Whats the redline difference between Sport crono On or Off?

Higher rpms? Is it 7200 without Sport Crono and 7300 with it? I read this in the FAQ "The soft engine rev limiter is replaced with a hard cut off at redline allowing you to get full power just below redline " What does this mean?

You maybe right about 7300... I saw a diagram somewhere on these forums comparing standard and SC throttle progressions, and it seemed to indicate that SC will let you push a little above 7200.

"Danger, Will Robinson!, Danger, Will Robinson!"

The rev limit does not change, just the way you reach it. First a few definitions: Rev Limiter - A safety device that cuts fuel, ignition or both at a specified RPM to prevent an engine from continuing to rev beyond its mechanical safety limit. Hard Rev Limiter - The most basic of rev limiters. The limiter does nothing until you hit the predefined engine speed at which point fuel and ignition are shut off. This can be very abrupt and hard on the power train as the engine cycles on and off at max RPM. The very first rev limiters installed were all hard rev limiters. Soft Rev Limiter - Because hitting a hard rev limiter can be uncomfortable for the driver and hard on the car, manufacturers created the 'soft' rev limiter. A soft rev limiter reduces power output by retarding ignition timing as the engine approaches its limit. This usually begins about 500 RPMs before the hard cut off point. As the ignition timing is retarded and power drops off, the resulting feeling of power loss signals the driver that it's time to shift. If a driver ignores this, ignition timing is retarded further until the rev limit is reached, at which point the resulting cut off is much 'softer' because the engine is not being cycled on and off between full power and no power. ​ So, now that we know the difference between a Soft and Hard rev limiter, we can better understand what Sport Chrono does. It does not change the cut off RPM, which remains at 7,300 RPM. It simply removes the 'Soft' cut off and allows the driver to have all available power from 6,800 - 7,300. A car without Sport Chrono will lose power from 6,800 - 7,300 RPMs because the computer will retard its ignition timing. No one has ever quantified the difference in horsepower in the 6,800 - 7,300 RPM range, but it is there by design. Anyone with sport chrono can attest that the engine will rush to the hard cut off in Sport mode, where in normal mode you can really feel a flat spot. I've hit my rev limiter a few times, always in Sport mode, never in Normal mode.

Gator you should add that info to the FAQ to help future readers, kudos to the OP for reading the FAQ!

Done deal. Thanks for reading the FAQs...! :cheers:

so the question will be how difficult is to damage your engine if you reach the rev limit 8,000 rpm?

How does Scotts Softronic ECU flash effect soft/hard rev limits? I think the upper limit is 7600 with the 4.1 flash but how is that limit enforced?

Really a question for Scott, but as I understand it, he is just moving the limit up a few notches. He is not altering the Soft/Hard approach. So..... If your car has Sport Chrono, you will still have the Soft limiter in normal mode, the Hard limiter in Sport mode. If your car does not have Sport Chrono, and you do not request a 'Sport flash', you will retain the Soft limiter If your car has Sport Chrono, and you request the 'Sport Flash', you get the Hard limiter

Not hard at all. I'm sure the engine won't explode at 8,000 RPMs, but the stress certainly would be detrimental over time. The M97.21 was not made to rev that high. Engines that are made to rev that high have many internal differences, particullary in regard to the connecting rods, pistons and valves. The cast pistons and fracture cast connecting rods in the M97.21 really aren't the best choice for 8,000 RPM use. The bigger question is, why would you want to rev to 8,000 RPM? Do you think you will get more power and go faster? Guess what? The M97.21 engine hits peak horsepower at 6,250 RPM. As you go beyond that, power is actually falling.

Gator is quite right about 8000RPM. It's not a disaster if you do rev to it, it certainly won't blow, but it's more signifficant to note why you revved to 8000. It's a totally different story if you miss-shifted on full power, and let the clutch go in wrong gear, on the power, into 8000RPM, and it's a different story if you're down-shifting, with no power on, and down-shift too early, making the engine rev-up past the limiter. Ultimately, revs are about peak power. Some engines have more going for them higher, some don't. Unless you alter cam profile, get some really funky induction tuning, or alter the VVT cam phasing, you should see little to no benefit from reving past 7500-7600, the power really drops off.

Then, all the Sport Crono feature does is to disable the soft rev limiter?

Exactly...

Gator Bite - Since the title and entire theme of this thread was concerning the "redline" effects of Sport Chrono , then I assumed jefeant was clarifying those sole effects of SC on the redline, not everything else. But concerning the scope of these forums and for the benefit of "idiotproofing" for future readers/searchers, it's probably better to be more detailed in responses. So to clarify, of course, SC effects change on MANY attributes... but as far as redline is concerned, it only removes the soft limiter (as opposed to actually changing the RPM of redline/cutoff).

I have hit it in normal mode, it is like someone is rapidly turning a valve supplying fuel to the off position, the cars engine seems to sputter, rather than just cut off.

I have the Softronic Flash w/ Sport Mode and have hit 7500 RPMs (that's just where I was at the end of the straightaway) not sure where the top is. Without the software there is a hard limit of 6800.

Ah... Yes.... My bad. I misunderstood.