Top Speed

[DarkTint]

I don't know about the rest of you, but when I found out that my 99 GT had the gutless top speed of 108, I was disgusted. Does anyone know what kind of top speeds a minimully tinkered with Grand Prix (GT or GTP) can achieve with the speed limiter removed? With the strength of the engine, I would think that it could hit 135 with confidence. Does anyone know why GM limited GP's to such a weak top speed? Insurance reasons maybe?

A little not-so-fun fact: If you look at the back of a Motor Trend magazine (or it could be Road & Track) where they list the stats of cars they've tested, they've got the stats of a 99 Grand Prix GT listed with the top speed of 108 highlighted with an asterict next to it. If you read the notes at the bottom of the page, it states that anything with that particular asterict means "uncommon results," or basically "uncommonly slow compared to anything else we've tested." That's almost as embarassing as my spelling.

[JJUBECK]

I do believe you could hit 135 with the reprogrammed pcm, this also get rid of your rev limiter and speed limiter.

[JJUBECK]

Grand Prixs don't have a governer that you can disconnect, they have mini computers that tell them what to do, if you get a reprogrammed pcm then it will take care of this problem.

this guy is just upset cause he can't afford a grand prix and is stuck driving a ford ranger

[JJUBECK]

hahahahahhahahahah

do you know who even makes bentley......go back to your tickle me elmo site little kid

[kilroypr]

jjubeck, I lost U here.

DarkTint: OEM speed for the GP is set up tp be 120mph. Why, because of the tires that it comes from factory. The speed limit can be removed reprogramming the PCM(ECU). IN my case the fastest I have driven my GTP was 145MPH and the car still had more juice to go by, just that I did not push it further. If your car just reaches 108 then check what is holding it. I only read Road & Track when new models come out but deffinetly I know that they are biased(corporate brives from Japan or Europe, not sure and is a shame)towards anything that is not american made. I really love what this great country has to offer and the great automobiles it can produce...

[JJUBECK]

Sorry there was a guy in here yesterday that was talking crap about Grand Prix's, and cursing out the moderators I guess they took his posts out.

[JJUBECK]

Well I know with my 99 gt it does have a rev limiter and the damn thing wont go over 108. There is plenty of pedal left in it and I'm only at about 3000 rpms by this time. The new pcm should fix this though.

[rockford0384]

128 here gtp

[DarkTint]

Is the 128 with the limiter or without?

[rockford0384]

with, I have a stock pcm, It dies as soon as the heads up says 128 it cuts out

[fast98gtp]

my 98 gtp used to cut out at 108 too.

[kilroypr]

fast, rock said 128mph not 108mph. I think you should check your car PCM. It is not normal to stop accelerating a 108MPH

[Ripn12s]

Only if he was still in 3rd gear

[kilroypr]

Well, yes but usually when looking for high speed you would not stick the shifter on 3rd(I assume he did not). Basically what I do when racing instead of play with shifting I use the performance shifht to start and after 75 I realease it so it do not fall back for more torque but keep pushing on high gear for higher speeds(even tought would have less acceleration).

[fast98gtp]

----''fast, rock said 128mph not 108mph. I think you should check your car PCM. It is not normal to stop accelerating a 108MPH"----

kilroypr, dude, i know what he said..and i said 108..it was a comment to everyone, not necessarily a reply to the previous message. i know that im not the only one that had their gp to cut out at that speed. some gps were limited to that speed. the pcm was set at that. and it didnt matter what gear it was in. i dont know if it was something that iv heard or read but i think it depends on the period it was built---somewhere around 98-99model years