Hey Bobl - looks like the crazy guy (BI) pulled you out of retirement for a day. You are a good man !

Yep, that he did! I built a small shop at my house so I can play a little bit. I'm building a Factory Five Cobra replica right now, so that's been keeping me pretty busy.

You would use corrected hp because theoretically when you have perfect air thats when it will need the fuel to support that number.
Injector math goes pretty easy: 72 lb injectors (72 lb at 3 bar/43.5 psi) 72x8= 576, assuming .50 bsfc they will support 1152 hp maxed out, at 80% they will support 921hp. IF motor makes 1020hp PLUS uses 50hp to turn blower it needs 535 lbs per hr of fuel at .50, at .55 it needs 588 lbs per hour of fuel. Using a injection calculator IF you raise fuel pressure to 50 psi the injectors now act like 77 lb injectors which support 1232 hp at .50 and 1108 at .55 maxed out and 985/886 at 80%. I ran 63 lb siemans dekas for years at 80-85 psi which made them act like 88lb injectors which would support 1400 hp at .5 maxed out and 1126 at 80% (I made 1115) , not ideal BUT there were no bigger high impedance injectors at the time, fwiw, Smitty

And IF OP was running 50 psi base with a rising rate regulator at 1 psi per lb of boost (9psi) that would be 59 psi which would put injectors at 84lbs, which would support 1344 at .5 bsfc, and 1075 at 80%, perfectly doable, ideal, maybe not as any difference cylinder to cylinder in flow is exaggerated when you turn up pressure. Now that its been tuned on dyno would I suggest changing them and starting over though, probably not.

The rising pressure in this application does not effectively raise the lbs/hr flow of the injector because it is opening into a pressurized environment. The rising rate reg is necessary to maintain the same flow in lbs/hr under boost as it would at base pressure. Also, the M4 takes a bunch more power to turn then an M3, and with that AFR I'm thinking .55 to .6 bsfc

Prob true also, I love a good technical discussion. I forgot about the fact the fuel has to overcome the boost!

Yup. That's why they do it that way. Imagine having to program the ECU without the intake vacuum / psi sourced regulator ? Yikes.

I did it to my Blown procharged motor last time on dyno after going to 80 lb injectors, wasnt really that hard, was running 55 psi of fuel pressure. Slow and painful using MEFI burn until you get used to it then its a cake walk, no auto tune! Used boost multiplier tables

I'll have to do something when I actually get to install the blower in the boat (have to get a real drive first)..
Looks like it'll work out to 90% duty cycle on the top end if I set the base pressure to 51 psi..
I'll be at full throttle for such a short period of time I'd think it should be fine..

The fuel table is set up as "volumetric efficiency" numbers so, in theory, when I raise the fuel pressure, I should be able to change the injector size in the settings until the A/F ratio falls back in line with what we had on the dyno as opposed to re-figuring the whole map...


Doug

The fuel table is set up as "volumetric efficiency" numbers so, in theory, when I raise the fuel pressure, I should be able to change the injector size in the settings until the A/F ratio falls back in line with what we had on the dyno as opposed to re-figuring the whole map...


Doug[/QUOTE]

Nice job !! I hope all goes well for you.