Eliminating Turbo Lag

[Steve Evans <sevans@radstone.co.uk>]

I recently came across an article, actually about the Ford Escort Cosworth,
which described a system intended to eliminate loss of boost pressure when
changing gear. The basic idea was, when the throttle was closed, to open the
air bypass (idle control valve) fully and to retard the ignition by some 30
degrees. The effect of is to allow a reasonable amount of fuel/air mixture
into the engine, and for it not to be ignited in the cylinders, but rather
in the exhaust manifold, where the resulting conflagration keeps the turbo
spinning with the added (noisy) bonus of flames shooting out of the exhaust!!!

Apparently it is very effective at keeping boost up whilst changing gear. With
the exception of the flames frightening following motorists, it seems like a
pretty good idea. I am wondering if it a similar idea would work for the urQ.
Has anybody come across such a system?

I cannot see why it should be necessary to retard the ignition rather than
simply inhibiting it altogether, so that bit should be easy enough (or would
this lead to plug fouling). That leaves the control of the bypass valve.
Although the urQ does not have an anti-runon facility as does the 200TQs, does
anybody know if the MAC12 ECU drives an output for anti-runon. If so, it
could be used to trigger inhibiting the ignition, and opening the air bypass
valve for say, half a second, every time the throttle is closed above 2000rpm.
Any longer that half a second would, I guess, be unnecessary, and would
certainly upset the neighbours (and the fuel consumption)!

Steve

'88 urQ  
__
Steve Evans                             Radstone Technology Plc.
Principal Design Engineer               Water Lane,
                                        Towcester,
Tel: +44 (0) 1327 359444                Northants,
Fax: +44 (0) 1327 358113                NN12 6JN
Email: sevans@radstone.co.uk            ENGLAND