GMT400 vs GMT800 Suburban

#61
Black Bear in person tune for now. Mapping was changed to increase performance. The shift points were changed and the ATM was also turned off. It is a beast. The mileage isnt bad as long as you keep the rpms under control on the highway and its very civil around town no weird or clunky shifting. When you stomp the skinny pedal the thing just jumps.

When they do it in person do they put it on a dyno? Because of the engine tune and torque management delete was there any concern about the trans handling all the mods?
 
#63
When they do it in person do they put it on a dyno? Because of the engine tune and torque management delete was there any concern about the trans handling all the mods?
No dyno when mine was done.
No concern for the trans its the 4l85e which is a beefed up 4l80e. It would take more than 500lbs or so to blow it up. The 4l80/5 trannys are essentially a computer controlled th400 with overdrive. The internals are identical with the addition of a seperate planetary and clutches for the OD. The 4l80/5 also has a lockup converter which the th400 doesnt. Th400s and 4l80s have been built for over 2000hp and gobs of torque. The 4l80s are a HD trans designed to keep the rpms up between shifts to keep the engine power up specifically for towing a load. 400hp and 500ftlbs is no issue for a 4l80. Especially one that isnt going to be abused every weekend at the drag strip
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jeep-N-montero

Expedition Leader
#64
No dyno when mine was done.
No concern for the trans its the 4l85e which is a beefed up 4l80e. It would take more than 500lbs or so to blow it up. The 4l80/5 trannys are essentially a computer controlled th400 with overdrive. The internals are identical with the addition of a seperate planetary and clutches for the OD. The 4l80/5 also has a lockup converter which the th400 doesnt. Th400s and 4l80s have been built for over 2000hp and gobs of torque. The 4l80s are a HD trans designed to keep the rpms up between shifts to keep the engine power up specifically for towing a load. 400hp and 500ftlbs is no issue for a 4l80. Especially one that isnt going to be abused every weekend at the drag strip
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Part of me is glad they didn't put the Allison in the Yukon/Burb with the 8.1, they eat up more power and can't tune the trans the way you can with the 80/85. I'm still on the fence about looking for a clean 8.1, but I'll see how the 6.0 feels after the BBP tune, it would be very difficult to find another Yukon as clean as our 03 that we bought from the original owners with 126k miles.
 
#65
Part of me is glad they didn't put the Allison in the Yukon/Burb with the 8.1, they eat up more power and can't tune the trans the way you can with the 80/85. I'm still on the fence about looking for a clean 8.1, but I'll see how the 6.0 feels after the BBP tune, it would be very difficult to find another Yukon as clean as our 03 that we bought from the original owners with 126k miles.
If you get the 6.0 tuned please post up the results. I had a 454 in my 99 and am curious as to if the tune in a 6.0 gets it anywhere near that.
 
#67
From what I can see on CL, GMT-400 2500 Suburbans are the best "sleeper" deal out there. Buy one for $3k, spend maybe another $3k or so in maintenance and repairs and you'd have a rock solid vehicle that would last as long as you'd likely want to keep it.

As a bonus, the interior on the GMT-400 seems bigger since it has more room floor-to-ceiling than the GMT-800 burb with its higher floor.
 
#68
From what I can see on CL, GMT-400 2500 Suburbans are the best "sleeper" deal out there. Buy one for $3k, spend maybe another $3k or so in maintenance and repairs and you'd have a rock solid vehicle that would last as long as you'd likely want to keep it.

As a bonus, the interior on the GMT-400 seems bigger since it has more room floor-to-ceiling than the GMT-800 burb with its higher floor.
I agree with most all of this except size. GMT 800 is bigger inside and out in my opinion. Inside, it felt bigger but not substantially or much. Outside, much bigger. My 2000 GMC 2500 ccsb had a 6inch suspension lift and 35's. My 2006 GMC 2500 ccsb had 4inch suspension lift and 35's. With 2 inches less lift it was taller and wider.


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#71
From what I can see on CL, GMT-400 2500 Suburbans are the best "sleeper" deal out there. Buy one for $3k, spend maybe another $3k or so in maintenance and repairs and you'd have a rock solid vehicle that would last as long as you'd likely want to keep it.

As a bonus, the interior on the GMT-400 seems bigger since it has more room floor-to-ceiling than the GMT-800 burb with its higher floor.
I gotta disagree on size also. My buddy has a nice clean 98 k2500 burb and it definately seems smaller inside and out. We had them parked side by side and the 800 is bigger. We havent broke out the tapes yet but even he commented on the difference.
 
#72
I gotta disagree on size also. My buddy has a nice clean 98 k2500 burb and it definately seems smaller inside and out. We had them parked side by side and the 800 is bigger. We havent broke out the tapes yet but even he commented on the difference.
Measure floor-to-ceiling. I'm pretty sure the 400's are taller because they don't have the spare tire under the body and the deck is lower.
 
#75
Measure floor-to-ceiling. I'm pretty sure the 400's are taller because they don't have the spare tire under the body and the deck is lower.
According to specs, cargo box height for both gmt 400 & 800 is 40.5". Ill measure mine when I get home from work to verify. The floor may be higher on an 800 but so is the roof.
 
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