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      11-16-2014, 03:39 PM   #68
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crashtestdummy81's Avatar

Drives: YMB F83
Join Date: Jul 2014
Location: UK

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I thought this all initially sounded good but looking deeper the advantages seem to be unavailable from such a system under real world conditions.

Using electricity to drive the T/C at low engine speeds will help reduce lag but the electricity has to come from somewhere, unless you are driving with sufficient load after pulling away (a situation where a normal waste gate would be opening) there can be no electric generation without slowing the turbo, the charge used for spooling the turbo will need to be replenished from the vehicles electrical system.
Conversely If you are driving under high loads where you have plenty of excess exhaust to drive the generator this charge needs to be stored somewhere, should the battery reach a state of full charge you have no facility to stop the turbo over spooling unless the waste gate is retained.
Based on this it would seem that the battery sizing and initial charge state would need to be tailored to the actual driving conditions the vehicle is about to experience to be fully effective.
Other manufacturers have had success with combined turbo+supercharging which removes the need for the (heavy) batteries these systems would require. The supercharger is clutched in only at low rpm before the turbo spools up or under heavy throttle for increased performance, so as to minimize power taken from the engine.

Ultimately though, I feel that the anti lag system employed in the S55 (even though I'm not really sure quite how this works) is sufficient to render the concept of electric turbos redundant.

The electric supercharging concept mentioned in the previous post may be suitable as a performance upgrade but you would have to consider the size/weight of any batteries required to run this for any sustained length of time. A mechanical supercharger would be a more efficient option should you consider using the vehicles existing (or upgraded) electrical system as you cut out the losses associated with turning mechanical energy to electrical energy, electrical resistance and then turning it back to mechanical energy again.
An alternative idea would be to use the electrical supercharger like a rechargeable NOS system, having a much smaller battery being trickle charged from the vehicle when not in use but giving a short term bump in power at the push of a button, only when "needed", before waiting for the battery to recharge.