I have considered trying it after seeing you talk about in other threads, but I get a little lost in the math trying to correalate the volume at idle to 4500 rpm where mine is starving...
Let me try and help you with that.These pumps are serious business. Even the stock 318 pump often has more output,running wide-open, at idle than the stocker will ever use.
A gas engine is said to require 1/2 pound of fuel per hp, per hour.
A gallon of gas is said to weigh about 6.25 pounds
A 400 hp engine thus requires 400/2/6.25=
32 gph. This equals 32/60minutes =.53 gallons in 1 minute, or just over 2qts/min, or 68 ounces/min; At the rpm of peak hp.
So at 4500rpm this mythical 400hp engine might be putting out 340 hp, requiring just
27gph, or 58 oz/min.
The spec for a stock pump is 1qt. per min@1000rpm. This is 32oz/min or
,19gph; To the carb!
So if your pump puts out 32 ounces in 1 minute at 1000 rpm,this is already good for 237.5hp
>I would not expect that pump to put out twice as much at twice the rpm; but I would expect it to be at least double by 5200/5400, the rpm of peak hp for the typical street cam.So if it doubles, that would be 38gph or good for 475hp.
On the HOs, the output is rated at
80gph free-flow, which is 170 oz/minute, good for 1000hp
>You could check your output at 1000 rpm for 15 seconds and record it. You could repeat the test at 2000,and 3000, and so on. Then graph the results, and extrapolate to 6000. You could then grab the qty,off the graph, at where your engine makes peak hp and convert it to pounds per hour and then hp/hr. Since this is a free-flow test on an installed set-up, this is the best situation to see accurate results.
If your pump cannot do it, before pitching it,check the return spring on the arm. In order for the pump to do it's job, the arm has to stay in contact with the eccentric,for 100% of the stroke. A weak spring will not return the arm fast enough, and the arm bounces or floats, and the output plateaus early.
>In order for the pump to achieve it's rating, it would need zero restriction on the suction side, and be running into zero restriction on the pressure side. Obviously, in the chassis, this is not possible. Every bend is a restriction, as is every connection,and the pick-up, and the filter, and the float valves. So by the time gas is entering the bowls, the freeflow spec is not telling the whole story. But your test on a running engine, having tee'd into the line as close to the float-valve as possible, is about as accurate a test as can be.
>Pressure is meaningful in so much as it tells us a little about the pumps ability to PUSH gas. But I tell you what, if you restrict the pump's output to as good as zero, the pump pressure will max out, but you won't have enough gas to power up your lawnmower, right? So pressure means only so much. The volume test tells you almost everything you need to know.It is, or should be, the first GO-TO when diagnosing a WOT or high-rpm problem.
>And the tools are minimal. A hose, a Tee, a jar, and some clamps. Fill the jar by stopwatch, and convert it to qts per minute.For dead-nuts accuracy, the line should be steel,up-sized,with a minimal curve to run over the fender, and a stop valve to make timing easier.That's all there is to it.
Go!
