I found good deals on 680cc injectors. Im picking up 4 of them to replace my stock 550's in my 87 turbo 2. In case you are wondering, I have full exhaust, Walbro fuel pump, upgraded compressor, greddy fmic on the way, and full intake which will go into effect after the injectors and fmic.

I have an apexi safc for tuning but I was told that initial startup and hot restarts will be almost imposible with larger primary injectors. Is this true??

How am I supposed to go about changing all my injectors to 680cc without too much enrichment?

Eric

 

Just use the S-AFC. Bring down your 1000 RPM point by about 45% after you start the car initially (do it cold), and go from there. Really, you may have flooding problems at startup with such large injectors since the ECU doesn't really look at the AFM during startup.

 

why dont u just leave the stock primary 550cc's???
not too many people change their primaries unless theyre makin some serious HP.... just a thought...

 

Also, if you have no other choice but to use them in your primaries, you will probably find a fuel cut switch VERY helpful in shutting down and starting the car.

 

I just figure it will be easier to tune with 4 injectors of the same size. If I used 550 and 680 then there would be a small gap right at 3800 rpms. Since the apexi safc can only tune at 3500 or 4000 then there will be a time when the mixture is too rich or too lean.

Im planning a Haltech ECU sometime this winter so this bandaid will be deleted soon.


So Arron, you are saying before I start my car cold, turn my safc down to like -40?? Then turn it back up when it warms up? Is that what I gather? Fuel switch sounds like a good idea. How are you doing it all with your turbo conversion?

 

I say go ahead and put all 4 680s in. I have some hesitation which I haven't been able to get rid of with my 720s in my secondaries. Pretty hard to tune out. Best reason to put all of them in is so you don't have to put them in later.