See Keith Potter's contribution to OzBrick on this subject here...

wastegate adjustment[850][T-5] LUIS -- Wednesday, 4 April 2001, at 7:52 p.m.

 Anyone done this? if yes how much more PSi did you get and is it a noticable difference and is ti safe?

 It all depends on what other mods you have done, and how much you shorten the length of the arm.

 One twist and you probably won't notice anything at all. Three of even four and you could get surge.

 I am putting on a 3" downpipe, 3" high flow cat, 2.5" cat-back with a single silencer and an open element K&N cone style air filter next friday. The air filter
 is already here, and the muffler is coming in next week, and I've booked shop time to have the exhaust put on next friday. When they install the exhaust,
 I'll remove the heat shield and adjust the waste gate to 2 turns. I promise to post my experiences when I get a chance.

 Bad things can happen if you go beyond 4 or even 3 turns. That's why I'm sticking with 2. I'm also putting in a PES-Tuning/GIAC chip in ASAP i.e. early
 May, so I don't want to over do it. I figure start with 2, if I want, I'll go another turn. And if that still works, another half turn.

 One guy in the area is running 255hp at the wheels with a 3" downpipe back exhaust, an AMSOIL open element air filter, and a wastegate adjustment. No
 lights, passes emissions, in fact, the only problem he has is chewing up tires rather quickly.

 I figure with the 2.5" cat-back instead of 3", I lose 5-10 peak hp, while gaining 5-10hp on the low end over the 3".

 I have 95 854T with 110,000 miles. I adjusted the waste gate for 3 turns. I didn't feel any difference. Since the turbo gauge has no number I can't tell the
 PSI. I can see it went up almost full though. Try it and let me know.
 Good luck.

 Sin, did you see the graph of this other guys dyno run? I'd love to see something like that if you could get something like that scanned in.

 Do did you decide to go with a custom 3" downpipe?

 -Michael Svard

 3" down, 2.5" back, K&N, Chip, Chip, (I didn't stutter)

 ~smokin' bald snow tires~

 I saw his run on the computer screen. He kept the print out.

 I decided to go with a custom 3" downpipe, 3" high flow cat (stainless interior instead of ceramic), 2.5" cat-back, 2.5" rear mount muffler with an oval tip.

 Luis,

 One full turn on the wastegate adjustment rod is ~ 0.05 bar, or 0.725 PSI.

 The full reading on the stock boost gauge (i.e. edge of the white area) is 1.0 bar, or about 14.5 PSI.

 On a stock turbo unit, with the 150/40 wastegate, you probably won't be able to generate more than 14PSI before the wastegate opens, since it can't
 hold the higher boost levels. I think stock is about 10PSI.

 If you want more than that, you will need to upgrade the turbo and wastegate.

 For example, I'm using a larger TD04HL-16T turbo, with a 300/70 wastegate, set for ~16.5 PSI at peak boost on my '94 850 Turbo.

 I've been running this setup, together with a custom 2.5" full exhaust system for nearly 7500 miles so far, with no problems at all.

 Good luck.
 --
 Mark B. '94 850 Turbo, 115K, upgraded turbo, exhaust, ECM, suspension & more

 I can verify that about two turns on the wastegate rod
 is good. I did not go beyond that, so cannot say what happens at
 3 or 4 turns. The car seemed to be more aggressive.
 Now, who can shorten the rod on my S60, 2.4T where the access is
 much more difficult?
 Rich

 Aaron;
 As I recall, the suggestion of shortening the wastegate rod came from someone at TME. Since the spring loaded diaphram in the control unit has some
 error at pressures below the maximum, the adjustment is said to allow more boost at lower speeds.
 I am not an expert, but it seems to be reasonable.
 Rich

 Mark,

 has that made a SIGNIFICANT difference in the way the car accelerates from 0 mph or, say, from 40 mph???

 Yannis
 --
 '01 V70 T5 M, Classic Red/Graph Lthr., Sunroof, Cold Weather, 4 CD Surr. Sound, Rear Spoiler, 17" "Tethys" alloys

 Weak link is the actuator rod. You can buy a heavier, open later, one from Kalmar Union. With ECU, Injectors, DP, Cat, and open element filter my car will
 make 18 psi when its cold out. In the summer I tend to lose about 2 psi. In my opinion anything more then a full bar is a bit much though.

 Yannis,

 Combined with the other upgrades (ECM, injectors, downpipe & exhaust), the answer is a YES! (Grin).

 The car was fun before, but not exciting. Now it's a real thrill to drive.
 

 --
 Mark B. '94 850 Turbo, upgraded ECM, turbo, suspension & exhaust

 Charles,

 I haven't had the car configured this way long enough to notice how changes in the seasons (i.e. hot & humid air) affect the boost levels.

 The way I have mine setup now, a firm, but not aggressive acceleration at 20-50mph will usually result in about 5-7PSI of boost.

 An aggressive acceleration in the same speed range and higher will result in a sustained boost of about 10-11PSI.

 A very aggressive acceleration, i.e. 3rd gear at 60+ mph, and kickdown to 2nd gear results in sustained boost of 16.5PSI. Of course, at that point, I'm
 getting much too close to triple digit speeds much to fast (Grin), so I've honestly never kept it there for more than a few seconds.

 I have noticed that the boost level will blip up to 18PSI when the tranny kicksdown, but I've never sustained that boost level for more than a fraction of a
 second.

 I guess what I'm saying is that you're probably right. For normal driving, more than 14PSI probably isn't needed. (Grin).
 --
 Mark B. '94 850 Turbo, upgraded ECM, turbo, exhaust & suspension

 Actually, since Volvo uses electronic wastegate controls changing the length of the actuator will not give more boost. The ECU(specifically, the
 boost control valve) will compensate and you may notice a "surge" but no more usable horsepower. If you turn the actuator too far the computer will just
 shut off the engine.
 

 --
 '95 T5R IPD exhaust, K&N

 That's what I thought too. But if that's the case, then why have the majority of those that performed this modification noticed increased gains in power?

 John G wrote:
 Actually, since Volvo uses electronic wastegate controls changing the
 > length of the actuator will not give more boost.

 A lot of us think it gives more boost.
 The manifold pressure pushes on a diaphram.
 A spring resists the pressure.
 If we increase the spring pressure the rod will not move as far
 due to the pressure.
 If the rod does not move as much, that means the wastegate does not bleed off as much boost.
 We are adding preload to the spring by shortening the rod.
 That is similar to having a stronger spring.
 I do not know of any report of the actual effect by measurement.
 I sure am watching for one.
 Rich

 It will give a slight surge but no noticable hp increase. TME's webpage under the questions page:

 4. Can I get better performance by turning up the boost pressure?
 No. The boost pressure is controlled by the ECU (Engine Control Unit), to get the ideal settings for each driving situation. By turning up the boost
 pressure, the boost control valve will readjust the boost pressure back to the pre set level in the program.By turning up the boost pressure so much the
 boost control valve can’t return the boost to the pre set level, the ECU will shut off the engine.

 That's why after a little more than four turns, things shut off. Up to that point the boost control valve keeps things in check. Maybe it's a mental thing!
 --
 '95 T5R IPD exhaust, K&N

 Any possibility TME is biased in their answer considering they offer hp increasing products?

 Just a thought.

 I was wondwering the same thing but I have read that elsewhere as well. Also if they made that comment it seems like it would cost them some serious
 credibility if it was found out later to be true.
 Not how I would run my company but who knows?
 I t does make sense though. I have seen wastegate diaghrams that will allow more boost and have seen a couple of comments about them in the past.
 Might be a better way of increasing boost.(?)
 --
 '95 T5R IPD exhaust, K&N