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, Tue, 21 Jan 2003 22:02:21
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If you go to Chris Moberg's excellent Sonett site, you can read an excellent article about carburetion in general (direct link is http://www.vintagesaab.com/sonett/ss/Carburetion/carburetion.htm in case you want to skip the frames.)
Although some of the info in the article (especially about availability of parts) is outdated, the theory still seems sound. To summarize, it says that installing a bigger carb OR a performance exhaust will increase engine power about 7%. This makes sense in that there's only limited advantage to getting more volume INTO the engine if there's no way to get it OUT, and vice-versa.
On the other hand, if you add the bigger carb AND a performance exhaust (such as the MSS Y-pipe system) they enhance each other, so you can see a power increase of about 20%. (Before you get too excited about that number, remember that a stock V4 only dynos at about 61hp, so these mods might at best get you up to the 73-hp number that Saab originally advertised!)
Is it worth doing? Well, when I got my car it had the original FooMooCow carb and the MSS exhaust. I swapped in a single-barrel Weber 34ICH carb, which was more tunable but didn't really increase perceived performance.
Then I went to the progressive 2-bbl Solex carb that was used on later European-spec 96es (from late 1977 on.) I definitely COULD feel a difference with this carb. The place I notice it most is in highway driving -- there's a feeling of more midrange power, so that when I step on the gas to pull out and pass somebody it feels like I've got some reserve power, rather than like the engine's about to run out of breath as with the single-barrel carb.
I assume a similarly-sized Weber would produce about the same effect as the Solex, although the Webers are available new and there are more tuning/rebuild parts for them, so a Weber would be easier to maintain. I'm continuing to run the Solex for now but probably will switch to a Weber as soon as I've got some spare cash.
PS -- You do know you need a new manifold as well as the carb, right? There used to be some squirrely adapter that let you mount a 2bbl Weber on the original manifold, but all it does is choke down the throat to the original size, so you lose most of the benefit of the bigger carb.
posted by 204.76.11...
, Tue, 21 Jan 2003 22:02:21
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