[CSG Mike]

Originally Posted by moto-mike

I'm fairly confident this is a data acquisition issue or stock like rev limit implementation. Acceleration has no momentum, so if you pull spark or fuel then it will stop accelerating. We've seen some of the devices out there (and even stock tachos) report a higher than actual RPM. It gives me that unsteady feeling when I spin a rotary to 10k indicated via the dash on the dyno when it is only hitting 8800 in reality.

This car that I drive has been beat to death with FI for over 30k miles, 40k total. I raised the revs to 7850 without finishing break-in. It has been to the dyno countless times. I prefer to use a dynojet with an actual spark pickup (vs calculated) and I've never seen a spike over my preset RPM. Again, data aquisition issue, or how the rev limit is being implemented. If they are using OEM style throttle cut, then it will overrev because you have to exhaust the plenum volume. Which when compressed will be substantial. But if you use an alternate method that is not an issue (all our tunes).

But in the grand scheme I don't think anyone has to worry about revs of 8k or below. Above 7500 I recommend a smooth rev limit to minimize cam chain slap. The STX auto-x and track folks we've tuned (dozens upon dozens) usually go for 8000-8100 rev limit. When you auto-x you spend a lot of time at the rev limit. If they aren't floating valves or stretching rods it is a non issue. Durability long term will no doubt be affected, but when you spin a rotrex blower which maximizes power at the top, there's nothing wrong with going a few hundred RPM higher to maximize its advantages. If we got 40k miles on it, 30k supercharged with all the testing we do, then the average person is highly unlikely to have an issue within a typical 150k mile life of a motor.

We'll agree to disagree.

We cater to a few national level (and champion) drivers, and we've all reached the same conclusion that an increased redline is not the way to go without a huge budget. The guys that can have ultra aggressive final drive gears and further enhance the aggressiveness with specific tire sizing.