How can I find out the duty cycle my stock injectors are seeing?

There is a way to calculate required injector size for a given HP level at RC web site, but I am not sure what to put in for "System Fuel Pressure at Fuel Rail"

I just want to make sure that I will not exceed 80% duty cycle with my stockers after I put in my cosworth cams...

If I can replicate Works power gains (11% over stock ATW HP after cams) I should be making around 45%+ more WHP than my stock baseline...

 

What max boost level, Boss and on what gas?

 

pump gas 92/93 octane. Boost is currently set to 22.5 and tapers a bit as the revs increase. We will probably shoot for 11-11.5 AFRs. However, we might also try lowering AFRs to have more room w/t timing and boost...

 

That will be more like 95% IDC. But there isn't much to worry about, the stock turbo regardless of mods can only push the stock injectors to about 102% IDC at 11:1. If you are 2% over 100 all that happens is you lean out 2%, or about 11.2:1. I ran this way for over a year before upgrading to 950s, just because DSMlink makes it easy.

Any calcs that use BSFC are little more than a guess, since everyone guess at BSFC. You can do the math the proper way if you know injector flow at what pressure, base fuel pressure, fuel specific gravity, target AFR, and airflow in mass/time. I have a spreadsheet I put together to make it easier that has proven to be accurate in all fields down to .1 unit.

 

thanks bud. just went to the shop and asked the guys over there as well. a friend was able to push 400BHP with the stock ones, so I should be fine...

did you ever get dynoed - what are you pushing currently?

 

I personally feel dyno numbers are based on pure magic, too many variables. I prefer to use the dyno for tuning, and go by the track performance. The most I dynoed in this car is 325 on a mustang dyno, but it went 122 mph.

 

fast as hell... Any tips on tuning? The dyno I go to reads so low, I don't even quote atw figures on evom. When I was stock, I put out 206WHP in 50F cool weather and the car was dead even in performance with an E46 M3...