Hey, I did search for this. What makes the series 5 redline at 8k and the S4 at 7k? Is it possible to "easily" get an S4 to rev to 8k safely like a S5? I assume this max rpm difference is the cause of the horsepower gap between the S4 and S5?

 

They have different redlines due to the s5 having lighter rotors. There's really no point in revving that high, 80% of the people here aren't making any power past 7k so it's just stressing the engine needlessly. The horsepower difference is because of higher compression rotors as well as the vdi intake system, the difference is rather small, (15hp 2ft-lbs)

 

It's not always useless to go past 7k... shifting is completely stopped acceleration... even if you're losing power past 7k you're losing more by shifting too early.

You probably knew that though.

And in case you didn't understand what Sonicrat said, no there is no easy way to make an S4 rev as high as an S5... and of course, no reason to.

--Gary

 

Yes, but that's arguing powerbands. Of course there's that nice spot where you shift just in time to be in the powerband without dragging the engine out at past 7k rpm. However most of the time this doesn't require you to rev that high.

 

Lest we forget,

The S5 had the VDI, which also enabled the motor to make a bit more power in the higher RPM band.

Fact is, if you do your homework, you would know that the S4s and the S5s are not particularly rev limited by the rotors as much as they are by the ignition system. But that fact is moot, there is no power up there anyways...

Rat