[s4nd]

Originally Posted by steve99

with standard injectors your probably going to get to the limits of what the direct injection system will supply with 9 psi boost you may need to increase the port fuelling percentage to say 30% at all rpm when loads exceed 1.


If your boosted your going to also need to raise your load limits and rescale the load axis on quite a few timing and fueling tables, else that will cause lean running.


If your using MAF based fueling you may also be maxing out the maf sensor maxium maf volts is 5v.


you want to keep your DI pulse width below 7ms and port injection pulse width below 15ms


else you risk maxing out one system or the other




here's a bit of info from a pro turbo tuner mot-east tuning


"I have grown to LOVE the split DI/PI system on this car. It is more work--yes, but in practice it works incredibly well. Out of all the things we can tweak on this car to make power, the DI/PI ratios and timings are the least touched. The engineers knew what they were doing here, and any tuner who actually spent time trying out the different variations empirically, will be using something very similar to OEM.

The reality here is that DI works BEST by injecting in a very narrow window, just as @arghx7 outlined. Too early and you're blowing out the exhaust, too late and you're still injecting when the combustion event goes off. Another factor is that you don't want to inject too far away from the spark, that's why it isn't just 370 across the board.

We've seen some tuners swear by DI only, and others use 50/50 split or even full on PI in really high HP applications. I don't think either one is a good solution.

Think of it this way: DI fuel delivery will always be the optimal method, UNTIL you make the mixture too unstable or wash the cylinders. Wash is unlikely, but once you approach 7ms injection times (250+whp with e85) you begin to lose some of that benefit. The mixture becomes less stable. Between about 300whp you cross over the threshold where 35% PI has no negative effect. 20% PI on OEM tunes? We have found absolutely no repeatable HP gains, as in 0, like none-what-so-ever. Despite changes in timing, leaner or richer, more or less aggressive cam timing, or different injection timings...I think one car actually made 1hp over 20% PI mix...which is within the margin of error between runs.

So in reality, there's just no reason to overstress the DI system with long IPWs. Take advantage of the dual injection, max out the DI to about 6 ms (this way in sub freezing temperatures you have headroom) and then run port at no more than 80% duty cycle, or about 15ms.

Also, as a comparison the DI equipped FA20 in the 15 WRX...we can't run half the timing on those! DI only we hit the knock threshold at a much lower HP using DI only. Can't explain it and it's still a very new system, but it made me wish for the BRZ setup having tuned it. "

Thank you very much Steve for the help, yes i had rescale load to 2.5g/rev both on fueling and ignition timing map, i also rescale maf sensor, and sorry, how can i increase port injector fuelling till 30% up?. what table or map should i modify?


cheers
Sand