torque "dip" and optimum shift points
06-19-2004, 05:17 PM
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torque "dip" and optimum shift points Having owned a Hypertech Power Programmer for some time now, the following questions arise regrading the optimum setting of WOT shift points:
Firstly, my current set-up:
98 Camaro Z28 with 4gear Automatic trans (gear ratio 2.73)
MTI air lid, K&N Air Filter, ported and descreened MAF
180degree PowerStat
Hooker Exhaust
Shift firmness 100%
NON-RFG tuning
rev limiter 6200rpm
...and the ability to get high octane fuel (98roz) here in Austria, Europe.
After studying the dyno curves found on the Hypertech website, I thought it would be a good idea to take the shift points down from the stock setting in order to have the ecu shift before torque decreases at about 5300rpm.
Here are the settings I tried: -2 (5500rpm), -9 (5200rpm), 0 (5500rpm)
First impressions were smoother acceleration and less jerky movement when the gears change at full throttle, which is good for traction in corners
. I am, however, not quite sure if the overall acceleration is better.
Now the problem seems to be that when driving at 40mph and opening the throttle (kick down), the gears do not change to one where the revs are high. Instead, I am left at about 2500rpm with little torque.
The values often recommended, +2 (5920rpm), +4 (5920rpm), 0 (5500rpm), feel real fast, but I'm worried that this isn't neccessarily a configuration that will ensure best acceleration...
Is it not better to stay in revs with high torque, instead of waiting for the red line before changing to the next gear?
Anyone have any ideas?
Firstly, my current set-up:
98 Camaro Z28 with 4gear Automatic trans (gear ratio 2.73)
MTI air lid, K&N Air Filter, ported and descreened MAF
180degree PowerStat
Hooker Exhaust
Shift firmness 100%
NON-RFG tuning
rev limiter 6200rpm
...and the ability to get high octane fuel (98roz) here in Austria, Europe.
After studying the dyno curves found on the Hypertech website, I thought it would be a good idea to take the shift points down from the stock setting in order to have the ecu shift before torque decreases at about 5300rpm.
Here are the settings I tried: -2 (5500rpm), -9 (5200rpm), 0 (5500rpm)
First impressions were smoother acceleration and less jerky movement when the gears change at full throttle, which is good for traction in corners
. I am, however, not quite sure if the overall acceleration is better.Now the problem seems to be that when driving at 40mph and opening the throttle (kick down), the gears do not change to one where the revs are high. Instead, I am left at about 2500rpm with little torque.
The values often recommended, +2 (5920rpm), +4 (5920rpm), 0 (5500rpm), feel real fast, but I'm worried that this isn't neccessarily a configuration that will ensure best acceleration...
Is it not better to stay in revs with high torque, instead of waiting for the red line before changing to the next gear?
Anyone have any ideas?
06-21-2004, 06:37 AM
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Originally Posted by Z28camaroLS1
Having owned a Hypertech Power Programmer for some time now, the following questions arise regrading the optimum setting of WOT shift points:
Firstly, my current set-up:
98 Camaro Z28 with 4gear Automatic trans (gear ratio 2.73)
MTI air lid, K&N Air Filter, ported and descreened MAF
180degree PowerStat
Hooker Exhaust
Shift firmness 100%
NON-RFG tuning
rev limiter 6200rpm
...and the ability to get high octane fuel (98roz) here in Austria, Europe.
After studying the dyno curves found on the Hypertech website, I thought it would be a good idea to take the shift points down from the stock setting in order to have the ecu shift before torque decreases at about 5300rpm.
Here are the settings I tried: -2 (5500rpm), -9 (5200rpm), 0 (5500rpm)
First impressions were smoother acceleration and less jerky movement when the gears change at full throttle, which is good for traction in corners. I am, however, not quite sure if the overall acceleration is better.
Now the problem seems to be that when driving at 40mph and opening the throttle (kick down), the gears do not change to one where the revs are high. Instead, I am left at about 2500rpm with little torque.
The values often recommended, +2 (5920rpm), +4 (5920rpm), 0 (5500rpm), feel real fast, but I'm worried that this isn't neccessarily a configuration that will ensure best acceleration...
Is it not better to stay in revs with high torque, instead of waiting for the red line before changing to the next gear?
Anyone have any ideas?
Firstly, my current set-up:
98 Camaro Z28 with 4gear Automatic trans (gear ratio 2.73)
MTI air lid, K&N Air Filter, ported and descreened MAF
180degree PowerStat
Hooker Exhaust
Shift firmness 100%
NON-RFG tuning
rev limiter 6200rpm
...and the ability to get high octane fuel (98roz) here in Austria, Europe.
After studying the dyno curves found on the Hypertech website, I thought it would be a good idea to take the shift points down from the stock setting in order to have the ecu shift before torque decreases at about 5300rpm.
Here are the settings I tried: -2 (5500rpm), -9 (5200rpm), 0 (5500rpm)
First impressions were smoother acceleration and less jerky movement when the gears change at full throttle, which is good for traction in corners
. I am, however, not quite sure if the overall acceleration is better.Now the problem seems to be that when driving at 40mph and opening the throttle (kick down), the gears do not change to one where the revs are high. Instead, I am left at about 2500rpm with little torque.
The values often recommended, +2 (5920rpm), +4 (5920rpm), 0 (5500rpm), feel real fast, but I'm worried that this isn't neccessarily a configuration that will ensure best acceleration...
Is it not better to stay in revs with high torque, instead of waiting for the red line before changing to the next gear?
Anyone have any ideas?
Any suggestions???
06-21-2004, 09:16 AM
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well the torque will get you out of the hole, but the shift extension.
IE RPM->SHIFT RPM on each successive gear change at wot should conver PEAK WHP.
It's likely your torque might start to fall, but hp remains flat. Would it not make sense to keep yourself in the PEAK WHP going down the track once you've made the hole shot?
Not easy to do with a small'ish converter if you loose 1400rpm per shift you can easily drop out of peak whp during a run.
maybe i got it backwards but thats how i thought my TC did its magic. holeshot of torque then good Shift Extension to keep the powerband as CLOSE to peak whp for the rest of the run.
IE RPM->SHIFT RPM on each successive gear change at wot should conver PEAK WHP.
It's likely your torque might start to fall, but hp remains flat. Would it not make sense to keep yourself in the PEAK WHP going down the track once you've made the hole shot?
Not easy to do with a small'ish converter if you loose 1400rpm per shift you can easily drop out of peak whp during a run.
maybe i got it backwards but thats how i thought my TC did its magic. holeshot of torque then good Shift Extension to keep the powerband as CLOSE to peak whp for the rest of the run.
06-21-2004, 09:22 AM
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Originally Posted by Z28camaroLS1
Is it not better to stay in revs with high torque, instead of waiting for the red line before changing to the next gear?
Anyone have any ideas?
Anyone have any ideas?
Not really familiar with the Hypertech tuner. The guys that tune the LS1/6 with "Edit" seem to like to have some dyno info to work with for fine tuning shift points. The consensus seems to be to shift these cars according to peak Rear Wheel HP, and shift them a few hundred RPMs above peak HP.
You could go ask around in the "PCM Diagnostics & Tuning " forum and get more informed answers, as I am no tuner. I just am telling you what I have observed/read posted by others who have many hours of experience with tuning. The guys in that other forum live & breath tuning these PCMs and even though they are no fans of the limited abilities of the HPP3, they can certainly answer any questions you have regarding shift points. Good luck, and your car looks great in your sig! Obviously well cared for.
Last edited by ChevyGoldfinger; 06-21-2004 at 09:58 AM.
06-21-2004, 10:59 AM
#5
TECH Senior Member
You're not even seeing your HP peak (afterall, HP IS a measure of work performed and therefore potential for acceleration.) You were faster with the stock shift points. Pick your shift points based on the HP curve. Understand that HP is a measure of WORK derived from TQ and RPM. HP = TQ x RPM / 5252
Alot goes into picking the absolute best shift points (it varies by gear and by a wide variety of factors) and really, only experimenting at the track will dial you in perfectly. However, to get you very close, shift at about 6100-6200 with your stock cam...6200-6300 if you have headers and a free flowing exhaust.
Alot goes into picking the absolute best shift points (it varies by gear and by a wide variety of factors) and really, only experimenting at the track will dial you in perfectly. However, to get you very close, shift at about 6100-6200 with your stock cam...6200-6300 if you have headers and a free flowing exhaust.
