cruise RPM

[batmanSC]

Just bought an 82 SC and am getting to know and love it. There was a thread some time ago on a similar topic, but it didn't directly address this issue.

One example: for cruising at, say, 50-55 mph, there's 5th gear and approx 2500 RPM or 4th gear at 3500RPM or so. While the lower RPM may be better for mileage, is one generally known to be better for the engine?

People seem to have slightly different ideas about shift RPM's, but I figure there must be some consensus about what the engine likes for an extended cruise.

Any help much appreciated!

[RexNoctu]

Fifth Gear? I don't shift until I either come up on redline or am going to be above 4500 for an extended time. Most of the time I cruise at 3500 to 4000.
A mechanic once told me, "These engines are designed to run at redline all day. And they will do it for a long time, but if you drive it like that when they finally do break expect it to be done."

But of course it is your car drive it like you want to, if you like how it sounds at 2500 then drive it there.

[stlrj]

Originally Posted by RexNoctu

A mechanic once told me, "These engines are designed to run at redline all day. And they will do it for a long time, but if you drive it like that when they finally do break expect it to be done."

But of course it is your car drive it like you want to, if you like how it sounds at 2500 then drive it there.

I would expect a mechanic to say that. That way, you would wear it out quicker for him to fix.

A 911 has bearings and pistons just like any other engine, and the harder you drive it, the sooner it wears just like any other mechanical device. Just because it is capable of running at red line, doesn't mean you should drive it there all the time.

Drive it like a normal car and it should last a very long time.


Cheers,

Joe

[Gunter]

+1

5th for level cruising is fine.
When it goes to a little uphill and the engine feels like it's being "lugged", shift down.

[Por_sha911]

If you've driven cars that run in the 1.5-2k range then driving your Porsche takes some getting used to. It doesn't like to run under 1.5-2K but you don't have to drive it above 3k all the time either. Like Gunter said, if you feel it lugging, downshift. If your car has the CASIS light like mine, you'll note where the Porsche programing thinks you should shift for optimum gas mileage. While this is not the best for performance, the good Doctor wouldn't have us shift there if it would hurt the car.

[dshepp806]

mine likes the 3500 - 4000- range..never lug these engines at low RPMS..

if Interstate,..I'll let her see fifth.....

Doyle

[teenerted1]

your RPM at cruising depends on the gears in the trans and the tire size.

so saying all porsches like it at 3000+rpm on the freeeways doesnt take any this into effect.

some 4speeds are crusing on the freeway at 4200rpm

[Grady Clay]

I think I have short gears 2-3-4 and perhaps standard 5th or one gear shorter. Coming back to Denver from High Plains Raceway (HPR), it was all I could do to resist a 140 mph attempt. It was SOoo comfortable at 90 in a 75 (same as the 18-wheelers).


EDIT
'79 SC Max Moritz 98 mm & short gears.

Best,
Grady

[Mitch Leland]

I look at my car for miles traveled and RPM's traveled. When on a level road and cruising at 2500-3000 RPM why do it at 4 grand unless you're going 100 MPH? 3100 is about 70 MPH in my in my car. Save it for the track... If I need to pass another car, pull a hill, then I drop down a gear. I never lug the engine so it's always happy... But this notion of the engine was made to red line I think is wasteful...

[dshepp806]

Originally Posted by Mitch Leland

I look at my car for miles traveled and RPM's traveled. When on a level road and cruising at 2500-3000 RPM why do it at 4 grand unless you're going 100 MPH? 3100 is about 70 MPH in my in my car. Save it for the track... If I need to pass another car, pull a hill, then I drop down a gear. I never lug the engine so it's always happy... But this notion of the engine was made to red line I think is wasteful...

+1.

Doyle