Drag Racing Gear Formulas

1sicklx · 08-10-2006, 12:07 AM

Quote:

Formula for max mph with gears:
(tire height x rpm's) / (gear ratio x 335)

Formula to tell if you have the right ratio for the 1/4:

ET x MPH= 1335, if higher than 1335 you need more gear, if lower you need less.

Ran across this and thought I'd share.

QWKSNKE · 08-10-2006, 04:59 AM

Check and see but i think that maybe one of the calculators in the FAQ section here

1sicklx · 08-10-2006, 11:03 AM

Close but different

slvrbullit · 08-14-2006, 03:09 PM

I guess I need more gear then.

Both my nitrous and N/A time = higher than 1335.

1sicklx · 08-14-2006, 03:40 PM

The more I mess with this the more I find it's pretty general and doesn't seem to take into account things like traction/60' times .. I think that the person that came up with this was basing it off of a perfect launch on slicks.

1sicklx · 08-28-2006, 04:09 PM

Discovered that these formulas were pulled from the FTI site as follows:

Compute the Ideal 1/4-Mile Pass

Elapsed Time X MPH = 1335
Examples:
13.35 x 100.00 MPH = 1335
12.00 X 111.25 MPH = 1335

If the factor is more than 1335, add more rear gear.
If the factor is less than 1335, reduce rear gear

How to Compute Your Miles-Per-Hour

MPH = TD X RPM / GR X 336
MPH = Mile Per Hour
TD = Tire Diameter
GR = Rear Axle Gear Ratio
RPM = Engine Revolutions Per Minute

08-10-2006, 04:59 AM	#2
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Re: Drag Racing Gear Formulas Check and see but i think that maybe one of the calculators in the FAQ section here __________________ 2009 Porsche Carrera S 2008 ///AMG C63.. Eurocharge Tune. RIP 2019 AMG GLC43..wife's 03 F250 SD.. Edge Evo, AFE Stage 1 CAI 08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's 01 Cobra vert... wife's I need a new toy

08-10-2006, 11:03 AM	#3
1sicklx BamaMafia 4 Life Join Date: Feb 2005 Location: Lake View, AL Posts: 2,577	Re: Drag Racing Gear Formulas Close but different __________________ 1999 Ford F-150 Lariat

08-14-2006, 03:09 PM	#4
slvrbullit Super Moderator Join Date: Dec 2004 Location: on the water Posts: 1,280	I guess I need more gear then. Both my nitrous and N/A time = higher than 1335. __________________ 2012 Jeep Wrangler Unlimited--- too many mods to list, about to be sitting on 1 ton axles. 2000 Ford F-350 Dually Lariat LE Crew Cab Short Box 7.3 auto 168,000 miles

08-28-2006, 04:09 PM	#6
1sicklx BamaMafia 4 Life Join Date: Feb 2005 Location: Lake View, AL Posts: 2,577	Discovered that these formulas were pulled from the FTI site as follows: Compute the Ideal 1/4-Mile Pass Elapsed Time X MPH = 1335 Examples: 13.35 x 100.00 MPH = 1335 12.00 X 111.25 MPH = 1335 If the factor is more than 1335, add more rear gear. If the factor is less than 1335, reduce rear gear How to Compute Your Miles-Per-Hour MPH = TD X RPM / GR X 336 MPH = Mile Per Hour TD = Tire Diameter GR = Rear Axle Gear Ratio RPM = Engine Revolutions Per Minute __________________ 1999 Ford F-150 Lariat

08-14-2006, 03:40 PM	#5
1sicklx BamaMafia 4 Life Join Date: Feb 2005 Location: Lake View, AL Posts: 2,577	The more I mess with this the more I find it's pretty general and doesn't seem to take into account things like traction/60' times .. I think that the person that came up with this was basing it off of a perfect launch on slicks.