Because the rate of air is different per the two turbos. So the smaller k04 cant compress the same amount of air efficiently. So you just cant flow enough air to get enough bang for more hp.
So you run leaner to make more bang but lean can be dangerous.
Maybe its fuel quality issue and not quantity
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More specifically, with the smaller K04 vs big turbo you're going to have more back pressure from the smaller turbine, so cylinder pressures may be even higher for the same power level compared to big turbo. This would cause higher injector duty cycle to get the same amount of fuel into the combustion chamber. In other words, it may take less fueling (injector/hpfp-wise) to run same or more power with a larger turbo due to efficiencies.
A lot of people maxing out the K04 run water/meth not just for the added octane and cooling, but also as a sort of auxillary fuel system where the methanol provides a portion of the fueling and reduces the amount of fuel needed to be delivered by the fuel injectors.
Would it also matter when during the intake/compression stroke the fuel is being added? If more fuel is added earlier in the cycle, I would think you could get more fuel flow due to lower cylinder pressures at the expense of maybe some knock sensitivity? Getting a little outside my knowledge base there.
I have a K04 and was running out of fuel in my Protune as well......
Everyone I've talked to says that a MK6 TSI should NOT have any fueling issues on K04 power levels. The latest revision of my tune has dialed back load a bit and my fuel trims are much better, but I'm down on power. I don't understand how big turbo guys can make near 400WHP on stock fueling, but my car cannot push a K04 to its potential.
To anyone with extensive knowledge of our platform's fueling setup: which aspect of the system is the most likely culprit; LPFP HPFP, or injectors?
The tune feels phenomenal, as I expected with Stratified, but I'm wondering if I'm leaving power on the table due to some sort of a mechanical issue.
What are you at for power level? Keep in mind that "K04 power levels" may really be something like 300-330WHP, at which point yes the stock fueling should be sufficient. "Pushing the K04 to its potential" may indeed require at least water/meth, all depends on what your perception of the K04's potential is.
Also, I'd be surprised if getting over 400WHP on stock fueling didn't also require water/meth or race gas. For reference, APR advertises 370WHP for their GTX2867 big turbo kit (that turbo is good for 550HP), so 400WHP is probably a pretty big stretch on stock fueling especially without water/meth.
