Could anyone tell me how a shift light works?? I know that when you hit the desired rpm it lights up. I want to know how it knows the rpm. Could I make a shift light at home??

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Godti
'89 Trans Am (Red)
305 TBI 5spd

 

The shift light is there to tell you when to shift up to get better gas mileage. I guess the ECM lights it by sniffing manifold pressure (engine load), gas pedal position and engine rpm. The right values of these are programmed to the prom.

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-88 GTA 305TPI/T5, 3.45 posi, minor mods (slightly ported+portmatched heads, base, plenum, multiangle valve job), Haltech E6GM, ~more to come. ET 15.2@93mph. www.helsinki.fi/~kjilehto

 

I guess I should have been a bit more specific. I am aware of the factory shift light. Im talking about those aftermarket ones, usually come with the monster tachs. You can set it up to light up when you want to shift, which is usually red line.

 

my light uses a pill, or chip, set to a specific rpm. i have a msd takes the same pills as the rev limiter so i only have to keep one kind of pill for both.

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-=ICON MOTORSPORTS=-
1st & 3rd

 

The shift light is just a light that's activated by some sort of rpm switch. The MSD lights use the pills. I use a Holley Annihilator ignition that has 2 built in rpm switches. I plug my shift light into one of them and adjust the switch to the desired rpm. I was shifting at 6400. I could use the other switch for anything. I was thinking of having 2 shift lights. 2 different rpm settings. One for the 1-2 shift and the other for the 2-3 shift.

To build one, you need to find some way to activate a curcuit (the light) at a specific (adjustable) rpm. It's probably cheaper to buy a real shift light or buy an rpm activated switch and use any light.



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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
454 Big Block buildup now in progress for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car
91 454SS daily driver
95 Homebuilt Harley

[This message has been edited by Stephen 87 IROC (edited November 09, 2000).]