I have an 89 Turbo II and I would like to put 3rd gen upper and lower intake manifolds on it and convert it to MAF. Does anyone know what is involved in doing so as far as wiring and other things? Any help is appreciated.

 

The stock system is MAF. Until I get my grubby paws on an e-manage and prove that it's possible, the consensus is that you cannot change the air metering type. You cannot use the third-gen LIM, but the UIM can be fitted with some creativity.

Brandon

 

Actually the FC RX-7 uses neither speed density or MAF sensing! Speed density uses a MAP (manifold absolute pressure) sensor to measure load (this is what the FD uses), MAF (mass air flow) uses a hot-wire airflow meter to directly measure the mass of the air being sucked in. The FC's flap (S4) and sliding cone (S5) airflow meters measure air volume flow and air temperature, and the ECU calculates mass airflow from that.

It doesn't matter what manifold is used, it depends on the ECU. You can't change the stock AFM for a MAF (hot-wire) airflow meter because the software required is completely different. Your only real option is to change to an aftermarket programmable ECU (e.g. Haltech) which all use speed-density (MAP sensor) and so don't require an airflow meter.

 

is there a way to get rid of the "sliding cone" in an s5?
seem like its a big restriction there

 

Technically, the stock FC does have a MAF (Mass Air Flow) system. However, modern slang does assign the MAF label to the heated wire type, and the mechanical types are generally called an AFM (Air Flow Meter). The third type of MAF system is the vortex flow sensor. They all measure the same thing, mass airflow, but just use different methods. A heated wire MAF sensor requires the ECU to control the wire heating, so it will not work with a mechanical-type AFM ECU which has no provision for this function. I doubt that the twin-turbo FD ECU will work well with your proposed hybred engine.

I think you will get better results by installing a stand-alone EMS which is capable of the more advanced Speed-Density measuring system, which measures Manifold Absolute Pressure and Engine RPM.

 

An aftermarket stand-alone EMS (ie Haltech, Electromotive, Microtech, Wolf, etc.) which will run in speed-density mode will allow you to ditch the sliding cone. The S5 isn't all that bad, but the S4 with it's vane-type AFM and half-speed computer is just begging for a modern upgrade.

 

You're right, but it doesn't have a mass airflow sensor, which a lot of people call them. This is one of those points I get a bit **** about. Unlike the hot-wire and Karman vortex AFM's, flap or cone types can't directly measure mass air flow, only air velocity and temperature seperately. The ECU does use mass airflow as it's load signal, but it can't actually measure it, only calculate it.
Yeah I know, get a life...

BTW, personally I wish aftermarket ECU's had the ability to use hot-wire AFM's. Large ones have very little restriction, and mass airflow sensing is actually far more acurate than the speed-density system that all aftermarket units use. This would be much more suitable for high-powered street cars where peak power isn't the only concern.