Eco modding the Tahoe Hybrid 40MPG Goal..

[Tahoe_Hybrid]

I want to Eco mod my Tahoe Hybrid chevy gave us a good start at 0.34 Coefficient
Same as a Geo Metro






but I noticed some issues that could offer me better mpg

both electrical
front end, rear end and underbody wise

I;ll start with the electrical system.. it's weak
there is some weird ground system that offers issues , too many connections (7 connections) inbetwwen the inverter and the battery.
it does not help they used crappy aluminium cables
this causes voltage sags once it's warmed up and robs gas mpg as the 60KW alternator has to run or siphon power from the HV battery..


it's going to cost 320$ to replace the cables and that includes a 6,000 Farad Capacitor bank system. I sourced some high Quality used caps on the cheap 30$ for each 1500F Big brand name.. and brand new copper cables so the electrons can flow freely..


second phase will do rear end work and then under body work... the goal is to keep it around $1500..

35-40MPG City is the Goal which is easily achievable... in EVT2 mode

YES I have gotten 31MPG (@ 42MPH) but in favorable weather conditions (the light wind shifted directions perfectly for me) I was able to keep it in EVT2 mode...


i have done 28mpg on the highway drafting behind 18wheelers i hate it though because they go too slow


25-26mpg by my self..

[M_a_t_t]

Are you mostly planning on doing drivetrain efficiency mods? You don't mention any plans for aerodynamics is why I ask.

[Tahoe_Hybrid]

Originally Posted by M_a_t_t

Are you mostly planning on doing drivetrain efficiency mods? You don't mention any plans for aerodynamics is why I ask.

Yes some Aero mods

under body (tire deflectors)and rear end




as you can see on #3 looks like there is a Aero issue

wing
the front end could use a few tweaks as well possibly installing a second air dam(found one for 39$ it's made for a vehicle ) I plan to add wheelbase side skirts as well


not sure if i will do a full Underbody (worried about the fuel vaporizing in the fuel line in the summer time as it gets very hot here into the 100 to 115F )


also LED lighting as well I modified some Sylvania Zevo LED 3157 bulbs and increased the brightness of them (it had some stupid plastic defuser on them deleted ) now they are SUPER crazy bright 2x2watt chips


it's like looking into the sun

I have to do something about the air wake in the rear it's a real drag (i see water pulled up from the ground when it's wet outside i.e not raining ) i don't see that on other SUVs





Looks like GM attempted to make it aero but that belongs on reddit /There was an Attempt

[aerohead]

Originally Posted by Tahoe_Hybrid

Yes some Aero mods

under body (tire deflectors)and rear end




as you can see on #3 looks like there is a Aero issue

wing
the front end could use a few tweaks as well possibly installing a second air dam(found one for 39$ it's made for a vehicle ) I plan to add wheelbase side skirts as well


not sure if i will do a full Underbody (worried about the fuel vaporizing in the fuel line in the summer time as it gets very hot here into the 100 to 115F )


also LED lighting as well I modified some Sylvania Zevo LED 3157 bulbs and increased the brightness of them (it had some stupid plastic defuser on them deleted ) now they are SUPER crazy bright 2x2watt chips


it's like looking into the sun

I have to do something about the air wake in the rear it's a real drag (i see water pulled up from the ground when it's wet outside i.e not raining ) i don't see that on other SUVs





Looks like GM attempted to make it aero but that belongs on reddit /There was an Attempt

If you're targeting 40-mpg,City,aero mods aren't going to return much of a benefit.You're basically battling momentum losses and transient loads.There's very little to do in the way of weight reduction.A 10% reduction in rolling resistance nets less than 2% in savings.You already have 'start-stop'.That was good for 7% mpg.GM has long electrified many engine accessories.'don't know what you'd do under the hood.

[Tahoe_Hybrid]

Originally Posted by aerohead

If you're targeting 40-mpg,City,aero mods aren't going to return much of a benefit.You're basically battling momentum losses and transient loads.There's very little to do in the way of weight reduction.A 10% reduction in rolling resistance nets less than 2% in savings.You already have 'start-stop'.That was good for 7% mpg.GM has long electrified many engine accessories.'don't know what you'd do under the hood.

my local speed limits are highway limits basically 45 to 60mph I want to keep it in CVT mode also known as EVT2 mode 6th gear.. 1000-1050 rpm = 38-45mph. 47mph it shifts into 4th gear (it's a 4 speed automatic with CVT )

the instant reading in CVT at 38 to 46mph is 40-45mpg If i'm able to keep it from leaving CVT mode if the engine load goes above a certain amount it will shift into 3th gear (4th gear is at 47mph) optimal speed is 59mph in that gear

a light breeze will increase the engine load and kick it out of EVT2..

Aero mods are needed to keep the engine load lower @the optimal speed which is 40-44mph

that is how I was able to get 31.1MPG locally I got lucky and had a slight tail wind and on my way back..

another issue is electrical load that could restart the engine at a stop light from Auto Stop


the under body is a mess as well as the rear of the SUV it has a large wake that sucks up air from under the SUV (heavy turbulence = lost energy)

[aardvarcus]

Your stock rear end taper on top is an excellent starting point for an add on tail. I have had great success with foam over fiberglass. See attached picture.

Have you already swapped to copper cables? I advise the use of marine grade (coated) copper lugs, crimping, dielectric grease, and lined heat shrink to terminate the cables. I used welding cable on my replacement battery /accessory cables. What’s the voltage on your 1500F caps?

I would consider adding a “splash guard” style belly pan from the factory air dam lip back to the front of the IFS crossmember, looks simple enough and would be a good use of a piece of black coroplast or ABS sheet.

Does the vehicle really need two mufflers? Seems odd… I guess people expect hybrids to be quiet. I assume your spare tire is in the trunk on the side. I definitely wouldn’t belly pan under the exhaust or you will create an oven. You could consider having the rear muffler removed (may even be able to use the rear exhaust pipe from a non-hybrid) which would let you add a diffuser style belly pan from the rear axle to the rear bumper.

[Tahoe_Hybrid]

Originally Posted by aardvarcus

Your stock rear end taper on top is an excellent starting point for an add on tail. I have had great success with foam over fiberglass. See attached picture.

Have you already swapped to copper cables? I advise the use of marine grade (coated) copper lugs, crimping, dielectric grease, and lined heat shrink to terminate the cables. I used welding cable on my replacement battery /accessory cables. What’s the voltage on your 1500F caps?

I would consider adding a “splash guard” style belly pan from the factory air dam lip back to the front of the IFS crossmember, looks simple enough and would be a good use of a piece of black coroplast or ABS sheet.

Does the vehicle really need two mufflers? Seems odd… I guess people expect hybrids to be quiet. I assume your spare tire is in the trunk on the side. I definitely wouldn’t belly pan under the exhaust or you will create an oven. You could consider having the rear muffler removed (may even be able to use the rear exhaust pipe from a non-hybrid) which would let you add a diffuser style belly pan from the rear axle to the rear bumper.

i could remove it, it will sound like a helicopter going down the road when in V4 mode


even with the muffler it's still makes some sound over 1300rpm


i have not done the cables yet but it's a "proprietary" cable so i can only Do the ground wires (and swap the aluminum cables for copper ones)

but i still can put new ones though because these were poorly designed


it's 1,500 Farads @ 12vDC Rated (15volts pack to handle peak volts in a car obviously )

[aardvarcus]

Looking at some online pictures, the three phase electrical cables coming off the transmission look very very difficult to replace, if those are the ones you are talking about. I would suggest (after disconnecting all sources of power) a good cleaning of all terminals, a light coat of dielectric grease, proper re-torquing, and see how they do after that.

If your cables are getting corrosion between the actual wire and the end connector and that is the source of your issues, then yes replacement would be your best option.

I think your rear "muffler" is more like a resonator. Up to you on whether or not it would be worth removing to be able to add an aerodynamic diffuser in that location. I certainly wouldn't recommend aerodynamic treatment in this area unless that was removed. Putting sound deadening on the rear cargo floor and rear hatch might offset the sound that actually makes it into the cab.

Many people seem to find loud or obnoxious exhaust sounds desirable, so if it ends up too bad you can buy a sticker from your aftermarket exhaust company of choice. With this sticker attached to your rear hatch, people will believe you intended and spent significant money for the vehicle to sound like it does.

[Piotrsko]

If he is in the LAAPCD jurisdiction, it is illegal to modify the exhaust in any manner. Doesn't mean people stop mods, swap parts, remove things. Just means inspections get difficult.

[Tahoe_Hybrid]

Originally Posted by aardvarcus

Looking at some online pictures, the three phase electrical cables coming off the transmission look very very difficult to replace, if those are the ones you are talking about. I would suggest (after disconnecting all sources of power) a good cleaning of all terminals, a light coat of dielectric grease, proper re-torquing, and see how they do after that.

If your cables are getting corrosion between the actual wire and the end connector and that is the source of your issues, then yes replacement would be your best option.

I think your rear "muffler" is more like a resonator. Up to you on whether or not it would be worth removing to be able to add an aerodynamic diffuser in that location. I certainly wouldn't recommend aerodynamic treatment in this area unless that was removed. Putting sound deadening on the rear cargo floor and rear hatch might offset the sound that actually makes it into the cab.

Many people seem to find loud or obnoxious exhaust sounds desirable, so if it ends up too bad you can buy a sticker from your aftermarket exhaust company of choice. With this sticker attached to your rear hatch, people will believe you intended and spent significant money for the vehicle to sound like it does.

haha only going to do the 12volt system don't be silly...


since it only happens in v4 might be able to get away with it since idle in v8 the front muffler takes care of it v4 only works when the suv is moving.. and when i leave i can shift it into M4 which will run it in v8 only
plus it keeps mentioning vehicles with less then 6000 pounds GVWR

remember this is a light truck with a GVWR of 7300lb

the Tahoe c1500 is 7,300 lbs GVWR



that is why i able to have the Tow hitch on all the time when not towing since it's a Truck chassis . aka GMT900
apparently it's only legal to test it in neutral gear which means it will be in autostop the output from the muffler will be 0db..(might constitute an illegal search to open the hood to have the engine start in neutral gear and it will still only be in v8 )
hahah loop hole ..