2270 Gear Ratios for 912

[tylinol]

Hi everyone - long time listener, first time caller. I'm building a Type 4-powered '66 912 and will be putting together a 2270cc kit form the Type 4 store. I've started down the journey of rebuilding the transmission, and need to decide on gear ratios.

I've got two transaxles right now - a 902/00 4 sped (A-H-Q-X ratios) and a 914 tail shift donor transmission (A-F-N-V-ZD). The idea is to use the internals of the 914 transmission to turn the 902/00 into a 5 speed.

The intended use for my 912 is 100% street, and it needs to be able to cruise comfortably at 70-75mph for a cross-country road trip I'm planning. Most of my day-to-day driving is around town, though.

Between the two transaxles, can I put together a set of ratios that will work will with a 2270 engine's torque curve, or should I be buying some different gears to do what I want to do?

[Bruce.m]

I’d go with the 914 ratios, for quieter highway cruisng but your tune (fuel & ignition) needs to be spot on since the fan will be running slower with a higher gear.

The 911 ratios are suited to the higher reving engine.

There are good gear ratios calcs online so you can check the rpm range vs speeds.