Quote:
Originally Posted by Blackcoog
Hey, I just curious what people were thinking. 
Here are the numbers:
Max Power: 325.45 hp
Max TQ: 277.71 tq
The MAF pegged 5V at 5700rpms so the computer tries to force the last known value but since more air is coming in it leans out slightly. With a larger MAF we should be able to squeeze a bit more out up top if we run it to redline. You can see we stopped short at 6500 because it was starting to lean out. I'm not sure what standard most people use but these are SAE numbers. The tuner said normally down south they use STD which bumps things up a bit more.
Here is the sheet: |
First off, nice numbers.
I'm sure you are running more than 6psi now, that is more like 10psi boost! The real congratulations are in the design of your pulley system though! Congrats on a working design.
Also, how did you measure maf voltage? Did you use MAF counts and interpolate it or actually measure it with an external instrument?
I disagree that adding more fuel up top will add power. In fact I think it will only cool down the combustion temps a bit and maybe add a bit more protection for higher rpm usage. 12.2:1 is very efficient and will not cause a power loss.
Remember that airflow on this engine is most efficient in the 5000-5800 range using SVT cams and duratec intakes. The airflow rate is going to drop once you passed your torque peak of around ~5500rpm. If boost pressure remains relatively constant then you will continue to drop airflow going into the engine proportionately with rpm. So the airflow into the engine may still be increasing but it will do so at a much lower rate and therefore the Load on the engine will go down as you pass your peak efficiency point. You can probably check this with a graph of load on your xcal2.
If your load is sloping off or going down then your airflow rate is decreasing and you can be fairly confident it has nothing to do with fuel. If your load graph is flat or increasing then you are getting sufficient airflow and I would maybe then agree that fuel and/or timing may need to be changed to take better advantage of it.
Also, that lower airflow means that the MAF may not actually be pegged once you get on the downslope of 6000rpm.
So it may be that you hit the natural decline in breathing efficiency of the intake/filter system, or cams/intakes at this point and your airflow numbers just dropped or at least leveled out with respect to the rpm range. I'm under the impression that you are not maxing out the vortec head unit when I make those assumptions.
You should check this against your datalog to see what the maf counts were at 6000 and 6500 rpm. In fact I'd like to see that myself.