The wait is over.Forge K04 actuator testing.

from what i understand you want to go faster/get more power w/o a fuel pump? good luck. as im sure you read its hit or miss with the fsi stock fuel pump. with this actuator here, if you tighten it too much, yea youll hold boost longer, but your also making the pump work harder for it to accommodate for those extra lbs as you climb in the rpm's, hence fuel cuts will def follow in order.

From what they tell me the stock fuel pump is like godzilla and it puts out more fuel as the rpms increase so if the extra boost comes on in the higher rpm range you'll be good

You NEED to fine tune the actuator to a level of boost that supports your other hardware/mods.The rest of the benefits come from the harder spring, that is fixed (meaning you install the yellow one,if it's not already in there).

You need to reach what peak pressures you see now, and then add a bit more extra.Then you let the ECU adapt, and this will be your final boost.Different setups will see different results...obviously....

If fuel pumps are required for Stg. 2 boost levels on the stock K03 turbo so as to avoid hitting fuel cut, and virtually all K04 kits require a fuel pump even without using the actuator, then yes, you can safely assume a pump will be necessary for the K04 with an actuator.

As far as pre-load settings are concerned, obviously you want at least a small amount beyond the flapper simply being in a closed position. How much you add, however, will be up to the user and whether or not their initial setting provides the improvement they are seeking. Incrementally increasing the level of tension will show further levels of improvement, which will be up to your discretion.

the stock FSI pump is not godzilla, its fail. hpfp ftmfw. and after rereading what mike wrote, i forgot this was about the k04, not k03, i was referring to the k03 turbo and fsi motors.

Hey Mike what spring do these come with?

I'd need a little more guidance if I decided to pick one of these up. Obviously you can't continue to "improve" the more you tighten it up. if the amount of "improvement is up to my discretion I'd crank it all the way up. Obviously there has to be a point where you get optimum results and increasing the tension further isn't a good thing.

Mike@Forge said:

As far as pre-load settings are concerned, obviously you want at least a small amount beyond the flapper simply being in a closed position. How much you add, however, will be up to the user and whether or not their initial setting provides the improvement they are seeking. Incrementally increasing the level of tension will show further levels of improvement, which will be up to your discretion.

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JoeyDaBomb said:

Hey Mike what spring do these come with?

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You must select your desired spring tension when ordering otherwise it will include a spring identical to stock (green):

Green - 5-10 PSI
Yellow - 10-15 PSI
Blue 14-18 PSI
Red 19-24 PSI

A41.8QTM said:

I'd need a little more guidance if I decided to pick one of these up. Obviously you can't continue to "improve" the more you tighten it up. if the amount of "improvement is up to my discretion I'd crank it all the way up. Obviously there has to be a point where you get optimum results and increasing the tension further isn't a good thing.

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Boost will continue to rise the more tension you add, which CAN show progressive levels of improvement, however, you will need to decide how far you want to go and whether or not your other hardware modifications, specifically your fueling and tuning, will be able to cope with the boost level you which to reach. If you go too far, yes, you will run out of fuel, and yes, you may have issues with your tuning. We cannot provide recommended settings for your unique setup.

On our K03 equipped cars, we are running the actuator with the yellow spring tightened to 1-2 full turns beyond closure of the flapper.

Depending on what spring you select for either the K03 or K04 actuator, and what boost levels you want to reach with either turbo respectively, these settings may or may not be appropriate for you.

I know you're used to "bolt-on and go" performance parts, where all the work has been done for you, but that's not the case with this product. If that's not what you're looking for, maybe it isn't for you, but dialing this product in to your individual needs is the only way achieve the potential improvements.

So what shortcoming is this part designed to address? Is there something wrong with the current software flashes available that you are trying to deal with? I rely on the extensive R&D and engineering done by APR to determine the appropriate boost and other specifications for my hardware. It sounds like futzing with this actuator is just second-guessing your chosen ECU tuner. I assume the specific boost map APR (or any other tuner) programs is selected for a reason.

Mike@Forge said:

I know you're used to "bolt-on and go" performance parts, where all the work has been done for you, but that's not the case with this product. If that's not what you're looking for, maybe it isn't for you, but dialing this product in to your individual needs is the only way achieve the potential improvements.

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Actuators are not offered to address shortcomings with software.

They are made to address shortcomings with the OEM actuator that software does not compensate for.

Similarly to how a weak blow-off valve can leak on the pressure side of a turbocharged application, a weak wastegate can leak on the exhaust side.

The stock actuator has a soft spring in it (~ 4PSI) that doesn't effectively keep all of the exhaust gas spooling the turbo in the most efficient manner all the time. Too much exhaust gas pressure can force it open effectively causing an exhaust gas leak that limits spool and boost potential. If you figure that you are pumping 15-20 PSI into the intake side of the motor, you will have an equivalent amount of exhaust gas pressure coming out of the motor on the exhaust side.

This is a phenomenon that a lot of people experience without even realizing it. Under a high load condition, such as a wide open throttle pull in 4th, 5th, or 6th gear, boost will quickly climb to a peak value and immediately fall off and fluctuate wildly up and down and which point you will hear a fluttering effect from the engine as the ECU tries to keep actual boost in line with requested. This is far more prone to occur on a smaller turbo at higher boost levels (more air flowing through a smaller space) than a larger turbo at lower boost levels.

No amount of tuning or additional N75 duty cycle will prevent the wastehate from being blow open prematurely by exhaust gas. N75 duty cycle doesn't apply vacuum to the actuator to keep it closed. It only delays the time that pressure signal is held back until it is sent to open the actuator.

The only way to prevent this occurrence is to increase the spring tension of the actuator. Adjusting the stock unit will have a similar effect but to a lesser degree because your working with an altogether lower spring tension, and adjusting it will only limit its travel and flow potential. A replacement unit with a stiffer spring will help to spool the turbo in the most efficient manner possible by keeping all of the exhaust gas flowing over the impeller wheel.

Okay, so I should run some logs and look to see if I'm meeting requested boost on the top end after peak, and also have a look to see what my N75 values are doing. That would be the diagnostics to determine if the stock unit is performing sufficiently? Unfortunately, since I don't have my K04 installed I can run logs on it. Once I have it installed I'm not interested in trying to install the new actuator.

Great info guys.

Mine arrived Wednesday morning and will be fitted Thursday morning. I'll be getting some logs beforehand....

Actual v specified boost
Lambda readings
N75 vs rpm

Should give a baseline to work from.:thumbsup:

What kind of tuning and mods you running?

A41.8QTM said:

What kind of tuning and mods you running?

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The K04 is the stock turbo on my UK Edition 30.

I'm also running K04 REVO stage 2+ with the SPS+ controller for fine tuning
DSG REVO stage 2 (7.4k redline, torque delimit etc)
EVOM's intake
Autotech HPFP
Forge Twintercooler
Forge DV
NGK Iridium Power IK24's
Milltek TBE
Custom decat

Obviously mine is also running different cams to the standard GTI, and the ED30 engine is a different spec from the factory.

:thumbsup:

The Forge actuator went in today and what a nightmare it was to get on. There seems to be less room to work in on the ED30 for some reason and due to this the intercooler downpipe, R/H side driveshaft and engine mounts all had to be dropped off/taken off to get at it. Fiddly ain't the word for it. This is a PITA job.

The good thing is that the car feels more immediate in the midrange and smoother. Backside dyno can feel a difference, but when you have a large amount of power anyway it is really hard to tell for sure whether it is the road conditions that have improved recently or the true pull of the car. I'll be taking the car onto the dyno next week and use the same dyno all the time, so should get some comparative runs for you all. The run will also show boost pressure. I'll get the graphs overlaid too for direct comparison.:thumbsup:

I got mine in yesterday, the wastegate looks very nice. The quality is top notch as it always is from Forge. My manifold goes for porting/coating next week then when it gets back I'll have it installed on the manifold and I'll snap a couple then.

Yes the pictures are huge, I just uploaded them as a attachment as is.