Changing stock actuator spring

[SeriesIIGTST]

Hi all,

Quick question, stock boost, as I understand it, is controlled mainly by the actuator spring being rated to open at approx 7psi. Does this mean a) a higher rated spring will result in more boost and therefore B) a lower rated spring will result in less boost.

The reason I ask is i've recently fitted an EBC which has 4 settings as was thinking of replacing the spring with a lower rated one so I can run lower boost when it's wet but then use the EBC to wind it back up for dry.

Thoughts?

Cheers!

[akeenan]

why not just drive carefully in the wet? eg: no hard accelerating

[dojobi]

Yeah that's what I do akeenan. I don't really see the point to low boost and high boost settings. If I'm wanting to go fast I put my foot down. If I want to take it easy I just don't put my foot down as much. I have absolutely no problems with fuel economy either.

Anyway, to answer your question SeriesIIGTST - I think I understand what you want and that's to run lower than stock boost right? If so, then changing the spring should do this (at least in theory). I don't know of any computer problems that this might cause though. Someone else will jump in if I'm wrong I'd say

[unwritten law]

i just bought a 32 and it has a 2 stage boost controller on it. the guy i bought it off said that the owner in japan might have but a larger spring (or uprated) fitted to run higher boost. The boost controller & gauge was fitted here and it appears to be running 10psi on low (or when it came out here, as stock/normal boost). i wound it all the way down on the low setting and i cant get under 10psi.

[Doctor]

Nah that about right for an R32. I had 11psi with no boost controller on mine. But with the r34 turbo on it runs only 5psi when the EBC is turned off. Do you guys think that because of of the week spring that it could mean more creep?

[nissky]

yep similar 6 psi with r34 turbo, the r34 actuator is set to open at a lower setting.......you could put the r32 actuator on, it should be a straight fit....actually i might do this myself ;p

[b2barker]

Is it a 7psi spring or a 5psi spring? If the stock 2-stage solenoid bleeds off air to get more boost at high RPM, wouldn't it be a 5psi with the bleed allowing 7psi. I don't see how it could do it with a 7psi spring to only get 5psi boost. I have asked this before in threads where people have suggested removing the stock solenoid to have 7psi throughout the range, but no answers. Anyone?

[turbomad]

I believe the 2 stage boost on the 33's was 5psi to 7psi, however it's hard to find a 33 with a stock exhaust to check, as the exhaust will alter the boost setting eg. my car had 7psi to 9psi with a 3.5" exhaust. So if I removed the solenoid I would have had 7psi throughout the whole rev range. You can also disconnect the solenoid from it's harness and wire up a switch in the cabin to feed the solenoid 12v constantly and then you would have the higher setting all the time (9psi) in my case. Another option is to wire the solenoid to open through a pressure switch or a micro switch on the throttle, just in case the constant 12v might make the solenoid too hot and burn out.

[armbrusb]

Can you change the spring on a stock actautor? How would you do that?

[turbomad]

The actuators are a sealed item so I doubt it can be modified, you can buy them with a higher psi opening pressure but your always better off with a boost controller to raise the boost rather than a higher actuator, mainly because of wastegate creep. To illustrate, if you had a 12psi actuator at half throttle you would not have 12psi yet as the actuator would have already begun opening the wastegate and slowing the rate of boost increase, so you would need to be damn near full throttle to hold 12psi, now my EBC with the stock 7psi actuator gets me 12psi at 30% throttle which is much more responsive to drive, a cheap bleed valve would still see you at 12psi by about half throttle.

[akeenan]

if you want to decrease power just block of some air flow! place a restrictor plate on top of your filter if its a panel filter or behind the pod if its a pod filter..

[Steve]

SeriesIIGTST, stock boost is 7psi, but it is staged from 5psi to 7psi

so you dont get the 7psi straight up. I dont know if running an aftermarket exhaust will prevent selecting such a low boost, but give it a try.

I wouldnt be in a hurry to put in a weaker wastegate acutator.

The reason is that the spring is not stiff enough to hold the wastegate shut against the pressure from the exhaust gasses aka wastegate creep.

The net result that you may not be able to wind boost up as far as you like.

For example a 14psi actuator will not allow the wastegate to open under 14psi, imagine if you had a 5psi actuator in there, and boost set to 14psi, the EBC has to do all the work between 5psi and 14psi, with a 14 psi actuator, the EBC only starts working when 14psi is reached,

or if you were to put a 10 psi acutator with stock boost control, you would get 10 psi straight up the same as if you had an EBC set to 10psi.

Turbomad, I think you may have got that one back to front? Big one last night?

[kjb_r33]

You will probably find that from the 33's up the spring would have stock MAX boost at around 3 PSI. The boost solenoid then switchs the flow from the manifold on and off (PWM) to allow the higher boost, ie 5-7 psi. The reason for this is so if you have a major sensor failure and go into "LIMP" mode, the max boost you can have is 3 psi. (no power to solenoid, no boost)Try disconnecting the solenoid for boost and see what your maximum boost is, i'll wager its VERY low.

The waste gates on the 32's as far as iknow are NOT ECU controlled, therefore it IS the sprind in the actuator that controls max boost, therefore its only ONE stage, not 2.

[turbomad]

No steve I havn't got it back the front, a 14psi actuator will begin to creep open before 14psi(that's what wastegate creep is), that actuator will give you 14psi but you will usually only get it at full throttle, That's why people buy EBC because they hold the wastegate shut for as long as possible without going over the preset level, and they deliver the preset level with very little throttle needed. Even Turbosmart bleed valves are gated (spring loaded ball bearing to keep air pressure from getting to the actuator too early) to eliminate wastegate creep.

kjb-r33 the R33's solenoid cannot lower boost to 3psi, it is normally closed and only opens around 5000rpm when the Variable Cam Timing switches back, all it does is open to bleed off a little air from the actuator thus increasing the boost 2psi, by dissconnecting it you will simply have your lower boost setting, 7psi with big exhaust and 5psi with stock one.

[Steve]

Turbomad, can you please explain to me why performance companies sell wastegate acutators with stronger spings then?

[SeriesIIGTST]

Thanks for all your replies. Looks like the only easy solution to lower boost is lower revs....bummer....i'm loving the more than standard boost anyway. Got my warning set at 0.85 bar and don't usually see much over 0.72 anyway.

[turbomad]

Steve, maybe for people who want to run 20+psi the higher rate actuators may be necessary, when you run high boost it can create back pressure in the exhaust housing and as you said it can force the wastegate open to escape thus dropping boost a little but this is not wastegate creep. I had a larger comp wheel/housing on my VL turbo and it did that very thing, I tried a larger actuator but it didn't help in my case because the exhaust wheel/housing could not flow enough gas to run more than 12psi.

I'm against using higher actuators to raise boost because you can't go below that level, and most Skyline owners wont run more than 13psi anyway, which the stock actuator can easily handle.