Build: VVT and JRSC in 93 NA
#41
Elite Member
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Location: Athens, Greece
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There are two issues here:
1) Fueling
2) Timing
Fueling: The VVT engine needs more fuel across the board than the 1.6. At some RPM/Load areas, it will require significantly more (ie near the redline), in some areas less than that. With a stock 1.6 ECU and a pressure regulator, you won't be able to make the fueling right. You will be very rich in some areas and very lean in others. And since something tells me that you won't even install a wideband, you won't even know, but you will be happy in your ignorance.
Timing: The stock 1.6 ECU commands more timing than the stock 1.8 w/VVT ECU. Add the supercharger (which significantly raises the IAT) and the boost it provides, and you now have a recipe for certain detonation. You need to be able to pull timing somehow, and there's no easy/cheap way to do it with a VVT engine.
1) Fueling
2) Timing
Fueling: The VVT engine needs more fuel across the board than the 1.6. At some RPM/Load areas, it will require significantly more (ie near the redline), in some areas less than that. With a stock 1.6 ECU and a pressure regulator, you won't be able to make the fueling right. You will be very rich in some areas and very lean in others. And since something tells me that you won't even install a wideband, you won't even know, but you will be happy in your ignorance.
Timing: The stock 1.6 ECU commands more timing than the stock 1.8 w/VVT ECU. Add the supercharger (which significantly raises the IAT) and the boost it provides, and you now have a recipe for certain detonation. You need to be able to pull timing somehow, and there's no easy/cheap way to do it with a VVT engine.
#44
Boost Czar
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Join Date: May 2005
Location: Chantilly, VA
Posts: 79,501
Total Cats: 4,080
Anyway, gasoline burns best at a certain ratio, say 14.7:1. Adding more air via a supercharger throws off the ratio, which you must add more fuel to compensate. Now, I can do that mechanically with fuel delivery. The curve may not be exact, as the 1.6 ecu is expecting certain things at certain rpms which are now off. But you can get it close enough. So that is my thinking. Is that not correct?
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