Cheapy tuning - Saab GM900 Turbo
Discussion
Hello, just acquired a very clean and nice 1997 Saab 900 Turbo. The engine has the red di cassette, so am I right in assuming this is a B204L with 185bhp? I understand that a bit more power can be liberated from these relatively easily, anyone care to tell me the best way to go about it?
The GM or NG900 doesnt have pot and an analogue boost computer but the T5 Trionic system using a MAP sensor. This is a Good Thing.
Yes, you can get a bit more out of it for next to no cost: standard boost is max 10PSi but if you add a commercial pressure-regulating valve (with suitable barbs screwed on and set to about 14.5PSI) in series from the turbine housing bleed to the BCV input (mounted on the front panel left of the rad.) you'll get to about 230Hp for a tenner or so. It is worth doing!
Do not be tempted to use one of those cheap and nasty 'bleed' valves to bleed wastegate pressure - they are rubbish, and do not work. And similarly, don't bother with 'dump valves' until you start blowing-up the Bosch standard reciculating device (unlikely) and even then, stick with a high-quality recirculating type*
You can't really go above about 14PSi boost on Trioinc 5 without further software mods because the MAP sensor triggers a fuel cutoff at 15PSI, and you can hit this on transient boost quite easily (when accelerating feels like you hit a brick wall until you lift off) Fortunately the standard Saab fuel map is a dab rich and no harm results.
However - rather than messing about just google for a Maptun or equiv remap, which will do the job properly , and take you as far as you like (or pockets are deep). I ran an NG900 at significantly higher than standard boost for 100K miles without ill effect - these are great engines! That, a rack/strut brace and an uprated rear antiroll bar (along with a set of decent tyres) will turn the much maligned 'new' 900T into something akin to a giant Mini. Have fun.
Yes, you can get a bit more out of it for next to no cost: standard boost is max 10PSi but if you add a commercial pressure-regulating valve (with suitable barbs screwed on and set to about 14.5PSI) in series from the turbine housing bleed to the BCV input (mounted on the front panel left of the rad.) you'll get to about 230Hp for a tenner or so. It is worth doing!
Do not be tempted to use one of those cheap and nasty 'bleed' valves to bleed wastegate pressure - they are rubbish, and do not work. And similarly, don't bother with 'dump valves' until you start blowing-up the Bosch standard reciculating device (unlikely) and even then, stick with a high-quality recirculating type*
You can't really go above about 14PSi boost on Trioinc 5 without further software mods because the MAP sensor triggers a fuel cutoff at 15PSI, and you can hit this on transient boost quite easily (when accelerating feels like you hit a brick wall until you lift off) Fortunately the standard Saab fuel map is a dab rich and no harm results.
However - rather than messing about just google for a Maptun or equiv remap, which will do the job properly , and take you as far as you like (or pockets are deep). I ran an NG900 at significantly higher than standard boost for 100K miles without ill effect - these are great engines! That, a rack/strut brace and an uprated rear antiroll bar (along with a set of decent tyres) will turn the much maligned 'new' 900T into something akin to a giant Mini. Have fun.
- the blow-off type can just suck crap i.e. unfiltered air into the engine for the 95% of the time you are off boost and running manifold vacuum - and generally signal a clueless owner.
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