[Walt Fricke]

I ran a modified 2.7 with a big cam and carbs to 8,000 routinely. Eventually the stock springs gave out - most of the inners (or outers, I forget) broke while on track and engine wouldn't pull beyond 7,600. So I finished the race. Even with only one of the springs working on some of the valves there was no noticeable float. With aftermarket better springs I finally dynoed the motor. Turns out 7,600 was the optimal upshift point for my track transmission and that engine.

Conclusion: with a stock cam and stock intake, you'll never intentionally rev it to where things break. The limitation on revs vs power is the intake - how much air you can cram in (or let out, but most good 3 into one exhausts will deal fine with that part of the cycle). If you are a track junkie you probably will use super rod bolts (if not also super rods) when you rebuild the motor, but with stock cams and stock intake diameters you won't exceed strength limits absent a money shift.

The 1983 US SC has the small port heads and intake runners. The lower compression early SCs (and all Euro SCs) have larger intakes and hence breath better at higher RPMs. They all use the same cam. I don't think that EFI is going to overcome the restricting effect of the intake, though it can help some.

Like most who comment I read the dyno graph as showing you can rev a lot higher. Easy to change the rev limiter. Optimum upshifting with stock gears normally has you shifting after the HP peak (figuring optimum upshifting is based on the torque curve, but the HP peak is always higher and you shift on the downside of the torque curve). This ignores track driving where you may want to stretch a gear to avoid a silly upshift.

Take it back to the dyno and don't get off the gas until 7,000 at least. Have the dyno guy tell you to back off when you have passed the hp peak if you are getting up toward 7,500, though I doubt you will.

While I upshift on the track at 6,250 mostly because that is the most efficient for my CIS '82 US engine, I'll stretch to 7,000 every time if that will get me to the braking point.

If you figure a 12% transmission loss, 193 flywheel HP is a pretty stout result for an engine Porsche said had 180 or so. But it is the air flow and not mechanical strength which is your practical rev limit on a largely stock motor.