GolfGTIforum.co.uk
Model specific boards => Golf mk5 => Topic started by: Kiddfrost on 21 May 2009, 20:59
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Hi,
I thinking of adjusting the wastegate on my k03 to put a bit more preload on it. I'm hoping this will make it hold boost a little longer. I'm wondering if anyone's got a bit more info about it before I start messing with it.
Thanks
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My advice is to not mess with it. If you want more boost etc get your car remapped.
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Am revo'd
Why do you say not to mess with it? or is it just one those things that should never be touched?
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I personally dont know a great deal about, but I know its soooooo easy to do more damage than good when playing with it. What DV have you got?
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OEM, the latest revision piston type. I've been though 2 of the earlier revisions.
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Ehhhhhhhh *thinks realllllly hard* Im pretty sure G is the latest version, mind has gone blank though.
Thats meant to be a pretty decent model. Mine is a Forge one and holds boost fine, from what I have read G version should be all good.
You feel like its not holding boost at the top end?
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I think its holding boost like any other k03 but I want to squeeze a bit more out of it.
My understanding is the wastegate bypasses the turbine to stop it from spinning too fast. With the overhead that manufacturers build into things I'm thinking I could get it to spin a bit more by altering the threshold level of the wastegate?
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I think adjusting the wastegate like that was fine for old school turbo's but in a modern car when the ECU detects something is (as far as its concerned) operating out of spec it will reign in fuelling etc to compensate and just generally fight you. Maybe better going down a custom remap route to get what you want?
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As above.. its a dirty oldskool trick, equivalent to a bleed valve. Wastegates are controlled electronically these days so I wouldn't go messing with the actuator rod. Dunno if anyone has tried swapping the boost solenoid out with one from a k04 engine.. worked on the old 1.8T gti engines.
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It's all controlled through the ECU, if you have Revo then you can adjust the settings manually to give you what you're looking for. If you mess with the wastegate/DV the car will just go into limp as it will think it has a fault.
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Ding dong,
Round one.
Forge have an actuator for the K03 GTI. It is a very long story but, The OEM actuator bleeds through air at around 4psi which increases the N75 duty cycle, which basically reduces overall power and torque attainment across the rev range.
On a typical test they simply swapped the OEM wastegate for the Forge version and the car made significant gains of up to 42whp and 48lbft
Now the not so good news. The guy in question had a leak that was present before AND after the dyno's. This means that possibly if he hadn't had the leak he would have "only" seen an increase of around 15whp and 15lbft. Still amazing though.
Here's hoping that a K04 version gives similar results.
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So there is a chance it could work then :smiley:
Is the bleeding a fault with the ko3 actuator or just a characteristic?
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I think adjusting the wastegate like that was fine for old school turbo's but in a modern car when the ECU detects something is (as far as its concerned) operating out of spec it will reign in fuelling etc to compensate and just generally fight you. Maybe better going down a custom remap route to get what you want?
A custom map would be nice but I want to stick with revo as I can switch to stock and adjust settings.
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The bleed through of pressure through the actuator wouldn't change with mapping.
The bleed is due to the spring rating. Forge have been testing varying spring ratings and have managed to drop the duty cyle down from 90+% down to 50-60%. This means that the pressure bleed through is less and so the turbo keeps spool longer, promoting faster response and more power.
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I measured the actuator on my stock '05 Audi 1.8t K03 with following results.
Listed is the PSi applied to actuator port and the corresponding rod movement:
3.5psi .25mm;
4.0psi 1.2mm;
4.5psi 2.8mm;
5.0psi 4.6mm;
5.5psi 6.2mm;
6.0psi 7.7mm;
6.5psi 9.2mm;
7.0psi 10.7mm
I did not measure above 7psi as there are only 10.4mm worth of threads on the actuator rod to move the locking nut over. Three full turns of preload seals the waste-gate flapper nicely. Any more is not (normally) necessary because the N75 determines actual boost by bleeding pressure from the actuator.
A person might think that tightening down the nut each full turn gains 1/3 psi in boost but again, the N75 controls boost by bleeding off pressure from the actuator and thereby keeping the waste-gate closed.
Keeping the waste-gate snugly closed is only effective in fighting exhaust back pressure in the turbo until the ECU decides the boost level is sufficient and drives the N75 to allow the waste-gate to open. So in summary: If your actuator is not pre-loading your waste-gate enough then cranking down on your actuator adjustment will help (assuming your waste-gate is in decent shape). The duty cycle of your n75 valve is the final answer to all these questions. You do not want it down near 0%. That would mean:
your waste-gate is going bad or,
your actuator is going bad or,
the actuator adjustment is too loose or,
your pressure hoses from the compressor housing, thru the N75 to the actuator are bad.
I am guessing anything above 15% duty cycle would be fine, otherwise crank down on the actuator adjustment and see if that helps raise the duty cycle. If it does not then you have to start looking at the other previously mentioned items.
Just understand that you can't hurt anything by cranking down on the actuator rod adjustment. If you do crank it all the way tight and improve your boost to about 7psi then your N75 and/or its pressure hoses are dead.