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HybridZ

Crushing the FPR


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Yes, I have done it and it is a fairly common no-buck mod in the DSM world. HOWEVER, there are lots of caveats:

 

- Do you know how much of an increase you want and what it will get you?

- If you go too far, there is no going back

- Do you have an accurate fuel pressure gauge? Do not attempt to do it w/o one

- If you are running the stock pump, make sure you do not exceed its capacity. I forgot what it is but TimZ posted the number recently so do a search

- Do it in small increments. You might have to de-install/install the FPR a couple of times until you get it where you want it

- If you go too far there is no going back.

 

In case you do not know the formula for calculating the flow rate, here it is:

Divide the new pressure by the old pressure, take the square root of that number and multiply it by the inj flow. Of course you must know the inj flow rate and what pressure it was rated at.

 

E.g., I believe (could be wrong) that the stock turbo inj is rated at 260cc @ 36#. If you raised the fuel pressure to 42#, the injs are then capable of flowing 280+cc. Make sure you set the fuel pressure at idle with the vacuum line off.

 

Go find TimZ's post and make sure the new pressure + max boost does not exceed the number he specified.

 

REMEMBER, IF YOU ARE RUNNING STOCK INJS, THEY COULD BE AS MUCH AS 20 YRS OLD.

 

Good luck.

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Thanks scottie i did it and it worked great a huge difference in acceleration.It's crushed to about 50 psi the gauge i used is a really good one i used air to find the pressure and crushed it in a vice.It runs a little rich but i'd rather have it rich than lean.I have a couple FPRs so if i want a lower psi i can just crush another.Could i just adjust the afm a little to compensate for the rich idle mixture?The pump is an after market high pressure high flow i changed it before the turbo engine was installed.I love that thing(turbo) i took this kid for a ride i just met him tonight he has a 300zx 85 he took me for a ride and then i took him for a ride he was ****ting when the boost kicked in.Nice guy glad to see another z lover in the area.

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