s400 surging

Toby Cashion

Toby Cashion

diesel racer
Joined
Aug 31, 2010
Messages
210
Having surging problems in 4th and 5th turbo is a s475 2.8 race cover/83X74/T4 1.10 ar. why is it surging? how can i fix this? Dont have a tach in my old 1st gen so i cant tell what RPM its doing it. thanks
 
any more fuel it drowns out, truck will turn over 4000RPMs but its surging so bad its hard to get it there when the turbo is bouncing from 40 to 10 PSI . would a smaller exhaust housing fix this?
 
yes... more load in higher gears spools the turbo sooner... the engine can't accept the air at that RPM, so it goes into surge.

you can keep the revs up, go with a larger housing, port the head more, or go with a bigger cam.
 
Comes from the compressor wheel having more leverage than the turbine.
 
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