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Originally Posted by veyron1  Ok. Here goes. Speed/density metering or mapping is usually dependent on engine speed, air density and MAP.
Alpha-n is the advanced version for mapping which can take in more radical cam profiles because it reads from the engine RPM and throttle body positioning only, bypassing the MAP. |
Alpha-N is not an advanced version for mapping. Its just an alternative. It works great on wild cam profiles because these cams produce a lot of pressure fluctuations in the intake manifold when they are working at RPMs other than designed for, confusing the speed-density system.
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Now, both systems/routings are prone to vacuum errors/stats.
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What errors are you talking about? Is it computed quantity of air in the system?
Alpha-N does not depend on vacuum anyway...
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The Escorts had TBIs. How exactly did the alpha-n system "improve" the combustion characterisitics? AFAIK, MPFI's have much more precise fuel metering, correct?
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right.. MPFIs are far better than TBI for precision and metering.. MPFIs can be Alpha-N too.
wrt escorts, when compared to a carb system, alpha-N TBI is definetly an improvement, but not wrt mpfi and/or speed-speed density ssytem for a stock car.
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Ok. Now for details. Let's have in detail the effects on cam profiles for alpha-n (since that's what's used for racing applications- we know that poppet and stem height are in direct relation to lift; so we'll go into that later),and ignition timing (both ignitor mapping and delco alteration-for the Escort). And how exactly do both of them alter IPW at WOT (assuming WOT is at 100%, both systems are giving 100% fuel flow)....
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i thought the escort had a distributorless setup...
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Simply put, let's have in detail the differences in ACTUAL practical applications, and how-to's...
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1. With Alpha-N its
very difficult to pass emission standards, even at OEM levels - E2,E3,E4,etc, as compared to speed-density or maf. Thats why we dont see them on street cars (execpt in limp home mode with a screwed map sensor system)
2. Alpha-N is prefered (actually a must) for individual throttle body and/or wild cam profile applications.
3. MAP or MAF is a must for turbo/supercharger applications
waiting for the guys to chip in.......