Twin-plug /4 motors...(pictures) |
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Twin-plug /4 motors...(pictures) |
Mueller |
Jul 30 2003, 10:48 AM
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#1
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
This is a Type I head, but it'll give you an idea for the 914 /4 motors.
Paul Guard, of Guard Transmission (maker of bitch'n parts for Porsche transmissions) loaned me this head to get an idea on how to twin-plug my motor. The secondary plug is a 10mm motocycle plug. A modified distributor cap from a Nissan 4 cyl truck engine is adapted to fit on the stock /4 distributor...the rotor is from Nissan as well. I have the drawings for this modification somewhere in my garage (IMG:style_emoticons/default/smile.gif) Using an aftermarket distributorless ignition would be ideal, but for cost savings, the above will work. There is a company that'll machine these heads for about 300 dollars or so (they do this for aircraft...not for performance, but for redundancy (saftey)) The sockets in the head are to give you an idea of the angles. Attached image(s) |
Mueller |
Jul 30 2003, 01:05 PM
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#2
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
From what I understand, the addition of the second plug was needed due to the increased cylinder pressure when RPM(?) installed the supercharger(s)* on the 914's.
*not sure how many had been installed, I have a copy of a magazine article with the /4 supercharged powered 914, it does not say if it was a one-off or if more had been built and sold. On a bone stock motor I'm sure you'd see some gain from the second plug, but it is cost effective??? I doubt it. Even in a run of mill aircraft powerplant, there is noticeble change in the running of the motor when one set of plugs is turned off while doing a magneto check. |
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