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Franisco · 10-13-2009, 01:02 PM

In 1998, Toyota's D4 direct injection system first appeared on various Japanese market vehicles equipped with the SZ and NZ engines. Toyota later introduced its D4 system to European markets with the 1AZ-FSE engine found in the 2001 Avensis and US markets in 2005 with the 3GR-FSE engine found in the Lexus GS 300. Toyota's 2GR-FSE V6 uses a more advanced direct injection system, which combines both direct and indirect injection using two fuel injectors per cylinder, a traditional port fuel injector (low pressure) and a direct fuel injector (high pressure).
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I understand that direct injection is supposed to make new strides in terms of efficiency and power. But what is it that makes direct injection so much "better" than port injection?
> Direct injection would mean you can calculate the exact amount of fuel to inject into each cylinder but i was under the impression
> that port injection would allow a more even air/fuel mixture since the turbulence from the intake manafold would help mix the air/fuel
> like a carburator would (crappy analogy i know)
>> With direct injection, you can delay putting fuel in till you've compressed most of the air and then create a burning wave front in >> the droplets as injected. This gives a more even burn.
>> Also with direct injection you can control the spray more accurately than relyign on swirl in the inlet ports. I saw some research >> on direct injection years ago and they used innovate chamber design to pre-mix the diret injection and create the near perfect
>> burn. I'm not aware that any of this is done in todays DI's

10-13-2009, 01:02 PM	#10 (permalink)
Franisco Member Join Date: Oct 2009 Posts: 83	In 1998, Toyota's D4 direct injection system first appeared on various Japanese market vehicles equipped with the SZ and NZ engines. Toyota later introduced its D4 system to European markets with the 1AZ-FSE engine found in the 2001 Avensis and US markets in 2005 with the 3GR-FSE engine found in the Lexus GS 300. Toyota's 2GR-FSE V6 uses a more advanced direct injection system, which combines both direct and indirect injection using two fuel injectors per cylinder, a traditional port fuel injector (low pressure) and a direct fuel injector (high pressure). __________________________________________________ __________________________________________________ ______________ I understand that direct injection is supposed to make new strides in terms of efficiency and power. But what is it that makes direct injection so much "better" than port injection? > Direct injection would mean you can calculate the exact amount of fuel to inject into each cylinder but i was under the impression > that port injection would allow a more even air/fuel mixture since the turbulence from the intake manafold would help mix the air/fuel > like a carburator would (crappy analogy i know) >> With direct injection, you can delay putting fuel in till you've compressed most of the air and then create a burning wave front in >> the droplets as injected. This gives a more even burn. >> Also with direct injection you can control the spray more accurately than relyign on swirl in the inlet ports. I saw some research >> on direct injection years ago and they used innovate chamber design to pre-mix the diret injection and create the near perfect >> burn. I'm not aware that any of this is done in todays DI's Last edited by Franisco; 10-13-2009 at 01:05 PM.