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Old 04-28-2013, 12:28 AM   #1678
Scooby Specialist
Member#: 290921
Join Date: Aug 2011
Chapter/Region: AKIC
Location: Eagle River, AK
2010 Impreza WRX prm
WR Blue


Originally Posted by Alaskan EJ20 View Post

what turbo and injectors, you want your jet or jets to match 30-50% of fuel flow at wot.

So if your using a vf 39 with 650cc injectors and your at 65% duty at wot:

650 x 4 (you have 4 injectors)= 2600cc (but only at 100% duty) so 2600x.65 (65% duty cycle)= 1690cc (full fuel flow at wot). Then 30-50% or 1690cc would be your jet size. so jets that would flow 500cc-800cc would be ideal.

Now keep in mind boost aswell, alot of these meth pumps flow at 150psi, but if your running 22psi in the intake manifold then that counters the meth pump output, so 150psi-22psi= 128psi, so you have to get a jet that flow 500-800cc when the pump flow pressure is at 128psi.

lmk if i can help.
I'm running a 20g & 1000cc ya I'm still lost on the sizing haha I'm trying to understand it and this is really good info I might head down to underground and talk to nick about it
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