4.2L @ 275hp and 275 ft/lbs for 2003

mcali17 · August 7, 2002

The 2003 4.2L I-6 is rated at 275 hp, which is up from the 2002's 270 hp. The torque is the same. Do you think they really "found" 5 more ponies in the engine, or was the engine just under-rated for 2002? Does anyone know if they made any changes that would warrant the 5hp increase? Not that I am concerned about 5hp, I guess I am just curious. Besides, if you go back and look at the old arcticles before the Trailblazer, Envoy and Bravada were released. The mags said that GM was building a 4.2L I-6 with a wopping 240 hp. I guess they were a little off at the start. Although, the 275 hp comes from GM.

tblazer503 · August 8, 2002

Lets see if I can give you some information that I found.

1)Pistons now have a polymer coating on them; its supposed to reduce scuffing and abrasions on the cylindar walls.

2)Oil pump has been revised to lower the noise output.

3)Automatic chain tensioner has been modified to be quieter.

4)Crankshaft Torsional dampener has been changed from a dual harmonic balancer to a single torsional dampener, supposed to reduce vibrations.

5)Head gasket refinements to improve coolant flow

6)New spark plug design that gives better efficiency and durability

7)Recalibrated PCM that gives engine more control and better idle. The variable cam can now be adjusted 24deg instead of 20deg by the PCM

I believe that most of the HP gains are through the recalibrated PCM, although the other changes are definitely nice, especially considering that the 4L60E went through some performance changes as well. I have already talked to GM about reprogramming my PCM(Power Control Module) with the '03 code and they say its not compatible. hmmmm.... maybe they just want you to buy a new truck... Oh well, guess I'll just wait and see what the superchip and hyperchip groups come out with.... nevertheless, all the more reasons for me to trade it in next year.

mcali17 · August 8, 2002

Even with my Dad as the dealer trade-in next year is out of the question for me. 0% financing for 5 years. I am not going to pass that up. Plus, my Dad built my truck as a 2003 model, and it added a couple thousand bucks to the price. I already have a PPIII from my 1996 Jimmy that I sold. Just waiting to see what they come out with and then it is back to HyperTech for re-programming.

mcali17 · August 8, 2002

Just a thought. Do you know if they changed the VIN code for the engine. My truck was one of the last 2002's built, I wonder where the cutoff was for the engine.

tblazer503 · August 9, 2002

The tech post did not mention a change in VIN, and there is no change on the engine code (LL8) I do think that hypertech will be a while before they come out with PPIII for it, though just because its taken them 18mos to come out with one for the original engine, but you never know, maybe they will see that the TB/triplets are in demand and people want performance.

02EnvoySLT · August 9, 2002

The cam phaser is capable of upto 25 deg. Does it only go upto 20 degree's in 02? I'll try to monitor it tonight and let you guys know.

Hypertech - I don't know how much performance they are going to be able to wring out. The stock timing curve looks good. We already shift at 6100rpm stock at WOT and Hypertech has never touched shift management (torque reduction through timing decrease) in the past. Shift firmness is worthless on the 4L60E's and I doubt many of us will be changing rear end gears in these things. We'll see, but it looks like GM tuned this thing as if it was a car engine and not a truck engine. Hmmm....

tblazer503 · August 11, 2002

It is true that it seems as though the triplets are tuned like a car, but I rode in my buddies automatic camaro, and it too has the 4L60E transmission and feels much firmer on launch and shifts, so I am pretty sure that the transmission can be vastly improved by reprogramming the PCM since thats the only difference in the two transmission. Just a thought.