Would an incorrectly adjusted actuater cause boost creep

Since i've fitted my RS around two years ago i have always suffered this eg; base boost 0.9 till 5k then to 1.1 at 7k

I have renewed all the greddy hose's fom the solenid to the controller and the compresser and actuater, and also bypassed the controller by going straight from the actuater to the compresser.

Still no joy

This morning i blew and sucked on the actuater pipe and heard a kind of quish,quish noise as i sucked and blowed down the pipe.
the sound was coming from the actuater.

Bare in mind i could only just suck a little bit of air through, would this be the cause off my creep.

Ben

I had a similar problem before and tried adjusting the actuator arm a million and one times without any joy. Have you check that your wastegate is opening/closing smoothly?

Disconnect the arm from the wastegate lever and try moving it by hand. If its ok, check the actuator is ok by connecting a pressured airline to it.

The wastgate can open smoothly a full 90' sweep.

I dont have a pressured air line to connect to the actater,
though i seem to recall its not advised to do that

Ben

Well if the air line pressure is controlled, I don't see how it could cause any problems.

To be honest i'm not sure what else it could be. When I had a similar problem, no one could really give me an answer as well. Eventually i tried using an exhaust restrictor ring to see if it helps. It does, but I wouldn't advice using it as its just too mcuh restriction on the exhaust. When i took the ring off, the car was flying again

What boost controller have you got?

i'll adjust the actuater a lttle more and see what happens,

the thing with the gt28rs actuater is its either a 7psi or a 14psi one/ 0.5bar or 1 bar .

if i had it set below these what effect would it have.

Ben

I currently run a restricter ring at the base of the dp and it still creeps to just under 1.2 at 7k

i run a greedy profec spec b

Ben

Be interested to hear your results Ben. I adjusted my wastegate to be firmly shut which now gives me better spool up but BIG boost creep.

I'll adjust it and see though im not confident it will work

The easier option will be is to buy a new actuater and see.

Ben

Or most people have ported the wastegate to prevent this.

I doubt its anything to do with the actuator. Adjusting the length of the arm will only affect how early or how late the gate is going to be open. I tried swapping actuators before as well..but it made no difference.

For some strange reason, my boost creep problem has disappeared now. Have you tried lowering the Gain setting on the greddy?

thats what I've done!

I have spoke to mark at owen developments and he assures me the 28rs's dont creep

as they have a fair size wastgate flap and he seems pretty sure its somthing else

Ben

I have serious Boost creep too. I can set mine to 0.8Bar (lowest) then at WOT and by 5K it can creep up to 1.7BAR I have the 14 psi RS actuator on a GT2871R with a full 3" system and a Blitz Dual. I actually don't mind this as it’s like having boost control with gears By 5K I have full traction and want more boost anyway

Right i've been out and disabled the greedy,

piece of new petrol pipe from actuater to the compresser and i have removed my restricter ring

result is that the greddy is not the problem.

i hit 0.7 then by 4.5k it starts rising to 1.35 just before 7k

so is this genuine boost creep or possibley a faulty actuater

Ben

Sounds like boost creep and the only real feasiable way of fixing it, is to have the internal wastegate ported out to a larger size. As the revs get higher, there is more exhaust gas getting in, but not enough flowing out the wastegate to keep the boost level acceptable.

TBH i dont really feel like taking the turbo off


The weird thing is that it is fairly controllable with the greddy in place

The min it will hold at the redline is 1.15

Ben

In my case it is down to the fact that I have a full 3" system causing less back pressure. To solve this issue as Begbie suggested porting out the WG is the way unless you wanna go external wg.

The wastegate needs porting, I had this problem with my 28RS although mine was creeping up to 1.6 bar. I tried 4 different actuators and the exhaust resriction thing, the only way to cure it was to port the wastegate

Get that dremel out

Can anyone give more details about porting the wastegate? and what should be exactly done? what size of porting?

so why don't I get boost creep then? Standard GT2871R with standard internal wastegate - 3" downpipe - the only substantial difference to everyone else is that I still run the pea-shooter sized Supersprint from the decat back

Because you have back pressure. 10% pressure is recommended for road turbos so if you run 1Bar boost you want 1.1Bar back pressure. I don't want back pressure I want more power .

Basically if you have a free flowing exhaust the lower the backpressure, this increases the speed of the gasses across the turbine wheel. Gases want to go the easy route rather than go through the restricted WG hole. This makes more boost which means more exhaust gas than the standard WG is designed to handle hence boost creep.

I knew I should have gone external WG .

It seems to happen at random
I've only got a Gtir and happened to me

Sorry I disagree boost creep is not random it’s a mismatch somewhere.

Quite right..but where? Exhaust too free flowing? Too much exhaust from engine? Strangely, it sorted itself out after I had a 3" downpipe installed.

Curious that I never had creep on my GT28RSR and yet I do in the GT28RS. Probably down to the bigger turbine wheel.