Top speed/ 5th 6th gear questions

[Nightrage]

Can someone remind me why our cars hit their top speed in 5th gear rather than 6th? Are Vette's and Vipers the same way?

What would happen if I were doing 150 in 5th, then shifted to 6th, not knowing that I can't do 150 in 6th gear?

Also, could someone tell me how gearing works? I know that 3.42 gears means that something turns 3.42 for every turn of something else, but I can't remember what's what.

[Jay 02 TA ws6]

The top speed is higher in 5th because the engine doesn't have enough power to turn 6th gear above a certain RPM. Give the engine 10,000 horsepower, and it would hit its top speed in 6th gear.

Depending on how much power your engine makes, if you were doing 150 in 5th and shifted to 6th, the car would slow down, even if you were at WOT.

3.42 rear gear means the driveshaft turns 3.42 times for every rotation of the axle.

[Nightrage]

But if you went from 150 in 5th, then shifted to 6th, would that damage anything? Would the car jerk violently? I'm asking because back when my dad had his Viper, he came close to topping it out. He never shifted into 6th though. If you're going that fast and don't know that you'll actually be "downshifting", it could cause you to lose control of the car.

[Dave M]

You would not damage anything. The only thing that would happen is that the car would gradually slow down until it got to the point where engine power and drag were equal. It would be like trying to go up a hill in to high of a gear, the car just wouldn't have the power for it. You are not downshifting by shifting into 6th. Downshifting would be shifting down into 4th at 150 mph... and yes, then you would damage something! The engine would be trying to turn way to fast, and that's not good. By shifting into 6th then engine isn't turning fast enough to provide the power to maintain that speed.

[ConElite]

shifting down into 4th at 150 mph... and yes, then you would damage something! The engine would be trying to turn way to fast, and that's not good. By shifting into 6th then engine isn't turning fast enough to provide the power to maintain that speed.

Ya i had a buddy that had a Porsche Carrera. An older model one with the wide rear package and all.. Had the bigger engine and all this crap. He was going like 145ish in 5th and he had to slow down quick so he pushed the brakes and starts to downshift. (keep in mind this thing stopped on a dime) So he goes to shift into 4th and by mistake goes into 2nd... Lets just say
"BOOM"

[ConElite]

As the man that won the Silver State Challenge said, "in order to go over 200mph safely, 550+hp is recommended. He won it in his 93 Z28 with an average speed of 220+ MPH. Pretty amazing.

[Nightrage]

Ya i had a buddy that had a Porsche Carrera. An older model one with the wide rear package and all.. Had the bigger engine and all this crap. He was going like 145ish in 5th and he had to slow down quick so he pushed the brakes and starts to downshift. (keep in mind this thing stopped on a dime) So he goes to shift into 4th and by mistake goes into 2nd... Lets just say
"BOOM"

I made that mistake once, though i was doing about 85 MPH less than your friend. Some jerk cut in front of me off an entrance ramp while i was doing 60. I stomped on the brakes and ripped the shifter from 5th to what i thought was 4th. I guess i pulled too hard and hanked it into 2nd. No damage done

[Mach83]

So what's the top speed of these cars then? Universally i hear 160mph a lot. But, a firebird book i have written by Dave Newhardt says the 99 Aniversary Edition (same drive train as Trans Am) will "top at 163mph before a speed limiting chip holds it". Can anyone clarify this for me?

[Jay 02 TA ws6]

So what's the top speed of these cars then? Universally i hear 160mph a lot. But, a firebird book i have written by Dave Newhardt says the 99 Aniversary Edition (same drive train as Trans Am) will "top at 163mph before a speed limiting chip holds it". Can anyone clarify this for me?

"Speed Limiting Chip?"

[Mach83]

i assume they mean some sort of governor. that's what the book said

[Injuneer]

The PCM includes a "speed limiter". It is set based on the speed rating of the tires that the car had on it when it left the factory. If you get the Z-rated tires (which are an "option" on the base models), the speed limiter field in the PCM program will have "255" entered into it (upper limit of an 8-bit binary field). If your car left the factory with lower speed rated tires, the PCM will limit you to the number in the program. For the LT1 cars, that limit was in the range of 108-114mph, depending on the year.

[ConElite]

For the LT1 cars, that limit was in the range of 108-114mph, depending on the year.

Ya b/c in my buddies car, his car never hit no limiter. It would do the 150 no problem (1993 Z28), but my brothers once he programed his car to stock programming, he only was able to pull like 110mph (96 Z28). But he toke that off right quick and in a hurry. Ya i have to take off my limiter on the Honda. The crap tops at 120. Does that with no problem and still has about 1000 more rpms to go. Thats in 5th too, and yes believe it or no but it still pulls at that high of a gear and speed. Right around 5200 rpms. Im going to get this chip that brings the rev limiter to 8200 rpms, and unlimited speed, and better air/fuel ratios. The will be nice.

[Jay 02 TA ws6]

Ya i have to take off my limiter on the Honda. The crap tops at 120. Does that with no problem and still has about 1000 more rpms to go. Thats in 5th too, and yes believe it or no but it still pulls at that high of a gear and speed. Right around 5200 rpms. Im going to get this chip that brings the rev limiter to 8200 rpms, and unlimited speed, and better air/fuel ratios. The will be nice.

Why the hell do you need to go faster than 120 mph in your Civic?

Also, if your car stops gaining speed at 5200 RPMS, meaning your engine reaches the point where drag equals accelerative force, then increasing your redline to 8200 is not going to make it go any faster. That's just like trying on a size 10 shoe, saying it's too big, and then trying on a size 14. It's still too big.

Better air fuel ratios may help increase the engines power, which would help it pull a few more RPMs, but certianly not 3,000 more RPMs.

But that brings me back to my original question. Why the hell do you need to go faster than 120 mph in your Civic? I also reckon it takes quite a while to accelerate from 80-120 mph, which means you're at some pretty reckless speeds for quite a while...

[ConElite]

Why the hell do you need to go faster than 120 mph in your Civic?

Also, if your car stops gaining speed at 5200 RPMS, meaning your engine reaches the point where drag equals accelerative force, then increasing your redline to 8200 is not going to make it go any faster. That's just like trying on a size 10 shoe, saying it's too big, and then trying on a size 14. It's still too big.

Better air fuel ratios may help increase the engines power, which would help it pull a few more RPMs, but certianly not 3,000 more RPMs.

But that brings me back to my original question. Why the hell do you need to go faster than 120 mph in your Civic? I also reckon it takes quite a while to accelerate from 80-120 mph, which means you're at some pretty reckless speeds for quite a while...

Alright I just made my story short. The speed limiter cuts off my fuel so the computer does not allow me to go any faster. Its not that the car does not allow me, its the programing in the computer. Thats why i wanna change the chip, or the computer for that matter. As for taking a while to get from 80-120mph, you would be surprised how fast it gets there... and ya i know its a honda, but you have to remember that my car weighs just as much as an f-body. Just about 100 pounds lighter. Plus when i did that high speed run, i had my system so that was an extra 200 pounds. (and that was b4 the cam and high flow cat+header.) So it handled pretty well. The coil-overs that are on this thing are pretty good. I just wounder how fast i can get her to go... Its not that im reckless. Dont get me wrong, the only time i tried it was with my buddy and his girlfriend in the car passed out after a long night of partying at around 3:30 in the morning on a 7 mile straight (i was 100% sober), but it was up to 120 within a minute, easy!! from around 75. If u think about it. If i redline this thing, i can pull 105 in 3rd. So im sure its able to pull 130+. Just not saying im going to try every second i get. Im have a little more control than that. Never tried crap like that when i have my sisters or when i used to be with my girlfriend... So its just somethng i wounder. Just as "why do u have to do 150+MPH.lol.
ITs all good Jay.

[Camaro84Berlinetta]

The PCM includes a "speed limiter". It is set based on the speed rating of the tires that the car had on it when it left the factory. If you get the Z-rated tires (which are an "option" on the base models), the speed limiter field in the PCM program will have "255" entered into it (upper limit of an 8-bit binary field). If your car left the factory with lower speed rated tires, the PCM will limit you to the number in the program. For the LT1 cars, that limit was in the range of 108-114mph, depending on the year.

256.... 8,16,32,64,128,256,512