out of injectors

[redhardsupra]

I think i'm starting to get close to the limits of my injectors, which is cool, cause with proper AFR (and i'm pretty damn sure it's good) i am finally making some decent power!

Yesterday i was scanning some second gear runs, and for example:
6100rpm, 73mph (top of 2nd with my 3.73s and 315/35-11 rears)
i was getting 19.7ms injector pulse at 6100rpm, that means i'm right under 100% duty cycle according to

http://www.ecanfix.com/~mdhamilton/dutycycle1.html

And it makes sense too, i was logging torque delievered, and i converted that to hp, and the injector duty follows the shape of HP curve, which it is what it supposed to be. either my car kicks all ass, or the lookup table is overly pessimistic, because there are people with H/C making 440rwhp on 26.4 lb/hr injectors that I have.

I played around with BSFC calculator (http://www.rceng.com/technical.htm) and i'm either making 460 crank hp (with 0.50 BSFC and 95% duty cycle) or my BSFC is different. i did an experiment and it said that i'd be making about 420 crank hp at 0.55 BSFC and 95% duty cycle.

So what do you guys think? out if injectors, bad lookup table, or just old clogged up injectors?

[MNR-0]

19.7ms at 6100RPM is fully loaded. You stand to make more HP with bigger injectors.

The calc. is (19.7*6100)/1200 = 100%

So go get some bigger injectors and haul some ass!

You want something along the lines of 13.7ms at 6100RPM, so something like 36#3bar (42#4bar) injectors would do nicely. That would put you at 70% duty cycle.

[DanaliHD]

i have a 6.0L gmc whipple with 11lbs boost, 42lb injectors and i'm seeing 22ms on my injectors. am i maxed? how can i tell?

[redhardsupra]

i created some tables for easy lookups, take a look:

http://redhardsupra.blogspot.com

[MNR-0]

i have a 6.0L gmc whipple with 11lbs boost, 42lb injectors and i'm seeing 22ms on my injectors. am i maxed? how can i tell?

I would say so. Presuming thats 42#3bar, I would suggest you get a swirl pot and upgrade the fuel pump before upgrading your injectors again.

[DanaliHD]

I have an inline 255lph fuel pump. What's a swirl pot?

[MNR-0]

You must have massive boost.

A swirl pot is a fuel reservoir inline between the fuel pump and injectors. It acts as a surge tank to fuel the difference from what is demanded at the injectors to what the fuel pump can realistically deliver.

[redhardsupra]

hmm...i would like to upgrade to svo30#'s (which are 34.6# really) for my small cam NA application. I do roadrace however, so I would like to prevent situations when fuel wouldn't be able to get from tank to injectors under cornering. Is the stock pump ok to supply 34.6# injectors with fuel under any conditions, or should I start looking for other fuel system upgrades?