Hi,

I'm a newbie here. I have heard the the 84 to 85 cars had 680cc injectors. AT what fuel pressure do these flow 680cc? I was also wondering what they look like. Do they look like bosch ones. I am wondering if I can use these on my Porsche 951.

 

The '84-'85 GSL-SE model RX-7s did use a pair of 680 cc injectors. There are indeed Bosch. I believe that they are tested at 3 bar (about 43 psi) as most injector are. However, I've heard of -SE owners having there injectors flow over 700 cc after being cleaned (at 43 psi).

Bosch #195500-0900
680cc peak and hold (low impedance)
orange top

I don't know about the Porsche, but if it uses top feed, Bosch injectors with low impedance (about 2.2 ohms), they should work for you. The only problem, is since they were only used for 2 years and only on the GSL-SE model (most expensive model), they can be a bit hard to get used. Typically they sell for about $100 or so for a pair of used GSL-SE injectors.

Kent

 

Thanks Kent. You know after I spent a few hours online looking into these injectors I remembered these were rotary engines and then i wondered how many injectors were on these motors.


My 944 turbo has bosch , low impedance (peak and hold). stock was 34# at 3 bar. Thanks for the info.

 

correction, 84 SE uses 680cc, 85 SE uses 720cc

 

The factory service manual states 692 cc/min at 37 psi. The injector part number shows the same for both model years as well. As for the 680/720 numbers, I have no idea where they came from.

To determine flow rate at a more typical efi pressure of 43.5 psi (3 bar), multiply the base flow by the square root of the pressure ratio. In this case:

692 x sqrt(43.5/37) = 750 cc/min. This matches well with test reports from stock injectors, as they usually test at 3bar. I can't speak to the fitment issues.