Setting Up Adj Actuator

[R TUNE]

hi guys,

my last boost controller started failing so me and my tuner decided to mod the stock actuator to make it adj.

my target psi is 14psi and using the stock actuator it held at 11psi.

my question is how much shorter/ longer do i need to adj it to reach my target psi. i have it currently set at 1 cm shorter than the stock length.

mods are as follows

45v4 turbo,

3 inch turbo back exhaust

cam gears

blitz fmic

nistune ecu

engine is a RB20DET.

last power out put was 165rwkw with boost topping at 16 psi by 4000rpm and dropping to 12 psi by 7500rpm.

regards

brentton

[Ben C34]

If you add more preload it will make the boost curve worse, like 20psi dropping to 14. Adjusting the preload won't change the point at which the diaphragm in the actuator operates.

[Kane_R32]

Not sure if HKS make an RB adjustable wastegate actuator (if they do get one).

Otherwise an Electronic Boost Controller (EBC) might be able to compensate for the boost drop?

[MrStabby]

If you add more preload it will make the boost curve worse, like 20psi dropping to 14. Adjusting the preload won't change the point at which the diaphragm in the actuator operates.

Thats the opposite of my understanding. The gate operation is a fight between the spring and diaphram. Increasing preload has the effect of increasing the force developed by the spring. The force that the diaphram produces depends on the boost. So if the spring force goes up, you need more boost to open the gate.

[scotty nm35]

Spring force isn't adjustable, it is a set force/mm.

If you decrease the length of the actuator arm you are forcing the spring to close more before the flap opens. It works, but not as well as replacing the spring with a stiffer one, and you could reach a point where the flap doesn't open enough to bleed boost off in the top end. (boost spike)

Try it out, just make sure you have a good gauge, I have seen too many that read 3-5psi out.

I would be hitting up Hypergear for a 14psi actuator. Install and forget.

[Ben C34]

From Hypergears thread, page 397

If you over pre-load you will get boost spike and then taper. Try to have it hold one consistent boost pressure off the spring only.

That actually looks OK. its making 150kw @ 4000 rpm which isnt THAT bad for a 200k+ auto. Have a fiddle with preload and just check VCT as said.

pg 398

Its extremely important remembering to preload the actuator as the tuner's tuning. keep on preloading if are seeing boost tapering off before the desired level. It might be 5mms or could be 15mms, the more you load it the higher up top boost level it will hold, more boost makes more power.

[scotty nm35]

It's a fine line, and can be a pain to get right. There is a good reason most of the bigger power cars run an external gate.

[GTSBoy]

Superben, that quote from page 398 is to be read as "adding preload stops the boost tapering off at the top end".

The corollary of that, and part of the page 397 quote is that it also tends to cause a spike as the boost comes on, which is not always (or even often) desirable.

[bananaweesle]

run a Turbosmart or Kando actuator they have springs inside that can be easily changed and the boost dropping of problem nearly disappears. the only reason boost drops of at higher rpm is because the pressure in the stock exhaust manifold is so high the gate actually gets pushed open and is unable to close. Once open with standard actuators and high boost the actuator nearly becomes useless as at about 4500rpm the actuator is forced open and cannot shut.

[R TUNE]

MMM interesting, i have been suggested to remove the ball and spring out of the boost controller and run it like that. Any one have experience with this.

[MrStabby]

Spring force isn't adjustable, it is a set force/mm.

You are saying the force produced by the spring can't be referred to as "spring force" - I disagree. Force/mm is not a sensible term, you should say either force/distance or if you're expressing it in units, use units both sides, eg. Newtons/mm. This property is known as the spring constant (or rate, or spring rate). I agree that spring constant is not adjustable.

OP - try increasing the preload a bit more, and see how it performs. If its sucks, get something else.

MMM interesting, i have been suggested to remove the ball and spring out of the boost controller and run it like that. Any one have experience with this.

If its one of those $20-30 boost controllers then removing the spring and ball makes it a very expensive bit of pipe....

[Kane_R32]

MMM interesting, i have been suggested to remove the ball and spring out of the boost controller and run it like that. Any one have experience with this.

You do realise the ball and spring are whats needed to "trick" the actuator into creating more boost? So removing both well render the boost controller useless and you will run wastegate pressure.

[scotty nm35]

No, they have a small bleed hole in the side, so it will actually run as the stock turbo does, bleeding a little of the pressure off to raise the boost. How much boost depends on the size of the bleed hole and the actuator spring.

[Kane_R32]

I would like to see what level of boost increase you would see though. I don't think the 1mm bleed hole would let out nearly enough boost pressure, compared to if the ball and spring was there to restrict flow, and increase boost.

[scotty nm35]

It's larger than the stock bleeder in the M35 Stagea, and that bumps boost from 7psi to 14 stock.

[Blackkers]

Hey guys sorry for bringing up an old topic. I'm having trouble with an EBC + RB20 actuator. max boost set to 1 Bar. The trouble is I can't find a good balance between response and overboosting with the EBC GAIN setting. I think it's because of the difference between my boost setting and the hardware setting (wastegate pressure)

Has anyone used the Kinugawa actuators on an RB25det highflow? using standard comp and turbine housing. They sell a 1Bar spring that would be perfect.

heres a link: http://www.ebay.com.au/itm/Kinugawa-Adjustable-Turbo-Wastegate-Actuator-Nissan-Skyline-RB25DET-R33-/281163573117?pt=AU_Car_Parts_Accessories&hash=item4176a7a77d

Thanks