I would like to use a 3.12 inch pulley when I install my supercharger this weekend, but I have not upgraded my injectors. Can anyone with stock injectors please chime in here? Are you guys bumping up the fuel pressure with a FPR or are you just relying on the FMU? What disc size are your running?

I was hoping that the 8:1 disc would give me enough fuel at ~10 PSI, but now I'm having second thoughts. I'll be running a stock ECU by the way.

Thanks in advance for your help.

 

Although I 've left the injectors stock when I went to the 3.125" I've upgraded to a Walbro 255 fuel pump at the same time. Several weeks ago I revamped the fuel system and was running around with just an Aeromotive fpr @ 34psi and the BEGI/Cartech fmu offline, so that meant I couldn't boost. I could boost once I had the fuel adjusted while on a dyno, putting the fmu online. The 3.125" is supposed to give you 11psi so more fuel is needed.


At the moment I'm gathering up some 370cc injectors.

 

Thanks for the reply. I'll be running the Vortech Aux pump--would I need an adjustable FPR or could I get away with just the FMU?

Wizard, what fuel setup are you running?

 

Well with the 3.125 on a V1 it should be about 10-11psi boost pressure. With an 8:1 FMU you would get 80-88psi fuel pressure. I have seen this done, but it is a bit on the risky side. Since it would only be at the very top of the rpm band and for a very short amount of time, it probably won't be a huge issue in the short term, but for really reliable boost you really need larger injectors and a quality tuning piggy back for large amounts of boost.

 

I've noticed that with the pancake filter on and the 3.125" I wasn't able to reach 10psi until I put on the monster filter (see my other thread about moving the windshield reservoir). I was only seeing 6psi.

 

So I could install the 3.12 w/o upgrading my fuel, but just keep the pancake filter on to stay at 6 PSI until I upgrade my injectors, right?

 

I would prefer that you hold off on installing the 3.125 until you have gathered all of the other ingredients: fpr, fmu, Walbro 255 and fuel rail adapter. Thats what I did.