Quote:
Originally Posted by KoolBRZ
FYI unburnt fuel DOES throw off O2 sensors, because the oxygen that would have been used to burn it would have been converted to CO2. Since the fuel is unburnt, the oxygen is also unconverted, so, there is more oxygen present along with the unburnt fuel. The fuel isn't unburnt because there isn't enough oxygen, it is unburnt because the conditions for complete burning were less than optimal.
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Unburnt fuel will be occur when injecting
before the exhaust valve closes. CO2 has nothing to do with it. The O2 sensor will read lean and not register the unburnt fuel. This is not throwing off the O2 sensor, as you put it, just something to note. You don't tend to get unburnt fuel after the spark event, if it's not fully burnt in the cylinder it continues to burn in the exhaust. This is why you get hot EGTs due to retarded timing or too much fuel etc.
Quote:
Originally Posted by KoolBRZ
The DI angle is changed to compensate for the increased scavenging caused by lower restrictions in the Intake and Exhaust. An optimal angle will burn more of the fuel, so the combustion is more complete before being swept out by the Intake air. Since I have less restrictive Intake and Exhaust than OEM, I have more scavenging than OEM. AVCS timing is also as much as 30 degrees different than OEM, to give the charge better conditions to burn completely.
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DI is alot less prone to bypassing the cylinder than PI due to location and fuel pressure to the injectors. Again you haven't really stated specifically what's wrong with the OEM values, you're making broad statements (assumptions) but no valid data to back it up. What you're actually wanting to do with the DI angles is adjust the EOI to spark timing for adequate cooling. This is more relevant for changes in fuel quantity being delivered rather than cam timing. Go read papers about DI SOI/EOI, there is very little mention of cam timing
Quote:
Originally Posted by KoolBRZ
DI cools the charge, is much less prone to knocking, but is limited by the size of the injector.
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... yet you can supply far more fuel from the DIs than PIs.