Cranking up the boost on a T4 mk1

[barney91]

4 of us bought what could possibly be the cheapest t4 in the UK. But this by no means mean it isnt bloody good.

130k, leather, working air con, tax, mot, good tyres & brakes. Well happy.

Driving it about it was deffinatley quickish (moreso than it felt), but missed a cirtain 'kick' i was expecting, and was gutless low down (boost maybe too low to begin with?)

So using information from:

http://au.geocities.com/ozbrick850/e...eithspage.html

And

http://www.saab9000.com/procedures/e...seboostadj.php

these two web sites, I set to work turning up the boost on the actuator.

Now, considering the milage, and the fact it wasnt a t5 or a saab, I went for 3 1/2 turns.

I'm a bit conserned I may have made a fatal error (that the boost pressure on a t4 is already really high? & the fact I didnt have a boost gauge), but i thought the t5 page did mention up to 5 turns, so I gave it a go.

The difference is huge in terms of drivability. A much more positive output of boost, and a stronger pull. Performance wise, I'm now really happy. No juders or power cut outs, and the boost is constant with no pinking. I'm I wont be red-lining it really as we are taking the car round spain for the student gumball.

Have I made a serious error, shall I turn it down?

Cheers

Barney

[barney91]

I also found out the standard boost pressure on a t4 is 13psi, and taking that each turn rases the boost pressure by 0.75 psi (for arguments sake), I am looking at a max pressure of 15.6 psi. Or am I increasing this wrong, and is it just the baseline pressure increased?

Barney

[timway]

Originally Posted by barney91

I also found out the standard boost pressure on a t4 is 13psi, and taking that each turn rases the boost pressure by 0.75 psi (for arguments sake), I am looking at a max pressure of 15.6 psi. Or am I increasing this wrong, and is it just the baseline pressure increased?

Barney

It won't increase it by that much because the maximum boost is controlled by the ECU and boost control solenoid. The wastegate setting just affects the baseline boost when the BCS is fully open. If the spring in the actuator has become weaker over time then tightening it should improve low-mid range response, if it is too tight then it might overshoot the target boost level then back off too much.
To increase the maximum boost you'd need either a Mechanical Boost Controller or a Remap, and fit a boost gauge ideally.

[barney91]

So assuming that is the case, I should be running just over standard basline pressure, and it should'nt be creating any terminal stress to the engine?

[bb54]

hi, ive done this to saab 9000's and T5's without making them go bang.
the car is equiped with an overboost protection system, so dont loose any sleep.
all i would say is dont stamp on the gas too hard at low revs cos high boost at low revs is where possible con rod damage can occur, running hard at high revs wont be a prob.

as has been mentioned, safest way is to find out off the forum what is a safe boost level to run, fit an MBC and boost gauge and stay below the safe boost limit.

wayne

[loopy]

i run mine at 14 - 15 psi and it flyes it got a kn induction kit s/s exhaust and a mbc bypassing the bcs and a dump valve it sound really good and goes well to