junk240sx

Just curious what fuel upgrades are the norm when doing a mild boost (~7spi) setup. Would you:
1. Just upgrade FMU
2. Upgrade FMU and fuel pump
or
3. Just upgrade injectors

Or would it be best to do all three? I've always been confused about how an FMU even increases fuel just by itself. Logically it would seem that FMU and fuel pump have to go together. *shrug*

beerbongskickass

With stock 240cc injectors an FMU/fuel pump setup would work under 7 psi. With the FMU/fuel pump setup fuel pressure will be really high and you won't be able to tune anything.

If you want to upgrade injectors you will need something to control them (afc hack, SMC, etc...). Getting larger injectors and some kind of fuel controller would be safer.

Check out the FAQ in the engine management section for more info.

Pat

Nick7

Well, my car is boosted for 2 days so far
I use FMU (10:1 ratio) and inline fuel pump.
I get arround 7psi boost, and so far works great. A/F meter shows rich.. car pulls really smooth with FMU. Hope to get this week to dyno to check exact A/F readings tho.
But.. if you do go FMU way - make shure you get inline fuel pump.

As for saying FMU suxx as you cannot tune it.. partly true, you can always change rings to change ratio. But, in that case, AFC is much much easier to tune. It all depends what you want...

hackish

I am of the opinion that chipping the ECU and running larger injectors is the best way to manage fuel. For the cost of an RRFPR you can usually get it chipped.

-Michael

beerbongskickass

I agree, but he never asked about that so I didn't say anything. :P

junk240sx

Becuase this is a 'junkyard' setup. I have clear goals as far as $$$ goes so I'm trying my best to keep under that. :P

Now with cars like mine (nissan), they have MAF. Would an AFC hack work with such cars? I thought that with MAF, any increase in air would automatically be corrected with more fuel so bigger injectors alone would take care of it without the AFC hack. Let me know if I'm way off.

Thanks.

deacon2377

I dont have experience with MAF's, but I imagine what you said is tru only up to the point when you start putting positive pressure into the system. The ECU's were never mapped to see boost, and when they do they usually freak out and send the car into limp mode.

Boosted_StinkyNuts

So how would a FMU(12:1),FPR, and afc(hacked) w/ 450 injectors run? Good setup for 10 PSI fellas? This is what I will be running as soon as I can find a good buy on an AFC.

88crxSi

you have officially ventured into uncharted territory here on HMT. I haven't heard of anyone on here w/ a MAF.