The 912E Drivetrain
A summary of what's inside

The transmission is a 923/02 unique to the 912E. It was based on the 915/44. The difference between the 915/44 and the 923/02 are the ratios on 4th and 5th gear, the ring and pinion ratio. The main shaft has 24 splines, versus the 20 on the 915 and the way the clutch arm operated was modified. It is the same as the 915 in every other way including the ZF limited slip and other goodies. Final drive is 7/31 (4.4285) fourth is 26/25 (.9615) and fifth is 29/21 (.7241).

I always love to help, so keep the questions coming. The engine bone stock developed max HP at about 4900 RPM (about 86HP). The max (usable) revs for the stock engine are around 5500 RPM. There is rev limiting built into the fuel injection control module that should kick in around 5800 give or take 100 revs. Pop off the distributor cap to make sure you don’t have the rev limit rotor that always cuts out before 5400 RPM. It is large and grounds out usually around 5250 or so though centrifugal action. BTW the tach is unique to the 912E as the 911 2.7 of that year maxed out at 6500, and the new Carrera 3.0 maxed @ 6800 RPM. Interestingly enough the 911 6 torque peek is at the same 4000 RPM as the 912E type 4. The type 4 in the 912E can propel the car up to around an honest 140 MPH (versus the stock, conservative 111MPH). You have to remove the FI, EGR, thermal reactors. Redo heads with big valves, port polish, dual webers, upgrade the ignition. Nice cam and oil system upgrades, Piston/Cylinder set upgrade to match the new breathing abilities through than new exhaust and the car will really scoot. I am going to be building a fun engine, and plan to rebuild the original to stock spec. That way you can pop in the carbureted high performance unit for fun and retain all the originality with a stock FI engine that can be dropped in any time.
Take care, Vince