Switched to a 03 6.0 Yukon from 05 5.3 Tahoe, seems sluggish

[Dan Acosta]

Completely understand. The fans were a premium at one time from the yards... I have a set rom an 05 Yukon I paid $250 for like a sucker. Rock auto sells brand new Dorman fans for like $130 which is what I have in my truck and it's a long story why I have 2 sets, but the short is do yourself a favor and use the factory wiring harness. I have the expensive factory ones in a box I need to get rid of, but due to size would be better to sell locally at a big loss lol.

Check the manifolds for broken bolts as we have all had them break and is a known problem. The tune would be a good start with basic maintenance.

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Bad scenario, first and last manifold bolts broken on drivers side. I see the front one has a stud sticking out - cant tell about the rear one yet. Do I buy the camps or attempt to remove the rest of them and replace with gasket?

 

[bottomline2000]

Bad scenario, first and last manifold bolts broken on drivers side. I see the front one has a stud sticking out - cant tell about the rear one yet. Do I buy the camps or attempt to remove the rest of them and replace with gasket?

Thats your call. I have a stripped bolt on mine. I was gonna put a helicoil in it and i just broke down and did the quick and ez clamp. It's a permanent fix. You may be able to get the one with the stud out but are probably going to need to pull the manifold off to get a good grip on it.

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[swathdiver]

Your Tahoe's final drive ratio in 1st was 11.41:1 and the 2500s is 9.26:1. 2nd gear is closer and 3rd is the same obviously and then you have the 2500 being about 1,000 pounds heavier unloaded. What is the horsepower spread between the two engines? 30 horsepower?

 

[Dan Acosta]

Your Tahoe's final drive ratio in 1st was 11.41:1 and the 2500s is 9.26:1. 2nd gear is closer and 3rd is the same obviously and then you have the 2500 being about 1,000 pounds heavier unloaded. What is the horsepower spread between the two engines? 30 horsepower?

Trying to wrap my head around the gear ratio thing... So the Tahoe "launches" quicker because the higher ratio - more revolutions of engine to driveshaft rotations. I would have thought the 2500 would of been designed with a lower (higher rotations) first gear ratio, since the assumed intent is for towing. Additionally I would think that since that is the case, the mpg would be better since the rpms are reduced - at least through city driven gears.

 

[Dan Acosta]

The clamps work great! I ended up buying the dorman units from Amazon, They were a little less expensive and the shipping was fast & free. I ordered yesterday morning and had them installed by 7pm (same day).

 

[swathdiver]

Trying to wrap my head around the gear ratio thing... So the Tahoe "launches" quicker because the higher ratio - more revolutions of engine to driveshaft rotations. I would have thought the 2500 would of been designed with a lower (higher rotations) first gear ratio, since the assumed intent is for towing. Additionally I would think that since that is the case, the mpg would be better since the rpms are reduced - at least through city driven gears.

The 4L80 is a computerized Turbo 400, same gearing with an overdrive. It's use is intended for durability. It was the advent of the 6-speeds with their steep 1st gear to get the loads moving and two over drive gears for economy that made them easier to drive.

A 2011 2500 Suburban for example has a final drive in 1st of 15.02:1. That's even steeper than a Duramax with the Allison transmission which is 11.54:1.