spinumZ28

i have a 94 auto Z28 and its got 115mph speedo??? what gives is this a rare thing i should keep cause i want the 160mph white speedo guages. this is my first Tech post so please excuse my ignorance if this is a common phenomenon. i know theres no such thing as a stupid question but...........there is lol............any help with this would be sweet.

Dave.

spinumZ28

As i said before pardon my ignorance........ i should have searched 115mph speedo means non z rated tires, and governed DAMNIT well at least i dont beat on it and never kicked in the gov, again sorry for not searching ( or just looking a few threads down on this page lol)

Brent94Z

With a PCM reprogram and a 150 mph speedo (and of course Z rated tires!) all your worries/concerns are gone

MyShibbyZ28

The 150 speedo cars came without governors?

Plague

I thought the governor was set at 160. But, that may only be for LS1 cars.

Injuneer

If you got the Z-rated tires, the PCM program speed limiter field is set to "255"..... the maximum value that can be entered in an 8-bit field.

Dave '97 Z28 M6

I always thought that the factory PCM on the V8 cars with Z-rated tires limited the top speed to 160MPH due to (among other things) excessive driveshaft vibrations at high speed. This might only apply to 3.42 equipped vehicles. Now I'm not sure.

Injuneer

The "255" I quoted is directly out of the factory PCM on my 94 Formula, M6, 3.42 gears, Z-rated tires.

Charging TA

Man, so we can do 255 mph? SWEET... hehe, just kidding around.

Donohue96M6Z28

ya i got bored once and got my car up to 210 in my neighbor hood.

that would feel crazy going that fast

Dave '97 Z28 M6

I might have gotten my info from an old issue of Road & Track; a test of the 4th gen, in which they checked out the top speed (est.)

Demon440

" don't worry this car is electronically limited to only 255 mph"