In Reply to: Re: Sebring vs. BEGI for 1.9 posted by Shawn Fogg on April 03, 1999 at 10:43:31:
: "I thought the "engine life issue" had more to do with the force of 7.5+ PSI blasting through the valves into the
: combustion chamber affecting the pistons/rods,"
: Nope, the engine life issue is really from two things. Can the engine handle the increased power ouput and is it knocking.
: Corky Bell has some very interesting information about the whole increased power ouput debate in his book 'Maximum Boost' which is about turbocharging but in this case is very applicable to supercharger. Basically he feels (and goes through a lot of math to prove it) that because of where in the pistons movements the forces on them are greatest (TDC and BDC) he shows that almost any engine (with all else in the turbocharger being done correctly..ie heat control.. not the same issue with a supercharger) should be able to handle the power increase from any reasonable amount of boost. Raising your rev limiter probably does much more wear and tear on your engine. I'd like to read his upcoming supercharger book when it's available.
: The knocking issue is much more important. Any engine that is knocking is hurting itself. (Side note: Those that say chips for your DME can't hurt your engine are kidding themselves. If the chip is done wrong and your engine knocks a lot you are going to kill your engine quickly.) The whole purpose of an intercooler is to help prevent knocking, not to help cool the engine.
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I think we're saying the same thing - different semantics. When I mentioned the Supercharger's extra boost force on the valves, pistons, rods, etc, I'm referring to engine's ability to absorb the extra shock from the greater combustion (more air/fuel). I've been driving German cars about 20 years now (VW, Audi, Mercedes and now BMW), and I believe that German cars are probably significantly over-engineered enough to handle the extra power. I'm weighing the evidence to decide between the Supercharger and the recent Dinan 1.9L upgrades - which won't produce quite as much power, but Might have fewer potential long-term negative affects. I might be interested in reading Corky's book, too.