Calculating Injector Size
Jul 10, 2005, 02:26 PM
#31
Originally Posted by JustDSM
I never did understand why people are so quick to jump into HUGE injectors. My Denso 660's are only running at ~80 duty cycle @29psi w/ 43.5psi base fuel pressure (Race Gas).
It's flowing 51lbs @6000ft ASL too
It's flowing 51lbs @6000ft ASL too
Jul 10, 2005, 02:28 PM
#32
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Originally Posted by fre
is 43.5psi higher than stock? Just curious because I might intall my aeromotive fpr if that is the case to get back into a safer duty cycle.
Jul 10, 2005, 05:58 PM
#34
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Because with my engine management setup I no longer use the resistor to drop voltage to the fuel pump under light loads. Now that my fuel system runs full steam all the time, I'd end up over-running the OEM regulator.
Jul 10, 2005, 06:31 PM
#35
Originally Posted by JustDSM
Because with my engine management setup I no longer use the resistor to drop voltage to the fuel pump under light loads. Now that my fuel system runs full steam all the time, I'd end up over-running the OEM regulator.
Last edited by fre; Jul 8, 2010 at 05:01 PM.
Jul 10, 2005, 06:39 PM
#37
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Originally Posted by fre
Interesting I haven't heard of this before. I just use a wahlboro and I don't believe I am over working the OEM regulator? I couldn't tell you though, because my car seems to run fine.
I've had to bypass the way the OEM ECU controls the fuel pump circuit. When I did this, I had to eliminate a nifty feature.
Nov 11, 2009, 09:27 PM
#38
Holy old thread lol. I understand this a lot better now, having an inline fuel pump on a direct circuit that only kicks on after 5psi. I actually had both pumps running all the time before, but had a fuel pressure regulator to keep it in check. As far as injector sizing goes, I would buy the biggest ones you can without screwing up your part throttle. I run 1150s without a problem on AEM. I say this, because I have upgraded my damn injectors three times now stock - 660s - 880s - 1150s hah.
Apr 24, 2010, 10:08 AM
#40
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You may want to PM Bryan at GST. He said that with a stock head, on 91 octane pump, with an Old-School Green at 24-25 PSI he was seeing over 94% DC with Denso 720's...I think. He stated that the 720's actually flowed more like a true 680 injector too.
Last edited by sparky; Apr 24, 2010 at 06:36 PM.
Jul 8, 2010, 04:57 PM
#42
Something else I can add to this thread is that from my inline setup to my dual in tank pump setup I just installed, I gained almost 15-18% injector headroom. I am now running 32psi and only hitting like 80% duty cycle on my 1150s with E85. For reference at the same boost with the inline pump, I would hit 95-98% IDC. I am pushing around 530-540whp right now. I figure if I wanted to exceed 580 or so I would need bigger injectors with this fuel setup.
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