2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Question about stock injectors/forced induction...

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Old May 11, 2004 | 04:35 PM
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777** The Anti-rice
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Question about stock injectors/forced induction...

How much power can the stock injectors handle for sure? Im asking because I dont know if i should upgrade them or not to accomodate The supercharger. Im planning on running about 8 psi. Would it be a good idea to upgrade all the injectors and the fuel pump?
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Old May 11, 2004 | 04:40 PM
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yeah i would just upgrade it cause eventually you aregoing to want to upgrade it anyways. but i am pretty sure that you are going to need some new injectors and also a new fuel pump.
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Old May 11, 2004 | 06:11 PM
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NA injectors are good for about 250hp as long as the pump can maintain the correct pressure. That bit's important, because with forced induction you need to add the boost pressure to the amount of fuel pressure required.
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Old May 11, 2004 | 06:27 PM
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777** The Anti-rice
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I highly doubt ill be exceeding 250 hp so thankfully i can leave my injectors... But if the NA injectors can handle 200 hp, whyd they make the T2 with bigger injectors when they are around 200 hp stock?
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Old May 11, 2004 | 06:40 PM
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Originally posted by DEZERTE
I highly doubt ill be exceeding 250 hp so thankfully i can leave my injectors... But if the NA injectors can handle 200 hp, whyd they make the T2 with bigger injectors when they are around 200 hp stock?
A lot of reasons. No room for margin, no room for upgrades. You will run the injectors at a higher duty cycle. 550cc is probably better for staged injection in a forced inducted enviroment.

Also, remember that both n/a and turbo have different compressions and different maps.
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Old May 11, 2004 | 06:40 PM
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Originally posted by NZConvertible
NA injectors are good for about 250hp as long as the pump can maintain the correct pressure. That bit's important, because with forced induction you need to add the boost pressure to the amount of fuel pressure required.
And thats with a standalone or stock efi?
Doesn't the stock ecu limit inj duty to 65%?
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Old May 11, 2004 | 06:54 PM
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Somebody (maybe Hailers?J-Rat?) already proved that the ECU pushes the duty cycles up into the 90's...Some guys don't give our injectors/ ECU's enough credit for the ability to make "beyond stock" power...probably the same guys that want to sell the aftermarket stuff to you
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Old May 11, 2004 | 07:00 PM
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And thats with a standalone or stock efi?
Both. That numbers simply based on the capacity of the injectors. It does not necessarily mean that the stock ECU's fuel maps will inject enough fuel to be safe, but that's what fuel controllers or standalones are for.
Doesn't the stock ecu limit inj duty to 65%?
No.
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Old May 11, 2004 | 07:38 PM
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Re: Question about stock injectors/forced induction...

Originally posted by DEZERTE
How much power can the stock injectors handle for sure?
It depends on your fuel rail pressure, BSFC of your engine, the max duty cycle you are willing to run, and the condition of the injectors. If you are using a roots type supercharger, then plan on a horrible BSFC, which would limit you to about 200hp on the stock NA injectors. The 250hp estimate quoted earlier is really more for NA engines with a much better BSFC.

Originally posted by DEZERTE
Im asking because I dont know if i should upgrade them or not to accomodate The supercharger. Im planning on running about 8 psi. Would it be a good idea to upgrade all the injectors and the fuel pump?
Unless money isn't much of a factor, it's probably best to just stick with what you have and watch your AFR and EGT very carefully during initial tuning. You can always buy higher-flow fuel system components later if needed.
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Old May 11, 2004 | 09:04 PM
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777** The Anti-rice
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Yo, thanks for all the technical replies, the people on this board are awesome
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