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How can I get more fuel to build up boost? I am trying to understand pw duration right now but am confused because at a given fp and mm3 it is just the time the injector is open so how does it effect the amount of fuel if it is always gonna be the same amount. Like if I add a high duration certain mm3 will that increase the amount of fuel? If you decrease fp it will require the injector to stay open longer to reach the necessary mm3.
Don?t look at your duration table for more fuel to build boost if you are talking the initial spool up, more duration in the upper rail pressure and fuel quantity will help to degrees in the upper end. Look at your limiter tables, timing and rail pressure. Examine a stock tune, particularly the big crater in the timing and rail pressure maps. Log a full throttle run and examine what everything does and how they track through the maps
I thought that the big crater was something we didnt want. I remember when I was asking about an mpg tune you said to smooth out the hole at the top end rail pressure
Still if adjust fp say increase it during spool up that will decrease my pw duration but still produce that same amount of fuel. Only thing that will change is how fast the fuel is delivered. 🤔🤔 will a faster fuel delivery increase spool with proper timing?Quote:
Originally Posted by Tony Bushmin
Increasing rail pressure actually does much more than deliver same amount of fuel at a faster rate. It alters the combustion shape and pressure rise rate. The shape of your rail pressure map will depend upon what you are building the tune for. Having a high pressure rise rate too early, especially depending on how timing is set up can be hard on the engine, hurt the engine, hurt performance and multiple things alike. During the initial spool up a slower pressure rise rate stretched out later in the cycle will help build more boost earlier by getting the hotter combustion gases more into the exhaust to get the turbine spinning more, thus turning the compressor wheel more creating more boost. Care must be taken to not push too far as you can cause the compressor to surge during spool up if it gets pushed too far to the left on its compressor map, outside of its efficiency range. In other words, too much pressure too soon. The turbo will have a threshold it will reach during spool up at which you can rapidly ramp up timing and fueling to really start hammering down power. But you also have other things playing a part in things at the ecm level, limiter tables, these need to be taken into account as well. On the 5.9 CR flattening our rail pressure and adjusting timing accordingly can help with fuel economy.
Analyzing a stock log like you said and rolling into the throttle while building boost the timing goes to 5-6* and once boost builds it goes down to 3-4*. Once boost builds even higher it goes into -4* 80mm3 and 17K fpQuote:
Originally Posted by Jim P
Rolling into the throttle is much different than putting the foot down and going full throttle. Rolling into the throttle you are gently letting the engine build speed, it?s not really working working, just putting out only what it requires to maintain speed. Your timing and injected fuel quantity doesn?t follow boost either. Compare a rolling into the throttle log to a going full throttle log. Much different and results are much different. Limiters come into play more so with going full throttle
what is the air limit. Wide open throttle and I have 133mm3. Stock Boost Limit A table but I did not even reach the boost limit. Could it maybe be a Engine Max Output limit
Attachment 85647
Baro limits