Too rich, will cams help?

[painmaster]

Hey guys I just went from 550 injectors to 780 injectors, and now I cant get the car lean enough without droping the base fuel pressure to 30PSI. Running the injectors at this presure feels like crap at all part throttle possitions. The reason I bought the 780's was becuase I had to crank up my base fuel pressure to 50 PSI to run 25PSI boost (with 550s), and I was planning on upping my boost to 30PSI (by buying a bigger turbo), and adding the 264/272 cams. Funny thing is that now I have larger injectors, I am running 30PSI without a larger turbo.

So here is my question, will dropping in the 264/272 cams increase my airflow so that I will be able to turn up my base fuel pressure to where the injectors need it. Or do I need to buy some 660 injectors before my cams come in? Anybody drop in cams when they were already running 25-30psi, and had to add in more fuel as a result?

 

[philipkrotch]

i dont see why not...they will allow more airflow.

 

[Mirage2LTurbo]

So in other words, you went from 550's to 780's and just turned the boost up to make up for the jump in injector size?

 

[painmaster]

So in other words, you went from 550's to 780's and just turned the boost up to make up for the jump in injector size?

I was running 25PSI boost on 550's with base fuel pressure set at 50PSI. This would put me at around 11.8 AF at WOT. Running at 50PSI base fuel felt good at full throtle but, part throttle acceleration was slugish. I played a lot with the base fuel pressure and my VPC and GCC settings, and I could tell that right at 43PSI base FP the low to mid throtle acceleartion was kick ass. Problem is that if I run 43 PSI with 550's at 25PSI boost the car goes lean at WOT and I get knock. That is why I turned up my base to 50PSI. My theory is that the injectors were designed to opperate with around a 43PSI pressure drop, and that maybe my spray pattern was being affected.

So I bought 780's with the plan of buying a larger turbo, and cams. I figured the larger tubo would allow me to run 30PSI boost, since my 20g would never boost over 25PSI, and this is with my wastegate never opening. I ordered the cams and I am waiting. I put the 780's in my car without any adjustments and my car went from 25PSI at WOT to 30PSI at WOT. I later added a 660VPC chip that helped my idle. I have my VPC and GCC max lean for WOT, but the only way to get the ratio to 11.8 at WOT is to drop the base fuel pressure down to 30. At 30PSI the car feels like crap, part throttle acceleration sucks, probably because the injectors cant operate properly at 30PSI.

So now I'm wondering if my new cams will allow my car to use more fuel at WOT, and thus allow me to raise my base fuel pressure back up to around 40PSI.

If my car doesn't run better with the new cams, I'm going AEM EMS!

 

[kessler]

Well first off ive ran a vpc and with a similar set up but i already had the cams in it, So id say right off the bat you need to go programable like i did and i havent had any tuning problems what so ever since i did that. The biggest problem your having is all that piggy back crap going on that its going to start crossing other stuff out and make it harder to work the way you want it to.. My sudjetion is to just straight up buy an AEM or a Haltech

 

[painmaster]

So id say right off the bat you need to go programable like i did and i havent had any tuning problems what so ever since i did that.

I wanted to try the VPC GCC one last time, before I went to a stand alone. I have no more adjustability where I'm at right now. I guess its time!

Did you go with AEM?