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Discussion Starter · #22 ·
I just wane say thank you john for u help today i mad my day lol im just happy with hoe the car drives better
 

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I don't agree with below. The stock fpr regulates the fuel pressure and adding bigger pumps when not needed will not provide any more fuel as fuel pressure stays constant. Same fuel pressure with upgraded pumps will yield same amount of fuel to your engine. You will need larger injectors and stock pumps will support all the stock turbos can handle on pump gas (only need upgrade if running E85).
Hks provided extra fuel by raising the fuel pressure with fpr using stock pumps.

Yes, injectors will be maxed out, but fuel pumps will give it a more head room.

-John
 

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I don't agree with below. The stock fpr regulates the fuel pressure and adding bigger pumps when not needed will not provide any more fuel as fuel pressure stays constant. Same fuel pressure with upgraded pumps will yield same amount of fuel to your engine. You will need larger injectors and stock pumps will support all the stock turbos can handle on pump gas (only need upgrade if running E85).
Hks provided extra fuel by raising the fuel pressure with fpr using stock pumps.
This isn't some new thing, we do this all the time on other cars.

Stock injectors & stock pumps vs stcok injectors & upgraded pumps = noticeable difference.

I also saw this AGAIN first had last week with two GTRs.

I'm not going to argue that pumps alone is the way to go, but for the person that doesn't want the expense of a custom map - this is most definatley the cheaper route.

-John
 

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Because at 67 psi of fuel pressure (17 psi boost) it can flow 250 lph or approx. 430 lb/min which is greater than the 6 stock injectors max flow rate. Based on the test, the stock fuel pumps can maintain the pressure at the fuel rail as designed and adding bigger pumps wouldn't help because the fpr will just bypass extra fuel to maintain the designed pressure. So both pumps will see same fuel pressure.

That been say, the only way to prove bigger pumps help is it maintain a higher fuel pressure than stock (Such as stock can't maintain design pressure).
 

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Only way to find out is put a fuel pressure gauge and see if you see fuel pressure drop while run through the boost. At certain pressure, injectors can flow certain cc/min which is volume over time. So at constant pressure, injectors will flow the same volume. There might be other issues such as clogged fuel filters that impede pump performance but it will show up on fuel rail pressure.
 

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Discussion Starter · #31 ·
Lets cut true this and put it this way im upgreading injectors and also the pumps to be sure im on safe side
 
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