computer update???

brax71 · October 29, 2001

I've been searching through this and other forums looking at the hypertech and such...

i read one post (from a long time back) with one small reference saying that GM could reprogram the computer for bigger tires (285's) and that it would increase performance/ mileage.

i don't care about the speedo -- i've driven past the radar trailers and it's close enough. i certainly can't afford to be driving at or above the top speed limiter. so with those two things in mind, i've gotten kind of turned off of the Hypertech as it's performance gains are at WOT only (right???). what's the scoop on the GM reprogramming, what's the cost and benefit??? Thoughts??

I've been getting 14.5ish no matter how or where i drive. it's kind of frustrating to see others with similar trucks getting high teens and i'm stuck that low -- even with the flowmaster and K&N.

if it's a disjointed message i apologize -- it's early monday... and i've already been here 2 hours...

chevy4x4trucks · October 29, 2001

I wish I was getting the MPG's that you are. I'm running a 4.8 w/ a flowmaster dual and a K&N FIPK II and I'm getting 12's. As for the GM recalibration I haven't heard of it. I always figured the hypertech was the way to go.

FIRECAT · October 29, 2001

I'm getting about 15 Avg around town and about 17-18 on the highway. I hate to say this but, you guys might be losing MPG because of your exhausts and K&N setup. My brother had a '99 Silverado that he added a Borla exhaust and a K&N setup to and his mileage went down to what you guys are getting. My truck is stock, except that I have changed to 5W-30 Amsoil and an Amsoil air cleaner. My Dad's 2000 is completely stock and he is getting about the same mileage as me. Both trucks are 5.3 w/ 3.73 rears.

BTW: Not to make you guys feel worse, but my brother's HD 8.1 W/3.73 rear is getting 12-14 MPG and a whole hell of a lot more HP. ???

97C1500&84Z28 · October 29, 2001

Wow, all these posts about gas milage and I'm wondering if got hold of a unique truck. I recently bought a 97 C1500 ext cab Silverado w/all the toys. It's a 5.7L 2WD and 3:73 posi and in the 3000 miles I've driven so far, it's averaged between 16.7 - 18 mpg. About 90% is non highway to and from work 35 miles round trip. Yes, I'm a fairly aggressive driver as well. The truck is 100% stock, and will pretty much stay that way until I need to replace things. Though I'm wondering if the replacement tires which are going from P235-75R15 to P255-70R15 will have a negative impact.