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Old 10-01-2008, 10:09 AM
desertdriver desertdriver is offline
 
Join Date: Mar 2007
Posts: 1,512
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Quote:
Originally Posted by chaz58 View Post
Direct injection twin turbo engines like the 335 or 123 don't have much of any lag. If you go to a single turbocharger and lose the direct injection, yeah you will have some. Direct injection seems to make the biggest difference - a single turbo with direct injection reacts very fast. A twin turbo without direct injection will have more lag, and then a single turbo without direct injection will have the most lag. (It also depends on the size of the turbo and the amount of boost - but I believe stock BMW's don't have large high boost turbos).
The 335i has virtually no turbo lag, as the turbos include a small one for low RPM(spins up real quick) and a bigger one for higher RPM, more HP. IMO, many 335 drivers mistake throttle lag for turbo lag. With turbo lag, RPM increases without acceleration, that doesnt happen with the 335. Throttle lag is when you push the pedal and NOTHING happens for an interval, no RPM increase, nothing. The 335 has a drive by wire throttle program that learns your style. When new, the program has quite a bit of throttle lag, but it learns and the control settings are advanced to reduce the lag over the first 1000 miles or so. In the step, the DS/manual mode has much less throttle lag, even when D mode learning is finished. In DS/manual mode, my '07 will snap heads back right after throttle application. In D mode there is a pause of almost 1 sec before the car responds. I understand the '08's were delivered with a V29 throttle program that just sucked, tons of lag. Now it is apparently remedied, runs like the '07 again.
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