mileage

[dkkim81]

What kind of MPG do you guys get per full tank? The fuel capacity is 22 gallons? On the freeway, I have to fill up after 300 or so before the light turns on. Local mileage is around 275 or sometimes even lower.

[Maleficio]

I average 14-15 mpg no matter what. I saw some dude here or on Rennlist that said he gets 21 city, 27 hwy!!

[dkkim81]

No way! I wanna know what he's doing right!!

[Griffinroydonal]

12-14 MPG average.

[harborman]

I am getting 20 hwy

[Maleficio]

Originally Posted by dkkim81

No way! I wanna know what he's doing right!!

I guess his car's running perfectly with zero vacuum leaks, very thin synthetic oil, low-rolling-resistance tires, and he never gets on it.

[Danglerb]

The middle 80's cars, especially the automatics, get the best MPG. Running really well is also a big step, a funky running car wastes a LOT of gas.

[1984928]

'84'auto running very well. Super high miles getting 17mpg on the highway

[XLR8928]

I'm getting about 20 on the highway. I think with some work I might even extend that to 21-22. I've found that my 928 gets better milage at 75 than at 70!

[JK McDonald]

The gas mileage Miss Purdy (84 Auto/Air Conditioning normally on) averages around 18 mpg, although I’ve sometimes been able to stretch it a bit into the low 20’s by consistently reining in my highway speeds and pacing my in town travels to avoid red lights. A couple of friends I polled said their 928 mileage was somewhat similar IF they kept their foot out of it. In normal driving the 80 - 5 speed reportedly got around 17 mpg and the 87 auto normally got 18 mpg.

It is too bad that there are no lock-up torque converter updates available for the 928 automatics. The newest technology now days allows a lockup converter mode in every gear on the D-10 Caterpillar dozer.

Michael

[Maleficio]

What does a lock-up torque convertor do?

[JK McDonald]

In the design of the early torque converter automatics there was a loss of efficiency between the engine crankshaft and the coupled input to the transmission. Think of two fans facing each other - The blades of the 1st fan are being powered by electricity (engine) and the 2nd set of fan blades (input drive to the transmission) are being rotated by the forced air leaving the blades of the 1st fan. You can think of the newer designed lock-up torque converters as one that allows the two sets of fan blades to touch (only at highway speeds) for a 100% direct drive transfer of energy from the engine to the input of the transmission. Naturally, there are a couple of logic circuits needed to monitor such things as engine load, proper engaged gear, ground speed and several temperature inputs.

Michael

[Maleficio]

Sweet. Thanks, Mike.

I was under the impression that all autos locked up eventually.

[Maleficio]

For my next question: with blades spinning and the swirling fluid pressure driving the receiver blades, what actually locks up?

[JK McDonald]

There is a disc plate and opposing mating surface centered directly between the two sets of fan blades (similar in application to a regular clutch and pressure plate). The clutch is only hydraulically engaged (pressed together) when all the proper logic and operating conditions are met. The lock up torque converter internal mating surface diameter and thickness is determined by the HP and transmission application (4-6-8 cylinder/two wheel/four wheel/domestic/off road/racing/earth moving equipment/etc)

Michael

[Maleficio]

Dude, you are good. Thanks.

[joejoe1]

I think I am the 'dude' from renlist that gets the good gas mileage. It is correct I do not run the car hard usually (mine is an '81) there are no vacuum leaks and car is very well maintained.

[Maleficio]

Originally Posted by joejoe1

I think I am the 'dude' from renlist that gets the good gas mileage. It is correct I do not run the car hard usually (mine is an '81) there are no vacuum leaks and car is very well maintained.

Auto or stick?

[JK McDonald]

Hey Joe Joe - 21 MPG in town and 27 MPG on the highway is tremendous - especially for a CIS system. The efficiency of the latest electronically controlled variable cylinder V-8 cars can not get those numbers in real world driving. I’ve worked with EPA techs for years and even variable V-6 engines can not maintain those numbers except in special circumstances. Before you sell your 928 to GM and Ford to be reverse engineered let the rest of us know how this is being done.

Michael

[joejoe1]

Mine is an auto. I am not sure why I get this mileage. before the trip to sharktoberfest I fill up, and drive 31/2 hours to anehiem. Before I leave I fill again and do the math. Last year it was 27 mpg. I did have a time when I could only get 10-11 mpg. Problem turned out to be vacuum unit inside distributor had fallen off. One of the po's had restuck distributor 1 tooth and dist. was at full advance. While it did have very good power best gpm was 11.5.

Now what really surprised me was that the car passed california smog twice before I addressed this problem (once when bought and two years later.

Even I was surprised with the mpg now. I thought the guage had gotten stuck.