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 > 2020 GM/Chevy gas 6.6L max towing test

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JIMNLIN

Oklahoma

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Posted: 10/21/19 07:57am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

At the end of the test they were going 2600 RPM at 25 mph. Truck wouldn't downshift. I wonder what would have been different if they put it in manual. To be honest I never put mine in manual, but I have not towed the IKE.

I use manual mode in a auto tranny for that type towing. I made a living for over 11 straight years with manual transmission LDTs so I know better than the ECM which gear to select and at what point a gear shift is or isn't needed.


Of course these test are better suited to for those that don't want to do the thinking/shifting for which gear is needed at that moment.
Results would be different up and down hill using manual mode by a experienced operator........or a smarter engine/tranny operating ECM.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

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Lynnmor

Red Lion

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Posted: 10/21/19 08:32am Link  |  Quote  |  Print  |  Notify Moderator

jfritz_drfritz wrote:


I wonder if it fails to downshift because at that altitude the engine doesn’t generate enough torque for the transmission to sense a downshift point


I wonder if sensors saw high temperatures after miles of full throttle and dialed back the power to save the engine or transmission.





ls1mike

Bremerton

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Posted: 10/21/19 08:35am Link  |  Quote  |  Print  |  Notify Moderator

JIMNLIN wrote:

Quote:

At the end of the test they were going 2600 RPM at 25 mph. Truck wouldn't downshift. I wonder what would have been different if they put it in manual. To be honest I never put mine in manual, but I have not towed the IKE.

I use manual mode in a auto tranny for that type towing. I made a living for over 11 straight years with manual transmission LDTs so I know better than the ECM which gear to select and at what point a gear shift is or isn't needed.


Of course these test are better suited to for those that don't want to do the thinking/shifting for which gear is needed at that moment.
Results would be different up and down hill using manual mode by a experienced operator........or a smarter engine/tranny operating ECM.


I just have not had to use it in this truck. They old truck was 4 speed. I would leave it in third sometimes. I am not towing really heavy and here in Washington we don't get anything that high in elevation so it stays in the correct gear.


Mike
2017 Chevy 3500HD 6.0 Crew Cab Long bed
2012 Passport 3220 BHWE
Me, the Wife, two little ones and two dogs.

ls1mike

Bremerton

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Posted: 10/21/19 08:39am Link  |  Quote  |  Print  |  Notify Moderator

Lynnmor wrote:

jfritz_drfritz wrote:


I wonder if it fails to downshift because at that altitude the engine doesn’t generate enough torque for the transmission to sense a downshift point


I wonder if sensors saw high temperatures after miles of full throttle and dialed back the power to save the engine or transmission.

In this video and the 2017 gasser video they mention all temps were in spec.

I am going to look at the Caprices tune tonight. It is pretty similar to the truck believe it or not.
I know the Caprice looks at speed/rpms/time/MAF/TPS. I will have to look and see it temp is part of it.

I really messed withe Caprice when I got rid of the AFM cam and installed an LS9 cam.

ShinerBock

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Posted: 10/21/19 08:46am Link  |  Quote  |  Print  |  Notify Moderator

ls1mike wrote:

Lynnmor wrote:

jfritz_drfritz wrote:


I wonder if it fails to downshift because at that altitude the engine doesn’t generate enough torque for the transmission to sense a downshift point


I wonder if sensors saw high temperatures after miles of full throttle and dialed back the power to save the engine or transmission.

In this video and the 2017 gasser video they mention all temps were in spec.


But that is just it. It could have defueled or cut power to keep the temps within spec. Diesel do the same thing. The Ram 6.4L did it as well the last Ike run they had. This 6.6L could have forced the truck into lower rpms to keep the temps at safe levels.

ls1mike

Bremerton

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Posted: 10/21/19 09:06am Link  |  Quote  |  Print  |  Notify Moderator

ShinerBock wrote:

ls1mike wrote:

Lynnmor wrote:

jfritz_drfritz wrote:


I wonder if it fails to downshift because at that altitude the engine doesn’t generate enough torque for the transmission to sense a downshift point


I wonder if sensors saw high temperatures after miles of full throttle and dialed back the power to save the engine or transmission.

In this video and the 2017 gasser video they mention all temps were in spec.


But that is just it. It could have defueled or cut power to keep the temps within spec. Diesel do the same thing. The Ram 6.4L did it as well the last Ike run they had. This 6.6L could have forced the truck into lower rpms to keep the temps at safe levels.


Right, but that is not a parameter in the transmission field. There are something close to 450 parameters for the 6L80E/6L90E. For the 6L80E and 6L90E time and pressure are the tow big ones. I will hook up the Laptop next time I tow and see. I don't remember reading about or being able to mess defueling in the program. I have HP Tuners. That thing is great if you understand it. It has really woke the Caprice up with the cam swap. I don't plan on messing with the truck at all. It is a great diagnostic tool too. Like I know guys who remove torque management. Not really worth it to me, I don't feel like rebuilding the 6L80E in the Caprice every other season.

ShinerBock

SATX

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Posted: 10/21/19 09:21am Link  |  Quote  |  Print  |  Notify Moderator

ls1mike wrote:

ShinerBock wrote:

ls1mike wrote:

Lynnmor wrote:

jfritz_drfritz wrote:


I wonder if it fails to downshift because at that altitude the engine doesn’t generate enough torque for the transmission to sense a downshift point


I wonder if sensors saw high temperatures after miles of full throttle and dialed back the power to save the engine or transmission.

In this video and the 2017 gasser video they mention all temps were in spec.


But that is just it. It could have defueled or cut power to keep the temps within spec. Diesel do the same thing. The Ram 6.4L did it as well the last Ike run they had. This 6.6L could have forced the truck into lower rpms to keep the temps at safe levels.


Right, but that is not a parameter in the transmission field. There are something close to 450 parameters for the 6L80E/6L90E. For the 6L80E and 6L90E time and pressure are the tow big ones. I will hook up the Laptop next time I tow and see. I don't remember reading about or being able to mess defueling in the program. I have HP Tuners. That thing is great if you understand it. It has really woke the Caprice up with the cam swap. I don't plan on messing with the truck at all. It is a great diagnostic tool too. Like I know guys who remove torque management. Not really worth it to me, I don't feel like rebuilding the 6L80E in the Caprice every other season.


You may not be able to all perimeters depending on the software or tuning tool you are using. I know I can see more perimeters with my EFI Live software than I can with my MM3. EFI Live is by far the best when it comes to how many parameters it can view/alter especially when it comes to GM vehicles.

deltabravo

Spokane, WA

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Posted: 10/21/19 05:25pm Link  |  Quote  |  Print  |  Notify Moderator

The 2020 Chevy HD is still ugly as sin.

I saw one in person a few weeks ago, they are extremely tall too.

2020 Chevy HD - too tall for my liking.


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LITEPHIL

AZ

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Posted: 10/26/19 09:51am Link  |  Quote  |  Print  |  Notify Moderator

For the weight they were towing and at that altitude, I think it did ok for a small block non turbo gas engine. That thing was probably gasping for air. Part of finding the true towing potential would be shifting gears manually if needed. I couldn't watch the whole thing since that one guy sort of gives me the creaps. It will be interesting to see a comparison with the Ford and Dodge gas engines. I very much doubt they'll do that much better. Gas,extreme weight and altitude are not the gas engines best friend.


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