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Old 03-29-2020, 03:51 PM   #1 (permalink)
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2020 - '08 Chevy Tahoe H
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Its not always about MPG

I'd really like to increase the MPG to 40-45MPG on this V8 6.0L Engine..


we had a 7mph tailwind the other day
it was reporting 40 to 45MPG on the instant gauge @ 60MPH steady speed..

flat land i think getting down to 0.28 from 0.34 will get me that 40ish at 60mph...

this is not about the MPG it's about improving the emissions output


that would cut the emissions output by 50% over EPA ratings

is it possible on a budget? say $200?


this would put my MPG right there with the Geo Metro
1.0L L3 GAS..



Hypermiling gets me about 31.5MPG (95% highway only) currently


Last edited by Tahoe_Hybrid; 03-29-2020 at 04:00 PM..
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Old 03-30-2020, 09:13 AM   #2 (permalink)
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Pretty darn impressive numbers.

Your main losses are aerodynamics, weight, and parasitic.

-Hybrid systems are often great for cutting parasitic losses, because they usually have infinite control of the rev range and can in many cases toggle the engine on and off as needed. With a quick search I wasn't able to figure out what kind of gearbox the Tahoe uses - is this something you know and can share? Is it a planetary gearbox like the Prius/Rav4/Volt? Anyway, given the great economy you already have, there probably isn't as much low-hanging fruit here.

-Rolling resistance is affected by vehicle weight and tire choice. It tends to dominate at low speeds but is likely less of a factor on the highway. However, anything you can remove when you're not using it (e.g. 3rd row seats) will help.

-Regarding aero, I can think of a few things.

*Mirror removal is highly effective because it cuts both frontal area and Cd, which are multiplied together in the drag equation. Many people use interior mirrors, panoramic central rear-view mirrors, and a few use camera replacements. Cameras like this are standard on the new Honda-e and were one of the drag-reducing tricks for the VW-XL1.





*A partial grille block is one of the easiest ways to cut Cd slightly. Some vehicles produced in the last ~5 years have active grille shutters, which remain closed until the engine is warm, and then only open enough to maintain temperature. There are some posts about active shutters on here, but a quick'n easy solution is to just put some coroplast across part of the grille, and either add or subtract until you find the right amount, which doesn't cause heat issues underhood but also doesn't let more air into the very aerodynamically dirty engine bay than necessary.





Smooth wheel covers help a ton. (image is from my velomobile wheels)





Smooth underbody paneling is becoming more and more common from the factory, but often these panels are pulled off when a vehicle is in for service, and discarded. Back in 2008, they weren't yet very common, and even vehicles that have them tend to have incomplete paneling. Coroplast is effective and cheap.

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Old 03-30-2020, 09:20 AM   #3 (permalink)
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Use less fuel, make less emissions all down the line.
That 40mpg of gasoline is more like 30mpg to the gallon of oil from the time it came out of the ground.
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Old 03-30-2020, 11:51 AM   #4 (permalink)
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Quote:
Originally Posted by oil pan 4 View Post
Use less fuel, make less emissions all down the line.
That 40mpg of gasoline is more like 30mpg to the gallon of oil from the time it came out of the ground.
our fuel is locally sourced(In State) right out of the ground .. the refinery is 160 miles away.. since it's locally sourced there is no out of country transport emissions...
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Old 03-30-2020, 12:13 PM   #5 (permalink)
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Quote:
Originally Posted by Ecky View Post
Pretty darn impressive numbers.

Your main losses are aerodynamics, weight, and parasitic.

-Hybrid systems are often great for cutting parasitic losses, because they usually have infinite control of the rev range and can in many cases toggle the engine on and off as needed. With a quick search I wasn't able to figure out what kind of gearbox the Tahoe uses - is this something you know and can share? Is it a planetary gearbox like the Prius/Rav4/Volt? Anyway, given the great economy you already have, there probably isn't as much low-hanging fruit here.
it's a standard 4 speed automatic.
it uses the Gear Ratios
1st — 3.69:1
2nd — 1.70:1
3rd — 1.00:1
4th — 0.73:1
EVT #1 — Infinity to 1.70:1
EVT #2 — 1.70 to 0.50:1
Reverse — Infinity to 1.70:1

the biggest losses are Aero drag


there is some weird Aero drag in the rear of the SUV... all the air from under the SUV circles in the rear creating a vortex or "wake" i noticed it when it was not raining but the ground was wet and the rear window was getting wet... i did not see it on other SUVs



the under body is a real mess
the mirrors are "big" as well

Last edited by Tahoe_Hybrid; 03-30-2020 at 12:18 PM..
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Old 03-30-2020, 12:30 PM   #6 (permalink)
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Where do the electric motor(s) connect in? Are they connected to the crankshaft via a belt, or after the crankshaft? Can the motors apply torque to the wheels without the engine turning?
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Old 03-30-2020, 12:44 PM   #7 (permalink)
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Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

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Quote:
Originally Posted by Tahoe_Hybrid View Post
our fuel is locally sourced(In State) right out of the ground .. the refinery is 160 miles away.. since it's locally sourced there is no out of country transport emissions...
Oh, that is assuming you are using domestic oil.
How do you think the gasoline components get heated to around 300F and fractionally distilled off, the gasoil/diesel components get heated 600 to 900F for hydrocracking, the lighter compounds get hydroformed into heavier chemicals?
You do realize the process burns some of the oil to create finished product right?
Have you ever been around an oil refinery they stink.
You want to talk about emissions, start at the refinery.
That oil didn't miracle it's self into finished products at the gas station.
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1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.

Last edited by oil pan 4; 03-30-2020 at 12:55 PM..
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Old 03-30-2020, 01:21 PM   #8 (permalink)
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Connect - '15 Ford Transit Connect XL
90 day: 21.26 mpg (US)

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Quote:
Originally Posted by oil pan 4 View Post
Oh, that is assuming you are using domestic oil.
How do you think the gasoline components get heated to around 300F and fractionally distilled off, the gasoil/diesel components get heated 600 to 900F for hydrocracking, the lighter compounds get hydroformed into heavier chemicals?
You do realize the process burns some of the oil to create finished product right?
Have you ever been around an oil refinery they stink.
You want to talk about emissions, start at the refinery.
That oil didn't miracle it's self into finished products at the gas station.
Sure, but this is going to be the case for ANY vehicle that runs on gasoline, or by extension any vehicle that uses any parts whose creation required any energy. Or heck, any object produced in our economy. Follow supply lines back and somewhere SOMEONE is burning gasoline. Best way to reduce emissions is to not spend any money, to not consume anything or buy anything new. Even batteries and electric motors.
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Old 03-30-2020, 04:00 PM   #9 (permalink)
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Basjoos said he spent $400 on his car in aeromods. Since you goal is lower than his you should be able to get what you are looking for in aero mods.
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Old 03-30-2020, 04:47 PM   #10 (permalink)
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2020 - '08 Chevy Tahoe H
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Quote:
Originally Posted by Ecky View Post
Where do the electric motor(s) connect in? Are they connected to the crankshaft via a belt, or after the crankshaft? Can the motors apply torque to the wheels without the engine turning?
it's inside the transmission it's integrated, 2ML70 transmission.. to be exact..


yes the electrical motors can drive the suv upto 30mph my local speeds are much higher so it's rarely "off" or auto stop.. i found getting to 40mph quickly as possible and taking routes with the lest amount of traffic control devices yields the best results


Last edited by Tahoe_Hybrid; 03-30-2020 at 04:54 PM..
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