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Eliminating Turbo Lag
Well, actually, if I remember correctly, the Rally cars used a back off v
alve (also called a "pop-off valve" I think), whick releases the pressure from
when the intake is clsed and all that pressure from the turbo needs a place to
go....this if high enough pressure, is what will blow hoses. This also prevent
s some of the lag.
Also, many of the Rally cars also had surge valves. The Audi S4 has one
of these two I believe. It works like the above, but channels that back off ai
r back into the turbo to keep it spinning while changing gears, etc. Then when
you hit the accelerator again, you are not starting from ground zero and have s
ome boost there when you need it. This greatly reduces turbo lag, which is ver
y noticable on the S4. If I remember correnctly someone last year put the S4 s
urge valve on a 5KTQ, and they work great. I think it is a rather inexpensive
mod as well....something to look into anyways.
Of courese, the Rally drivers best ways of keeping boost up while cornerin
g was to hit all three pedals at the same time, thatway they were braking, yet
the boost was still up and they'd slide through the corner and off the gas and.
....whaaaaaaa!!! They'd wail right on by!