390cc for 680cc

[95gsttsi]

So I recently did a stock floating head swap with a freshly built head and pulled 390cc injectors from my old head well one of the black plastic pieces broke off tue bottom of one and at this point all I have is a stock set and a set of 680cc injectors.. I am running a walbro 255 an aftermarket fpr and a fmu wity fuel cut.. on the 390's I was pushing 20psi no problem. My fpr is set at 43 psi at idle. And ranges between 43-60psi under a load... what I'm getting at here is with my fpr set the same will the 680's dump too much fuel? And is tyere anything I can do to compensate?

 

[dsmcrzy]

Yea there is a way if you have megasquirt.

On the stock ecu you will be stuck 'fooling' the ecu into thinking you have small injectors.

 

[silvreclips]

680cc injectors are going to be way to big for the fuel system your trying to use. It sounds like you plan on making some decent power so you should really think about upgrading either to Port fueler or Megasquirt. Running a FMU with that much boost is just asking for trouble. And not using anything to pull some timing at that boost level Im surprised you havent blown the motor up already.

 

[Slo2gen]

I still don't see how 20psi and 390cc injectors agreed with each other.

 

[95gsttsi]

Its a slow spool but once it hits 15 its goes a lil faster but not much but the 680's are a no go my wideband shows and it just putts at idle