Adjustable Waste Gates

[portaz]

Hi guys I have done some searching but cant find the answer, I was wondering the theory behind adjustable waste gates (internal) and how to set them up and if a boost controller is required or will they hold required boost level on their own? The turbos are nismo rs580 with nismo actuators. Sorry in advance for such a vague question.

Scott

[MrStabby]

Pretty sure you will always spool better with a boost controller. If you dont have one it will be softer when you get close full boost. Set the actuator to open at a little above the pressure you actually want it to open at, so that the controller doesn't have to work too hard. Of course you'll need a hand pump with gauge to pressure up the actuator to make it move.

[W0rp3D]

Pretty sure you will always spool better with a boost controller. If you dont have one it will be softer when you get close full boost. Set the actuator to open at a little above the pressure you actually want it to open at, so that the controller doesn't have to work too hard. Of course you'll need a hand pump with gauge to pressure up the actuator to make it move.

you actually want to set the wastegate below the pressure you set the ebc at.

most internal wastegates will start to open as you get towards full boost, a properly set up ebc will eliminate this and wont release the pressure to make the wastegate open till a fraction before or right on the boost setting.

[portaz]

Thanks guys so profec b it is then

Scott

[R31Nismoid]

I've never run a EBC in 7 years.

Boost response is perfect in all setups.

You need to ensure a heavy duty actuator, bleed as close as possible etc. Takes a bit of stuffing around so in some ways the EBC is certainly easier.

[W0rp3D]

I've never run a EBC in 7 years.

Boost response is perfect in all setups.

You need to ensure a heavy duty actuator, bleed as close as possible etc. Takes a bit of stuffing around so in some ways the EBC is certainly easier.

do you know of any good tutorials, for legal reasons i would rather not run an ebc but it seems like the way to go unless you can shed some light on how to set up an adjustable gate properly.

[R31Nismoid]

It's a bit hit and miss, replace the feed with a piece of metal pipe and drill a hole in it.

Acts the same way as a bleed valve in a sense but it's always doing exactly the same.

obviously pre-load on the actuator and so on is also required. Hence it is a bit fiddly.

If i get time i'll pull mine out/photos . But that wont be for a while as im pulling 12-14hr days

[zebra]

It's a bit hit and miss, replace the feed with a piece of metal pipe and drill a hole in it.

Acts the same way as a bleed valve in a sense but it's always doing exactly the same.

obviously pre-load on the actuator and so on is also required. Hence it is a bit fiddly.

If i get time i'll pull mine out/photos . But that wont be for a while as im pulling 12-14hr days

Thats how people used to cheat in the Summernats Dyno comp.

Not allowed to change boost settings between runs, so they would poke a hole in the silicon lines going to the wastegate(s) to get more boost if needed.

[R31Nismoid]

[W0rp3D]

also sounds a lot like something i heard a long time ago, putting welding tips in the vac line.

[MrStabby]

My understanding of the theory is that the exhaust pressure on the wastegate flapper combined with the boost pressure on the actuator will start opening the gate before you reach target boost. So, you use a boost controller to bleed off pressure to the actuator until you have reached full boost to keep the gate shut until then. If we plotted boost vs rpm, it would looks something like this (below). Whether its important of not depends on the size of the difference between the two plots.

[Trozzle]

My understanding of the theory is that the exhaust pressure on the wastegate flapper combined with the boost pressure on the actuator will start opening the gate before you reach target boost. So, you use a boost controller to bleed off pressure to the actuator until you have reached full boost to keep the gate shut until then. If we plotted boost vs rpm, it would looks something like this (below). Whether its important of not depends on the size of the difference between the two plots.

Without a boost controller will ofter see your boost level drop off higher in the revs. This is because the pressure on the wastegate flap is also acting against the spring in the actuator.

[R31Nismoid]

My understanding of the theory is that the exhaust pressure on the wastegate flapper combined with the boost pressure on the actuator will start opening the gate before you reach target boost. So, you use a boost controller to bleed off pressure to the actuator until you have reached full boost to keep the gate shut until then. If we plotted boost vs rpm, it would looks something like this (below). Whether its important of not depends on the size of the difference between the two plots.

Ye in theory. But I think back to when i had external gate.

7psi spring running 17psi - I had massive gate creep, you could hear it

14psi spring running 17psi - no creep what so ever. gate opened @ the same RPM everytime

It's the same principle with internal gate. It's interesting to think that perhaps because it's twin turbo, dual actuator - it wouldn't suffer as much as say a GT35 with an internal gate/single actuator.

I might be totally wrong there as well though.

Might have to get a run or two done with the gates locked and just see how it ramps

look @ the sheets i posed in the RB26 comparo earlier this year.

One of the -5 graphs holds 21psi flat to 8,000rpm (redline).

[MrStabby]

With respect to creep, I dont think there'd by any difference between bleed valve and boost controller because they're both doing similar things at that stage (in the general case). Again all theory tho, and oversimplified - I havent even considered flapper size, and how diaphram size/spring constant affect things. My guess is if you looked at the ratio of the actuator diameter to the flapper diameter, the higher the ratio the less benefit a boost controller gives you.

[Scooby]

Might be missing something but isn't the advantage with an ebc that it's either on or off, so it lets nothing through until the pre set limit is reached and so there's no creep. Wastegates are sprung devices so by definition there's elasticity so if they're set to be fully open at say 20 psi they're likely to be part open at 18. Hence the creep.

Edited April 30, 2011 by Scooby