg.
Robert
AAR 4-speed 3.91, Tor-Red; 70 440 6 pack Roadrunner 4-speed 3.54, Plum Crazy; 68 Formula S conv 383 4-speed 3.23, Electric Blue; 69 Barracuda conv Slant 6 OD4 2.94, 71 B5 Blue; 78 Lil' Red Truck, Red; 70 Challenger S/E. 505 6 pack, Passon 5-speed, 3.55, B7 Blue
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Re: What kind of MPG increase did you get from adding OD?
[Re: feets]
#2126609
08/06/16 04:33 PM
08/06/16 04:33 PM
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Joined: Apr 2006
Posts: 4,220 West Plains, MO
DrCharles
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West Plains, MO
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I am also amazed... my slightly warmed-over '70 Valiant (stock 383 rebuild, .484 purple shaft, 750 vac sec, dual-plane, A833, 3.23 rear) got about 15 mpg on the highway at 65 mph, around 12 mpg mixed city/hwy and my lowest tank was 8.3 mpg since it was all going to the store for a quart of milk 1/4 mile away And my '76 Valiant with stock /6 and OD A-833 (don't know the rear) would get about 23-24 mpg at a steady highway cruise. Maybe they're talking Imperial gallons?
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