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Carrera3.5L Carrera3.5L is offline
Doesn't want/need a 3.6L
 
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Join Date: May 2004
Posts: 1,635
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You can search my 3.2L to 3.5L engine build threads for some ideas. As you will find when your engine is completed, the power output can be quite good provided you get away from the std. heat exchangers and run a better exhaust. 255-265 crank horsepower is realistic for a street 3.4L twin-plug motor with the right modifications.

You WILL NOT get away with any more then 10:1 CR with 91 octane, even with twin plugs. 9.8:1 and twin-plugs will be a good, safe combo for 91 octane. Don't believe me? Talk to Andial. They will tell you the same thing. I have 9.5:1 CR in my 3.5L and have a special Steve W chip that retards the timing even more when the weather gets hot so the motor doesn't ping. Version 1 makes 239 at the wheels and Version 2 makes 246 at the wheels.

Your engine build plan sounds pretty good. I would really twin-plug regardless of compression ratio with the bigger bore for the extra safety margin it provides. Modesto can and does get awfully hot in the summer.

A 3.4L twin-plug with extrude honed plenums, bored throttle body, custom Steve Wong chip, SSI's or headers and 964 or Web 20/21 cams will make for a very nice and driveable street car. Either cam set listed above will pass CA smog. Obviously, SSI's or headers will not but putting the heat exchangers on every 2 years for the smog check and then back off takes a 1/2-3/4 day.

I went against the advice of the "experts" on this board and shuffle pinned the case after seeing a whole row of 3.0L and 3.2L cases at Ollies' Porsche Machining that were damaged due to case movement. George and Ike probably see more machine work then anyone else in the country and they also do the machine work for Andial and Porsche Motorsport. Both have been around for over 25 years and their experience carries more weight with me. Talk to various machine shops who do these day in and day out and then make your decisions regarding custom machine work.

Boattailing the case and mooning the cylinders are other individual choices, but I did those as well. Maybe I wasted some money, maybe not. Although I have never seen a dyno sheet that showed a horsepower gain, I also have never seen any dyno sheets that prove that these are a waste of money either. Frankly, I don't believe that anyone has ever done a before/after test. Again, talk to various machine shops who work with these motors day in and day out and make your decision based on their responses.

It sounds like you will have a nicely done motor in the near future, show some pics as you move along!

Ralph
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1988 Carrera w/ 3.5L Twin-Plug

2008 Cayman S (coming soon)

Last edited by Carrera3.5L; 02-04-2005 at 09:13 PM..
Old 02-04-2005, 08:30 PM
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