logging pan/block psi

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

  1. noslin

    noslin New Member

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    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
    Dean
     
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  2. Mike Canter

    Mike Canter Top Dragster

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    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.
     
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  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    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.
     
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  4. rb0804

    rb0804 Member

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    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.
     
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