RPM & Gas Mileage: Effects on Overdrive Vehicles

  • Thread starter Thread starter Greg Larsen
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SUMMARY

The discussion highlights the significant impact of RPM on gas mileage in overdrive vehicles. An example is provided with an '82 Buick Riviera, which achieved 26 MPG on the freeway at 1500 RPM, compared to two 1968 Chevys with carburated 327s that averaged 17 MPG, with RPMs of 2400 at 70 MPH. The differences in rear end ratios (2.73 and 3.08) further illustrate how gearing affects fuel efficiency. Overall, lower RPMs in overdrive settings contribute to better gas mileage.

PREREQUISITES
  • Understanding of RPM (Revolutions Per Minute) and its role in engine performance
  • Familiarity with overdrive transmission systems
  • Knowledge of rear end gear ratios and their impact on vehicle speed and fuel efficiency
  • Basic comprehension of carbureted engine mechanics
NEXT STEPS
  • Research the effects of different rear end gear ratios on fuel economy
  • Explore the mechanics of overdrive transmissions in various vehicle models
  • Learn about tuning carbureted engines for optimal performance and efficiency
  • Investigate RPM optimization techniques for classic cars
USEFUL FOR

Classic car enthusiasts, automotive engineers, and anyone interested in optimizing fuel efficiency in overdrive vehicles.

Greg Larsen
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I was reading a post about the effects of RPM on gas mileage, It was from 2007 so I couldn't reply to it. RPM does make a difference on gas mileage when it comes to overdrives. I had an '82 Buick Riviera with a small block engine with an overdrive and a quadrajet that got 26 MPG on the freeway and about 21 in the city. I now have two 1968 Chevys with carburated 327s that only get about 17 MPG. One had a 2.73 rear end and the other a 3.08. The RPM on the Riviera going 70 MPH was only 1500. The '68 with the 2.73 was about 2400.
 
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