Any MPG Fans here??

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351FUN

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Yeah, this is a lost cause for me. My car gets 16.7 mpg, the Blazer was averaging 11, and the F250 I don't even want to know.
 

L31MaxExpress

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This guy did a 4BT Tahoe, similar weight to a van and states it too gets mid 20s MPG. The factory GMT400 MWM 4.2L I6 diesel Tahoes and trucks get mid 20s all day long and closer to 30 mpg cruising. Although good luck finding parts or an engine here. I have seen a few though.

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If I could find a MWM 4.2L, I would put one into a GMT400. Way quieter and smoother than a 4BT with similar power and MPG potential. This is a factory Diesel/5spd Tahoe.

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Moparmat2000

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PATC make a kit to run that 47RH as a stand alone setup without a computer as well. Makes that 4BT swap a little easier.
 

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eXo0us

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Yeah, this is a lost cause for me. My car gets 16.7 mpg, the Blazer was averaging 11, and the F250 I don't even want to know.
I got a electric car for commuting (120 MPGe) and keep the Smallblock Vortec for joyrides.


Aero has some effect on the old Vans/Trucks. But they are just not designed with that in mind. They are tall bricks with terrible disturbed underbodies.

When you look under a modern truck - everything is streamlined. You got good inner fenders which channel the air, an Airdam and Splitter at the front - even the top of the Tailgate has a small spoiler and the top of the cab. There is a lot going on in a Post 2010s Vehicle. + we get a lot more torque out of Gas engines down low. Which wasn't the case only two decades ago.

The 2000s 5.7L Vortec maxes torque out at 330ft/lbs Around 2800-3000rpm. In comparison a newer RAM 1500 5.7L Hemi - starts with 330ft/lbs at 1500rpm. Goes up to 410ft/lbs

2019 Express van powered by a Gasoline 4.3 V6

IMHO You need low RPM torque to drive efficient. HP doesn't matter - that's why Diesels are so good at MPG - low RPM grunt.
 

Pinger

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Diesel is a denser store of energy than gasoline, so there's that too.
Yes, and if we are to explore exactly why diesels are more fuel efficient we have to include higher compression ratio, unthrottled inlet, lower (mean) temperature combustion, more favourable ratio of specific heat during expansion, extended expansion ratio due to turbocharging (to the benefit of reduced 'air work' on the inlet side). It is less that low rpm delivers good fuel efficiency for them, more that low rpm is all that they are capable of!
Dr Diesel threw himself overboard. A pity he didn't take his engines with him.
 

0xDEADBEEF

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Of all the things you've said, this statement is the most telling.
A person with even a very basic understanding of physics realizes that a vehicle shape which causes less resistance requires less energy to move it.
No wonder you have been unsuccessful at this for 20 years, you have no idea what you're doing.

IIRC, the effect of air resistance is exponential. Square of velocity times something.
 

Pinger

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IIRC, the effect of air resistance is exponential. Square of velocity times something.
Worse that that, I think it's to the cube.
Say 100 mph is attainable in a (reasonably slippery) vehicle with 100 hp. To go 200 mph would require twice cubed, 2^3. 2^3 = 8. 8 x 100 hp = 800 hp. Which sounds about right for 200 mph.
 
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