Good place to get started ? want to get at lest 40-45MPG.highway.
 

I would like to start Aero modding my HYBRID SUV

times are tough and it's 3.99 a gallon here (91 octane)


my 6.0Liter V8 ❤ 91 octane


it has a 6 speed with 3 OVERdrive gears


4th = traditional transmission mode Primary OD Gear at about 30mph

Second mode:
[EVT1]5th = OD 35mph+
[EVT2]6th = OD it's rarely in this Gear only a feather light load will keep it in this gear (or deceleration event) mostly at 38mph to 49mph(with a tail wind above 45mph)


The Goal is to get 40mpg to 45MPG out of it on the highway and at lest 30MPG+ in the city

AFM is disabled via Rangetechnolgy Performance Chip....(at this point it's cheaper to spend money on gas then spend it repairing the engine because of a lifter failure bc of AFM, that would cost $3,000-3500 repair bill)





I all ready have the Tires pumped up, to 50PSI using

Michelin Energy Saver Tires, these are ultra light weight tires....


I see the underbody has plenty of low hanging fruit

I did notice a HUGE parashoot area between the second muffler and bumper... (I'm sure this could rob MPG)



keep in mind this is RWD so objects need to be keep away from the aluminum drive shaft. :) most likely i would not be able to find another one if it was to get damaged.. since it trim specific... and they don't make the part anymore..

https://ecomodder.com/forum/attachme...1&d=1619851884
https://ecomodder.com/forum/attachme...1&d=1619851884
https://ecomodder.com/forum/attachme...1&d=1619853679
https://ecomodder.com/forum/attachme...1&d=1619853679



Don't tell me to buy a prius

if I wanted to die in a accident i would have bought a smart car instead...


The speed limits are high in my AREA 45 to 60mph in the surface streets and if you get hit at that speed you're dead.... even if you have 20 air bags

I have seen it happen lots of times

Maybe worry less about mileage and install NASCAR level safety equipment? Add a boat tail/crush zone in back?

What mileage does it get now?

it's getting about 22 in the city in v8 mode right now...


The BEST ever was 35.8mpg weather conditions were perfect

It's hard to see how you could make that improvement in mileage with any aero mods.

Lol

Might start by trying to create a speed vs mpg chart, at least a mile long bi directional runs. I think a lot of vehicles peak in top gear at the lowest speed they can maintain. With an overdrive you rarely get into and v8/v4 you might have unexpected results

"Man reach must exceed his grasp, or what's a metaphor?"

35.8 to 40-45 isn't too much of a gap. Full underbody, four-wheel skirts and a full boat tail.

Taking an average of those figures gives a 17 per cent required improvement in mileage. I don't have drag data vs mileage for that car, but that's likely to need a 35 - 50 per cent reduction in drag.

If everything came together perfectly it might be possible, but that doesn't seem very likely.

Well, Tahoe_Hybrid, the challenge is thrown down.

I approve of setting your sights high. The 'first approximation' is two counts per mpg, or vice versa, I forget.

Aerocivic used dual side skirts to fill the gap between the front and rear tires. Whatever your do around the driveshaft.

Could you live with a boat tail? Plasma acutators?

35.8 was with a tail wind I just got lucky in both directions

The best full size cars get about 40 to 45mpg and suv usually get half the fuel mileage of cars so it looks like you're already there.
You know what it takes to almost get 40, just have to unrealistically cancel out most of your aerodynamic drag and there you go.

I'm sorry, but I don't believe that ginormous = safe propaganda one bit.

Sure, in a head-on collision you're safer in a heavier vehicle. But looks can be deceptive. A 2021 Ford F-150 starts out at around 4,000lbs, the same as a lot of full sized sedans. Depending on options a Dodge Charger can weigh 500lbs more than an F-150 curb weight. Sure, your Tahoe has a curb weight of around 700 to 1,000lbs more than that. But you could load the Charger with about that much weight if you wanted to.

Besides, weight and size isn't everything. You're more likely to get into a rollover accident in an SUV. That can cause you to become partially ejected from your vehicle right before it crushes you. I saw a guy kill himself this way right in front of me. He didn't even go off the road, just rolled his Jeep right in the middle of the road with no cars coming after hitting a patch of ice and then dry pavement. Roll overs also let things penetrate your vehicle. I had a friend who rolled his SUV and got impaled by a fence post. I don't know about you, but where I live nearly all highways are lined with metal fence posts waiting for SUV and pickup drivers to roll over on top of them. And I know, you're probably thinking that you're such a good driver that you'd never get into a rollover. But roll overs can happen when other cars just slightly bump into yours. Ever see a police car do a pit maneuver on an SUV? It usually ends up in a rollover.

You're also more likely to get killed by your own cargo than in a sedan, unless you have a good cargo net. Years ago this is how the neighbor lady died. She was in a single car accident, reportedly going only 25 mph before the accident, and was killed by her ski equipment coming up front from the back of her SUV. Of course the same principle applies to hatchbacks and station wagons.

You are also more likely to run over other people, including your family members, especially young children. This is because it's harder to see you're surroundings. When driving school bus there was one time a girl decided to rest on the front of the bus. Good thing we have crossover mirrors on school buses. This is also the reason a pickup truck driver ran over the rear of my flatbed trailer at the Home Depot parking lot. You don't stop for what you can't see.

Looking at driver death rates, the 2008 Tahoe is pretty good statistically, with 18 in a million dying in the 2WD model and 10 in a million dying in the 4WD model. Speaking of the Prius, looking at 2010 to 2011 data 16 in a million Prii drivers have died, which is very close to your Tahoe's statistics. Subarus usually have the lowest death rates statistically. Looking at similar years the Subaru Legacy has a 0 in a million death rate.

Personally I met in the middle of heavy weight and nimble hybrid and got a full sized Toyota Avalon hybrid that gets 40-45 mpg on the highway with no modification or special way of driving other than avoiding going over 65mph.

using this tool
https://ecomodder.com/forum/tool-aer...resistance.php

and these variables-

Vehicle weight: 2812.3 kg / 6200 lbs
Crr: .008
Cd: .35
A: 2.9 m2 / 31 ft2
Fuel energy density (Wh/US gal.): 33557
Engine efficiency: .28
Drivetrain efficiency: .95
Parasitic overhead (Watts): 0
rho: 1.225 kg/m3


I don't think you can consistantly get the MPG you want with aero mods alone.

Good, because it's just propaganda. And what the people who espouse this idea fail to recognize is that driving a heavier vehicle increases crash energy for *everyone* involved an accident.

If you want to be safest in the event of a crash (which, first--don't drive unsafely and you will likely be able to avoid one. In 20+ years driving, I have only been involved in two accidents. Both were rear-ends in which the other drivers were at fault), get a car that deforms, not the popular idea of a "strong" car or truck that doesn't. Deformation dissipates energy and increases the time it takes for you to come to a stop inside the vehicle and the vehicle to stop moving, which reduces the magnitude of your acceleration and thus the force that acts on your squishy insides. The same principle underpins the design of airbags.

The thing is there's no one perfect factor that makes a vehicle safer than all the others. Sure, we can point out little pros and cons all day. But in the end there are only these lines that can be drawn in the sand, the older the vehicle generation the less safe it is, and vehicles with extremely low safety equipment (e.g. motorcycles and some super small economy vehicles not normally imported to the USA.) Other than that there's no fine line between sedans, coupes, hatchbacks, station wagons, CUVs, SUVs, pickups, minivans, full sized vans, and other similar vehicles. Just pick a row of vehicle that works for you and then pick the one with them best safety features, ratings and statistics.

If according to the IIHS 18 out of every million Tahoe drivers are killed compared to 0 Subaru Legacy drivers, in which vehicle am I safer? The Tahoe, which is a large SUV, or the Legacy, which is a mid sized wagon?

Can somebody please explain me why you guys are so obsessed with absurdly large and heavy vehicles?
Also 3,99$/gallon is dirt cheap, here we're looking at the equivalent of 6-7$/gallon.
Get a normal car and you will get the fuel economy you desire.

Drivetrain efficiency of 95% is REALY optimistic for a front engine RWD automatic vehicle.
85-90% is more realistic.

With realistic values for drivetrain (0.85) and engine (0.22) efficiency as well as rolling resistance (0.010), I'm looking at about 20 mpg at 60 mph/100 km/h.
If I reduce the CD to 0.25, wich would mean a lot of aerodynamic modifications, we're looking at about 24 mpg.
Only when you're going full Basjoos and drop your CD to 0.17, you're getting close to 30 mpg but that's before factoring in the reduced engine efficiency at low power(17-26 hp).
Gasoiline V8s aren't exactly great at that.

TL/DR
You won't average 40 mpg at 60 mph with that car unless you go to the extremes.

I think it has to do with low self-esteem.

I put in the most optimistic numbers. It's a hybrid, so I upped the efficency of engine. It most likely goes into atkinson cycle. Also, my front engine RWD truck is is more efficent than .85. with lock up torque convertors.

TL/DR

Just saying he not getting 45 mpg using the most optmistic numbers. which is what you're saying also.

So many people in Georgia riding in full size trucks, often 3/4 and 1 ton, with a 6 inch lift and 35 inch tires. They all look alike. I think most people are followers and desire to have and be like others in the herd. Low self esteem plays into that, because they don't want to try something different, for fear of not being liked.

Another part is gas is cheap.

HWY mpg
 

A thought experiment, because it's safe, would be to draft a semitrailer at very close range on an isolated test course, at your chosen velocity, and see whether or not the engine could reach anywhere close to your target mileage.
If that didn't do it, nothing would. A Go NoGo.

0 City

Simpson's
 

Chris Payne, of 'Who Killed The Electric Car?' paid FOX $ 50,000 for a clip from 'The Simpsons' in which some of the townspeople felt that simply looking at a Prius would cause spontaneous sex change. ;)

according to the meter the Best MPG zone is at 45mph which runs the engine at 1050-1070 RPM in v8 mode... it will show a consistent 40mpg on the display.meter..with the A/C on ( no change if the A/C is off ) the issue is wasting a ton getting up to speed..


it's really hard to keep it in that gear If I was able to keep it in that gear longer i would net better mpg so it seems like even slight changes would have a huge benefit.... also i noticed the hood flaps around in the wind this could potentially effect the aerodynamics :confused:

In other words, it's a measurement that only gives the maximum possible outcome. Indicating that average fuel economy will be less than that.

It's not an mpg monster, it's a large SUV, ours is 4x4, that can tow 6000lbs and get 20+ mpg average. Also keeping in mind this is 15yr old technology that was originally designed for buses and large trucks.

Hood flapping in the wind is maybe 1% aero drag increase, which at those speeds is pretty low. As ksa8907 said, it is a huge frontal area, 2.5 tonne, 6.0L V8 powered vehicle and you are expecting hatchback economy from it.

At 45mph 2/3 of your drag is rolling resistance, so unless you are going to be removing the hybrid system, seats, headlining and carpet there is not much you can do about it. Play around with the numbers in the calculator, even if you half the drag coefficient, you still would only get 47mpg at 45mph

https://ecomodder.com/forum/tool-aer...ToStep=5-200-5

It is a tradeoff, you want a huge and heavy car, you get high drag. You want good economy, sell the large car and buy one that is a reasonable weight, and a reasonable size for your goals.

I'm glad I went small. Last month I drove about 1,500 miles, cost about $30 worth of electricity normally, but the last 2 months my power bill has been $0 because of the the solar panels.
If I was driving a gas murdering suv, that would burn at least 70 gallons worth of gas. No thanks.

45-mph ?
 

At the time I moved away from California ( 1975 ), it was still legal to drive 45-mph on any freeway. Is this going to be your target velocity?
You know where the engine's BSFC sweet spot is. If all efficiency gain is to come at 45-mph, and only from aero drag reduction, then, after streamlining, the Tahoe's gearing must be such that is absolutely matches the load you're seeing now, keeping it on the same BSFC pounds per brake horsepower-hour island, perhaps requiring a Gear-Vendors overdrive unit if you can't find a ring and pinion tall enough.

I do believe there's only one way to get +40mpg permanently out of this vehicle. An EV conversion. If it's a hybrid you apparently already have half the parts to do it. Next step would be to fill the vehicle up with more batteries. (It'll be heavier, which is what you want anyway, right?) Add a way to charge them and figure out how to cheat the system so the ICE won't turn on. And Violà! A 45mpg-e vehicle!

I agree but the original post said "times are tough and it's 3.99 a gallon here" batteries would be so expensive that it wouldn't be worth it. If the poster wants american cars then the Chevrolet Volt easily gets at least 40-45mpg on the highway.

The tahoe is worth $10 000 - $15 000 according to autotempest ads in california and a base model Volt is currently for sale in california for under $10 000. Sometimes the best mod, is a car swap.

Less likely to tip over, newer, better MPG, lighter, safer in a crash. Isn't a prius, fits all the criteria Tahoe_Hybrid mentions.

https://www.cars.com/vehicledetail/d...paign=atempest

But the weight of the vehicle and rolling resistance means than 40MPG is pretty much impossible, even if aero drag was zero (obviously impossible), but even if the aero drag was zero, the maximum mpg according to the calculator is 42MPG https://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=2500&WeightUnits=kg&CRR=.015 &Cd=0&FrontalArea=20&FrontalAreaUnits=ft^2&FuelWh= 33557&IceEfficiency=.22&DrivetrainEfficiency=.95&P arasiticOverhead=0&rho=1.225&FromToStep=5-200-5
I agree with what you say aerohead about regearing, I am just disagreeing on the practicality in this specific case.

impossible
 

At #25 permalink, the Tahoe, at Cd 0.37, was already achieving 40-mpg at 45-mph, with it's existing aero, mass, and tires.
I don't know what the 'target' velocity is, so I'm asking.
The Tahoe could be looking at Cd 0.10 pulling a 1-wheeled, gap-filled, full-boat-tailed, tadpole trailer, so there's some wiggle room on travel velocity.

The only reason we kept the hybrid yukon and sold the volt(gen 1) is we needed more than 4 seats. I prefer to drive the volt, way more engaging!

"a 1-wheeled, gap-filled, full-boat-tailed, tadpole trailer..." :thumbup:

https://ecomodder.com/forum/member-f...13-9-20-42.png

Extra points if it's made from an old VW Beetle body.

Everyone's circumstances are different. It sounds like the OP wants the Tahoe because he thinks it's safer, not because he needs more space.

My thoughts are that as a fad there's a lot of propaganda to make SUV's seem better than they are, and safety is one of them. Statistically there is no fine line between SUV's and alternatives such as sedans. (Sorry for beating the dead horse a again.)

Personally it makes sense to get a vehicle that meets your needs while avoiding overkill. More than 4 seats could work out in a 5 seat vehicle like a Prius V or Camry or Avalon hybrid. Then there's the Pacifica minivan, which in general a minivan should be more efficient than a large SUV and still haul pretty much the same. But on the other hand sometimes the "perfect vehicle" wouldn't be practical because it costs more to own for other reasons. For an example, I feel that in my situation a newer station wagon would fit my needs the best while still getting the best fuel mileage possible. But alas, the only station wagons available are luxury vehicles, with the exception of a Subaru. Or I'd have to jump into a less aerodynamic CUV or SUV. Sometimes I feel like going mod-crazy and make my Avalon into a station wagon.

Sometimes I feel like going mod-crazy and make my Avalon Dasher lift-back into a station wagon shooting brake.

What's a shooting brake?

He could do this but would need a way to manually shift and lock up his XMSN

https://ecomodder.com/forum/showthre...mpg-33961.html

Basicly a wagon with a roof that follows the aero template in the rear.

Unfortunately the key word there is could, I agree, that with vast modification and streamlining, full undertray and near full boat tail the Cd could be near to 0.1, but realistically this person is looking for easy mods to get to at least 40-45mpg highway, even if you count 45mph as highway, it is still a tall order aerodynamically to even get to 45mpg without significant rolling resistance decrease.

I may have been pessimistic in my assumption of Crr at 0.015 but even with very LRR tyres (probably not available for a car of that weight) at 0.01 and absolutely no aero drag, 64mpg is all that is achievable.

Everything is a compromise, very often what you think you need is different to what you actually need.