Sifting on time instead of RPM

Old 06-17-2009, 06:22 PM
  #1  
kod99
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Default Sifting on time instead of RPM

I have a BBC super comp dragster with a powerglide. Right now the transmission shifting is being controlled on RPM (7400) by my Biondo Mega 450. I would like to figure what time interval I should enter into the box, for a starting point, to allow the shift into second gear when the box is controlling the shift by time. I am not using the throttle stop at this time.
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Old 06-17-2009, 06:54 PM
  #2  
hammertime
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Default Re: Sifting on time instead of RPM

Originally Posted by kod99
I have a BBC super comp dragster with a powerglide. Right now the transmission shifting is being controlled on RPM (7400) by my Biondo Mega 450. I would like to figure what time interval I should enter into the box, for a starting point, to allow the shift into second gear when the box is controlling the shift by time. I am not using the throttle stop at this time.
use the playback tach and find where it hits 7400 and shift on the timer.

FYI its illegal nhra and ihra to shift the car by the mega 450 rpm and have the tach wire hooked to it :shock:
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Old 06-17-2009, 07:28 PM
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kod99
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Default Re: Sifting on time instead of RPM

Originally Posted by hammertime
Originally Posted by kod99
I have a BBC super comp dragster with a powerglide. Right now the transmission shifting is being controlled on RPM (7400) by my Biondo Mega 450. I would like to figure what time interval I should enter into the box, for a starting point, to allow the shift into second gear when the box is controlling the shift by time. I am not using the throttle stop at this time.
use the playback tach and find where it hits 7400 and shift on the timer.

FYI its illegal nhra and ihra to shift the car by the mega 450 rpm and have the tach wire hooked to it :shock:

Thanks, David. I haven't looked at the playback tach yet. I assume it shows time and RPM? When I had the chassis certified the NHRA inspector told me that I had to not only unhook the tach wire from the box but cut the dash enough so the tech inspector would be able to see the tach terminal on the box. I assume this is only for sanctioned events?
Does anyone shift their dragster manually? Is it possible without causing damage?
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Old 06-18-2009, 06:08 AM
  #4  
hammertime
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Default Re: Sifting on time instead of RPM

Originally Posted by kod99
Originally Posted by hammertime
Originally Posted by kod99
I have a BBC super comp dragster with a powerglide. Right now the transmission shifting is being controlled on RPM (7400) by my Biondo Mega 450. I would like to figure what time interval I should enter into the box, for a starting point, to allow the shift into second gear when the box is controlling the shift by time. I am not using the throttle stop at this time.
use the playback tach and find where it hits 7400 and shift on the timer.

FYI its illegal nhra and ihra to shift the car by the mega 450 rpm and have the tach wire hooked to it :shock:

Thanks, David. I haven't looked at the playback tach yet. I assume it shows time and RPM? When I had the chassis certified the NHRA inspector told me that I had to not only unhook the tach wire from the box but cut the dash enough so the tech inspector would be able to see the tach terminal on the box. I assume this is only for sanctioned events?
Does anyone shift their dragster manually? Is it possible without causing damage?
He is right on the tach wire but dead wrong on cutting your dash. All ihra or nhra events are this way, bracket racing or div/nat racing. Think of it this way, you won and someone says check his tach wire. Busted and your now labeled a cheater :shock:

You can shift manually but its not consistent, add a rpm switch and be done with it.
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Old 06-18-2009, 06:11 AM
  #5  
dparker
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Default Re: Sifting on time instead of RPM

Originally Posted by kod99
Originally Posted by hammertime
Originally Posted by kod99
I have a BBC super comp dragster with a powerglide. Right now the transmission shifting is being controlled on RPM (7400) by my Biondo Mega 450. I would like to figure what time interval I should enter into the box, for a starting point, to allow the shift into second gear when the box is controlling the shift by time. I am not using the throttle stop at this time.
use the playback tach and find where it hits 7400 and shift on the timer.

FYI its illegal nhra and ihra to shift the car by the mega 450 rpm and have the tach wire hooked to it :shock:

Thanks, David. I haven't looked at the playback tach yet. I assume it shows time and RPM? When I had the chassis certified the NHRA inspector told me that I had to not only unhook the tach wire from the box but cut the dash enough so the tech inspector would be able to see the tach terminal on the box. I assume this is only for sanctioned events?
Does anyone shift their dragster manually? Is it possible without causing damage?
Yes its possible and won't damage anything, but Not if you want to go to the later rounds. In our Southwest Super Charger class they don't allow electronic shifting and everybody shifts manually. The magic word being everybody. In bracket racing you'll be one of the only ones manually shifting, big disadvantage IMO.
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Old 06-21-2009, 07:13 AM
  #6  
chevyfireball
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You wouldn't want to be shifting by time would you? If you have any launch problem it may shift too soon.
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Old 06-21-2009, 08:00 AM
  #7  
hammertime
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Originally Posted by chevyfireball
You wouldn't want to be shifting by time would you? If you have any launch problem it may shift too soon.
Time shifting actually works very well but car has to go down the track all the time.
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