logging pan/block psi

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by noslin, Nov 23, 2018.

  1. noslin

    noslin New Member

    Oct 29, 2016
    Likes Received:
    newb question.. Im wiring sensors up for my FED and wondering about putting a map sensor on the block to measure vac/psi. im guessing on blown app if psi then rings bad or ? can you tune using this data, if so how would you use/read the data? what are all the benies to logging pan/block psi/vac?

    Thank you
  2. Mike Canter

    Mike Canter Top Dragster

    Mar 10, 2004
    Likes Received:
    If you can get some vacuum then you will gain some horsepower because less wind resistance to moving parts. Unless you have either a vacuum pump or a really good oil pump with multi scavenger sections and you seal up the motor very tight then you may get less positive pressure. If you note the average pressure with a healthy engine then you can tell if you have a pinched ring later. Haven’t found a way to tune by it.
    noslin likes this.
  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    May 6, 2003
    Likes Received:
    i have found it useful as a running leakdown test for your rings/cylinders. Obviously if you hurt something and pressurize the block, you will see it and when it happened, which may help in diagnosis.
    noslin likes this.
  4. rb0804

    rb0804 Member

    Aug 7, 2010
    Likes Received:
    This isn’t like a nitrous engine where your gonna see a fluctuation in the pan pressure at a specific point and know your rings are fluttering due to detonation. It’s gonna be what it is all the time, until you hurt it and then it’s gonna spike. The base pressure number in the pan may even scare you if your used to N/A or nitrous engines. Racing with a mechanically injected Blown alcohol engine is more like Stone Age, caveman technology; at least that’s my opinion anyway.

    What the lower budget top fuel teams do is once the pressure in the pan gets to a certain level it triggers the Leahy box, killing the ignition and the fuel so they don’t have a huge firey blow up disaster. That is probably the only thing the pan pressure would be good for. It could also help you diagnose if you need to pull the head or not. I can look at the plugs and know right away if the head needs to come off. But like Will said, if you have a suspicion, just leak it.
    noslin likes this.

Share This Page