Originally Posted by aardvarcus
So is your accusation that I am lying simply because my 1994 Suburban gets better fuel economy than your 2008 Tahoe does? I can see how that would be frustrating for you.
Since you like looking up metrics, go to “fueleconomy.gov” and look up a 1994 Chevrolet K1500 Pickup 4WD 6.5L, 8 cyl, Manual 5-spd. (Note they don’t have the correct factory engine or transmissions for the Suburban, hence look up the K1500 so you can actually select the powertrain I am using and not a generic 5.7 with 4l60e) Note the highway fuel economy estimate (original MPG 21 highway, New 20 highway). Note that is the estimate for a stock vehicle (mine is highly modified at this point), but even if I hadn’t modified it getting MPG 14% higher than the original highway fuel economy estimate isn’t that spectacular… Perhaps I should be ashamed at only getting 24 MPG in a vehicle with that engine transmission combination…
There were many other reasons besides fuel economy that GM scratched the 6.2L/6.5L diesels (competing higher HP options), but the US Army kept them around long after that (e.g. 6.5 still being produced last I checked). Thus a variation of the 6.2/6.5 engines has been in continuous production since 1984 to now. Pretty good run in my book. GM did significant detail optimization for the GMT400 platform (1988-2002), but lost many of it’s good details in the transition to the GMT800 platform (1999-2007) such as flush door handles, tight fitting headlights to grill, available flush wheel covers, etcetera as those made way to revised styling and the “shape optimization” to get back to the desired cD to hit their desired fuel economy with the new LS engines. If you spent several hours crawling over a stock GMT400 vehicle with an eye to details, your opinions on the cD might change... but perhaps not...
My odometer readings have repeatedly been both GPS and Google Maps distance verified. With 235/85R16 tires they will spin 656 revolutions per mile, which at 70 mph means 834.9 times a minute, which with 4.10 gears means at 70 mph my driveshaft spins 3423.1 times a minute, and with my modified 0.643494 overdrive gears (22/38 cluster ratio, 51/19 gearset) means my engine will be turning 2202.7618 RPM when traveling at 70MPH. (With 3.42 it would only be 1837 RPM, but I am not ready to do that swap yet, need to finish my bodywork first) My odometer is reading off the transfer case FYI so only the tires affect it, which I account for as verified per above.
I have alluded that my vehicle is modified, I have a full build thread on here, but to help support my outrageous claim of 14% better than epa estimated fuel economy, the cliff notes for back when those fuel economy figures were set were are a 2010 6.5L Diesel GEP Optimizer running Naturally Aspirated, NV4500 with custom overdrive gears, mechanical injection system swap which included me completely rewiring the vehicle from scratch to eliminate the computer, weight reduction, Michelin Defender LTX 235/85R16 tires, electric fans, DOT legal LED headlights, Duramax alternator swap, roof rack removal, flush bumper swap, WT grill swap, rare large bore OEM cast iron exhaust log manifold, custom air intake, conveyor belt air dam, and many other small tweaks.
I also don’t know where you are getting 5-7 from at 70MPH, even my 2001 Chevrolet 2500HD tow pig with the 8.1L and Allison gets better than that... It get about 12MPG average. Or perhaps I am lying about the 12MPG…
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