From NISSAN engineer... each parts have diffrent rev for RB26 because that problem is for the cost. The crankshaft rev is about 7,800 rpm. Standard harmonic Balancer is same. The standard valve spring is about 8,300 rpm. But the valve guide is not strong enough for such rev. If you make the best clearance for the valve guide, that engine is no problem 8,300 rpm. When NISSAN raced with RB26 that the short distance race was 8,300 rpm rev (It was sometimes 8,800 rpm rev thouht). The Long distance race was 7,500 rpm rev.