Section cut C20XE-C20LET head pictures?

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Thread: Section cut C20XE-C20LET head pictures?

  1. #76
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  3. #77
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    duplicate

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    Quote Originally Posted by TELVM View Post
    My favorite would surly eliminate the dead area on the intake side.




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    Re: Section cut C20XE-C20LET head pictures?

    Yes I know this is a old thread but since there was never a conclusion....

    Has anyone ever gone ahead with this modification?

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    Re: Section cut C20XE-C20LET head pictures?

    Always interesting to read something new.

    I would summise that the way it works is two fold.

    Under compression stroke, as the piston approaches the head, combustable gases are tapped in the squish/quench area and are forced out, causing turbulence. However, this also increases the temperature, especially near the edge of the chamber where the gases can't escape - in extreme cases this will cause either detonation as the combustion gases raise the temperature in the unburned fuel enough to cause localised ignition, or actual pre-ignition, when the gases are heated enough to initiate the combustion process.
    I would expect these slots allow inproved gas flow from the quench area, so reducing the peak pressures and thus temperatures and so reducing or eliminating the gas ignition problem. this would also mean a lower octane fuel may be used as less anti-detonation additives are required.

    Under combustion, when the spark ignites the mixture, the expanding gases can cover a greater area of the piston and so increase the pressure on the piston more rapidly.

    Seems to be a win-win situation, a similar advance to the fire slots on high dome pistons.
    I expect this improved combustion means reduced ignition advance is required - the advance is to maximise the average pressure on the piston - which will increase torque as there's less pressure BTDC to be overcome.

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    Re: Section cut C20XE-C20LET head pictures?

    I done these groove things to two of my head (1400nv and 1300mk1 golf) and for sure it does improve low-mid performance. as for advance curve I did not really notice much as allowed as both the heads i used already have super low CR, 1400nv is something 9:2 and the golf was 8:8. Do remember when you cut grooves in you further reduce compression.
    111 BHP@6,300 - 121 Ib-ft@2,500 - 3,200 from a 1400 SR with modified C14SE head, weber 32/34 on varijet inlet manifold, magnex 2" bore S/S exhaust system! Woohoo

  9. #82
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    Re: Section cut C20XE-C20LET head pictures?

    Hi all,i know it's been a while but did find someone the best cuts for the XE\LET head?If automotivebreat is right that mean that i have to cut 2 grooves from intake valves and 1 groove from exhaust valves.Or more grooves will make more effect?

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