GM Big Block is Dead
#16
10-03-2006, 09:32 PM
#17
10-03-2006, 11:54 PM
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Originally Posted by duramaximizer
The GM small block has always been a runner. I knew from the begining that the 8.1 wasn't going to last. The motor was only out 1 year when GM actually decreased the hp of the motor. I think it was mostly emmisions and not dependability issues.
Not only that, but I do believe that the 8.1 did worse at pulling than the 6.0. The 6.0 always had the 4L80 that was better spaced for the gassers rev range than the Allison. Also the Allison robbed any additional hp or torque advantage that the 8.1 had over the 6.0. I think the Allison was more designed to be mated with the Duramax due to its shift points, gearing etc. I just don't think the 8.1 and Allison were as good together as the 6.0 and the 4 speed. That seems to be my take on the whole thing even though people love the Allison and all of its features.
I think GMs new 6 speed light duty trans will take advantage of the hp and torque of the new 6.0, and I think the new 6 speed will be lighter built than the Allison, so it will get more hp to the ground and still be every bit as durable for the application. Hopefully GM will incorperate all of the tap shift and grade braking features of the Allison to make a great drivetrain no matter gas or diesel.
Fairwell 8.1
BTW we owned a 99 GM 6.0 gasser, and that thing would scream pulling a camper, but the fuel mileage didn't really ever drop. Around town we averaged 11-12 and pulling a 5th wheel camper, we average 10-11 at 75mph. Go figure.
Not only that, but I do believe that the 8.1 did worse at pulling than the 6.0. The 6.0 always had the 4L80 that was better spaced for the gassers rev range than the Allison. Also the Allison robbed any additional hp or torque advantage that the 8.1 had over the 6.0. I think the Allison was more designed to be mated with the Duramax due to its shift points, gearing etc. I just don't think the 8.1 and Allison were as good together as the 6.0 and the 4 speed. That seems to be my take on the whole thing even though people love the Allison and all of its features.
I think GMs new 6 speed light duty trans will take advantage of the hp and torque of the new 6.0, and I think the new 6 speed will be lighter built than the Allison, so it will get more hp to the ground and still be every bit as durable for the application. Hopefully GM will incorperate all of the tap shift and grade braking features of the Allison to make a great drivetrain no matter gas or diesel.
Fairwell 8.1
BTW we owned a 99 GM 6.0 gasser, and that thing would scream pulling a camper, but the fuel mileage didn't really ever drop. Around town we averaged 11-12 and pulling a 5th wheel camper, we average 10-11 at 75mph. Go figure.
Interesting............I have only driven the 8.1/Allison on a test drive, otherwise a TRUCK TREND test is the only comparison vs the 310HP V10 I can cite.
The V10 was slightly quicker empty to a lot of speeds and the 8.1 would win when loaded.
Fast forward to '04........buddy has the 6.0 in his GMC. He concedes there is no comparison to my V10 when pulling a trailer full of quads....after less than 2 years and 10MPG average he traded for the D/max (the one I'm always bragging on) The other weird thing was the 6.0 almost felt diesel like off the line (ie: sluggish) buddy claimed it was a GM thang not allowing full throttle power off the line (?)that he researched on-line. At that point, he really missed his 5.3...........untill the '06 D/max.
Based on those scenarios/magazine data, I find it hard to believe the 6.0 would stay with an 8.1 when loaded............or empty for that matter.
Last edited by DOHCmarauder; 10-04-2006 at 12:02 AM.
#18
10-04-2006, 06:11 AM
Originally Posted by tmyers
When talking about the LSx series motors most people don't realize how flat the torque curve really is. You have over 300ft lbs of torque(LS2) from 2000rpms till 6000rpms. Peaks at the rear wheels at about 350#. Those are dyno numbers from my Vette.
It would not be my choice for a pulling motor but I bet it would outpull most any small V8 on the market. And when not pulling would out gas milage them all when mated to the 6L80 tranny.
It would not be my choice for a pulling motor but I bet it would outpull most any small V8 on the market. And when not pulling would out gas milage them all when mated to the 6L80 tranny.
http://www.media.gm.com/us/powertrai...calade_SAE.pdf
Here is the graph for the 6.0:
http://www.media.gm.com/us/powertrai...o%20HD_SAE.pdf
Here is the graph for the 8.1:
http://www.media.gm.com/us/powertrai..._Silverado.pdf
Running down the freeway at 65-70 mph, you will probably not be turning 2000 rpm, especially with the new 6-speed auto (tuned for MPGs).
As soon as you hit any kind of hill pulling a load, that tranny is going to be reaching for a new gear, maybe several times.
I'm not saying the engine won't pull it, but all that downshifting gets tiring on a long drive. Too much drama. Too much noise.
I've driven my diesels for 10-12 hours at a stretch pulling 8000-10000 lbs., sometimes with no downshifts at all. Sometimes with only 2-3.
Last edited by jschira; 10-04-2006 at 06:18 AM.
#19
10-04-2006, 07:58 AM
#20
10-05-2006, 10:54 PM
Fleet Mechanic
I just heard today that the Big Block isn't dead. The new G.M. HD's are not going to offer a lot of options when they first come out (anyone notice no manual transmissions are available?) but after production starts more powertrain options will be available. The new 8.1L (8.2L?) is supposed to have higher H.P. and torque ratings, too.
#21
10-06-2006, 12:00 AM
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