Is there a Volvo S40 T4 BBS ?
23 January 2002, 09:56 AM
#3
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Boost pressure on the T4 is 11.5psi if I remember right. They respond pretty well to tuning: big intercooler helps keep the charge temp down. ECU upgrades are pretty expensive though.
23 January 2002, 12:21 PM
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I'd be careful with the Dawes, the T4 ECU uses a very unusual boost management strategy compared to Scoobs (I used to have one as company wheels, hence my username).
It does not have a manifold pressure sensor, or boost pressure sensor -- instead, it maps fuelling, boost etc from a 3D map of inlet charge temp, air mass and exhaust gas temp so it's not as simple as just aiming for a set boost pressure that's just below the nominal fuel cut.
What I did with mine was to tighten the wastegate actuator rod 2 full turns (dead easy, 3 bolts to remove the turbo heatshield and you're straight at it, 20 minutes max.) The factory assembly tolerance is plus or minus one full turn, so two makes it just right!
Edited here to say that there isn't usually enough thread on the rod to allow you to do more than 3-4 turns tighter.
I've heard people have had good results with bleed valves etc but I think it may be better to put a Dawes in the line between the solenoid and the wastegate to stop wastegate 'creep'. Again this would need a lot of experimenting, I've no idea what pressure the wastegate spring is rated at.
Couple of tips I picked up were -- double check the hose that goes from the manifold to the recirculation valve: this gets trapped very easily and will reduce throttle response if it does. Make sure it's free. Also check carefully where the "blue" hose goes from the boost solenoid into the inlet trunking between airbox and turbo, on mine this did not look airtight so I sealed it with clear silicone.
Good luck ...
[Edited by brickboy - 1/23/2002 12:23:26 PM]
It does not have a manifold pressure sensor, or boost pressure sensor -- instead, it maps fuelling, boost etc from a 3D map of inlet charge temp, air mass and exhaust gas temp so it's not as simple as just aiming for a set boost pressure that's just below the nominal fuel cut.
What I did with mine was to tighten the wastegate actuator rod 2 full turns (dead easy, 3 bolts to remove the turbo heatshield and you're straight at it, 20 minutes max.) The factory assembly tolerance is plus or minus one full turn, so two makes it just right!
Edited here to say that there isn't usually enough thread on the rod to allow you to do more than 3-4 turns tighter.
I've heard people have had good results with bleed valves etc but I think it may be better to put a Dawes in the line between the solenoid and the wastegate to stop wastegate 'creep'. Again this would need a lot of experimenting, I've no idea what pressure the wastegate spring is rated at.
Couple of tips I picked up were -- double check the hose that goes from the manifold to the recirculation valve: this gets trapped very easily and will reduce throttle response if it does. Make sure it's free. Also check carefully where the "blue" hose goes from the boost solenoid into the inlet trunking between airbox and turbo, on mine this did not look airtight so I sealed it with clear silicone.
Good luck ...
[Edited by brickboy - 1/23/2002 12:23:26 PM]
23 January 2002, 12:29 PM
#6
Thinking of by-passing the Boost Control Solenoid with the Dawes, but leaving it electrically connected and setting it to about 13-14psi.
The Dawes I have is currently set to that, as have just taken it off me Scoob.
Not sure yet tho' as I havn't even put my head under his bonnet yet.
[Edited by Scott.T - 1/23/2002 12:30:20 PM]
The Dawes I have is currently set to that, as have just taken it off me Scoob.
Not sure yet tho' as I havn't even put my head under his bonnet yet.
[Edited by Scott.T - 1/23/2002 12:30:20 PM]
23 January 2002, 12:49 PM
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Scott, you could try that way, I know that's how a lot of Saab turbo owners run their Dawes -- I'd start low and build it up because as I say, EGT is a big factor in boost control for the T4 and if you go too far, you'll get a lot of Check Engine lights etc
Good luck, it's all easier to get at than a Scoob!
Good luck, it's all easier to get at than a Scoob!
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