|
|
|
|
Original Message
|
| RE: Yes that is true........ |
| By allan - 10/22/2003 3:12:58 PM; IP 130.76.96.14 |
I agree with what you say. Its been shown in the EPA milage ratings that bigger and heavier vehicles get less milage than smaller ones. That has been a driver in the widespread use of overdrive transmissions. But the design of the drive train....engine, transmission, & rear end usually all go into the tradeoffs of what we wind up with in the end.
When we look at just adding overdrive to a drivetrain that wasn't originally designed to operate with it, I think there may be some downsides to consider. That's part of my original question in that the power band of a stock 390 4V may be fine for a three speed tranny with a 3.00 rear end. But what happens when you reduce the rpm by 27% at the cruise speed you normally have? Do you see a 27% increase in milage? Or, does the rest of that original engine design struggle to maintain some semblance of efficient operation at cruise speed now that rpm is lower at the same load conditions. Would it be like driving up an incline all the time at the lower RPM since you have shifted the load to a lower point in the power band without changing anything else? |
|
|
This thread, so far...
|
|
|
|
Post A Response
|
|
|
|
|
|