RomRaider

Hey

So i was wondering if anyone had experimented with the actuator on the wastegate.

Its been a trick that i have used on a few vehicles that i have owned over the years, and willing to share with everyone, thats if it wasnt 100% realised already.

its as simple as this, the waste gate actuator connects to the waste gate flap and the length is adjustable by undoing the lock nut, popping the clip out that keeps it on the wastegate flap and then you can wind in the length to make the rod overall shorter.

It achieves 2 things, reduces wastegate creep, and also raises boost pressure.

As I have found the wastegate control limited on my subaru legacy (boost drops off after 5000rpm or so even at 100% duty) I will be reverting to this manual system.

I know some of you run seperate boost controllers, but this is a no cost, easy mod.

Warning: if you make it to short the wastegate isnt going to open in a hurry and could obviously cause excessive boost.

I will be logging and doing some testing over the week and see how flat and controlled i can get the boost curve if at all. firstly i will turn off the ECU control as such, and manually get the closest result, then after that I will use the ECU control to help if at all needed. my goal is 15psi

Again, im unsure if this info is already around, but thought i'd mention it.

Thanks, stay tuned

how does increasing wastegate preload increase the max flow rate through the wastegate (which is the solution to boost creep)?

.............how does increasing wastegate preload increase the max flow rate through the wastegate (which is the solution to boost creep)?..............


I dont think i follow your comment, 'increase the max flow rate through the wastegate', as I am trying to reduce the movement of the wastegate (which is reducing the flow of exhaust gas through the wastegate) to raise the boost pressure,

Do I have a different definition of waste gate creep? I think possibly there may be a difference in my terminology.


I have shortened the rod and done some basic tests between work and home (no full log runs) but had the logger open to observe min/current/max figures.

As standard I would achieve approx 9psi, with the adjustment I am now producing 13psi, please note, these are not full 3rd gear logged runs, but a starting point for information none the less, hopefully next 24 hours will see me with some full logged runs which I can find what my max possible boost is in the current adjustment, if it is too much I can adjust back some, if i want more boost i can adjust more, just to show the difference of what this adjustment does make I will log the runs, and compare apples to apples and share here for clarification. Wastegate duty is 0% so the ECU will not offer any help,

My goal is to achieve 15psi flat boost curve.
Problem is even at 100% duty the boost dies off and I am left with about 11 psi boost at the higher rpm levels

So by first setting the mechanics of the wastegate spring closer to my goal, then using the ecu to finish off the adjustments.

Im unsure of the results in the end but will soon know

you can't really hold a flat boost curve on the TD04 - it's exhaust side isn't up to the task that's why the boost tails off. Even if you lock the wastegate shut you'll still see a taper.

Adjusting the preload can help if you have an older/lazy turbo and you need a little more low down punch - but go too far and you'll see it overshooting your boost target and the ECU safety cut will become pointless (as the wastegate boost is now too high).

Use the preload to help with spooling the turbo and reaching your peak boost figure, use the boost solenoid duty cycle to try and keep as much boost as you can (within reason, you still need to hold a decent AFR and ignition advance otherwise your not making power, just louder dump valve noises).

http://lmgtfy.com/?q=boost+creep

first result

single scroll td04s with small cylinder head intake ports - the taper struggle is real

just to double check, is 15psi ideal for this turbo?

oh and i see you have mixed up the term 'wastegate creep' with 'boost creep'

wastegate creep is what i mentioned initially, and is different.

an interesting article on changing wastegate creep by lengthening and changing the volume of the hose to the actuator.

http://www.autospeed.com/cms/article.ht ... p&A=111119

but there is no need for this modification, simply adjust the boost solenoid duty cycle and there will be less pressure reaching the gate. Adding mechanical things like this will often leave you with mapping problems later as the mechanical side isn't responding to what the ECU is trying to do.

ok....

so i have adjusted wastegate duty to 100%

and by 6500rpm it is down to about 11.5psi

what is the solution in this case?

I also ask, have you done this mod? as you are making claims of failure of operation after this mod is performed.

while you think about that....

I have run some logging earlier and at 100% duty I am now just under 14psi after the mod at 6500rpm.

I have noticed a good 2 psi difference in boost pressure. and the wastegate duty is being more effective and controlling to what I want out of the car, having to pull WG duty out of the bottom range with ease of reaching 16+psi

I still have a little more movement left in the adjuster, and plan to go further when i have the time,

I have now just about got a flat boost result, still WG duty to setup and I am not finished.

using 3rd gear WOT pulls from 2000rpm Boost hits at 5psi-2500rpm, 10psi-2850 and reaches its goal 15psi at 3200rpm which ranges +/- 0.2 to about 5500rpm, and then its a fight of spring verses exhaust gases down to 13.5psi at 6500rpm.

The problem with the factory circuit is that the wastegate spring load is not strong enough to hold back the exhaust gases, but by adjusting this rod shorter it is giving the effect of a heavier wastegate spring and keeping the wastegate shut more.

I have never had a mechanical issue with this setup and while subaru tuning is new to me, I have used this easy $0 method previously with nothing but success.

yes - it wouldn't be unusual to put 1 or 2 turns on a WRX when trying to get the boost up a little. But you should have no problems building 18psi at 2800rpm and maintaining that to around 5000rpm (depending on your atmospheric pressure and fuel quality).

adjust the arm too far and you lose the ability for the ECU to safely drop boost in the event of a problem (where there is a problem the ECU will drop to wastegate pressure, however if your wastegate pressure is already 16+psi instead of 7 then the ECU can do nothing to save your engine). Also in higher gears (4th and 5th gear up to top speed) you'll be much more likely to overboost quite fantastically.


If you could show your map or some logs maybe it would help, at 100% duty assuming a clear exhaust path, no boost leaks, working solenoid and uppipe cat removed there should be no issues in building boost and holding it to what you need.

Even if you were to weld the wastegate shut, it won't make the turbo more efficient at high rpm, the boost pressure must be reduced in order to make decent power output on regular fuels/intercoolers otherwise your just flogging a dead horse.

Yup. The boost psi without ecu control is only a few psi more so I don't have a high boost floor. Where you would see 9psi you now see 11psi. Except for above 5000rpm where it just drops off. Getting boost down low wasn't a problem although I had to have duty very high to get any where near 15psi.

Now after adjustment lowrpm to 5000rpm is easily controllable with medium duty numbers (50%) and I have to crank the duty after 5000rpm to maintain as much boost as possible.

I'm still fiddling. But I hope I can use the ecu target system etc to keep the boost where I want it as 3rd gear wot pulls are not the biggest load the car will see so I already understand my setup for 3rd gear wot may bite me elsewhere.

So far I am smiling as I am achieving something without spending $$$

I will share my logs in a few days.

Is .csv format ok?

yes csv is fine, also check your LTV info to make sure all is well.

Did a quick run today, decided to aim for 14psi as some form of compromise, standard turbo and all.

still fiddling with wastegate duty tables, and will likely edit the ranges to get some better control around areas that need it, reasonably happy so far.

included tune file, which is pretty much standard, with a few degrees timing taken out here and there. standard ignition table is no good. knockity knock