What happens when it tops out?

[cerbomark]

Hey guys, what happens when you top your cars out?
Last night in Mexico, i got past a 'authorized vehicle' post and rolled into it hard, got 131 and it felt like it cut out, then maintained it. Stayed at 5500ish RPM. 2nd pass, i rolled in easy and it did the same thing, my co pilot said i was 4k, maybe i lifted, but it hit 133ish.
I was hoping to hit 160!

The cutting out you describe is what you feel when it hits the limiter it is set at. Sounds like 130 ish is where it s set. Remember having the limiter taken off my GM trucks (set at 95). I think it was a speed setting and not a tach setting for the top speed.

[Navy Lifer]

Just one of many examples - http://www.apexgarage.com/tech/gear_ratios.shtml

Using OE specs, as follows:
Tire diameter - 27.4"
Gear ratio (6th) - 0.6667
Final drive - 2.92

159 mph is achieved under these conditions at 3800 RPM, which, as I mentioned, I suspect is not doable in 6th tear--max speed would more likely be achieved in 5th gear. The Michigan State Police testing set maximum speed at 154 MPH, but that was in their test, and may have had a straightaway length limit that prevented more time/distance to max out speed.

Being nowhere near max engine speed, and not aware of whether there is a fuel cutoff that is speed controlled, it is more likely that the stock tuning, tire diameter and overall gear ratio, with the L77's power, the car reaches max speed based on aerodynamic drag--there's not enough power available at 3800 RPM to push the car faster.

Change the 2.92 to a 3.27, 3.45 (Camaro), 3.70, or 3.91 (Camaro), the car would accelerate quicker, and probably be faster, since it would put the engine closer to max power, even with stock tune. There are other things to consider--higher engine speed means more flow through the engine, and there could be further limitations to total system flow with the PPV exhaust vs the same basic system from an SS sedan, since it's made with the LS3's flow characteristics in mind.

For example, if only the final drive ratio was changed from 2.92 to 3.70, the speed is 165 @ 5000 RPM, and 198 @ 6000 RPM - in 6th gear. Still not saying it's DOABLE, just mechanically that would be the result. Rolling down the road is a very different story than sitting on a dyno.

The choice of the 2.92 ratio is a compromise that met performance expectations for law enforcement, and kept fuel consumption and other concerns in mind at the same time.

So, 6000 RPM in 6th gear, with all stock specs, would be just over 250 MPH, just for sake of curiosity. That would call for at least 2x horsepower of the stock L77, and a number of other changes to support the engine at that power level, and would require additional vehicle mods on the aero side to actually go that fast.

[Numbah1]

Awesome! I literally just sat down on break and was about to do the calculations!

[Pursuit]

If I am remembering correctly, whatever horsepower is required to achieve 100mph, it takes 8 times that to achieve 200 mph...

Maurice