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Re: 276, 294, 323 rear gear
[Re: mgoblue9798]
#2978805
10/27/21 08:52 AM
10/27/21 08:52 AM
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Joined: Jan 2006
Posts: 8,162
USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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I find it is much, much better
to talk about MPH per 1000 rpm
instead of differential gear ratios.
If you are turning 2000 rpm at 80 mph
your ratio is 40 MPH per 1000 rpm,
etc
Doing it this way combines tire size, overdrive ratios, and differential gear ratios.
In highway driving there is considerable fuel economy improvement up to a ratio of 40 MPH per 1000 rpm,
slower improvement above 40. I like this thought... but I like to take it another step and figure displacement per mile. Right now I am a hair over 2000@60mph. so about the same displacement per mile as if I had a 159 CID engine running 4000@60mph. if I slow it to 1500@60mph it is like the 159 running at 3000RPM at 60mph witch is close to what my neon was running in displacement per mile with tiny tires and no OD 122 CID at just over 3000 RPM, so actually I would still be slightly more displacement per mile so I don't think it is un doable, I know it is a truck but not a very big or heavy one at all by todays standards. The long term plan is to do some stuff to increase the low end TQ like zero deck the pistons and take about .030 off the heads and better spray pattern injectors... maybe a bely pan and some other aero tweaks. I had a 93 Dakota with 5.2 518 combo. Picked up nearly 1mpg average on interstate driving just by adding a tonneau cover.to the bed. I had a very similar experience - 1995 Ram Club Cab 5.9/518 3.21 picked up 1 MPG with an ARE fiberglass tonneau at 70 MPH on my “test track” of I-40 from Durham to Wilmington and back. Lost 1 MPG when I removed the Tonneau. GM has a very interesting US Patent on a Tonneau for the S-10 pickup. https://patents.google.com/patent/US4573730A/en?oq=4573730Knowing that there is a “horizontal tornado” behind the rear window helps a lot in understanding the drag reduction graph in the GM patent. There is a similar “horizontal tornado” behind the tailgate “Wheeler Vortex Generators” create tiny double horizontal tornados. Airtabs are molded plastic improvements on the Wheeler originals.
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Re: 276, 294, 323 rear gear
[Re: jcc]
#2978816
10/27/21 09:49 AM
10/27/21 09:49 AM
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Joined: Jan 2003
Posts: 10,702
North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,702
North Dakota
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I believe they also made a 3.08 gear, for Nascar? back in the day, I have tried for over a decade to locate such gear, but have come up zero. In the AMC world they had a 3.15 ratio for the AMC 20 rear end. A great highway/town gear.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: 276, 294, 323 rear gear
[Re: 360view]
#2979287
10/28/21 03:43 PM
10/28/21 03:43 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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You guys can keep your tonnoue covers, I am constantly putting things in and out of the bed so that's a no go, I have had em on trucks I bought before and HATED them!
My truck has 3.55 gears, don't know why anyone assumed 3.23s? The tach is reading a little higher on the dash than it is with the scanner hooked up but still, just over 60 it hits 2000 rpm verified by GPS. Trans works great.
When I had a 318 4wd dakota I had zero issues running it down to 1000 RPM in 5th around town and got nearly the same MPG in town lugging it like that as I did on the highway where I could not lug it because it was turning too many RPM, that truck had 3.55 gears but taller tires, they were 17 R/T wheels but don't remember the exact size. It was a bigger heavier truck with much taller tires and I still found myself wanting a higher gear, maybe I should swap in a 6 speed Manual with a .50 OD ratio instead. Leaving the 3.55 in there would give me a 1.77 final drive ratio where the 2.76 a-500 only gives me 1.90 final drive. Some cars in the 80s had 2.20 ratios with less tq, 318 magnums easily have enough TQ to work that low and like I said I can easily add a few more foot pounds of torque. Now to find a 6 speed...
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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