Texas Trans Ams
RPM - Gear - Tire - Speed Calculator

The following online calculator is designed to estimate vehicle speed at given engine speed, transmission gear ratio, axle gear ratio and tire circumference.  Popular Pontiac values are listed below the RPM calculator.

Enter next 5 values to calculate vehicle speed.  Click the Calculate Speed button for results.

Engine Speed:

  RPM

Transmission Gear Ratio:

  :1

Axle Gear Ratio:

  :1

Tire Circumference:

  Inches

Drive Train Loss:

  %

Estimated Results

Drive Shaft RPM

  RPM

Axle RPM

  RPM

Inches Per Minute

  IPM

Miles Per Minute

  MPM

Miles Per Hour "Gross"

  MPH

Miles Per Hour "Net"

  MPH


Popular Pontiac Engines top horsepower at RPM

1970 400 CID Ram Air III

345 HP @
5000 RPM
1970 400 CID Ram Air IV  370 HP @
5500 RPM
1971 455 CID H.O. 335 HP @
4800 RPM
1972 455 CID 300 HP @
4000 RPM
1973 455 CID  250 HP @
4000 RPM
1973/74 455 CID 290 HP @
4000 RPM
1975 455 CID 200 HP @
3500 RPM
1976 400 CID 185 HP @
3600 RPM
1976 455 CID 200 HP @
4000 RPM
1977/78 400 CID 180 HP @
3600 RPM
1977/79 403 CID (Olds) 185 HP @
3600 RPM
1977 400 CID T/A6.6 220 HP @
4000 RPM
1978/79 400 CID T/A6.6 220 HP @
4000 RPM
1979/81 301 CID T/A4.9 150 HP @
4400 RPM
1980 301 CID T/A4.9 Turbo 210 HP @
4000 RPM
1981 301 CID T/A4.9 Turbo  200 HP @
4000 RPM

Transmission Gears

Turbo-Hydromatic 250/350  First Gear  2.52:1 
Second Gear 1.52:1
Third Gear 1:1
4 Speed Manual First Gear
Second Gear
Third Gear
Fourth Gear

10 Bolt Rear Axle Gear Ratios

Standard gearing for 403 Automatic transmission 2.41:1
Standard gearing for 400 Automatic 2.56:1
Optional rear end for most automatics 2.73:1
Standard gearing for Turbo engines and Super Duty with Air Conditioning 3.08:1
Standard gearing for 4 speed car (220 HP 77 - 78 w/ Auto Trans) 3.23:1
Option for early model (Super Duty with out Air Conditioning) 3.42:1
Early model 4 speed
3.73:1
4.10.1

Popular Tire Circumference

P225 70R15 85.44 inches
P255 60R15 83.75 inches
P235 60R16 84.375 inches



"Restoring Old Dreams"

Owner and Operator, Mr. David Mars
Serving the community since 1991
Email: david@texastransams.com
4588A Kennedale - New Hope Rd.
Fort Worth, TX  76140
Phone:
817-563-2121

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All rights reserved. Duplication only with prior approval.
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