Yes, but WHY?
COBB allows much more customization on a per car basis compared to the other tuning tools, and can be tailored towards the individual car.
I guess I'm looking for a much more technical reason why running leaner like the 5150 protunes do, is better.
Hi there,
So we are talking about small changes in AFR. Peak power is going to be around 0.88-.92 lambda on these vehicles. I don't like using AFR since stoich changes depending on fuel source (11 afr on ethanol is way leaner than 11 afr on gas).
Port injection vehicles inherently need to run a little richer due to the way the air/fuel charge is dispersed (homogeneous mixture). As you increase the amount of incompressible unburnt liquid into the cylinder, your potential for power will go down. A lower lambda target can indeed be used as method of lowering combustion temperatures, but usually at the expense of power. Water injection is a good example. If you don't increase timing or boost, water injection will actually lower power output (decreased volumetric efficiency). You also increase emissions running richer.
On a DI motor, since the injectors run over 10 times the pressure of a conventional port injection injector, the spray pattern is much better and can be aimed directly at the source of ignition - the spark plug. You can in theory run an overall leaner AFR but for all intents and purposes in the area of the cylinder where knock is most likely to occur, the mixture can be richer. It also allows a shorter window of injector pulse width and increases efficiency.
So when comparing a DI and PI motor, DI can run quite a bit leaner and still be ahead of PI in detonation resistance.
Without throwing your car/mk7's on the dyno, you'll never know how much power you are giving up running a richer mixture than what makes the most power. Personally, running really rich has caused phantom knock in some instances just like what water/meth seemed to do for me. If you are increasing unburnt fuel you better be increasing timing to make the power. Remember that air scavenges quickest when hot, which is why velocity matters so much in exhaust design.
I can't give an answer on how much power you are giving up. I will say tons of people run mid to low .8's lambda with 400-500whp on the stock motor with no signs of any melted valves or internals. You are safe.
