Well we finally got my buddies Drag turbo kit on the other night its running about 7psi right now. We ditched the inline pump to go w/ the holley 255 HP pump for forced induction. The car feels smooth and opens up when gets to vtec.

Now he wants to turn the boost up to around 10psi should he run 100 octane. I know i can check plugs to see how they are burning and i know if they get white its lean. Timing is set to about 4degrees behind stock. Any tips on what else we need to run the 10psi... B/m regulator fuel pressure guage and if we raise base pressure w/ the FMU compensate according to what base pressure is set for.. for instance

40 psi base pressure FMU 1.1 + 10psi = 50psi final fuel pressure is that how it works or would it be based on what stock fuel pressure plus the rising rate.


Should we do a few pulls through seond, third and fourth and just read the plugs. Any advice would help


[Modified by turbodsmpower, 6:32 PM 10/25/2002]

 

Are you running larger injectors? Correct me if I'm wrong, but a 1:1 FMU
will not provide sufficient fuel through stock injectors.. On top of that, you
really should run an inline pump anytime you're using a FMU... I'm guessing
that no inline is fine for a 1:1.. maybe.

Most kits run 12:1 through stock injectors.. you might be running too lean.

 

yes i am running stock injectors but doesnt base pressure become raised w/ the intank pump? and doesnt all the fmu's w/ drag kit raise fuel pressure 1:1 if not what do they raise pressure to?

 

All FMUs with Drag/Revhard come with either 10:1 or 12:1

AND although those intanks flow alot of fuel, it doesn't mean that they
can keep the pressure up. I think perhaps a it could keep up with a 1:1, but
definitely not with a 12:1/10:1

 

I also dont think your fuel lines can handle that kinda pressure. When a fuel line busts under the hood and your whole car goes up in flames, you'll wish you spent the extra money for injectors and a real fuel management system.

 

Your fuel lines can hold the pressure, at 7psi and a 12:1 fmu setup with stock injectors sees more then 120psi of fuel pressure..... it sucks but thats how that setup works.

Intank will NOT suffice, it can't keep pressure much over 100psi, you absolutly need an inline pump... I would highly not recommend running over 7psi on a fmu only setup.... think about the 120+ psi your already running... add 3 more lbs of boost and add another 36psi of fuel pressure....

remember double fuel pressure != (does NOT equal) double fuel delivery with stock injectors.......

You need bigger injectors + afc, or straight up standalone if you wanna be "safe" and "reliable"

 

Don't freak the guy out too much... you just shouldn't run stockies much above 65-70 psi... they kind of stop working good. The fuel line is good to like ???psi...

Lets calm down with some math....

270 cc x sqrt(100psi-10psi/40psi) = 405 cc

405 cc / [0.5 BSFC x 10cc/hp] x 4cyl x 80% = 259 Hp (dangerously lean, maxed injectors)

Not much room. Better to start with 310's if you are doing the FMU route.

Remember, the 12:1 FMU regulates fuel 12 times greater than manifold pressure:

1lb boost = 40psi + 12 x 1psi = 52 psi
5 lb boost = 40psi + 12 x 5 = 100 psi
10 lb boost = 40 + 12 x 10 psi= 160 psi (HOLY ****!)

There is no way an in-tank can provide this kind of pressure.

Sorry, its late. Had to re-re-edit.

Sean


[Modified by hybridsol, 3:47 AM 10/26/2002]

 

with an FMU setup and no inline fuel pump, i hella leaned out at just 4psi. you using the upgraded intank fuel pump helps but you need that inline fuel pump. big big mistake. either get larger injectors (and something to control them) or slap on that inline asap. fyi i ran 10psi w/ an inline/fmu setup and it worked fine.

 

i have a set of 450's but no fuel control right now so im not putting them in. It would be useless till i get an afc or something.

so let me get this straight fuel delivery from the fmu is not a 1:1 but 12:1or 10:1 meaning 12lbs of fuel pressure for every pound of boost.