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Discussion Starter #1
I have racked up abouyt 700 miles on my Sky at this point. I have always used Premium Gas (93% or greater) since getting it. I had her out last night for a ride with the top down. She was really smooth even at 100 mph, which was suprising to me. My grand prix felt like she was shaking apart at that speed. I generally dirve on the slow side, but last night it was so beautiful out I had to test her a bit.

Anyway, my question is with reguard to automatic shifting. If I start from a stopped position, and floor the gas pedal all the way, I notice that the car will not shift out of first gear until the RPM's hit 7k (redline). The same happens with 2nd gear. I was under the impression that when engines are at or near their redline, they are not operating under maximal efficiency. Shouldn't it be shifting between 5-6k RPM's?
 

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By shifting after their peak power, it puts the engine closer to it's peak power in the next gear. If you were to look at a hp or tq graph and take a 2000rpm window of it, you will have more area under the line if your window is +-1000rpm from the peak than if you looked at the 2000rpm leading up to the peak. The area is the total power or energy made, so higher is better.
 

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Azzhauler is dead on. Generally you want your acceleration curve to be smooth with no dips or spikes in power. Unfortunately with the Sky there isn't a scanner I know of currently that will log the information necessary to see if the curve out of the factory is linear. I'm willing to bet it dips a bit after the shift.

Also, utterly off topic, what year Grand Prix did you have? Mine feels pretty solid to 145 and the Sky was planted to over 110.
 

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Discussion Starter #6
Robotech said:
Azzhauler is dead on. Generally you want your acceleration curve to be smooth with no dips or spikes in power. Unfortunately with the Sky there isn't a scanner I know of currently that will log the information necessary to see if the curve out of the factory is linear. I'm willing to bet it dips a bit after the shift.

Also, utterly off topic, what year Grand Prix did you have? Mine feels pretty solid to 145 and the Sky was planted to over 110.

My Grand Prix was a 97'. Truthfully, I don't drive very fast that often. I live in southern Delaware and the roads are very well patrolled by the police. I have used the, "I'm a doctor on the way to the hospital" once already with the cops around here (it happened to be true that time), but I don't want to press my luck.

And Robo, I posted in an earlier thread that we had (well, you still have I guess) the same year Grand Prix GTP.
 

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Dyno test

Gelfling said:
I have racked up abouyt 700 miles on my Sky at this point. I have always used Premium Gas (93% or greater) since getting it. I had her out last night for a ride with the top down. She was really smooth even at 100 mph, which was suprising to me. My grand prix felt like she was shaking apart at that speed. I generally dirve on the slow side, but last night it was so beautiful out I had to test her a bit.

Anyway, my question is with reguard to automatic shifting. If I start from a stopped position, and floor the gas pedal all the way, I notice that the car will not shift out of first gear until the RPM's hit 7k (redline). The same happens with 2nd gear. I was under the impression that when engines are at or near their redline, they are not operating under maximal efficiency. Shouldn't it be shifting between 5-6k RPM's?
Last year I got to "drive" a GTO with automatic transmission on a Dynonometer - the guy told me to simply floor it and hold it there - at one point Idid have to let off the throttle a bit to get it to shift - from 3rd to 4th I think. I have driven mostly manual transmission cars for the past 10 years but generally speaking an auto trans will delay shifting until higher RPM when you are pushing it at higher throttle - not sure all the reasons for this from a technical/mechanical perspective - but what I would suggest is you try taking it up to maybe 6000 rpm and then let off the gas pedal to between 1/2 and 3/4 for a couple seconds (should shift) then apply the desired throttle.
 

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Discussion Starter #8
Lil GTO said:
Last year I got to "drive" a GTO with automatic transmission on a Dynonometer - the guy told me to simply floor it and hold it there - at one point Idid have to let off the throttle a bit to get it to shift - from 3rd to 4th I think. I have driven mostly manual transmission cars for the past 10 years but generally speaking an auto trans will delay shifting until higher RPM when you are pushing it at higher throttle - not sure all the reasons for this from a technical/mechanical perspective - but what I would suggest is you try taking it up to maybe 6000 rpm and then let off the gas pedal to between 1/2 and 3/4 for a couple seconds (should shift) then apply the desired throttle.
Its funny you should say say that, because that's sort of what I have been doing without really realizing it. I feel like the actual acceleration that occurs between 6k->7k rpm is really minimal, so at about 5.5-6k rpm I let of the gas a tiny bit, it shifts, then I punch it again. Granted, I don't do this all the time, because really there is no need to be punching the accelerator when driving around town. However, for someone with no formal "driving training" its fun to feel things out.
 

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I too have a 97 GTP with a decent ammount of mods at 130 the car still feels very solid and plenty responsive no vibrating or wind noise.. havent ever taken it higher due to the tires i put on it are only H rated and dont get out of town enought to buy a higher rating tire to take it faster not that i need to..


how do you like your Sky do you prefer to drive that other the GTP?

im hoping to get a redline sometime next year
 

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SPooN said:
I too have a 97 GTP with a decent ammount of mods at 130 the car still feels very solid and plenty responsive no vibrating or wind noise.. havent ever taken it higher due to the tires i put on it are only H rated and dont get out of town enought to buy a higher rating tire to take it faster not that i need to..


how do you like your Sky do you prefer to drive that other the GTP?

im hoping to get a redline sometime next year
Well...they are two different cars. Here is the GTP:



(Sig from Club GP)


So it's a little beyond lightly modified. Before the aftermarket SC went on she ran a best of 13.412 @ 103 mph at Firebird raceway in Phoenix, AZ. Now, that's exactly the way you see it there...street tires, pump gas, no weight reduction...full street trim. After putting the blower on (was the only car in the country with that exact setup on it) we found we outflowed the MAF and within 1 second chipped a piston and had a piece lodge in the #1 intake valve. Now the engine is being completely rebuilt and will go back in the car soon I hope. Times should be EASILY into the mid 12s and maybe a high 11 at Sea Level...again, street trim.

There is no way the Sky, except a Mallett, can compete with that. So for straight line "Wholly crap this sucker is fast" excitment, the Pontiac wins. For room and practicality...the Pontiac wins.

But you put this Sky in a twisty road...the Pontiac won't touch it until it can accelerate. Handling the Sky is a LOT more fun than the Pontiac. Style...Sky wins. Fun when cruising on a nice warm sunny day...Sky wins. Uniquness...Sky wins.

That's why I have my signature here the way I do...I really have the best of both worlds. I have the practical, mild looking sedan that will push you back in your seat with muscle car like authority then I have the swank, nimble little roadster than handles like a dream. Both of these cars will get equal driving duty because they are both fun...but in different ways.
 

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i reconize your sig from clubgp the name sounded familiar to begin with tho

btw im in AZ did you come down here for the SW wbody meet last year??
 
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