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Old 06-03-2019, 03:17 AM   #21 (permalink)
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Hyhoe - '08 Chevy Tahoe HY2
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Originally Posted by slowmover View Post
Neither was safety a goal it appears.

The police-spec Tahoe’s are heavily modified (lowered) to run those speeds.

Pickups and their SUV progeny are SOL if anything goes wrong from 60-mph+

Today’s tires and electronic stability band-aids don’t change physics.

.

59MPH is the optimal speed on the the highway(it's down hill from there)
41MPH in optimal in the city OR auto stop 0-29MPH



testing I have done over 4,000 miles

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Old 06-03-2019, 10:54 AM   #22 (permalink)
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Our Yukon also has the lowest gears available, I believe 3.08:1. Typically that would be a good thing but I think it is reducing our ability to stay in 4cyl mode. Above about 64 on flat pavement it likes to keep running as a v8.
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Old 06-03-2019, 08:40 PM   #23 (permalink)
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Originally Posted by ksa8907 View Post
Our Yukon also has the lowest gears available, I believe 3.08:1. Typically that would be a good thing but I think it is reducing our ability to stay in 4cyl mode. Above about 64 on flat pavement it likes to keep running as a v8.
Cruse Control?
Hows the Oil pressure?


3.08 is highway gearing. Tall Gear. if it had a shorter gear it would run higher RPM engine speed
i.e 3.23, 3.42, 3.73 or 4.10....


The shorter the gear(higher RPM = more fuel used) the more fuel consumption...

The hybrid has a lot of torque..


you could put taller tires or shorter tires to change the Final ratio as well...
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Old 06-03-2019, 09:06 PM   #24 (permalink)
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Quote:
Originally Posted by Tahoe_Hybrid View Post
Cruse Control?
Hows the Oil pressure?


3.08 is highway gearing. Tall Gear. if it had a shorter gear it would run higher RPM engine speed
i.e 3.23, 3.42, 3.73 or 4.10....


The shorter the gear(higher RPM = more fuel used) the more fuel consumption...

The hybrid has a lot of torque..


you could put taller tires or shorter tires to change the Final ratio as well...
Yes, we use cc a lot.

Oil pressure is great, might benefit from an oil cooler, after a couple hours driving it gets down around 40psig.

No offense intended, I do have an engineering degree and have been wrenching since I was old enough to turn one. I am well aware of gear ratios and the effect on engine load and fuel economy.

My point is, with numerically higher rear gears the engine would be under a lighter load allowing more use of cylinder deactivation.
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Old 06-03-2019, 10:24 PM   #25 (permalink)
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Quote:
Originally Posted by ksa8907 View Post
Yes, we use cc a lot.

Oil pressure is great, might benefit from an oil cooler, after a couple hours driving it gets down around 40psig.

No offense intended, I do have an engineering degree and have been wrenching since I was old enough to turn one. I am well aware of gear ratios and the effect on engine load and fuel economy.

My point is, with numerically higher rear gears the engine would be under a lighter load allowing more use of cylinder deactivation.
Yes but the electric motors have a lot of torque.
so it benefits with the 3.08 ratio...

6qt of 5-w30? or 0-w30?.. mine runs at 55-60PSI@1500 rpm on the highway 50PSI idle....


FYI my last fill up came in at 25MPG Combined (247miles)

19-MPG City
31-MPG Highway
25-MPG Combined
(US MPG)
40% city 60% highway

If you want your V4 mode to work better at higher speed I suggest using 91-93 OR E30-E85 (only if you got a FLEX Fuel..)

get it from a name brand like Chevron or Texaco I seem to have the best luck other gas stations seem to be pumping 87 at the 91 price ( I could tell since I was keep dropping to 3rd gear were it did not on 91octane)

in v4 you lose power because of the retarded timing because of engine AFM stuttering...


the AFM stutter with 87 octane fuel sucks I see more v8 mode and 3rd gear with 87 octane then with 91 octane fuel.

(highest here unless you get racing fuel but not worth it since it cost almost 10$ a gallon)

Last edited by Tahoe_Hybrid; 06-03-2019 at 11:28 PM..
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Old 06-04-2019, 08:59 AM   #26 (permalink)
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The oil is whatever the mfg specs and the dealer puts in. Oil pressure is similar to what you describe, go for a 2+ hour highway drive and report back. When the oil gets hot the viscosity drops and pressure goes to around 40psig cruising.

Don't forget this is a hybrid. The electric motors are also the generators so the hv battery can feed the 12v system.

At highway speeds the electric motors are just along for the ride and power is coming primarily from the engine. Even if the electric motors are providing motive power, that power is also coming from the engine which would mean again, it has to work harder therefore would benefit from numerically higher rear gears.

Edit: would benefit by staying in V4 more often.

I have no doubt we would get similar mpg to what you are if we lived in a warmer climate, had lighter wheels, had the aero improvements, and had 2wd not 4wd. I do love this vehicle though!
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Old 06-04-2019, 06:54 PM   #27 (permalink)
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Quote:
Originally Posted by ksa8907 View Post
The oil is whatever the mfg specs and the dealer puts in. Oil pressure is similar to what you describe, go for a 2+ hour highway drive and report back. When the oil gets hot the viscosity drops and pressure goes to around 40psig cruising.

Don't forget this is a hybrid. The electric motors are also the generators so the hv battery can feed the 12v system.

At highway speeds the electric motors are just along for the ride and power is coming primarily from the engine. Even if the electric motors are providing motive power, that power is also coming from the engine which would mean again, it has to work harder therefore would benefit from numerically higher rear gears.

Edit: would benefit by staying in V4 more often.

I have no doubt we would get similar mpg to what you are if we lived in a warmer climate, had lighter wheels, had the aero improvements, and had 2wd not 4wd. I do love this vehicle though!
Have you cleaned out the HV battery?

the blowers in these HV are pretty much dust collectors

Last edited by Tahoe_Hybrid; 06-04-2019 at 07:10 PM..
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Old 06-04-2019, 08:13 PM   #28 (permalink)
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Quote:
Originally Posted by Tahoe_Hybrid View Post
Have you cleaned out the HV battery?

the blowers in these HV are pretty much dust collectors
I cleaned the screen in front of the motor but I didn't remove the case. It didn't look too bad so here's to hoping i don't have any trouble!
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Old 06-08-2019, 12:09 AM   #29 (permalink)
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Originally Posted by ksa8907 View Post
I cleaned the screen in front of the motor but I didn't remove the case. It didn't look too bad so here's to hoping i don't have any trouble!
I want to service it my self I just have to get the High voltage gloves..and a mutimeter (premium brand name)


if they had dogs inside it could be a issue

the dealer wants 179$ to service it every 7,000 miles which is a bit nuts


10-15k is fine (mild cleaning of the fan)



the bus bars could have corrosion on them which would cause some impedance(premature battery failure) etc.. Poor Performance

says you will need boric acid NiMH (to neutralize anything that leaked out) and catsup to clean the bus bars (cleans Copper up like a shinny new penny ..)

Last edited by Tahoe_Hybrid; 06-08-2019 at 12:16 AM..
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Old 06-08-2019, 12:47 AM   #30 (permalink)
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90 day: 38.02 mpg (US)

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90 day: 21.48 mpg (US)
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I would think that unless you had water intrusion or some kind of metallic dust getting in there, cleaning battery connections should not be a normal procedure. Even under the hood, most 12v batteries stay clean and corrosion free. Inside the cabin in an enclosed battery case? Forgetaboutit!

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