Max HP With Stock Injectors Plus Fuel Pressure Regulator FPR - Advice!
Thread Starter
Joined: Jan 2007
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From: Scottsdale, Arizona
Max HP With Stock Injectors Plus Fuel Pressure Regulator FPR - Advice!
Hi Guys,
My car (1994 FD) currently has stock pri's and secondaries 550cc + 850 cc ( i think)!
My car also has a Nismo FPR fitted.
My question is with my T04R. What limit will the stock injectors plus my FPR take me to? What HP will it be good for?
Any help appreciated.
Thanks!
My car (1994 FD) currently has stock pri's and secondaries 550cc + 850 cc ( i think)!
My car also has a Nismo FPR fitted.
My question is with my T04R. What limit will the stock injectors plus my FPR take me to? What HP will it be good for?
Any help appreciated.
Thanks!
Thread Starter
Joined: Jan 2007
Posts: 69
Likes: 0
From: Scottsdale, Arizona
HI Buddy,
My FPR is an adjustable unit by Nismo. Pic attached. Also, it has a uprated fuel pump Walbro 255 and running Apexi Power FC ECU. What do you think buddy, be good to know others thoughts.


Thanks!
My FPR is an adjustable unit by Nismo. Pic attached. Also, it has a uprated fuel pump Walbro 255 and running Apexi Power FC ECU. What do you think buddy, be good to know others thoughts.



Thanks!
If it is a RRFPR, you have the ability to increase fuel pressure, thus not needing to upgrade the injectors. i.e. the stock FPR is a 1:1 for fuel pressure and manifold pressure. With a RRFPR, you could make that 2:1, or something to increase the amount of fuel used per the same rate of manifold pressure without requiring the need for larger injectors.
What's the limit? I don't know. That's something you'll need a wideband 02 and some tuning time to see what you can do.
What's the limit? I don't know. That's something you'll need a wideband 02 and some tuning time to see what you can do.
You can only raise the fuel pressure so far before the pump's output starts falling off (especially with the Walbro). I doubt you'll get more than 330-340 rwhp on a safe tune. I'm curious as to why the effort was made to adapt an aftermarket FPR when all of the injection system remained stock. Why didn't you put larger injectors in when you had everything torn apart to do the single turbo install?
Since you are already screwed for smog, I would run the 1600cc Bosch injectors with an aftermarket secondary rail. I hope you have a smog hookup.
Since you are already screwed for smog, I would run the 1600cc Bosch injectors with an aftermarket secondary rail. I hope you have a smog hookup.
Thread Starter
Joined: Jan 2007
Posts: 69
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From: Scottsdale, Arizona
Hi Guys,
Thanks for your advice.
Just an update. The car was fine tuned today on a dynapack chassis dyno and made 410 rwhp at 1.1 bar boost. The injector duty cycle was around 98% so we called it a day. But I am happy with the result, your thoughts?
Next step is 1600cc secondaries and Water Injection.
Thanks for your advice.
Just an update. The car was fine tuned today on a dynapack chassis dyno and made 410 rwhp at 1.1 bar boost. The injector duty cycle was around 98% so we called it a day. But I am happy with the result, your thoughts?
Next step is 1600cc secondaries and Water Injection.
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Originally Posted by Lai-ca
Just an update. The car was fine tuned today on a dynapack chassis dyno and made 410 rwhp at 1.1 bar boost. The injector duty cycle was around 98% so we called it a day. But I am happy with the result, your thoughts?
What ratio are you running the FPR? How about A/F?
BTW, some people will probably balk at your high duty cycles, but IMO its not an issue until you want/need more power.
Thread Starter
Joined: Jan 2007
Posts: 69
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From: Scottsdale, Arizona
Thanks for responding! 
AFR was around 11.5
What are your thoughts on the excessive LIM with fuel rail and block off the stock primaries and run all 4 injectors off the Excessive fuel rail??

AFR was around 11.5
What are your thoughts on the excessive LIM with fuel rail and block off the stock primaries and run all 4 injectors off the Excessive fuel rail??
Originally Posted by Lai-ca
What are your thoughts on the excessive LIM with fuel rail and block off the stock primaries and run all 4 injectors off the Excessive fuel rail??
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