BPW Constant, Lightly confused
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Car: A Camaro
Engine: Weak
Transmission: Weaker
BPW Constant, Lightly confused
Well I upgraded from the stock TBI injectors (40#) to 55# 350 injectors today and I'm a little confused with respect to the BPW Constant. The formula that I've found for it is:
1461.5 * (Displacement of one cylinder in liters)
------------------------------------------------------------
Injector flow rate in grams/sec.
Using this, the stock BPW would be:
1461.5 * .6247 liters
------------------- = 181.7
5.040 grams/sec
But it's not, in my bin, and every other LO3 bin I've seen, it's been 134. So when I changed my fuel pressure a while back from 12 psi to 14.5 psi, I changed my BPW to:
Old BPW * Sqrt (12/14.5) = 122
And tuned from there
So for the new injectors:
BPW = 1461.5*.6247/ ( 6.9299 * sqrt (14.5/12)) = 120.2
Or I could take the old BPW * multipy it by .727 (ratio of the injector flow rates) and use that (88.72)
There's a big difference between the two (duh). Where am I going wrong? Is the stock BPW way off or am I missing something in the math?
Tony
1461.5 * (Displacement of one cylinder in liters)
------------------------------------------------------------
Injector flow rate in grams/sec.
Using this, the stock BPW would be:
1461.5 * .6247 liters
------------------- = 181.7
5.040 grams/sec
But it's not, in my bin, and every other LO3 bin I've seen, it's been 134. So when I changed my fuel pressure a while back from 12 psi to 14.5 psi, I changed my BPW to:
Old BPW * Sqrt (12/14.5) = 122
And tuned from there
So for the new injectors:
BPW = 1461.5*.6247/ ( 6.9299 * sqrt (14.5/12)) = 120.2
Or I could take the old BPW * multipy it by .727 (ratio of the injector flow rates) and use that (88.72)
There's a big difference between the two (duh). Where am I going wrong? Is the stock BPW way off or am I missing something in the math?
Tony
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Car: check
Engine: check
Transmission: check
The regular 350 injectors are closer to 61#/hr, so I'll use that.
61#/hr = 7.686 gms/sec
bpc = (1461.5 * .6247) / 7.686
bpc = 119
RBob.
P.S. Flow rate conversion: gms/sec = (lbs/hr / 3600) * 453.6
61#/hr = 7.686 gms/sec
bpc = (1461.5 * .6247) / 7.686
bpc = 119
RBob.
P.S. Flow rate conversion: gms/sec = (lbs/hr / 3600) * 453.6
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