Rich9928p

As I drove my '83 daily driver I observed that the tach never goes above 2,000 RPM with normal driving. I'm wondering if these low RPMs in everyday life contribute to a much longer engine life vs. 5 speeds where the drive is likely to spin the engine up to much higher RPMs.

Any real life experiences?

Rich

Jessa

If I'm driving my 5-speed in a relaxed manner, it doesn't get above 2k either. Since its a daily driver now, most of its miles are 'easy' ones. Of course, I still rev the bejesus out of it when mood strikes. A driver's style probably will play a bigger role in engine life than the tranny type.

Every time turn of the engine adds wear, but many people say that that an engine needs to run its full rev range to avoid build-ups. How true is that? Just how much revving is good revving?

ViribusUnits

Hum...

I was always under the impression that engine block wear was like gun barral wear. Most if it isn't caused by the movements of the pistion/bullet, but is instead caused by the blow by. The blow by, being high velosity, high tempeture gas would be alought like takeing a welding torch to the rings and wall. So most of the block wear would come from WOT opperations, where the cylinder pressures and tempeturs are at their highest, and hottest. Thus I was always under the impression that opening up the throtal under any conditions would hurt ring and block life, no matter the revolutions.

Same basic idea would go for the lower end of the engine. At WOT, the forces of the bushing and bearings along the crank and connecting rods would be at it's highest. So thus the most friction, and thus the most wear. (,that is assumeing the oil doesn't have problems getting to places at any specific rpm)

I guess the upper engine wouldn't be effected on way or the other, WOT or not. So maybe the upper end of the engine might last longer at lower revs?

Old & New

As long as you're not talking about valve life when it sees a lot of lugging...

WallyP

Most engine wear occurs during the first minute of operation. If there is a proper oil film, there is no metal-to-metal contact on the crank bearings, and virtually none on the pistons and rings.

The 928 engines just don't seem to wear out. We sell a LOT of 928 parts, but almost no engine rebuild parts due to wear.

One of my wife's vehicles is a Cadillac STS with the Northstar powertrain. It is now pretty well accepted that if you drive the Northstar gently, it will use much more oil than if you drive it in a spirited manner. Apparently the rings stick.

Several years ago, one of my neighbors drove a Corvair to work - about four blocks. After six months of this, the car would no longer pull up her driveway. I would take it for a twenty-mile drive at increasingly higher speeds, and the car would run better and better. I would then take it home, change the oil and filter, and give it back to her for six more months of torture.

For many years, it has been my practice to use full-throttle acceleration at least once on every drive that is long enough to get the engine fully warmed-up. I think that it is good for the engine.

goodspeed928

My a/t is at 2100 at 65 mph. 3000 at 100 mph

KBlair

Well, any excuse for full throttle acceleration!

jpitman2

I agree with Wallyp on wear - first few minutes, before full temp is up, not fully oiled. Highest loads on crank are at WOT, loaded down to torque peak, probably also worst on pistons as torque peak is at peak BMEP (psi on piston).
I find the 928 warms up quicker than anything else I have driven, even brand new GM product with electric fans (3.8V6).
jp 83

ViribusUnits

If most of the wear occures before everything is oiled up, has any one tryed to put a electric oil pump on the car, and get the oil pressure up to spec, before the car is started?

I guess the wear isn't normaly enough to worry about but...

Weissach

I have noticed that the motor mounts on the autos last about 20k longer than the 5-speeds. But unlike the 5-speeds, you are not really "driving". Your just along for the ride like a passenger.

In the long run, the 5-speeds are quiter, smoother, and much faster. Since there is less shifting gears(ride the power band).

Weissach

One more thing. The automatic tranny lasts longer and is WAY cheaper to rebuild($850 vs $1,400+)