Anyone got a high flow turbo from GCG?

[Sydneykid]

Hi Joel, you asked "So the Stage 2 GCG turbo would work well on the RB30DET then?!?"

I haven't tried one, but in theory the extra 500 cc's would move the compressor surge line a lot further away to the left. I have tried a Stage 1 on an RB31DET though, and it was awesome, if you like that big capacity V8 feeling from idle. It had almost 1 bar at 1,800 rpm and only started to run out of airflow at 7,000 rpm. Huge power band, any gear, anytime.

We went to the GT3040 after that, so didn't try the Stage 2.

[Cubes]

ahhh ok.. I was under the impression you used the stage 2 to make 260rwkw on the RB30DET at 1bar was it? The one that made peak torque at 2750rpm.

[rb20-calais]

Sydneykid,

When you use the Stage 1 on RB20's what is the power figures you usually get? Also what is the turbos efficiency range?

Evan

[grepin]

Hi Talej, this is thread hi jacking, but sorta relevant...

A boost controller solenoid works by opening (bypassing) and closing rapidly to limit the boost the wategate actuator sees.  So you can have say 15 psi but the wastegate actuator only gets say 10 psi.

The boost controller also works when you are trying to steepen up the boost curve by keeping the wastegate shut longer.  Some are rated at 10 psi but start opening at 5 psi, some people call this "boost creep" which is not strictly technically correct.

The problem with all boost controllers happens when you have a big difference between the initial opening psi of the wastegate actuator (say 5 psi) and the boost controller (say 15 psi).  The solenoid has to work very hard to bypass this much pressure.

What we have found works well is to increase the pressure of the wastegate actuator.  A stronger spring, lengthening the actuator rod, spacing the actuator away from the turbo body or using a higher psi wastegate actuator (eg; a RB20DET actuator on an RB25DET) all achieve this.

If the wastegtate actuator is now say 10 psi, this means the solenoid (still 15 psi) only has to bypass half as much.  This results in much better accuracy of boost control.

Another issue can be the size of the wastegate itself, if it is too small it won't allow enough exhaust to bypass the turbine and you end up with boost creeping upwards.  This can also be a problem with dump pipes that don't allow enough exhaust flow from the wastegate.

There are a number of other possibilities but I have hijacked the thread enough with this post.

Hope it helped in some way

Merry Xmas to all

Just reading back through some old threads to see if I can sort my problem. I have a 2835pro internal gated turbo. it has a very large well pivoted (42mm) wastegate. It wants to start opening very early before 5000rpm. Had a standard actuator on it 7psi which broke for reasons I wont go into here. Tried a 14psi actuator with no controller made 8psi at best. Tried a dual solenoid actuator so setup like an external gate. Once again 10psi. With all these actuators you can see the actuator starting to open early. Tapped a boost guage into the exhaust housing and when the actuator is working on spring pressure alone it reads 10psi in the actuator and 10 psi at the plenum. Havent quiet got my head around this concept yet. Anyway there seems to be that much pressure inside the exhaust housing that I will need a huge spring to hold it shut. This has been sujested that I go for a 20-30psi spring to get 14psi. Sounds like backyard theory to me. Anyway any theories or ideas appreciated. I can get higher boost through the boost controller however it is working like a one arm ass kicker to hold boost.

[rb25]

back pressure problem? check exhaust and cat (if any).

-rb25

[grepin]

back pressure problem? check exhaust and cat (if any).

-rb25

So are you saying the turbine is not spooling as well as it should and the gasses are pushing there way out the wastegate. However if it is backpressure against the wategate that would help stop it opening. I have 3inch all the way and no cat. It has been considred however a large expense to find out its not the problem. Have you seen or experienced the same problems and this has fixed them?

[Cubes]

If it were a back pressure problem in the exhaust housing holding or pushing the wastegate flap open the use of an EBC wouldn't allow it to hold boost any better.

That would make you wonder is the actuator really a 14psi actuator.

or..

The exhaust isn't allowing the turbo to pass enough exhaust gas?

You may have to drop the exhaust and see how that affects boost.

But that brings us back to why does the EBC allow it to make the boost?

Whatsisname... Is he running a 3.5"?

[grepin]

If it were a back pressure problem in the exhaust housing holding or pushing the wastegate flap open the use of an EBC wouldn't allow it to hold boost any better.

 

That would make you wonder is the actuator really a 14psi actuator.

 

or..

 

The exhaust isn't allowing the turbo to pass enough exhaust gas?

 

You may have to drop the exhaust and see how that affects boost.

 

But that brings us back to why does the EBC allow it to make the boost?

 

Whatsisname... Is he running a 3.5"?

I can make the car produce 286rwkw however I need to drive the boost controller about 5psi higher than actually achieved plus it drops from 20psi down to 15psi in high revs. I cant help but realise the potential if I can stop the wastegate progresively opening and hold boost at the top end. Also I tried holding the actuator shut with a screw driver and it ramps up nicely.

[Cubes]

Drop the exhaust. It has to be ruled out.

[Sydneykid]

Just reading back through some old threads to see if I can sort my problem. I have a 2835pro internal gated turbo. it has a very large well pivoted (42mm) wastegate. It wants to start opening very early before 5000rpm. Had a standard actuator on it 7psi which broke for reasons I wont go into here. Tried a 14psi actuator with no controller made 8psi at best. Tried a dual solenoid actuator so setup like an external gate. Once again 10psi. With all these actuators you can see the actuator starting to open early. Tapped a boost guage into the exhaust housing and when the actuator is working on spring pressure alone it reads 10psi in the actuator and 10 psi at the plenum. Havent quiet got my head around this concept yet. Anyway there seems to be that much pressure inside the exhaust housing that I will need a huge spring to hold it shut. This has been sujested that I go for a 20-30psi spring to get 14psi. Sounds like backyard theory to me. Anyway any theories or ideas appreciated. I can get higher boost through the boost controller however it is working like a one arm ass kicker to hold boost.

Hi Grepin, the are two things that are important to remember with wastegate actuators. The previous post of mine covers them both, the first is the spring rate which you appear to have addressed. The second is the preload on the wastegate actuator spring. An example, the spring rate is 14 lbs per inch (not 14 pounds per square inch). So if you have the spring compressed one inch it will put 14 lbs of preload on the wastegate. But if you only have 1/2 inch of preload then the spring will only put 7 pounds of preload on the wastegate.

So my suggestion would be to increase the preload. You can do that by lengthening the actuator rod, if it is adjustable. If not, use a longer actuator rod. If you don't have a longer actuator rod then you can weld an extension onto the one you have. Alternatively, if the wastegate actuator bolts onto the housing from the wastegate side, then you can use some longer bolts with spacers (washers) to move the actuator closer to the wastegate thus increasing the preload.

I can guarantee that the addtional preload will hold the wastegate closed, the trick is to ensure that you don't add too much preload sa as to exceed the boost target.

Hope that helps

[Cubes]

I've been doing a bit of reading.

Have you got an adj. actuator rod?

This works in the same manner as an adjustable external wastegate.

Basically it reduces the wastegates travel which allows more boost to be held.

Kind of a band-aid fix but this is what I had also done on the stocker RB20 turbo.

Instead of using an adjustable rod I simply re-drilled the holes in the actuator's bracket that bolts on to the turbo.

I then pulled the actuator towards the front of the engine bay putting more preload on to it in turn also reducing the maximum travel.

Instead of boost dropping to 13psi it will now hold 16psi.

Still doesn't explain the problem.

It does appear to be a very common problem. After reading around a bit it has really made me think twice about going internal gate.

I keep telling me self the turbo is a HKS dammit and has had R&D gone in to it so it should work. Its not some t3/4 turbo shop jobbie.

DIY http://home.flash.net/~joeao/greg/adjwastegate.html

[grepin]

Hi Grepin, the are two things that are important to remember with wastegate actuators.  The previous post of mine covers them both, the first is the spring rate which you appear to have addressed.  The second is the preload on the wastegate actuator spring.   An example, the spring rate is 14 lbs per inch (not 14 pounds per square inch).  So if you have the spring compressed one inch it will put 14 lbs of preload on the wastegate.  But if you only have 1/2 inch of preload then the spring will only put 7 pounds of preload on the wastegate.

So my suggestion would be to increase the preload.  You can do that by lengthening the actuator rod, if it is adjustable.  If not, use a longer actuator rod.  If you don't have a longer actuator rod then you can weld an extension onto the one you have.  Alternatively, if the wastegate actuator bolts onto the housing from the wastegate side, then you can use some longer bolts with spacers (washers) to move the actuator closer to the wastegate thus increasing the preload.

I can guarantee that the addtional preload will hold the wastegate closed, the trick is to ensure that you don't add too much preload sa as to exceed the boost target.

Hope that helps

I know you must be sick of repeating yourself however if I lengthen the rod anymore the wastegate opens and becomes loose. To shorten the rod it pulls the wastegate harder aginat the seal. I canot lenghen it anymore (increase the preload) or the wategate is lifted off its seat. Or am I confused.

[grepin]

I've been doing a bit of reading.

 

Have you got an adj. actuator rod?

 

This works in the same manner as an adjustable external wastegate.

Basically it reduces the wastegates travel which allows more boost to be held.

 

Kind of a band-aid fix but this is what I had also done on the stocker RB20 turbo.

 

Instead of using an adjustable rod I simply re-drilled the holes in the actuator's bracket that bolts on to the turbo.

I then pulled the actuator towards the front of the engine bay putting more preload on to it in turn also reducing the maximum travel.

Instead of boost dropping to 13psi it will now hold 16psi.

 

Still doesn't explain the problem.

It does appear to be a very common problem. After reading around a bit it has really made me think twice about going internal gate.

I keep telling me self the turbo is a HKS dammit and has had R&D gone in to it so it should work. Its not some t3/4 turbo shop jobbie.

 

DIY http://home.flash.net/~joeao/greg/adjwastegate.html

Thanks joel I think you answered my question as above. However I believe this is how the origonal actuator broke from being wound up so tight. The mechanic involved has had a falling out at my workshop and I cant confirm this

[Sydneykid]

I know you must be sick of repeating yourself however if I lengthen the rod anymore the wastegate opens and becomes loose. To shorten the rod it pulls the wastegate harder aginat the seal. I canot lenghen it anymore (increase the preload) or the wategate is lifted off its seat. Or am I confused.

It depends on which way the wastegate actuator works to open the wastegate.

If the wastegate actuator PULLS the wastegate open, then you lengthen the rod.

If the wastegate actuator PUSHES the wastegate open then you shorten the rod.

The idea is to seat the wastegate firmer and make it harder to open.

[Guest Robo's]

I just bought a adjustable HKS actuator and once i put it on i was getting 5 to 7psi. After finally working out which way to adjust it (short & tightening it with pre-load) i then spent a couple of days of getting the boost right. So now i can drive around with 13psi with a stock turbo. But to my dismay, im getting 11psi at 3000rpm, gradually building to 13psi, then falling off to 11psi at the top end. With the standard actuator and a bleed valve, i was getting 13psi at 3000rpm.

So at the moment im not totally convinced with it. If it doesnt hold more boost up high, (soon to be tested and dynoed) i might get rid of it and keep the stocky or wait for a new turbo.

[Sydneykid]

You should still use the bleed valve, it just won't have to work as hard with the stronger seat pressure on the wastegate actuator.

BTW, you probably already know this, but 13 psi with a standard turbo is not a good idea.

[Guest Robo's]

I agree about the use of bleed valve and recently i have backed off the preload and put the bleed valve on to fine tune the boost.

Yes i know about the 13psi, but until i goes bang im happy.

[BHDave]

Definately sounds like a back pressure issue.

try dropping the exhaust off the back of the front pipe and it should make a massive difference. Then check the cat/mufflers to make sure none of em have collapsed.

[Sydneykid]

Definately sounds like a back pressure issue.

try dropping the exhaust off the back of the front pipe and it should make a massive difference. Then check the cat/mufflers to make sure none of em have collapsed.

I am confused, since the wastegate opens outward (away from the turbo and into the dump) excessive back pressure will tedn to hold the wastegate closed, not open it prematurely. Or have I missed something? :confused:

[grepin]

I am confused, since the wastegate opens outward (away from the turbo and into the dump) excessive back pressure will tedn to hold the wastegate closed, not open it prematurely.  Or have I missed something?  :confused:

However if it was backpressure maybe its felt on the turbine slowing its spool up and forcing the air out the wastegate (doubt it due to power figures I am making). Anyway I have been playing around with the dual port wastegate and may be able to plumb it up using all three connections on the solenoid instead of one venting to atmo. Or failing that will try a rediculously heavy spring. If I hold the gate shut with a screwdriver it ramps up nicely so tend to rule out backpressure. Anyway it will be sorted this week I will keep people posted. I wont stop until it is.