Fuel rails
#6
Boost Pope
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Speaking of which, I haven't seen Abe around here in forever. He still owes me money...
#9
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,497
Total Cats: 6,905
Not just two guys, mind you- two guys on the internet!
Abe constructed a test stand consisting of a fixture to hold a stock fuel rail with four injectors above four graduated cylinders. A hose was used to tap into his car's fuel system and the fuel pump was switched on to supply fuel to the test fixture. The fuel rail was from an NA with the FPR still attached, and it was set up to be operated in either single-feed or dual-feed mode.
Then, a Megasquirt was attached to the injectors and set to test mode. The injectors were run for a while at varying duty cycles, then stopped and the level of fuel in each of the graduated cylinders compared.
In each test there were some variations in the amount of fuel in each cylinder, however to determine whether this was due to variations between the injectors themselves or their position in the rail, the injectors were moved around and re-tested.
Basically, there was a measurable difference in net flowrate from one particular injector to another (regardless of its position in the rail), however the flowrate did not, on average, seem to vary substantially from one location on the rail to another. In other words, if during the first test cycle injector A in position 1 flowed 150cc and injector D in position 4 flowed 140cc, then on the second test cycle with injector A in position 4 and injector D in position 1, injector A would still flow 150cc and injector D would still flow 140cc. (the exact numbers here are made up, but that's basically the trend that the data revealed.)
Here's a picture of the test setup:
I honestly can't recall what sizes of injectors we had available at the time. They certainly weren't anything really large like 750s (or Gotpsi's 1200s, which are just silly) so it may well be that at significantly higher flowrates than we had available, you'd start to see a difference. Whether this would be a product of the dual-feed-ness of the rail or simply the larger bore is a question for which I have no answer.
What exactly did you witness? How did you test the flow?
Then, a Megasquirt was attached to the injectors and set to test mode. The injectors were run for a while at varying duty cycles, then stopped and the level of fuel in each of the graduated cylinders compared.
In each test there were some variations in the amount of fuel in each cylinder, however to determine whether this was due to variations between the injectors themselves or their position in the rail, the injectors were moved around and re-tested.
Basically, there was a measurable difference in net flowrate from one particular injector to another (regardless of its position in the rail), however the flowrate did not, on average, seem to vary substantially from one location on the rail to another. In other words, if during the first test cycle injector A in position 1 flowed 150cc and injector D in position 4 flowed 140cc, then on the second test cycle with injector A in position 4 and injector D in position 1, injector A would still flow 150cc and injector D would still flow 140cc. (the exact numbers here are made up, but that's basically the trend that the data revealed.)
Here's a picture of the test setup:
I honestly can't recall what sizes of injectors we had available at the time. They certainly weren't anything really large like 750s (or Gotpsi's 1200s, which are just silly) so it may well be that at significantly higher flowrates than we had available, you'd start to see a difference. Whether this would be a product of the dual-feed-ness of the rail or simply the larger bore is a question for which I have no answer.
#10
Wow, I had been dreaming up something of that sort in my head. Glad I dont have to do it now. I didn't figure a dual feed rail made any difference. Especially on a stock rail. Just seemed like another potential point of failure.
I'd imagine that with huge injectors a larger bore diameter and better FPR would make a difference though.
I'd imagine that with huge injectors a larger bore diameter and better FPR would make a difference though.
#12
I'm still on the stock rail and its doing just fine at 300 on the ID1000's and e85
If you're planning on flowing something ungodly like 500-600+ worth of fuel I'd also probably go with a larger rail.
And there were a couple people that did the same test as Joe and Abe, and the results were pretty much exactly the same. Patrick (patsmx5) did one too IIRC.
If you're planning on flowing something ungodly like 500-600+ worth of fuel I'd also probably go with a larger rail.
And there were a couple people that did the same test as Joe and Abe, and the results were pretty much exactly the same. Patrick (patsmx5) did one too IIRC.
#14
Not just two guys, mind you- two guys on the internet!
Abe constructed a test stand consisting of a fixture to hold a stock fuel rail with four injectors above four graduated cylinders. A hose was used to tap into his car's fuel system and the fuel pump was switched on to supply fuel to the test fixture. The fuel rail was from an NA with the FPR still attached, and it was set up to be operated in either single-feed or dual-feed mode.
Then, a Megasquirt was attached to the injectors and set to test mode. The injectors were run for a while at varying duty cycles, then stopped and the level of fuel in each of the graduated cylinders compared.
In each test there were some variations in the amount of fuel in each cylinder, however to determine whether this was due to variations between the injectors themselves or their position in the rail, the injectors were moved around and re-tested.
Basically, there was a measurable difference in net flowrate from one particular injector to another (regardless of its position in the rail), however the flowrate did not, on average, seem to vary substantially from one location on the rail to another. In other words, if during the first test cycle injector A in position 1 flowed 150cc and injector D in position 4 flowed 140cc, then on the second test cycle with injector A in position 4 and injector D in position 1, injector A would still flow 150cc and injector D would still flow 140cc. (the exact numbers here are made up, but that's basically the trend that the data revealed.)
Here's a picture of the test setup:
I honestly can't recall what sizes of injectors we had available at the time. They certainly weren't anything really large like 750s (or Gotpsi's 1200s, which are just silly) so it may well be that at significantly higher flowrates than we had available, you'd start to see a difference. Whether this would be a product of the dual-feed-ness of the rail or simply the larger bore is a question for which I have no answer.
Abe constructed a test stand consisting of a fixture to hold a stock fuel rail with four injectors above four graduated cylinders. A hose was used to tap into his car's fuel system and the fuel pump was switched on to supply fuel to the test fixture. The fuel rail was from an NA with the FPR still attached, and it was set up to be operated in either single-feed or dual-feed mode.
Then, a Megasquirt was attached to the injectors and set to test mode. The injectors were run for a while at varying duty cycles, then stopped and the level of fuel in each of the graduated cylinders compared.
In each test there were some variations in the amount of fuel in each cylinder, however to determine whether this was due to variations between the injectors themselves or their position in the rail, the injectors were moved around and re-tested.
Basically, there was a measurable difference in net flowrate from one particular injector to another (regardless of its position in the rail), however the flowrate did not, on average, seem to vary substantially from one location on the rail to another. In other words, if during the first test cycle injector A in position 1 flowed 150cc and injector D in position 4 flowed 140cc, then on the second test cycle with injector A in position 4 and injector D in position 1, injector A would still flow 150cc and injector D would still flow 140cc. (the exact numbers here are made up, but that's basically the trend that the data revealed.)
Here's a picture of the test setup:
I honestly can't recall what sizes of injectors we had available at the time. They certainly weren't anything really large like 750s (or Gotpsi's 1200s, which are just silly) so it may well be that at significantly higher flowrates than we had available, you'd start to see a difference. Whether this would be a product of the dual-feed-ness of the rail or simply the larger bore is a question for which I have no answer.
Hmm, pretty cool. De bunks a new myths, but I still like my shiny black m-tuned rail . I'll keep pretending like it gives me extra power, even if it doesn't at least it looks pretty. I like the speaker wire for injector wiring... lol
#17
Has anyone set up a return setup 1999 rail in a 2001 motor with dual feed goodness? I'd imagine leave the FPR on the end of the rail drill out the firewall end and drill into the top near the FPR (between 1 & 2 injectors)? The issue with putting it in the location in Joe's picture is that the FPR hits the intake manifold.
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