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FW: [T3] Quiet Mufflers


Toby wrote:

An extractor helps to draw in more of the air/fuel mixture.  I fail to see
how it can induce a lean mixture.  The vacuum extracts the exhaust more
efficiently and thus pulls in a greater intake charge.
>When you improve the flow characteristics of a motor, you are potentially moving beyond what the carb/s is /are jetted to deliver.  If you're jetted to deliver a correct fuel curve for a basically stock motor and suddenly you are delivering more air through the carbs by reducing or eliminating back pressure, you might need to bump up main jet size(s) to compensate or you'll run lean at speed.  Leaner is hotter in an air cooled motor, and can cause Bad Things to happen.  At the very least you will be altering the performance characteristics of the motor, for good or ill.  For info you can read any DBHVW's dyno testing article, or Gene Berg had some interesting things to say about it in his catalog. 

Having several years experience with dual and single quiet packs on a stock and modified engine I know they won't cause burned valves.
>My experience came the hard way, by dropping valves on an engine that weren't jetted to match the overall flow characteristics of the motor.  Too much flow, not enough gas, overheated and bam it was toast in 20,000 miles.  The whole valve actually burned off the stem.  This wasn't a performance motor, just a decent, original mile formerly fuel injected engine.  Needless to say I got on that learning curve pdq.

My personal preference is the dual system.  Produces less noise and still allows equal or better exhaust flow.
>But compared to what, and equal to what?  You are running a 2 liter monster, the dude was asking about a 1600.  I suspect the folks down at Kawell didn't just slap carbs on your motor withm)×
ing it to match your cam, exhaust, etc.  If they did I'd be pissed.

Everything beyond a stock motor is a balancing act.  Get beyond the correct parameters for your setup and you will not go as far.  Those of us former feulies not lucky enough to find stock dual psdit's and manifolds for a dual port t-3 at the swap meet (woohoo!) are left to choose from the aftermarket stuff, which isn't usually designed to be a stock replacement.  Phatty duals might look kewl, but may not be appropriate for your motor.  Then again it might be just what you need, if you're running too rich in the first place.  

Curt
70 sb (soon to be VW carbed and possibly stock exhausted again)
66 Bus (absolutely bone stock)

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