Please double check my math (fuel injector sizing)
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Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
Please double check my math (fuel injector sizing)
I've got some lucas D3165BAs (37.27lb/hr @ 43.5psi).
Converting to 58psi of fuel pressure, that's:
SQRT ( 58/43.5 ) * 37.27 = 1.1547 * 37.27 = 43lb/hr
So, these will theoretically support (assuming a middle of the road BSFC for NA cars):
((injector size * max IDC) / BFSC) * number of cylinders =
((43 * 0.8) / 0.475) * 8 =
579 hp at the crank
Through my M12, that's around 475-500 at the rear wheels.
If I push my "acceptible" max IDC to 85% I could squeeze 615 crank (525 rwhp) without upping the fuel pressure (and redoing the factory rails).
Converting to 58psi of fuel pressure, that's:
SQRT ( 58/43.5 ) * 37.27 = 1.1547 * 37.27 = 43lb/hr
So, these will theoretically support (assuming a middle of the road BSFC for NA cars):
((injector size * max IDC) / BFSC) * number of cylinders =
((43 * 0.8) / 0.475) * 8 =
579 hp at the crank
Through my M12, that's around 475-500 at the rear wheels.
If I push my "acceptible" max IDC to 85% I could squeeze 615 crank (525 rwhp) without upping the fuel pressure (and redoing the factory rails).
Drifting
Joined: Dec 2006
Posts: 1,523
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From: Holly, Michigan
Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Math looks about right.
I am running Lucas 38#. They will easily support over 500 at the wheels.
Yours appear to be the 37#, not quite the same as mine, but if it helps, my IFR table:
Same table, in metric:
I am running Lucas 38#. They will easily support over 500 at the wheels.
Yours appear to be the 37#, not quite the same as mine, but if it helps, my IFR table:
Code:
Injector Flow Rate Manifold Vacuum PSI Value (Lbs/Hour) 0.0 43.899431 0.7 44.147450 1.5 44.395470 2.2 44.705494 2.9 44.953513 3.6 45.201533 4.4 45.511557 5.1 45.759576 5.8 46.007596 6.5 46.255615 7.3 46.565639 8.0 46.813659 8.7 47.061678 9.4 47.309697 10.2 47.557717 10.9 47.805736 11.6 48.053756
Same table, in metric:
Code:
Injector Flow Rate Manifold Vacuum kPa Value (Grams/Second) 0 5.531250 5 5.562500 10 5.593750 15 5.632813 20 5.664063 25 5.695313 30 5.734375 35 5.765625 40 5.796875 45 5.828125 50 5.867188 55 5.898438 60 5.929688 65 5.960938 70 5.992188 75 6.023438 80 6.054688
Last edited by Y2Kvert4me; Aug 25, 2009 at 05:42 PM.
