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

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.


https://i.imgur.com/l2dQI8Hm.jpg


*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.


https://i.imgur.com/XYdlUd5m.jpg


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


https://i.imgur.com/uakOAOIm.jpg


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.

https://i.imgur.com/P6Ok37dm.jpg

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...

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

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?

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.

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.

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

here is some photos you can see the Aero issues that are quite visible


the mirror is not small it's huge i have a 10 inch hand span you can see how big it is



Objects are bigger then they appear in the photos due to the extreme wide angle of the lens

https://ecomodder.com/forum/attachme...1&d=1585605378
https://ecomodder.com/forum/attachme...1&d=1585605378
https://ecomodder.com/forum/attachme...1&d=1585605378
https://ecomodder.com/forum/attachme...1&d=1585605378
https://ecomodder.com/forum/attachme...1&d=1585605378
https://ecomodder.com/forum/attachme...1&d=1585605378

You need to compare your Tahoe to a regular one. You'll find a lot of aero tweaks have been done. So the small stuff has already been done. I'll google, see if I can find a list of differences.

Edit:
Fist find, the GM list:

Aerodynamically enhanced exterior:
Aluminum hood and liftgate
Lowered front air dam
Aerodynamic assist steps
New rear fascia, rear spoiler and D-pillar appliqués for aero improvements
Lightweight aerodynamic aluminum wheels
Low rolling-resistance tires

I know that's not a complete list, as I know the panels above the taillights are unique, and not listed.

Should be able to find the Cd improvement too...

edit:
Looks like .379 to .360 And aero mirrors are mentioned.

https://gmauthority.com/blog/2010/06...g-coefficient/

https://ecomodder.com/forum/attachme...1&d=1585610143

The original version above.

the original is 0.363 and this is 0.34

yeah not much lower

So you do know about the tweaks. As I said, it's just going to make it tougher to find little things that help.

And you realize something like 80 or 90% of the emissions are due to cold start and warm up on the EPA cycles, right? The next big chunk is transient and intrusive diagnostics. Steady state emissions, driving down the road, are effectively zero. The cats are converting everything to water and CO2.

You will cut CO2 though, if you are considering that.

Are those numbers for the '13 model? Did it change? Stuff I found was old, but only mentioned the first couple years.

the next update was 2015 which the front end changed 0.34 and smaller mirrors (these mirrors can be modified to fit on mine) but it's pricey at about 350$ for just that the 2019 might be slightly lower as they added air ducts

the biggest drag in the front is the mirrors, because of the size of them.



you can hear the wind dragging on them at about 75 or so


the only reason i'm able to get the good mpg is because i use 91oct as it's able to keep it in V4 mode much longer then 87oct ( it hyper switches from v8v4v8 i'm pretty sure that is bad for the engine i.e wear and tear wise to the AFM system )

I was thinking of a full skirt wrap around and drop the front to about 1" of clearance. sides 2 inch of clearance ridged but needs to be flexible if anything in the road .. i'm just wondering what everyone else uses

Lawn edging or conveyor belt material work well. I've used the former on a vehicle - it got torn up during a Vermont winter, but so does literally everything else.

I did some clearance checks

and the front has

8 inches

sides have 10 inches

the rear at the muffler is 13 inches



would a bigger airdam help?

I've read the air dam should hang down as far as the lowest point on the underside of the vehicle, any lower and it's increasing frontal area, which adds drag. I can't cite my source, but if true, going all the way to the ground would be counterproductive.

but it does look like it has some Parachutes type items under it, especially the rear bumper..



how about wheel splats? I was thinking of using 18 wheeler mud flaps(cutting them though) it's 33.30$ for a pair to do all 4 tires

the 2015+ has built in wheel splats to the front air dam..
.
https://ecomodder.com/forum/attachme...1&d=1585714583


but i think might be able to do a Vent duct where those plastic covers are ?

My understanding with wheel spats/deflectors is that much more drag occurs on the upper half of the wheel is moving against the wind at twice the speed of the vehicle. This is what mine shipped with:

https://i.imgur.com/d2dNt0o.jpg

This is what some ecomodders have done:

https://i.imgur.com/MgBwQhc.jpg


As for the sides, even a tiny spat at the top of the wheel arch is going to give most of the benefit, since that's where the tire is moving most rapidly against the wind.

https://s3-prod.autonews.com/s3fs-pu...OMEHEGRMGY.gif

40-45 mpg
 

On three occasions I've seen 39.9 mpg @ 60-mph,steady,interstate cruising,Texas to California and back .That's with 4,220-lbs all up weight, around 29-sq-ft frontal area,Cd 0.2675,and REGULAR UNLEADED.With a direct-injection turbo-diesel we'd be looking at 51.87 mpg at the same velocity.
The Tahoe is heavier and of larger frontal area.Your V-engine has higher internal friction.Your drive-line has higher internal friction.
In materials,$200 is quite reasonable,but you might be looking at 800-1200 man-hours in fabrication time to create a low enough drag,requiring the most difficult to achieve compound curves,everywhere.

V-4 mode
 

GM chose the V-8 for the Corvette to allow it to remain in the V-4 mode as well.A V-6 wouldn't cut it.I can see the octane issue.Ford's EcoBoost engines require premium when towing or heavy load.

airdam
 

Hucho warns that a deeper airdam can increase drag.Extremely low dams can cut drag,but without being 'active' they're torn off on the first driveway ramp.
Brett Herndon,of Aerolid fame,constructed an absolutely fabulous airdam for his F-150,but was forced to modify it,as it's extended depth cut into fuel economy,just as predicted by Hucho.Active aerodynamics is the solution,but adds a couple orders magnitude to build complication.:o

parachute
 

Technically,the rear bumper fascia cannot 'parachute' unless you've got a belly pan all the way to it,and fully attached flow.Subaru lowered the drag of their 1985 XT by 'adding' a parachute rear bumper.Drag went up without it.
If you're going to the trouble of doing a belly pan,you'd want to do a diffuser,to wring out all the drag reduction possible.

If it has not been mentioned, consider a rear diffuser. That space in front of the rear bumper cover is awful.

It has very aggressive DFCO. That is how i'm able to get that many mpg in the first place..

I suspect the Electrical motor is spinning the engine in DFCO... with a OBD reader you can see 0.00v on the upstream o2 sensor. that mean no fuel to air ratio.


when i first saw that i thought my sensor was broken or some other issue..


since there is no "engine braking"
it feels like it's in "neutral gear"

if I shift it into Manual Mode it has "engine braking" and you stop pretty quickly

i pumped up the 4 tires to 44PSI
i think a good mod would be for the hood gap stripping it tends to flap around in the wind... you can see the hood get a little bit of lift and flex i'd assume this is causing drag...

seems to keep in auto stop much longer with it pumped to 44psi i had them at 40psi before

should i block off the lower or upper portion of the grille (have to be careful as i have an aluminum block)

If you don't have one already, you can get a Bluetooth OBD II dongle from Amazon/eBay for around $5 which will let you monitor engine temps exactly. Just need to run it long enough to know if your grille block is too much or not.

Can't wait to see how it improves!

The only problem with putting max air pressure especially in newish tires is the center of the tire wears out faster.
I air up old tires to higher pressure that have been properly rotated front to back and they look like they are going to wear out on the shoulder first.
Also better tires help. The new energy saver tires with normal 34 to 36psi get the same milage as the warn out ecopia tires with 44psi.

Lowering springs, replace side mirrors, underbody aero, rear diffuser and kammback. Those are my picks

spats and fender skirts
 

Perhaps I am being picky about terms but I would like to see some consensus on what we are calling spats and what we are calling skirts. I was under the impression that spats are the little plastic rectangles that most car makers are using in front of the tires, like the white spats we wore to cover the front of our black shoes in marching band (or the massive ones on the green Jetta).

In the 50s, fender skirts came down over the top of the rear tire. In the 90s we got side skirts that lowered the rocker panels between the front and rear tires.

OP- I think you will have to go full Basjoos on this to significantly decrease your Cd. I have found air dams all get ripped off sooner or later. I am using a full belly pan with diffuser, inner and outer side skirts and small spats in front of the tires. All have stayed on winter and summer and have greatly increased coasting distances and mpg in my experience. A full boat tail is too hard to live with day to day for me and has not been done yet on my car.

Even though the rear live axle would presumably make it harder to get a full belly pan, I'd give it a try. Rear diffusers might help a lot too. Messing with smaller mirrors is something I wouldn't be so comfortable with, but maybe it could be worth if their aerodynamics is better. For smaller vehicles I'd often recommend the ones out of some sports motorcycle which usually have a more aerodynamic housing, but maybe if you set them a little further back than stock position it may not be so bad at all.

I thought about using some 2015 model they are smaller and more Aero shaped but it would really kill my budget it's like 300ea since i have DL3 mirror trim level

power folding, signal, auto dimming ,heated etc..

Everything nicely tucked in above the frame including the drive shaft, tell the rear differential pumpkin.. slightly sticking out

also the belly pan would need an access panel for oil changes i do them every 4500 miles or so+- 100 miles

https://i.postimg.cc/nzS8Xkd9/20200119-162534.jpg

https://i.postimg.cc/vTPWF1Zs/20200119-162642.jpg

https://i.postimg.cc/L50ZQrx4/20200119-162637.jpg

https://i.postimg.cc/QdcHc9Zd/20200119-162724.jpg

https://i.postimg.cc/h47zK3Zm/20200119-162605.jpg

https://i.postimg.cc/5twKc3dW/20200119-162553.jpg

Are you saying aggressive as in, it barely slows down? I would interpret aggressive as sudden and strong braking action.

The scangauge says my Accord is open loop when DFCO'ing. I don't have the capabilities for monitoring sensor voltage. DFCO in general means cutting fuel while slowing down. The electric motor doesn't have to help spin the engine, as the momentum of the vehicle is already doing that. It may be true that the motor is helping spin the engine under DFCO, but it is also likely that manual mode causes regen, resulting in that increased braking feel.

That's good, cause i've got some worn ecopias and am about ready to swap to the energy savers.

RPM is not married to the Speed in "Drive Gear"

50mph or less it's 1,000 RPM engine speed w/DFCO
above 55 the RPM is 1500 w/DFCO i.e 85mph

what i meant about aggressive is it drops to v4 mode or v4-DFCO

if I have it in M1-4 gear then engine braking occurs RPM is married to the speed.


there is not much drag with the regeneration.. it's not very noticeable while in Drive.



on the accord you should be able to use an OBD reader to get the sensor voltage

Please with the ridiculous fe claims. The fuel log shows the truth. "... almost the same mpg as a Metro..." Give us a break.

"It's not always about mpg"- got that right. For most, most of the time, it isn't. It's about impressing people that don't even know them or care with conspicuous consumption.

I had problems with the electrical causing issues with the Engine control Module & hybrid controller.. Preventing EV and auto stop from working correctly over the last year...

it will be higher this month. as i fixed the issue :) the positive cable was caked on with dirt and oil... it will be in the 24-25 range for the city. this month..


also i said 40-48mpg could be possible if i could lower the drag. a bit as it will be in EVT mode.more often . which runs the engine at 1,000 rpm at 38mph to 48mph..


the best I have gotten was 31.2mpg on the highway.
as i was able to keep in in the eco mode most of the time.. 40+MPG would be possible on the highway... with some aero mods..


I'll make another entry one for City and one for highway so everything will get deleted and re install the numbers

My wifes Hyundai sonata gets between 40 and 48mpg and it'd a full size car that sits fairly low to the ground.

don't worry my 6.0L is doing a bit better then that 3.0l engine you got there.

what i'm worry about is making sure the battery does not go flat at this point from it sitting about it's 4900$ for a replacement.. Yes i can afford it

I rather invest that once the market bottoms out in the next week it should be crumbing by Monday or Tuesday.. it's going to be a real shell shocker market correction... it's going to drop down to about 13-14k. when it goes back up i could buy many batteries. then with the 5k = 30k = 1 free battery :)

yeah I only got 18.4 last time but it was idling for 4 hours :thumbup: but the majority of the time in autostop(had to keep warm waiting inline at the store not for Toilet paper (just for general items for the week) ( i stocked up on TP & water months ago when they first mention it back in January ..) 200IQ! :D