ET Differences Between Varying Powerglide Low Gear Ratios?
 

I was curious to know how much ET could be gained/lost by changing the low gear ratio of a Powerglide? I know the ratios typically range from 1.76-2.18, but is there a sweet spot for how much harder the car leaves vs. subsequently how long the car is in high gear? Or do the 60' gains outweigh the longer amount of time in high gear?

Background: I currently have a 1.94 low gear PG and I am looking to speed up my 60's. Would a 2.08 / 2.18 low gear be worth the investment?

Thanks,

JP

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

How much power are you making,and tq. The 2.18 is a pretty weak gear set. I ran a 2.18 in my ss 327 it was about 4 hun in the. 60 ft fasted than the 1.96 I broke it last year but i did run for about 5 years. Lot of thing factor in , weight gear tire etc etc/

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

Thanks Jim,

I have a 3230 lb car with 775 hp and 500 ft lbs of torque. I have also seen that the higher ratio low gears tend to have an HP disclaimer on them.

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

A bunch of years back when I was messing with our A/SA '67 Corvette, I had a glide with a 1.98 low. 1.94 - 1.98 always seemed to be the sweet spot. I broke the planetary at a division race and the only spare I had handy was a 1.82 geared bracket glide. Car left like a turd and lost .04 in 60', but only slowed .02 in ET. Most if not all of the .02 was the bracket trans didn't have the lightweight parts and all the other tricks. While all that gear helps the leave, doesn't really make much of a difference in overall ET.

Your mileage may vary...

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

Using a gear ratio - RPM - MPH calculator you can figure out what RPM the engine drops to when the transmission shifts to high gear. If the RPM is below the stall of the convertor, there will be slippage until the RPM reaches the stall speed. Plug in different 1st gear ratios to figure it out.

http://www.wallaceracing.com/gear-speed.php

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

I agree with Jeff especially with the HP you're making. A 1.82 should be more than enough.

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

Looks to me in that calculator the trans and rear gear data inputs are reversed. Should be: tire diameter, rear gear, trans 1st, trans 2nd, trans 3rd

Re: ET Differences Between Varying Powerglide Low Gear Ratio
 

If the same converter is used in low gear comparisons the results may be slightly off. A 1.76 low gear will work the converter harder leaving than a 2.18, the 2.18 will work the converter a lot harder on the high gear shift. At one time I bracket raced an A/SA some, when on slick tracks I would leave in 2nd gear and always saw more quite a bit more flash.