raise rev limiter/shift point on 986 Boxster?

[blue2000s]

Originally Posted by Flavor 987S

Why?

The peak power band is from about 4,500 RPM to about 6,500 RPM.

Is your a Tip?

Max torque at the road is at redline in every gear.

[Flavor 987S]

Originally Posted by blue2000s

Max torque at the road is at redline in every gear.

LOL! That's news to Porsche (and me).

Boxster S 3.2L
280 HP
236 lb.-ft. at 4,700-6,000 RPM
Redline is 7,200

993 Twin Turbo 3.6L
400 HP
400 lb. ft. at 3,500-5,500 RPM
Redline is 6,700

[blue2000s]

Originally Posted by Flavor 987S

LOL! That's news to Porsche (and me).

Boxster S 3.2L
280 HP
236 lb.-ft. at 4,700-6,000 RPM
Redline is 7,200

993 Twin Turbo 3.6L
400 HP
400 lb. ft. at 3,500-5,500 RPM
Redline is 6,700

I doubt it's news to Porsche, all engineers learn this in school, maybe to you though. Multiply the torque by the gear ratios and wheel diameter. There's always more torque at redline in the lower gear than at the same road speed in the next gear up in a street Porsche.

[Tobz]

Hey blue2000s

I think ur getting engine torque mixed up with gearing. Yes a lower gear will produce more torque, but the engine will be losing it pulling power as the rev rise. So yes u are correct a lower gear at 40kmh will produce more torque than 40kmh at a higher gear, but ur poor engines torque output is in decline after it reaches its peak output.

What u will find is even though the higher rev range may be available, if the engines peak torque is at 5000rpm and peak power at 6000 rpm u won't want to rev past 6500 as the engines pulling ability just won't be there, it would be more beneficial to change to the next gear. Remember a gear box only multiplies the engines torque output, and Porsche spent hours working out the ratios to ensure maximum performance through the gears.

If in this case the turbo has changed where peak power and torque is, then yes the limit might need to be raised, but this could have reliability issues for the engine as it was made to rev to a certain limit.

[Flavor 987S]

Blue2000, just look at the graphs in your Owner's Manual. You'll see it.

[jmatta]

A high reving, turbo M96...sounds like a recipe for disaster. How many hours do you think that engine will last?

[blue2000s]

Originally Posted by Flavor 987S

Blue2000, just look at the graphs in your Owner's Manual. You'll see it.

The plot that I made above came from the data in the owners manual.

[blue2000s]

Originally Posted by Tobz

Hey blue2000s

I think ur getting engine torque mixed up with gearing. Yes a lower gear will produce more torque, but the engine will be losing it pulling power as the rev rise. So yes u are correct a lower gear at 40kmh will produce more torque than 40kmh at a higher gear, but ur poor engines torque output is in decline after it reaches its peak output.

What u will find is even though the higher rev range may be available, if the engines peak torque is at 5000rpm and peak power at 6000 rpm u won't want to rev past 6500 as the engines pulling ability just won't be there, it would be more beneficial to change to the next gear. Remember a gear box only multiplies the engines torque output, and Porsche spent hours working out the ratios to ensure maximum performance through the gears.

If in this case the turbo has changed where peak power and torque is, then yes the limit might need to be raised, but this could have reliability issues for the engine as it was made to rev to a certain limit.

Torque follows a curve, but it's multiplied by the gear ratio. As long as the gear ratio is low enough, the torque at the lower gear will exceed the torque at the next gear up. As long as it's making more torque in the lower gear, that's where you get the best acceleration. Just about every sports car will be geared to take advantage of the entire rev range. See attached for the 986S.