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dd74 dd74 is offline
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Join Date: May 2002
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In following up Souk's argument I saw on one of this year's earlier dyno days posting by RDane that very little horsepower gain was netted by the installation of 20/21 cams in (at least) a late 3.0 - all of 5 horsepower. This 3.0 as well had SSIs and a Triad dual-in-dual-out exhaust, and also was recently rebuilt. Its horsepower was 198.

Remember: SSIs are the best "new" heat exchanger/exhaust manifolds available for the 911, and 20/21 cams are the most radical cams one can use while retaining the CIS fuel system.

Given that a same model 3.0 without the cams, and with pre-1975 heat exchangers has been recorded to make 193 horsepower, one should second guess the thousands of dollars involved to gain only 5 horsepower.

In all, when I asked "What's wrong with a stock 3.0?" I asked this from a practical sense. I've seen quotes approaching $4,000 to modify the CIS and install 20/21 cams. Tack on another $1K for SSIs, and another $500 for a known muffler. Give or take $6K and you have 15 more horsepower than a stock SC motor. Is that practical? Of course, with an earlier 3.0 (78-79) you'll have a bit more power, which might have to do with the larger induction system, but still, the bottom line is the hp-to-$ ratio, which does not lean toward "value."

RDane is correct when he says "dream on" (sic) about getting 21 more horsepower from a CIS-based 3.0. Now you're in to tear-down territory with your engine, and might as well do a whole host of "additions" that will make spending $10,000 worth your while. Hence, if it ain't broke, don't fix it.

I believe the 3.0 engines are designed (stock) to an optimum point where race motor meets street motor. They're not V8s or Japanese motors. They don't allow cheap horsepower upgrades. Your best bet to gain a more lively ride is to lighten the car and do suspension work. Even before that, you should learn the car's parameters on a race track. A stock SC (or any 911) might be far beyond your driving talent, and could consequently be asking you for a "driver upgrade."
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The Terror of Tiny Town
Old 12-02-2004, 08:56 AM
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