View Full Version : RB20 Wastegate actuators - is mine a freak?
Nic_A31
24-12-2010, 11:05 PM
First question first (dumb question)
What response should I be getting from an RB20DET stock turbo.
Before I got my halfcut motor running my impression was they start spooling around 2500 and hit full boost around 4000 rpm?
The actuator I've got (on it's own accord) starts spooling around 2000rpm and hits 10PSI at 3000rpm, occasionally hitting 11 or 12.
With a Turbotech manual boost controller (http://www.listingfactoryhost.com/users/trialuser/eBayAuctions/turbotechorigianlwithhot4s/images/P1000377basiccapend.jpg), it responds slower (begins around 3000-3500) and while it hits 14PSI it doesn't pull as hard at high rpms.
Should it be doing this?
I've tried adjusting this controller a hundred times and same deal - amount of boost changes, response time is still slower and it starts losing it in the high revs. Even set to <10PSI it doesnt feel the same as running the factory actuator standalone - the time it takes from 5000-7000rpm is notable slower with the manual boost controller installed, although level of boost stays the same in high revs...it doesn't spike/drop regardless of peak boost.
All this really seems to be doing is creating another ~1500rpm of lag for the same, more or less boost.
Using a Bosch 040 pump.
the mbc (if plumbed up right) will delay the actuator seeing any boost signal pressure, so something doesnt seem right.
ive allways had good results with them - especialy when coming on boost.
Risk10k
25-12-2010, 09:01 AM
Boost leak? I'm not too sure about the RB's, but do they run a solenoid/bleed valve for boost control - did you run it in series with it, instead of replacing it?
SimonR32
30-12-2010, 12:58 PM
I think you may have the boost controller around the wrong way?!?
Nic_A31
30-12-2010, 02:05 PM
Tried it both ways still no luck. Secured that Alen bolt down harder and it improved a bit, but no matter which way it's setup, I can't get it to spool up as quick / quicker. It's off for now, no biggie. I'll chuck it back on when I've done more mods. Handy for more boost but for now I prefer the quicker response.
lysdexia
30-12-2010, 02:28 PM
The actuator I've got (on it's own accord) starts spooling around 2000rpm and hits 10PSI at 3000rpm, occasionally hitting 11 or 12.
first point, yep that's perfectly normal for an RB20DET actuator, whoever told you that it would be laggier than that has clearly never owned one.
as for your boost comtroller issue, a turbotech controller should make it even more responsive, as it stops the actuator from seeing any boost at all (so it stays closed) until the desired boost level is reached. make sure you have it set up correctly, it should go from the nipple on the compressor housing, into the bottom port of the boost conroller, out the side port of the boost controller, and into the actuator. there should be nothing else connected within this series of lines.
other than that, check to make sure you don't have any boost leaks, split vaccuum lines, or anything like that.
i prefer to run the signal line off the intake manifold rather than the compressor nipple.
lysdexia
03-01-2011, 08:00 PM
why? all that does is give you an unused nipple to block off from the turbo, and an ugly ass vac line and t-piece over the top of the engine..
plenty of good reasons, but heres 2.
the mbc will see less pressure spikes because its signal will be coming after the intercooler (which acts like a diffuser), & the boost setting should be derived from where the engine is actually getting the boost from (intake manifold) - these mbc's are just a variable check valve afterall.
so what about blocking off a nipple & running a longer signal line, it can be done neatly with a bit of thought & if the perfromace gains are there (better boost curve), why not do it.
of course if looks are important to you then go ahead & stick with the 'safe' option of running off the compressor.
Nic_A31
03-01-2011, 10:20 PM
I'm not keen on running a metre odd of rubber hose for 2 reasons, it looks untidy, and being rubber hose, 10+PSI IS going to expand it, maybe slightly, but that is more delay which is what I'm avoiding, along with bullshit amounts of heat in the engine bay at the moment, definately better off just using 2 small pieces of hose and running it off the compressor housing like it was before, tucked away behind power steering reservoir.
I don't have provisions for a solid line since A31's do not run a BOV of any kind (so I can't use the solid line for the BoV in the crossover pipe, and there isnt really anywhere I can steal it from.
1. from your gate to the intake manifold (or fuel reg) is no where near a meter
2. decent quality vac lines will not expand at 25psi (or more) so with a rb20 snail i dont know what your worried about.
please yourself.
Lonewolf
03-01-2011, 10:52 PM
doesnt really matter where you put it, as long as its tuned correctly for the right boost amount.
Different to a boost guage which should be at the manifold.
Its possible you have a dud turbotech, as mentioned it should bring boost on a bit sooner and harder than the factory actuator.
it does matter actually, some places are better than others in regards to turbo response & boost curve when using a mbc.
pretty easy to test if the mbc is working too - pretty hard to have a dud one.
OP, have you tested it yourself?
Nic_A31
03-01-2011, 11:10 PM
What you mean by tested it myself?
I don't have another controller to test it against.
If I run line properly along the crossover pipe and down to the turbo, it'd be just short of a meter, I'm not going to run random-ass lines all over the engine bay, and like I said, the amount of heat around that area at the moment, I'm not keen on running vac lines anyway, it's already melted a few lines that go into that canister.
i have to agree with cranky on that one, ive played around with different mbc setups and the longer pressure source has worked better for me also
its a less aggressive pressure source meaning the actuator has slightly longer delay in opening and the pressure has less variation from the manifold as compared to the compressor cover
just try it for yourself, it may work - it may not.
your here for suggestions you may aswell try them
SimonR32
04-01-2011, 08:30 AM
plenty of good reasons, but heres 2.
the mbc will see less pressure spikes because its signal will be coming after the intercooler (which acts like a diffuser), & the boost setting should be derived from where the engine is actually getting the boost from (intake manifold) - these mbc's are just a variable check valve afterall.
so what about blocking off a nipple & running a longer signal line, it can be done neatly with a bit of thought & if the perfromace gains are there (better boost curve), why not do it.
of course if looks are important to you then go ahead & stick with the 'safe' option of running off the compressor.
Just so you know... YOU ARE WRONG!
Thank you for pointing that out. Was hurting to read that.
mitchy
04-01-2011, 11:32 AM
yup... when me bendy bus came over the wastegate line was running off the plenum, switched it to the compressor housing as per RRob's reccomendation and it reduced a bit of the lag.
Just so you know... YOU ARE WRONG!
lol, well i will agree with what Corky Bell (& others) have written on the subject, so you can think what you like :)
What you mean by tested it myself?.
its just a variable check valve, not too hard to work out.
have you taken it apart?
set the mbc to be open (back the cap head screw right off) - you should be able to blow thru the circuit (with your mouth)
adjust the screw sightly tighter until the spring takes over & restricts your 'signal' getting thru - if it does that its working.
install the mbc with screw at its backed off position & go for a drive - max boost will now be set by factory actuator.
gradually tighten screw to increase boost.
SimonR32
29-01-2011, 08:44 AM
lol, well i will agree with what Corky Bell (& others) have written on the subject, so you can think what you like :)
Good on you, keep trucking with your 1960's knowledge!
You're still wrong :)
Nic_A31
29-01-2011, 09:17 AM
its just a variable check valve, not too hard to work out.
have you taken it apart?
set the mbc to be open (back the cap head screw right off) - you should be able to blow thru the circuit (with your mouth)
adjust the screw sightly tighter until the spring takes over & restricts your 'signal' getting thru - if it does that its working.
install the mbc with screw at its backed off position & go for a drive - max boost will now be set by factory actuator.
gradually tighten screw to increase boost.
Yes, I've done that and the controller does as you describe exactly, but it still does nothing fancy in the way of response.
I meant that all I have here is stock actuator and MBC, I don't have another controller to compare it against.
Next question.
What's normal actuator behavior in cold weather?
I'm assuming the following is normal since cold air is more compressed therfor has similar effect to higher compression ratio:
In the rain/cold nights, it'll start spooling around 200rpm and make 13-14 PSI (with NO boost controller fitted) around 2700rpm on it's own accord.
Again I ask since with my other Cefiro (R32 motor) and other RB20's I've never experienced this.
Have you made sure AFR's are ok? No pinging?
If it's safe 14 psi will be fine.
Good on you, keep trucking with your 1960's knowledge!
You're still wrong :)
well the books were written in the 90's, but nothing much has changed since then lol.
its not exactly rocket science lol, but you can think what you like - these guys know alot more than you. :)
What's normal actuator behavior in cold weather?
I'm assuming the following is normal since cold air is more compressed therfor has similar effect to higher compression ratio:
In the rain/cold nights, it'll start spooling around 200rpm and make 13-14 PSI (with NO boost controller fitted) around 2700rpm on it's own accord.
Again I ask since with my other Cefiro (R32 motor) and other RB20's I've never experienced this.
just get it on dyno & post up a boost curve graph.
then we will know whats going on for real.
Nic_A31
29-01-2011, 11:28 AM
Haven't checked A/FR, I dare say it'd start leaning up around 14PSI?? but no pinging/bad behavior.
Cranky, why would I want to do that? Not trying to be a wanker here, but all I wanted to know was if such actuator behavior was normal for cold air temps. It boosts fine without a controller on a normal day, even better in cold weather, and worse all together with the controller fitted. There's no problem here that I'm trying to solve, just trying to work out why my actuator is happier when it's left alone.
well the books were written in the 90's, but nothing much has changed since then lol.
its not exactly rocket science lol, but you can think what you like - these guys know alot more than you. :)
Every brand car that I work on has the boost source for the actuator as close the the turbo as possible if not out of the compressor housing. Are all those highly paid engineers wrong to put it there? Are you related to Corky?
mitchy
29-01-2011, 01:09 PM
Garrett recommend using a line off the compressor housing, and NOT off the manifold so as not to put a vacuum onto the wastegate diaphragm.
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_optimization.html#Wastegate
Cranky, why would I want to do that? Not trying to be a wanker here, but all I wanted to know was if such actuator behavior was normal for cold air temps. It boosts fine without a controller on a normal day, even better in cold weather, and worse all together with the controller fitted. There's no problem here that I'm trying to solve, just trying to work out why my actuator is happier when it's left alone.
i thought you thought there was an issue with the mbc or actuator, so getting a baseline boost curve (or just a check) is what i would do, if your happy or dont think its worthwhile then thats obviously ok for you.
Garrett recommend using a line off the compressor housing, and NOT off the manifold so as not to put a vacuum onto the wastegate diaphragm.
the comp housing see's engine vac just like the intake manifold.
SimonR32
29-01-2011, 08:40 PM
the comp housing see's engine vac just like the intake manifold.
LOL
Every brand car that I work on has the boost source for the actuator as close the the turbo as possible if not out of the compressor housing. Are all those highly paid engineers wrong to put it there?
we are talking MBC's here - not ebc's that are standard fare on most production engines - there is a big difference.
also, these highly paid engineers dont allways have ultimate performance in mind with your average production car & importantly most of these cars have poorly sized intercoolers from the factory.
corky & others go into great detail on why they select this location off the comp housing & performance is not one of them.
the comp housing see's engine vac just like the intake manifold.
Maybe back when Jesus played full back for Arabs... Or on draw through carby set up.
the engine sucks (vac) thru the intake filter & the comp housing is in between them isnt it...?
SimonR32
30-01-2011, 06:58 PM
the engine sucks (vac) thru the intake filter & the comp housing is in between them isnt it...?
Corky had trained you well...
In having no idea
lol, prove it douche bag :)
the comp housing sees' vac when its not at +ve pressure, fuck knows how anyone with 1/2 a brain could think otherwise
Nic_A31
30-01-2011, 07:03 PM
Is my thread on it's way to the pool room ?
SimonR32
30-01-2011, 08:29 PM
lol, prove it douche bag :)
the comp housing sees' vac when its not at +ve pressure, fuck knows how anyone with 1/2 a brain could think otherwise
And what causes that vacuum genius?
an engine.
whats your point?
do i sense a backpeddle coming :)
2jzlux
30-01-2011, 09:12 PM
Are you related to Corky?
http://sunskier.com/wp-content/uploads/2010/05/chrisburke.jpg
Lol at engine vacuum at comp housing, not going to happen!
Go switch your brake booster hose to the other side of your throttle plate and drive down a hill then come back and post the results.
If its the engine creating the vacuum why do diesel's need to have vacuum pumps?
lets not confuse the issue.
you tell me how vac does not get to the comp housing when its directly connected to the intake of the engine & negative pressure makes its way to the air filter/inlet of the turbo?
put a vac gauge on the intake manifold at idle you will have negative pressure - put the same gauge on the nipple of the comp housing & it will be in vaccuum as well.
thats why when you have boost at the comp housing you have boost in the intake mani - whats so hard to understand about that LOL
SimonR32
30-01-2011, 09:48 PM
lets not confuse the issue.
you tell me how vac does not get to the comp housing when its directly connected to the intake of the engine & negative pressure makes its way to the air filter/inlet of the turbo?
put a vac gauge on the intake manifold at idle you will have negative pressure - put the same gauge on the nipple of the comp housing & it will be in vaccuum as well.
thats why when you have boost at the comp housing you have boost in the intake mani - whats so hard to understand about that LOL
You do realise there is a throttle body between the engine and the turbo compressor housing that causes the vacuum in the inlet manifold?
You have boost at the intake manifold and compressor housing at the same time because the throttle body is open...
Where is your bike?!?
yes, btw since the mbc is just a check valve, its going to stop any vac from getting to the actuator anyway, so the whole point is invalid.
You have boost at the intake manifold and compressor housing at the same time because the throttle body is open...
yes but what about when off boost with plate open, that negative pressure will be acting further up the intake than just at the manifold/butterfly wont it.
SimonR32
30-01-2011, 09:58 PM
THE NEGATIVE PRESSURE IS CAUSED BY THE THROTTLE BUTTERFLY!
You just don't get it...
yes but does that negative pressure stop at the tb? i would have thought it continued on a bit further than that.
anyway, like i said its a moot point because the mbc (where ever it gets its signal) only acts in one way so vac wont be able to get to the actuator.
SimonR32
30-01-2011, 10:08 PM
http://i231.photobucket.com/albums/ee24/MaxVest/backpedal.jpg
2jzlux
30-01-2011, 10:11 PM
yes but what about when off boost with plate open, that negative pressure will be acting further up the intake than just at the manifold/butterfly wont it.
No
You dont have vacuum when the the plate is open.
hth
http://starlyon.com/bugle/forumpics/dash.jpg
i know at wot on n/a there is no vac, but the air filter/airbox are under neg pressure at times in petrol engines are they not?
2jzlux
30-01-2011, 10:19 PM
Go switch your brake booster hose to the other side of your throttle plate and drive down a hill then come back and post the results.
Do this, make sure its a big one.
lol, plenty of big hills around here.
but yeah there wont be enough vac for the brakes to work as designed.
but what about my question above? "the air filter/airbox are under neg pressure at times in petrol engines are they not?"
lets not confuse the issue.
you tell me how vac does not get to the comp housing when its directly connected to the intake of the engine & negative pressure makes its way to the air filter/inlet of the turbo?
put a vac gauge on the intake manifold at idle you will have negative pressure - put the same gauge on the nipple of the comp housing & it will be in vaccuum as well.
thats why when you have boost at the comp housing you have boost in the intake mani - whats so hard to understand about that LOL
What brand vac gauge do you recommend to test this theory?
And can you point out where to put T piece?
http://www.orau.org/PTP/collection/xraytubescoolidge/xraytu1.jpg
fucking nice pipe, yours?
Nic_A31
30-01-2011, 11:43 PM
......IBL on my own thread.
Go connect a boost gauge up before the throttle body.
Do it.
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