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914World.com _ 914World Garage _ Whether to twin plug or not

Posted by: DNHunt Oct 15 2003, 07:09 AM

I meet a guy this weekend from Portland who has spent his whole life as a Porsche mechanic. Currently, he specializes in rebuiding trannies but it sounds like he's done it all. He worked on a rail with type IV power that ran methanol for Pike's Peak. So, I tried to pick his brain. (Hope he didn't hate talking cars as much as I hate talking teeth at a party.)

Anyway, he was not too impressed about the idea of either twin plug or coil on plug. He didn't think enough would be gained with coil on plug. I thought I could get a hotter spark so he said get and MSD. I said I have one and I think it's great. So, he said trigger the MSD with a programmable ignition. The only argument I could come up with was boring so, I kept my mouth shut.

He sort of brought up all the arguments I've read and thought about. He felt that the wedge shaped combustion chamber made positioning the plug tough and that the plug angle would be poor. He also felt that the heads are fragile and why spit into the wind and ask for more cracking. So I think I can close the book on that idea.

So, some of you guys that are wiser than me give me some input.

Also, I scrounged a bust head at Parts Obsolete so I could play with plug angle for a second plug

Dave

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Posted by: Mark Henry Oct 15 2003, 09:18 AM

I would have to agree with him on twin plug, Dave.

Twin plugs are only needed for very high CR, turbos (or SC) running high boost and aircraft for a back-up system.