NefMoto

So having fixed with the help of Nyet my logging issues with Load I now have a tune that I'm pretty happy with accept for one 1 thing.

If you have a look at the boost plots below you'll see that I'm only hitting 18psi even though I'm requesting 22-23psi I can understand this at lower rpms as the turbo spools up but it remains across the rev range. I am confident it's not a boost leak as I have run an 18psi map and it holds actual v requested across the RPM range which in my mind say there are no leaks.

I have a stock actuator, all be it brand new so possibly this isn't holding or possibly the N75 duty cycle isn't right but I have increased the N75 maps to 95% at high loads and it's not helped.

The only other thing I think it could be the forge actuator which has a green spring and when I increased the load maps I get a definate flutter which sounds very like the DV so it might possibly be that leaking boost.

could anyone shed some light please..

i  get the same thing with my hybrid under very high load i blocked off the DV to narrow it down made no differance did think waste gate nope!! starting to think restrictive hot side not allowing gases to get out quicker than the cold side produces???? just guessing gone through everything now ive tested then double tested every thing still the same 

Cheer's it's good to know someone else with the same setup is getting the same issue!

Which manifold are you running? I've got the tubular manifold which I know can flow well, I also know a similar setup to mine flowed a solid 23psi so I think the engine can do it. I'm pretty sure the turbo can supply the air , well I hope it can! I'm going to add some preload to the actuator to see if that makes a difference as I'm wondering if the actuator just can't hold the wastegate shut and thus leaking exhaust it out..

Can some tell me if I can go open loop on the N75 IE max the table at 100% and run an MBC? to see if the wastegate is blowing opening

On OEM mani at present very restrictive i know, had it maxed out to just over 23psi on dyno equipment got no doubt on turbo producing the boost good but the exhaust pressure (exhaust restriction) i think is the problem, im very close to fitting uprated jbs k04 mani to mine and thinking of getting the exhaust blades clipped while its all out to cure it?? sure its not waste gate problem as ive tested this by locking it up  still the same

Are you getting high EGTs? Mine are still around 800 , I would think if it was a restriction then they would go through the roof. Admittedly the stock manifold is crap so any help with that is going to help, the k04 turbine housing is also the weak link, which is probably where the backup occurs.

Personally I'm against clipping the turbine , can't see the point. You do it to allow more air past faster but at what cost?  the inducer on the rs6 turbine (2283)and stock k04 (2275) are identical so what do you achieve by making the rs6 Exducer less restrictive.. If its less restrictive it has to be less efficient so are you making it slightly better than stock turbine wheel or a poor rs6....

In my mind making the port, which is what I do larger is the way to go. Reason being that the inducer does a lot of the work in spinning and the exducer flows the air out . The inducer on the turbine takes high pressure low volume/mass air and turns it into power this conversion slows the air and makes its volume increase and speed,  the exducer takes high volume, fast gasses and moves it on mass out the turbo, it's the opposite of the compressor. If you enlarge the port on the turbine you allow air to flow past the exducer once it's works done by the inducer, it's the same as clipping however it retains the full capabilies of the blades, the whole point of the blades is to move air, you clip them you reduce that.. The ideal answer would be great a large scroll on the turbine housing ie larger A/R ratio, this is the case of the k04 which is run in the TTRs/S3 which can make 360bhp with the same internals.

I'm going to try blocking the dv port to see if that helps and also just run an mbc set at 20, then 21,22 and 23 psi to see where I end up.

I've also got another hybrid which I'm going to block the exhaust outlet and inlet and pressure test the turbine/actuator to see at what pressure it cracks open, I have a feeling that as my waste gate is heavily ported the increase in volume and thus area acting on the waste gate penny flap has increased the flap is being forced open artifically . We will see

i do get massive EGT's as expected with manifold but dont use it for long periods of time ATM until manifold fitted ,
well you've talked me out off the clipping turbo (saves me moneys) just hope you have more luck than me solving this issus with hybrid unit be good bit of research finding out what pressure the wastegate blows open untill then im running low(er) psi

I would maybe suggest getting the turbine housing bored out to help. If you decide on it I can get it done for you be about £40 return posted...

I'll tighten the preload on the actuator tomorrow and see if that helps.

if you read the links I posted to the hybrid thread I have had running for a couple of years now, you will see you are treading well trodden ground...
clipped turbine wheel fixed surge.. on 2283 wheel'd hybrid... 300rpm slower to get going, but no loss of top end flow.. 21-20psi maintained and 332bhp so far, and no timing pull still. unclipped, the engine/turbo is just not ready for the flow until past 4200rpm in my experience.
http://www.seatcupra.net/forums/showthread.php?t=298188
http://www.seatcupra.net/forums/showthread.php?t=298190
http://www.seatcupra.net/forums/showthread.php?t=304931

Watch the wg push open when its seeing the ex mani pressure build up and overcome the static preload from the actuator... green spring aint up to it..  12psi or more needed in my experience..

Cheers for the info...

I read the posts and followed them at the time along with Wellys exploits.My WG is definitely blowing open and causing the boost to taper off! I did some tests today, locking the wastegate etc its opening around 20-21psi, so I think an updated actuator is definitely needed if you plan on 300bhp+ I've managed a rough 300bhp at 18psi  the dv is definitely an issue as well, I've got hold of a blue spring to test so will try that and if that's to strong just buy a yellow one.
I'm going to add a spring tomorrow to actuator to add some more pressure, check the cracking pressure by unplugging the n75 and adjust the n75 maps again. All fun and games...

I dont want to scary you, but my hybrid turbo did that when my rods was bent.

Got ie forged rods. So not worried about bending rods. I put an extra spring on the actuator/wastegate , home made style to help keeping the wastegate closed. Definately helped with the wastegate opening so a uprated one is Definately on the books.

Ok so quick update. I fitted a spring to the actuator /rod today to help with keeping the waste gate closed as a temp measure to prove my wastegate was been blown open. I found an old VW type 1 spring I had from my old turbo manifold which fitted perfectly with a bit of work. Ran the car with the n75 unplugged and it went from the original 6psi to 11psi... So with an mbc I can now hold 23psi to the red line... Although it surges heavily around 3250-4250 which I excepted but over that it's solid and I ended up with 272grams on the maf.. Now I just need to work the n75 maps to control the surge and stop the massive over boost i'm sure I would have if it weren't for the mbc..

It seems the critical point for these kinda setups is the 3250-4000 rpm range.

Small conclusion at the moment is if you want to run 300bhp then a stock actuator is ok , over than then an updated one is essential.

as per my findings, in every respect
you are reinventing the wheel you realise?

Not trying to re-invent just learning how to roll it at the moment:-)  I totally appreciate you have a wealth of experience and this is all old to you but I am still learning and whilst it's very useful to read stuff i find it much better to put it all in context and see it for myself when doing it.

Wow 272grams on maf what's your hybrid specs and mani?
I think start looking for uprated actuator now then

It's a 2283 compressor with rs6 turbine ( larger exducer than the k04) I have also the relentless xs power manifold and blue flame 3" Dp, cat and exhaust. It's on a small port head with an fmic .

you been on a dyno yet?

littco what is the end result just added extra pressure (spring) to the waste gate and adjust n75 map for surge ?? as im in the same boat as you atm will be adding relentless mani very soon which will only add the waste gate issue

Hi, no not been on the dyno yet. A local lad to me ended up buying the car , he's doing some work on the body work and then he says he get it down to the dyno near me, I've offered to pay for the dyno time, book it in etc but he doesnt seem that bothered, he was just happy it was faster than his Leon cupra R!

In the mean time though I've just bought a TT which is going to have the same treatment although a different spec turbo. And that will Definately get dyno'd.

I should have got it dyno'd really before I sold it, but there's only 1 place locally I can use without a 150mile round trip. I'm seeing the guy who bought it on Sunday so in going to try and twist his arm to get it dyno.

End result of the spring was that it held 23psi to the line, so I ended up buying a 10psi t3 actuator and fitted it to a stock actuator bracket. Very simple mod to do and had the same effect of keeping the wastegate closed at high rpm. Since then all the other hybrids I've done I've fitted the same actuator as standard. You do need, as pointed out before , an MBC to cap the boost. Running 18psi below 4750 to prevent surge is fine on the n75 but when you try to run more boost the pid controller just can't cope if you go from full throttle, off then on again, it spikes really badly, by the time the n75 goes ohhhh "I need to open the wastegate as boost is rising to much" it's over shot the requested and will under some conditions induce surge only way to prevent this is with a MBC or I guess hours and hours of PID tuning,

where abouts in the country are you based dan?
no where nr glos?
N75 driven by fixed duty cycle will work... used this a few times once I got the hang of what the hell seemed to be going on.. and some tips off niki to set me in right direction.
9-12psi actuator is what I ended up with from the Cr spec'd units.. kept it closed as a compromise of backpressure vs control..  Now I can do fixed duty cycle control a very strong actuator or possibly running one in dual port would achieve the same "keep it closed" desire

Thanks Bill, unfortunately I'm down south in Surrey so a fair trek over to you, but I'm working on a TT now with a newer hybrid version and will Definately take a trip up to for RR when I can as I'm hoping this hybrid will be better than the previous versions. I think with the help of Barks we've got a pretty good n75 map now but I'll have to see if it copes next time round.

no worries.. just let me know and we can sort that.