Please Help Me With My Very Lazy Gt2860-9's!

[STATUS]

Did that -5 gtr pick up 900rmp on the street or the dyno? Whats its boosting at now ( sorry cant open the link at work)

Car was totally different after re tension, at least 700rpm on the road in lower gears..

[STATUS]

Trent, where do you measure that 10mm from? Hole center on the act arm to stud center on the wg flap?

yeah sometimes up to 15mm but its car dependant.

[tommis85]

Car was totally different after re tension, at least 700rpm on the road in lower gears..

Thanks! This has been most helpful and had great success this morning! I drove around with actuator lines disconnected and there was a massive gain - much bigger than that from the new cat. I'm going to add a couple more mm's of preload like you suggest and should gain even more! Exciting stuff....I guess it's off for a re-tune after that.

Funny though, because I thought my actuators would have been strong enough. I had the same stuff happen with my 33 N1 turbos!

Will also test the pressures asap and adjust the rods to suit (if there is a difference)

[Don Dada]

Yea had some decent gains in response with adjusting actuators but I had 9psi acts I think, and was able to get it to what even seemed like better than stock response. And as my logs have shown these turbs are capable of 18psi at 4k so tweaking pre-load and ebc should definitely get them there or very close, and even better with cam gears

Be careful adjusting tho as you would be playing around in critical part of the map where boost comes in and it might knk

Now noticed you have adj cam gears, do you know what the setting are?

Edited June 27, 2012 by Don Dada

[SiR_RB]

Can u tighten the wastegates to a point where they don't fully open? Or there isn't enough thread on the arm to allow this?

[tommis85]

Yeh you have to be careful with over-tightening the actuator rods. It's a fine balance between keeping the gates shut as long as possible AND, letting the gate open SMOOTHLY when target boost level is nearing. You don't want the gate being strained open and then suddenly snapping open - it'll cause all sorts of top end dramas. I guess it's a simple matter of applying more and more pre-load with these particular turbos till you get a nice steep power curve and making sure you don't continue to tighten up the rod once optimum curve has been achieved. Alternatively one could get stronger actuators and pair it up with electronic boost control.

Yep, mine can definitely be wound so far in that the gate won't open at all...hoewever, it would be impossible to get the actuator rods back on because you simply cannot reach down there properly You'd have to hook them up to a compressor or something! But I don't really want to run 30 pounds right now

[tommis85]

Yea had some decent gains in response with adjusting actuators but I had 9psi acts I think, and was able to get it to what even seemed like better than stock response. And as my logs have shown these turbs are capable of 18psi at 4k so tweaking pre-load and ebc should definitely get them there or very close, and even better with cam gears

Be careful adjusting tho as you would be playing around in critical part of the map where boost comes in and it might knk

Now noticed you have adj cam gears, do you know what the setting are?

Yeh Don, once I'm sure I have my "lazy turbos" sorted out she'll be going back for a re-tune...

[tommis85]

Yep and you're dead right with the ebc and tweakage. See how I go on the weekend

[STATUS]

Can u tighten the wastegates to a point where they don't fully open? Or there isn't enough thread on the arm to allow this?

Not really, i often preload them up alot more to hold a base of 18psi... there is obviously a limit, so trial and error is the best way to adjust.

[Don Dada]

Are those hks acts you referring to? I would sure like to know how they determine their max figure cause they rate them 0.8-1.1kg/cm2 (11-15.6psi) but we know they can wind up more than that....

I don't think you'd get say a 10psi act to preload up to 18psi? The travel will be significantly reduced and thus cause creep/over boosting?

Edited June 28, 2012 by Don Dada

[tommis85]

I think that in the end you want to have actuators that are close to your target level, that have a big can and piston on them for finer tuning....and, that are fed with an EBC ;-)

[tommis85]

You gotta also remember that the actuators will crack at a certain value and then gradually open no matter how much preload you set. All you do with preload is move the whole thing up into higher boost area. If you had too much preload on a certain actuator it will make the crack-to-open transition a very rough one. I've talked to peeps in the know about this and have also seen dyno plots showing the roughness up top.

[tommis85]

Ah crap I forgot to update you guys with how I went!

Ended up getting a better cat put in along with straightening one portion of the exhaust out a bit to get rid of an unnecessary bend. That kinda improved things a little bit.

But, the biggest improvement came when I played around with the actuators. The first thing I did was run the car without vacuum lines attached to the act's which yielded a small improvment....however it was when I ran a thin wire to each waste gate flapper lever to stop them from moving altogether that I noticed the biggest difference!

So, confident that it's the actuators, I added a load of pre-load to the actuators (about 10mm) to ensure that they're firmly shut and I seem to start to make some solid boost by 3500 onwards - but not 16psi by 4000 like some claim on here. I seem to reach about 12-13psi by 4000.

I also did some testing with a normal footpump+gauge hooked up to the actuator lines. The 16psi actuators will crack by as little as 5psi and are already open by about a quarter by 10psi! With the 10mm of pre-load they now stay firmly shut till about 12psi where they then start to budge. By around 16-17psi they're open.

I am yet to tweak it all and get it back on the dyno. With any luck I'll be able to get some more pounds by 4000 with a re-tune. I'm also suspecting that I maaaaay have to wind some of the pre-load off as I'm thinking they may overboost

[tommis85]

Makes you wonder how the rate an actuator at whatever it is. Like, where in the actuator rod's travel to they rate the 16 pounds? Obviously a 16 pound actuator doesn't have 16 pounds when it's in it's "home" position....it builds it up somewhere along the line as the spring gets compressed further and further. Ie. the spring doesn't get installed into the actuator canister with already bearing on the piston (as proven by pumping actuators with foot pump)

Maybe they mean that when you make the actuator rod as short as possible and then put it onto the wastegate flapper lever it will then have an immediate 16psi pull on that lever

[tommis85]

*with 16psi already bearing on the piston (as proven by pumping actuators with foot pump)

epic typo

[scotty nm35]

It really needs a stronger spring inside it, so you don't loose travel. Pre-loading is only a little effective because you aren't changing the spring rate, just bumping up the start point of the travel.

[tommis85]

It really needs a stronger spring inside it, so you don't loose travel. Pre-loading is only a little effective because you aren't changing the spring rate, just bumping up the start point of the travel.

Yeh you're right about that - otherwise it's a bit of a balancing etc and I'm thinking that ultimately you will lose out on a bit of response again. I'll see how it goes....but I do see myself getting an EBC and stronger actuators....more $$$

[Piggaz]

more $$$

Yeaaahhh. Get used to it

[tommis85]

Haha yeh

[tommis85]

Not really, i often preload them up alot more to hold a base of 18psi... there is obviously a limit, so trial and error is the best way to adjust.

^^ I'm going to try to do something similar. I'll see if I can get the preload just right to hold something like say, 16 pounds and then maybe bleed off the final couple pounds. Not sure how it will turn out...it will no doubt be a compromise between actuator resistance, rod length and bleed valve