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Twin plugs or not?
I have been rebuilding my 911 for a year now and I am at the point of my engine build. I am doing a 2.7 RS and was wondering about the twin plug concept or not. Anyone have andy thoughts on this?
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12-08-2008, 01:22 PM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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Twin-plug heads help in a few situations:
1) cylinder diameter increases over 95mm. A 2.7 will have 90mm cylinders when used with a 70.4mm crank. 2) Static compression is increased above 10:1 Could be less if bore gets larger. 3) Available fuel quality is low and detonation is a problem. There are way too many posts in the archives to retype it all here. STart your reading here. http://www.rennsportsystems.com/2a.html
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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12-08-2008, 01:33 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,078
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Just do it, even if you never use it , its a plus..........Makes it EZ to change your mind dwn the road.
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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12-08-2008, 01:52 PM
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AutoBahned
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Quote:
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12-08-2008, 01:55 PM
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Registered
Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
Posts: 21,140
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I looked into twin plug for my act with same 8.5:1 RS pistons.
If I ran S cams, would the engine always ping like a 1960s piece of worn out crap on regular gas was a good question for me? figuring I must have high test gas to use S-cams and gas is getting worse quality every few years I'd definately get twin-plugs. anyway I run E-cams and regular gas on single plug
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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12-08-2008, 02:06 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,078
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The S cams alone will not help much w.o. a bump in C/R and the CIS pistons I believe will have to be replaced to accomplish that.....
As written many times, you can push a lot higher C/R with T.plugs. To loosely Quote Corky Bell...with twin plug and really High comp is more doable then in the middle.Well maybe not more doable but the equation seems to run away in your favor after a pt.
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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12-08-2008, 04:17 PM
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