Additional Injectors vs. Larger Injectors
05-08-2002, 02:33 AM
#1
Racer
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Additional Injectors vs. Larger Injectors
Can someone help me out here? Racer's group is suggesting to add 2 additional injectors (As CJV has) to be custom mapped to add fuel on certain points of the map where the car runs lean. That is understood. But why can't they put larger injectors to replace the factory ones to address the fuel issue.
In my SUPRA (Here we go again..i know I keep bringing the SUPRA up, but thats where my tuning knowledge lies,)
we replaced the 560cc injectors with 720cc and had the ECU control the larger injectors and increased size of fuel lines and replaced fuel pumps. Now, an ecu programmed to control larger injectors in my opinion is preferred over using AICs (additional injector controller)... UNLESS, the flow required for the power output is such that the injector duty cycles would simply be too low at idle, yielding uneven spray or essentially "dripping" fuel. I know that as injectors get larger and larger... at some point, it will start to yield roughness at injector duty cycles... but, I don't think w/ an expected output level of even 650HP or less, that our cars requires AICs for that reason. Also, fuel pressure, pump, and fuel line size affect injector performance/specs greatly. Why not optimize rather than add? Its cheaper, less noticable, but is it even possible on the Porsche?
-Ryan
In my SUPRA (Here we go again..i know I keep bringing the SUPRA up, but thats where my tuning knowledge lies,)
we replaced the 560cc injectors with 720cc and had the ECU control the larger injectors and increased size of fuel lines and replaced fuel pumps. Now, an ecu programmed to control larger injectors in my opinion is preferred over using AICs (additional injector controller)... UNLESS, the flow required for the power output is such that the injector duty cycles would simply be too low at idle, yielding uneven spray or essentially "dripping" fuel. I know that as injectors get larger and larger... at some point, it will start to yield roughness at injector duty cycles... but, I don't think w/ an expected output level of even 650HP or less, that our cars requires AICs for that reason. Also, fuel pressure, pump, and fuel line size affect injector performance/specs greatly. Why not optimize rather than add? Its cheaper, less noticable, but is it even possible on the Porsche? -Ryan
05-08-2002, 08:29 AM
#2
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It seems other top tuners manage to get over 600ps without altering the size of the injectors:
<a href="http://www.rs-tuning.de/strasse/996/996turbo_kit5.htm" target="_blank">http://www.rs-tuning.de/strasse/996/996turbo_kit5.htm</a>
<a href="http://www.rs-tuning.de/strasse/996/996turbo_kit5.htm" target="_blank">http://www.rs-tuning.de/strasse/996/996turbo_kit5.htm</a>
05-08-2002, 10:23 AM
#4
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VS
The "Drosselklappe" is a larger throttle body for presumably greater air flow volume. I note RS-T's other 996tt kits do not include this item so it seems only necessary above the high 500hp outputs.
The "Drosselklappe" is a larger throttle body for presumably greater air flow volume. I note RS-T's other 996tt kits do not include this item so it seems only necessary above the high 500hp outputs.
05-08-2002, 08:39 PM
#5
Three Wheelin'
cjv, I have changed the fuel pressure regulator on some of my other turbo upgrades when fuel flow has been on the lean side and injectors were not available. Would it be possible to upgrade the FPR for increased fuel flow?
