Forge K04 wastegate actuator fitted

[Hurdy]

I have heard rumours that you can adjust the OEM actuator that will do the same thing, can't say it's true or not though

Yes, you are right, but if you adjust the stock actuator then it will have less travel and more pressure on a weaker spring. Not something I would be happy to do myself for the long term reliability of the car.

[RedRobin]

....

Seems like an excellent mod. The one thing that concerns me is that if it's trial-and-error to achieve the optimum setup, what about the hassle involved in access to it for adjustment each time? Or am I mistaken? I'm thinking about the installation steps I've seen posted.

[Hurdy]

Adjustment is done from the other end of the actuator on the threaded rod and makes it easier to adjust. Fitting is a PITA though!

[RedRobin]

^^^^
Ah, and so I assume that the threaded end is easily accessible.

[Hurdy]

still fiddly to get to (knuckle scraper time ), but at least you don't have to dissasemble half the car

[Janner_Sy]

when you planning on the dyno run again hurdy. if you had VCDS it would have been good have to seen logs to see how well it built up and held boost in comparison to the stock actuator

[Hurdy]

Quick update,

Been flitting about between Revo and logging data and the actuator needs backing off slightly. At the moment the bottom to midrange is mad fast, but the top end seems like it is holding back. Spoke to Carl (big thanks!!) at Revo, who helped me analyse the data and the actuator is wound on too far keeping it open longer and then when the actual boost exceeds requested it is having to back off which is killing the top end grunt.

Also it looks like I may need to investigate my cam follower as there is a difference in requested and actual rail pressure across the board under load.

The initial "after" dyno lost me 25bhp and 9lbft

Going back once the car is set right. Already feels better at lower boost setting, but needs the actuator adjusting first.

[Janner_Sy]

this is what puts me off of this. quite a few of the guys in america seem to have had the same problem. its not the waste gate being the problem. its all problem to do with the adjustment of the spring causing issues. plus you have been able to adjust your settings with your SPS, i dont have that luxury

[Hurdy]

Yeah, I know what you mean. The only real option is to have REVO and the SPS+ if you want to get the most from the actuator. A great mod once set right, but it is one of those "finger in the air" mods for the first few attempts at setting. If you haven't got VCDS (or access ) then you're pretty much stuffed too

[GTIjames]

well got this fitted by jkm yesterday they removed the turbo in the end to install as i was getting some arb's fitted so lower subframe was off which i believe made it easier, not cheap but on the plus side the turbo still looks in pretty good condition they say

initial impressions was that boosty certainly came on earlier and stronger, in fact its the strongest i have ever felt it, but as hurdy mentioned it also seemed to loose some umff in the higher rev range. this was all with my pre-actuator settings B8T5F6.

managed to get out this evening and do some logs, also turned down the boost to 7 and its seems pretty good, probably needs more time to adapt but this was a pull in 4th unfortunately due to traffic it was difficult to get to higher revs -



still quite new all this vagcom stuff but hows it looking?

[Hurdy]

The logs look similar to mine, but your duty cycle stays on maximum slightly further in the rev range and your "actual" boost pressure is going waaaaay over where it should be. When mine was initially set up boost pressure was sitting at a peak of over 3000mbar and the only way to bring it down was to adjust the actuator as it was beyond what the SPS+ could change. My actuator is now set about 1.5 turns after the flap closes, any more and I was getting too much overboost. Too much overboost and you'll get a really strong torquey midrange but a blunted performance at the top end. Back it off and the midrange is still very strong, but you'll get your top end urge back too.

[john_o]

that looks around 27-28psi peak ! Id be careful and look to getting the actuator adjusted a bit as Hurdy says.
Im not expert , but i dont get why your N75 duty cycle hiccups just as you boost starts to overshoot, I thought it was always a smooth transition. I'll go and have a readup 

glad its gone well, I guess it really needs some setup time 

[SteveS]

Bump :)

Whatever happened here?

Nice vid i just found, how it applies to the gti i dont know..

As long as you have a HPFP upgrade, and either REVO or APR pump-specific software, it can provide a healthy jump in boost and power. We've seen around 20 peak whp and tq with APR software and around 40 peak whp with REVO software due to the ability to adjust various settings.
GIAC software doesn't seem to like the upgrade very much.

The higher than stock base spring pressure within our replacement units allows for the wastegate flapper to be held closed tighter and for longer against the exhaust gas pressure flowing through the turbo.
Consider that by increasing the boost pressure entering the motor on the intake side of the system, you will see a similar and corresponding increase in exhaust gas pressure that is exiting the motor into the exhaust manifold to spool the turbo. It is a common practice to upgrade the bypass valve to a stronger unit that will better support the increased boost pressure on the intake side, however, you need to also increase the spring tension of the wastegate actuator on the exhaust side to better contain/sustain these higher exhaust gas pressures as well.

With the weaker spring of the stock unit, the exhaust gas pressure can sometimes force the wastegate flapper open prematurely. When this occurs, the exhaust gas that is supposed to be spooling the turbo is dumped, which will subsequently slow the speed of the compressor wheel and limit the potential to make boost in the most efficient manner.

Tightening the stock actuator and adding preload to the stock spring will have the same effect as our replacement, as many people are finding with wastegate tweak mods, but to a much lower degree. You're still working with an altogether weaker base spring pressure to begin with. the stock FSI actuator has a cracking pressure of 4 PSI.

We can assemble our units with any one of 3 different base spring pressure ranges stiffer than stock (10-15, 14-18, 19-24) so the possibility of the exhaust gas pressure prematurely opening the flapper against this higher spring pressure is minimized, if not completely eliminated. All of the exhaust gas is then kept within the exhaust housing of the turbo to continue spooling the wheel keeping boost at it's peak potential at all times.

A boost controller, mechanical or electronic, and including the stock boost control solenoid (N75 valve) will still allow you to adjust up from the base actuator spring pressure, and it will open the actuator when the target boost pressure is reached, but with the stock unit, there is still the potential for the exhaust gas pressure to prematurely force open the wastegate BEFORE the target boost is reached and the boost controller would send the signal to open the actuator.

With our unit, the N75 valve will still function in the same way, sending the pressure signal to the actuator to open it fully when the target boost level is reached, but there is far less chance of the exhaust gas pressure opening the flapper before that occurs.

Depending upon which base spring pressure is used and how the units are adjusted, you may see changes like quicker spool, less tapering, and an overall increase in the area under the boost curve.

[bacillus]

Bump :)
Whatever happened here?

iirc the overall consensus was it wasn't really worth the time and hassle to install and calibrate it correctly with a k04.

[Hurdy]

Not something I'd do again as the benefits are minor.