Power adder

RIPMF · September 30, 2001

Ok have a ? has anyone put a superchip on there 8.1. Wanting to up the tire size but doesn't want to mess up the allison didnt no if it would hurt it. Would like to put 285/75/16 on.The 245 firestones suck they dont bite had a cummins pull me backwards all I could do is burn all 4 so I need some more bite and i guess alittle more power from the chip wouldn't hurt much to. truck has 3.73 in it

chevy4x4trucks · October 1, 2001

My suggestion would be to get the Hypertech Power Programmer for it. If you look around you can get it for about 325. It will let you set different tire sizes, firm up shifting, increase power and torque

8100HD · October 2, 2001

Ripmf, I have 8.1 with a Jet chip in it with no problems whatsoever, Allison does not appear to be affected now with 4500 miles with the chip, Hypertech chip does not allow for tire size calibration for the Allison trans. I am running 285's right now and my speedo is off by approx 7-10 mph. Truck has plenty of power can smoke my 285's from a stand still. Next is a Superlift Tru-speed for the speedo, and eventually a Rancho 4" lift with 295's or 305's.

Garmat · October 2, 2001

8100HD,

What kind of boards do you have on your truck? They look like factory GM boards like what is on the Surburbans....

RIPMF,

My dealer told me that they can only recalibrate for 265s. They also wanted $105 bones to do it (what a rip off) I have seen the Hypertech programmer, and I know they claim to have settings for other tire sizes, I just don't know if they can do it for tires larger than 265s. HOW could you let a Dodge pull you backwards???? You need to avenge that failure! Put you some decent tires on there and go kick his butt. You don't need a chip to do that!

chevy4x4trucks · October 2, 2001

I don't think that the trucks are either calibrated for 245 or 265, if you go to tyres1.com and figure out the tire diameter and then punch that in on the speed calc with old size, new size, and a speed, it will tell you how much your speedo will be off. Between 245 and 265 it's almost nothing. I wouldn't worry about it, cops give you some leway. Look into the HPP III because it says to have settings for different tire sizes and gear ratios, no one else has told me otherwise.

8100HD · October 3, 2001

The boards on my truck are from Steelhorse.

Hypertech has told me that their HPIII for the 8.1/Allison does not recalibrate for tire size or shift points as of yet, but does do engine tuning. My truck runs flawless with the Jet chip and if you can deal with your speedo being off a little then I would definetly recommend it.

PCAB · October 3, 2001

RIPMF,

265/75R16's are as big as the factory can reprogram. I was at the dealer yesterday and asked about it (no cost and 5-10 minutes). He told me the tranny doesn't really care what tires are on it, the reprogramming mainly corrects the Speedometer error and reprograms the ABS computer. A 265 tire is about 2-3 mph off from a 245. Not critical unless you drive in snow and ice and depend on the ABS like me and I want that accurate. Good luck!