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Old 02-10-2018, 01:40 PM   #26
weq92f
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Location: Dallas Texas
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Re: Best fuel efficiency

Every time I get in the wife's commuter ( 2013 honda CRV ( 4 cylinder engine/ 4 speed OD tranny/ front wheel drive ), I think with amazement how it would probably outrun my first car: 68 chevy step 350/350 and get better gas mileage while doing it.

The thing is geared for quick speed off the line and low RPM cruising at freeway speeds. Plus it gets 25-27 MPG.

It's just the perfect little go-getter that is designed specifically to do just that.

What would happen if I did a driveline swap from the CRV into a 67-72 short-fleet? I suspect the tranny wouldn't last very long, but...

Weight:
Both vehicles weigh about the same 3500 for the honda and 3800-4200 for the truck, so we're close there.

Brick vs. wedge:
The CRV is a nice wedge shape
The Truck is a brick

Front vs. Rear drive
That would take somoe doing, maybe mount the motor normal ( not sideways ) and adapt a 200r somehow? Swap in the entire front CRV clip?

My guess is that a swap like this, would not yield the same 25-27 MPG out of the truck. The extra weight combined with the added wind resistance at speed and other detriments like rolling resistance and mechanical power loss through the tranny and diff would kill the highway mileage, probably down below 20.

-klb
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Old 02-10-2018, 03:03 PM   #27
Captainfab
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Re: Best fuel efficiency

An old boss of mine was a big fan of Buick V8's. Back in the '80's he put a Buick 455 in his '73 C20 with a 3.08 rear gear and was able to knock down respectable mpg's. I don't remember exactly what he was getting but it was around 20+
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Old 02-10-2018, 04:52 PM   #28
truckster
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Re: Best fuel efficiency

I put an Olds 455 in a Buick Estate Wagon with a 3.23 rear and it averaged about 11 MPG. I decided to see what kind of mileage I could get out of it once - I got on the freeway and kept it at 60 MPH, never touching the gas. I got 16 MPG, but there was absolutely no fun in driving it that way.
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Old 02-10-2018, 08:30 PM   #29
D13
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Re: Best fuel efficiency

So I generally try to stay out of these, but..

23mpg is very possible in a square. 200+ hp is easy.
Together? also possible. But.. the cost to do so will be more than the savings on gas, ever.

1981 C20, 250 inline (about 120 hp), no overdrive, 3.43 gears and 235/85LT16.5's, I can make it get 15 mpg at 55, 17 mpg driving slowly everywhere at 48mph max (no kidding. actually did it one week just to prove a point to my dad).

1987 R10, 6.2 diesel, 700R4, 3.08 axle, P235/75R15, gets me 22-23 mpg in mixed driving. If you run it constant 53-58 mph it will return 26+ mpg. At 70mph, 20 mpg should be good. About 145hp with the J code intake.

My 2016 K10 regular cab long bed has a 5.3l, active fuel management, 3.08 gears, topper, and gets 22mpg with way over 300HP on tap. Runs on 4 cylinders at 65mph on flat ground and hauls butt when pushed, even as a 4wd.

Squares have poor aerodynamics (they are a giant barn to air flow). You need to drive 55. Period.
6.2 sips fuel but is gutless. So, swap in the AFM 5.3l drivetrain. Whoa, that's gonna cost about 4 grand.

For my 20000 miles per year, at 20mpg, that's 1000 gallons of gas. At 25mpg that's 800 gallons. So if I save 200 gallons a year times the $2.50 gas is running that's $500 per year. So in 8 years I have made back the cost of the updated drive train.

OF course, this assumes you can keep your foot out of the 5.3, never drive over 55, don't live in the city, don't tow, etc.

Other option is the 4.3 V6 or a 250 straight six, with a turbo set to kick in at 2200 RPM +. Cruising rpm of 1600, need to pull downshift and spool up. Cost about 3 grand to get it set up, using TBI for fueling. Still not cost efficient but cool.

#1 factor in fuel economy is driving behavior, # 2 is weight, #3 is aero, and #4 is engine efficiency. This is because the drive can control the efficient use of the power to manage the weight and the aero.

BTW I currently drive a 4 banger Equinox, 29.8mpg over the last 80,000 miles, can make if get 30+ for a week if I really care to. The 87 and the '17 sit in the barn until I have a specific need for a truck, or just want to kill skeeters.
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Old 02-10-2018, 09:14 PM   #30
garyd1961
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Re: Best fuel efficiency

I have an L31-R vortec crate engine, long tube headers, Holley 4 barrel, th350 trans, 307 gears, and 255/70/15 tires all around. I never really checked the gas mileage but I do know it will get really good mileage if I keep it around 45 mph and it will drink up when I get on it. It has a wide range when it comes to gas mileage. I don't usually worry about mileage because I built it to have fun on weekends but I just cruised around for several hours one day and never got over 45 mph and I couldn't believe how little gas I burned.
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