is it safe with 12psi???would only be making 250whp or less probably(d16y7 turboed with forged pistons and rods)...someone told me my stocks WITH the fmu would probably only be good for 6psi, but that did not make sense too me..greddy SOHC users run there stock injectors with sometimesup to 9psi on the blue box and there fuel pressure is normal..why would my stockies only be good for 6 with the fmu??that doesnt make sense????

 

depends on what fmu and what injectors

 

6-7 psi max on stock injectors/pump/12:1 fmu...

 

It is desirable and recommended to keep your max fuel pressure at 110 psi or less. 110 is not safe, IMO, but many people have done it ok with an inline pump.

You do the math.

Sonny

 

your stock injectors will not support 250whp they are only 240cc.
with stock injectors and a 12:1 fmu i would limit your boost to 6psi at the max.
Lets do some math here...say you want to run 9psi with your set-up.....
12 x 9 + 50 = 158psi of fuel pressure. You'll never see that much but thats what would be required. Explanation 12 (fmu ratio) 9 (psi of boost) 50 (40 static + 10psi the stock fpr adds under full throttle).
So trying to get that much fuel pressure out of a stock system designed for about 60psi max is plain stuipid. most any fuel pump you get will max out about 120psi anyway. The greddy blue box works by increasing the injector pulse width to get more fuel when it opens, fmu's use high pressure to force more fuel everytime the injectors open. I've never heard of anybody runing 9psi on a blue box sucessfully. I believe 7psi is pushing it.
If your spending all that money on building the engine why not tune it better? invest some money into the tuning. At least run 440cc injectors and a v-afc. Anything you can do to stay away from high fuel pressure your car will thank you.Ultimatly going stand-alone is your best bet but you will still need larger injectors.
12psi on that engine will net you about 210-220whp if it's tuned decently.
so to answer your question no it is not safe to run 12psi with a 12:1 fmu and stock injectors

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16ahybrid &raquo;</TD></TR><TR><TD CLASS="quote">your stock injectors will not support 250whp they are only 240cc.
with stock injectors and a 12:1 fmu i would limit your boost to 6psi at the max.
Lets do some math here...say you want to run 9psi with your set-up.....
12 x 9 + 50 = 158psi of fuel pressure. You'll never see that much but thats what would be required. Explanation 12 (fmu ratio) 9 (psi of boost) 50 (40 static + 10psi the stock fpr adds under full throttle).
So trying to get that much fuel pressure out of a stock system designed for about 60psi max is plain stuipid. most any fuel pump you get will max out about 120psi anyway. The greddy blue box works by increasing the injector pulse width to get more fuel when it opens, fmu's use high pressure to force more fuel everytime the injectors open. I've never heard of anybody runing 9psi on a blue box sucessfully. I believe 7psi is pushing it.
If your spending all that money on building the engine why not tune it better? invest some money into the tuning. At least run 440cc injectors and a v-afc. Anything you can do to stay away from high fuel pressure your car will thank you.Ultimatly going stand-alone is your best bet but you will still need larger injectors.
12psi on that engine will net you about 210-220whp if it's tuned decently.
so to answer your question no it is not safe to run 12psi with a 12:1 fmu and stock injectors</TD></TR></TABLE>
my thoughts exactly...

 

ouch this really bites...i wasnted to use stockies so i could have a stock idle..right now these crappy 450's idle like ****, run like **** and just give problem after problem... would 550rc's workbetter??right now i'm using smc..the first version so it isnt exactly precise..

 

what car do you have? I found that the smc2 diagram is WRONG. the MAP wire is in the wrong spot, hence RUNNING LIKE ****...

oh ya, after thinking the SMC was a pos, we put that in my bros 4th gen, installed a VAFC in its place, and both cars run GREAT now...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GOLDBERG &raquo;</TD></TR><TR><TD CLASS="quote">ouch this really bites...i wasnted to use stockies so i could have a stock idle..right now these crappy 450's idle like ****, run like **** and just give problem after problem... would 550rc's workbetter??right now i'm using smc..the first version so it isnt exactly precise.. </TD></TR></TABLE>

um if your having a poor idle problem it's probably because your runing to rich so swapping to larger injectors will just compound the problem.
my understanding of the smc is that you can shorten the injector pulse width to lean it out. So you should just get it tuned on a dyno w/a wide band o2 sensor.I've heard of quite a few people using that set-up with great results so it sounds like you just need to do some tuning.

 

not sure..idleing gets worse if i lean it out at all..i havent hooked up my wideband yet..need to find nuts for my downpipe bolts.. and yeah the smc wiring diagram was wrong...only the map wire was correct... i went and tapped rpm wire @ dist for rpm and battery for 12v

 

I'm only gonna say this because if I don't I'm going to have a stroke.

YOU HAVE FORGED INTERNALS, GET SOME MANAGEMENT!


I just don't wanna see your post later on about how you spent so much on bulding your engine and now you don't know why it blew up.

seriously, listen to me or the other members and upgrade your system.

 

umm i havent put in the internals yet..and i just said i have the smc and a wideband..but i really needa upgrade to the smc 500...