fuel split for 14-71

Discussion in 'PSI Superchargers Tech Questions' started by hemi altered 378, Jan 6, 2008.

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  1. wildride boy

    wildride boy Top Sportsman Racer

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    Mike ,
    Very interesting post and your explanation to how to calculate that, is very good , but the last post from Gene has also lot of sense .
    Did you ever check with a flowmeter on a fuel system flow bench vs flowmeters on a race car , to see if the vacuum pulse on the intake port over the boost pressure may influence the fuel volume?

    Thanks
    Claude
     
    #21
    wildride boy, Jan 8, 2008
  2. SoDak

    SoDak Active Member

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    I'll throw a monkey wrench in this. When I built my flowbench I was very particular on the fact that my port nozzles were working against boost. In my case 20-30 lbs, with my fuelbench in its current state, it made no difference. I've been using it succesfully without boost compensating but I intend on revisiting this. Maybe its because I use the bench as more of a trend investigator. I've not yet put the flowmeter on the track.
     
    #22
    SoDak, Jan 8, 2008
  3. Mike Canter

    Mike Canter Top Dragster
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    Gene, I believe that with a blower car it doesn't make much difference if the intake valve is open or closed because of the positive boost pressure. I also monitor the boost pressure through that second port nozzle hole right alongside the main port nozzle. If it is changing it is at such a fast rate that I don't see it and I don't believe the nozzle changes its flow that fast.

    Davenport's Jetsize software also compensates port nozzle flow based on boost pressure. There are flow benches that have the port nozzles screwed into a pressurized container/tank that is kept at the dialed in boost pressure to give you true flow as what would be in the car going down the track.

    If you take flow bench data with no boost correction on put it into Jetsize then you first have to turn boost to zero and enter the flow data. Then Jetsize is calbrated to the flow bench figures the boost is then entered. You can see the GPM change.
     
    #23
    Mike Canter, Jan 8, 2008
  4. 23T Hemmee

    23T Hemmee Member

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    Mike,
    Even though there is positive pressure in the manifold, would there be any kind of siphoning effect on the nozzle body/orifice, given its position in the intake runner from the air flow going past the nozzle?
     
    #24
    23T Hemmee, Jan 8, 2008
  5. Mike Canter

    Mike Canter Top Dragster
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    If there is there is no compensation for it. I believe that if the fuel pressure is high enough that the nozzle maintains a fairly constant flow. Maybe one would have that problem if the fuel pressure was way down.
     
    #25
    Mike Canter, Jan 8, 2008
  6. eli

    eli Banned

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    Right, It happens so fast your monitor cant see a change, because there is no change, Like you said if the pressure is to low you might see a change, but then your car would be running like $hit anyway so whats the difference.:rolleyes:
     
    #26
    eli, Jan 8, 2008
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