quote:

Originally posted by TORQIN:
All 3 of my dragsters have 4.30 gears...

quote:

Originally posted by Mike Rietow:
162 mph and down (lower) will cross @ 7000 or down (lower) with 9% converter slip and 10% tire growth 34-35 diameter tire 1/8 mile, these are conservative percentages at 162mph.

I'd be thinking 1.64 low with a 4.56 if I ran 1/8 mile exclusively at around 165-170mph. That would make it hustle when put it in high gear. 6% slip and 10% growth crossing 7300 @170mph. 35

1.64 x 4.56 = 7.47
1.80 x 4.30 = 7.74
1.80 x 4.10 = 7.38

quote:

Originally posted by NC3x58:

quote:

Originally posted by Mike Rietow:
162 mph and down (lower) will cross @ 7000 or down (lower) with 9% converter slip and 10% tire growth 34-35 diameter tire 1/8 mile, these are conservative percentages at 162mph.

I'd be thinking 1.64 low with a 4.56 if I ran 1/8 mile exclusively at around 165-170mph. That would make it hustle when put it in high gear. 6% slip and 10% growth crossing 7300 @170mph. 35

1.64 x 4.56 = 7.47
1.80 x 4.30 = 7.74
1.80 x 4.10 = 7.38

Was just talking about this with a group of buddies.. If you took a car that has a 1.80 first gear PG, 4.30 gear and little bubba tires and switched it to a 1.69 first gear, 4.56 and left the tire the same, using the Wallace calulator for starting line ratio, first gear would essentially be the same (I got 7.74 vs 7.71) and then you would gain more mph in high gear, would make a good 1/8 mile setup for typical bracket dragsters IMO

quote:

Originally posted by Lenny5160:
I've been having this debate for the upcoming season. My car has always had a 4.10 gear and always a 33.5 tire.

I really want to go to a 34.5 or 35 tire, and I want to replace the gear set in the car due to age. I can either stick with the 4.10 and lose about 4% gear ratio, or change to a 4.30 and gain about 1%. This is using 106 and 110 as the respective circumferences, right off the Hoosier spec chart. I'm not sure how real-world measurements and growth will affect it.

I'm really happy with how the car works, but it needs tires and I like the idea of a little more ground clearance and like how the tall tires look.

The car is mostly used for Super Comp on the quarter mile, with just a couple 1/8 mile bracket races per year.

quote:

Originally posted by Mike Rietow:

quote:

Originally posted by Lenny5160:
I've been having this debate for the upcoming season. My car has always had a 4.10 gear and always a 33.5 tire.

I really want to go to a 34.5 or 35 tire, and I want to replace the gear set in the car due to age. I can either stick with the 4.10 and lose about 4% gear ratio, or change to a 4.30 and gain about 1%. This is using 106 and 110 as the respective circumferences, right off the Hoosier spec chart. I'm not sure how real-world measurements and growth will affect it.

I'm really happy with how the car works, but it needs tires and I like the idea of a little more ground clearance and like how the tall tires look.

The car is mostly used for Super Comp on the quarter mile, with just a couple 1/8 mile bracket races per year.

"Real world growth" There's an equation. Gear,rpm, Mph, converter slip at the stripe and Tire part #, is the input. They grow more than you might think, 10% to 20% depending on the MPH.

quote:

Originally posted by Mike Rietow:
105.19 vs 108.33

The equation to figure roll out at the stripe, is the more pertinent observed number to know,for performance. No matter the roll out (33.5, 34, 35) sitting on the starting line. A trend more accurately forecasts.

quote:

Originally posted by Lenny5160:

quote:

Originally posted by Mike Rietow:
105.19 vs 108.33

The equation to figure roll out at the stripe, is the more pertinent observed number to know,for performance. No matter the roll out (33.5, 34, 35) sitting on the starting line. A trend more accurately forecasts.

Well thanks for doing 3.14 x 33.5 and 34.5, Mr Wizard! Not quite the same as putting a tape around a mounted and pressurized tire.

quote:

Originally posted by diceman1530:


What rpm do you run in 1/4 ?