My manual N/A S60 RPM's are as follows:

70mph - 2,850 RPM's
80mph - 3,350 RPM's
90mph - 3,750 RPM's

I noticed while using a loner, S60 LPT Automatic, runs at much less RPM's at these speeds.

1. Does the 2.4M N/A engine should last less than the turbo? If it does, I made the wrong decision, because the reason I selected the N/A was because I though it was more durable. I use my cars for at least 10 years.

2. Does chipping the ECU helps reduce the RPM's at these speeds? I drive 60 miles/day averaging 80 mph. The car is virtually 100% highway driving.

The car runs absolutely great at these speeds, although it does not have the take off of a Turbocharged. Although I am not into the take off power, I enjoy high speed power, which there is plenty on this car.

The car rides really motivates me to go to work.

NOTE: I just remebered a car I used to drive, Audi 80, I4 whith similar RPM's at these speeds. I used the car for probably 150,000 miles with no problems at all, no oil consumption, and no compression loss though.

Thanks much guys for your input,

It is good to have a forum like this with so well experienced people that can really help.

So, I'll keep pushing the car, great!!!!

Thanks,

Rene,

The difference probably lies in the final drive ratio on the LPT and your n/a.
Running the engine at 3,300rpm for 60 miles a day should not be a problem. Hell, it would probably run all day at 4,300 without incident. Running the engine at these speeds should not decrease its life, unless something else is wrong with it. Lugging it at a low RPM will probably do more damage than the occasional high speed run down the highway.

The turbo is probably geared higher because it produces max. torque at a lower RPM than the n/a engine. Your engine, at those lower RPMs, would not be in its powerband. The gearing in your car is optimized for your engine, and the gearing in the LPT is optimized for that motor, which has different performance characteristics.

For what it's worth, my old '86 240 (114hp 4-banger with 4spd+OD manual trans.) does 2,600rpm at 70mph, 3,000rpm at 80mph and 3,400rpm at 90mph. Fuel economy is about 25mpg on this car @ 195K miles. Not bad for an old square brick. :-)

-Jim

The owners manuals typically list the gear ratios for
all available engine combinations for the year the manual
applies to. You could check it and see if they are the
same.

My S70 with a 5 speed has same engine RPM as my wifes
855 with a 4 speed automatic in high gear. Newer cars
have a 5 speed automatic so maybe the newer automatics
are geared a bit higher (or the tire sizes were slightly
different) then the manual transmissions.

By the way, the engine speeds you listed are very close
to what both of our cars see.

Rene, first of all, the I5 engine in your S60 is designed for high-rev operation. There is absolutely no way to change the RPM with chipping. The engine speed is tied to the wheel speed via metal gears and nothing short of changing those gears (or wheel size) will change the RPMs. What you have observed with the LPT is a different gear ratio in the final drive. I am not sure why turbos have a different (higher) final drive ratio, but I am sure there is a good engineering reason for it (torque difference between the N/A and turbo?). If I were you I would enjoy the ride and not worry about the RPMs of your engine. In fact if you drive it mostly on highway at an average of 80 mph, the engine should live for a loooong time, since it is near its optimum power and torque. I love to get my N/A S70 to about 4,000 rpm because at that speed the engine comes alive and feels very healthy (I have a manual gearbox, so I can have my fun at any speed). Also, the valve train gets cleaned when the revs are over some threshold (I think somwhere around 3K), at least on my '98, the newer engines may have an updated valve train design. In any case, you have a high-rev engine and you are not abusing in the least by keeping it around 4K RPM for long periods of time, in fact I think you are running it cleaner than if you putted around town all day. So, enjoy and don't worry.

Cheers.
--
Vladimir. 1998 S70. Base, 5-speed manual.