Hypermiling Auto Trans w/ Tach

[brucepick]

Looking for other people's experiences on hypermiling an auto tranny with tach.

My '89 tranny does NOT have a lockup torque converter so I've been observing a certain amount of t/c slip.

Anyway, it seems I can keep the tach at say 2000 to 2300 rpm and that is a pretty effective way of maintaining a steady load on both engine and tranny. I've been doing this for a couple weeks now. Today I logged my best mpg so far, 28.5 in a car with EPA highway rating of 24. I kept the tach real close to 2000 rpm for the 2nd 60 miles of this 120 mile fillup. First 60 miles was a more aggressive P&G on hills with downhill speeds up to 70.

Any thoughts?

Without a lockup t/c, opening the throttle has the RPMs increasing fairly quickly while mph goes up much more slowly. Eventually the mph stabilizes at whatever speed the throttle position will support based on grade, load, etc.

[Bill in Houston]

Seems like an '89 would have lockup... Odd.

Sounds like you had a good tank. Congrats. No tips from me, just congratulations.

[brucepick]

"Seems like an '89 would have lockup... Odd."

Pretty close. First used on the 740 in 90, first used on the 240 in '92. For both models, first year's cars did not all get lockup.

Volvo auto trans reference ("L" in trans model = lockup)
http://www.brickboard.com/FAQ/700-90...delInformation

[MorningGaser]

Get a ScanGauge because relying solely on the tach can be deceiving....you might think taching low would always get you the highest MPG, but this is not always true...for example, going 35 mph at 1,800 rpm gets worse milage then taching at 2,300 at 43 mph....you need to factor in the gear the tranny is in, and the load on the engine....the ScanGauge can help you with that.

[brucepick]

Originally Posted by MorningGaser

Get a ScanGauge because relying solely on the tach can be deceiving....you might think taching low would always get you the highest MPG, but this is not always true...

Thanks, but unfortunately, '89 is too early for a ScanGauge. You need something like a '92 or '93 for that. I hear there's something called a SuperMID but I don't know enough about it yet. Apparently you hook it up to a fuel injector wire.