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ttweed ttweed is offline
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Join Date: Mar 2002
Location: La Jolla, CA
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Originally posted by kenikh
1. Is it worth twin plugging my stock 2.0S during this install?
That is still a "value-laden question" which depends on many personal aspects of the situation, such as "how fat is your wallet" and "how much do you want the cool-factor of twin plugs?" The performance aspect of twin-plugging the stock motor will not be huge, compared to the expense.

2. Would it only be worthwhile if I go with custom pistons to raise compression?
IMHO, yes, unless the afore-mentioned "cool-factor" means a lot to you.

3. If so, how high is reasonable for a twin plug 2.0S?
Depends on what fuel you use. If you are going to run the cat-piss we get for gas in CA, I wouldn't go any higher than 10.5 or 11:1 on current 91 octane fuel, depending on how far you push ignition advance. If you are willing to run race gas, 13:1 or greater would get you a lot more power.

4. How would these mods affect the character and longevity of the otherwise stock 2.0S?
Raising compression will generally be detrimental to longevity, as it will increase stress on the pistons, rods, crank and case. The higher you go, the greater the stress. There is a reason that race motors are "freshened" every 40 hours. The "character" will be changed by giving the motor more grunt due to the higher compression, and it will probably run crisper and cleaner, with fewer misfires, due to the twin plugging.

5. Should I just be happy with the single plug MFI and spend my money elsewhere?
IMHO, yes. So far, I have had no problems with my '67 2.0S carb'ed motor with 9.8:1 compression running our CA 91 octane, except for having to increase idle jet size a little bit and installing a CD ignition, to make up for the increased volatility (RVP) of the newer fuels. I think a mixture adjustment with your MFI will be all you need to get satisfactory performance from premium pump gas with your motor, and you already have a CD ignition, so there is little to be gained without spending cubic dollars on it. Just drive it and be happy. If you want more power, swap in a bigger engine. "There is no replacement for displacement."

Tom Tweed
Early S Registry #257
R Gruppe #232
Rennlist Founding Member #990416-1164
Driving Porsches since 1964

Last edited by ttweed; 08-22-2005 at 09:18 AM..
Old 08-22-2005, 09:12 AM
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