I'VE GOT A 1995 LEGACY TWIN TURBO
CAN ANYONE TELL ME WHAT BOOST PRESSURES
TO EXPECT AT WHAT R.P.M.

I'M GETTING 10 lb ON THE FIRST TURBO BUT WHEN
THE SECOND KICKS IN AT ABOUT 100 KPH.
BOOST DROPS OFF TO 5 lb.
IS THIS NORMAL ?

 

All the Subaru Twin turbos have this boost valley, 10-11psi with the first turbo, then a gap as this turbo runs out of puff before the second comes in at about 4500rpm, you usually get about 5psi in this valley and then back upto about 10/11 after 4500 all the way through to the redline.

Scoobysport are designing a new exhaust system for my car next week, free flowing silencers, bigger pipe, removing the big cat (there are two cats - a large one where the 2 downpipes join and a smaller one in the downpipe of the small turbo) and a new downpipe for the big turbo. This should reduce the spool up time for the big turbo and make the gap between the turbos much smaller. The small cat should hopefully keep emissions at Bay for the MOT

Paul

 

Paul,

I'd be interested in hearing your thoughts about the Scoobysport exhaust once you've had a chance to try it out. I may be in the market soon for a new system for my '96 Legacy RS.

Thanks & regards,
Brian

 

THANKS PNEBBS !
GOOD TO FIND SOMEONE THAT KNOWS THESE THINGS !
OKAY PROBLEM NOW IS I'M NOT GETTING THAT
SECOND BOOST HIT AFTER 4500

THE BOOST REMAINS AT 5 PSI THROUGH TO
REDLINE .

ANY IDEAS ?

 

It's a very complicated system that I haven't fully fathomed yet, - It could be that the wastegate is jammed open on the big turbo, although I would have thought this would reduce boost on the smaller turbo as well (The bigger turbo is the one on the drivers side, RHD)

It could be that the big turbo has failed (seized?) and the smaller turbo is producing all the boost

If I get any more ideas I'll let you know

(By the way, try taking the caps lock off)

Paul

[This message has been edited by pnebbs (edited 16-03-2000).]