Wastegate Actuator Mod

[EnricoPalazzo]

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

Anyone tried this. If it allows me to hold boost better i will.

Cyas

[EnricoPalazzo]

Also this one.

http://www.denverspeed.com/wastegates.html

[Guest INASNT]

best way to control boost is with an external gate and spring tentioned to what boost u wanna run.

[Cubes]

First one is a bit like my bodgy mod.. reduces the travel.

[Sydneykid]

Hi Enrico, as previously posted ...............

I am not fan of adjusting the spring tension on the wastegate actuator, all you are going is changing the preload. So if it had a 6 psi spring in it, it still has a 6 psi spring in it. By lengthening the actuator rod or moving the bolts you are not changing this. Adjusting the preload to, say, 10 psi is simply changing the wastegate opening point to 10 psi. But once it is open, it still moves in proportion to its spring rate, ie; 6 psi.

By way of comparison, if you changed to, say, a 10 psi spring rate, then it would still open at 10 psi but once open it would move in proportion to its spring rate ie 10 psi.

So if you have, say, a 2 psi change in boost then the 6 psi spring will allow the wastegate to move 66% further than 10 psi spring. This can mean it can easily open too far or close too much. This leads to far more opening and closing of the wastegate than is necessary to keep the boost stable. Result = unstable boost and a very hard working boost controller (whatever type).

My suggestion, as always, has been to use the closest spring rate you can find to the minimum boost you want to run. Then use the boost controller for achieving the small amount above that you require.

Hope that helps

[EnricoPalazzo]

SK: can i just buy a spring, say to make the wastegate actuator total 12 psi, and add it to the standard w. a? Or do i have to purchase a totally new one.

Otherwise, if i install a 32 w. a., will this b able to hold 1 bar to redline, as currently i cant hold anythin more then 12 to redline.

Thanks

[Sydneykid]

Hi Enrico, you can buy numerous coil springs from your local shop (yellow pages). If you have a 7 psi wastegate and you want 10 psi, then buy a 3 psi spring. All you need to quote is the rate (3 psi) and the length and diameter you want. Make sure it is heat resistant, it gets very hot in that area.

As for holding boost, if the wastegate is the problem then it will fix it. But if the wastegate isn't the problem, then it won't. It could be the turbo is too small to supply the necessary airflow at higher rpm, so the boost drops away. Maybe the turbo can supply enough airflow but it could be the pipework or intercooler restricting the airflow. etc etc

Do the wastegate first, it's easy and cheap. Then move onto the harder and more expensive solutions (intercooler, pipes and turbo).

Hope that helps some more

[EnricoPalazzo]

would u be able to explain to me how to add another spring to the actuator. i will try to do this tomorrow.

thanks again.

[EnricoPalazzo]

also i have seen numerous r33s able to hold 1 bar to redline. Ive also seen heaps that have the exact problem as mine. Im hoping it is the acutator as it is only rate to 7psi

[Guest Robo's]

SydneyKid,

Out of your experience, do the stock R33 GTST turbo hold their boost at say 12psi to redline?? Im loosing about 2psi!!

[Jay95R33]

SydneyKid,

Out of your experience, do the stock R33 GTST turbo hold their boost at say 12psi to redline??  Im loosing about 2psi!!

Robo - I'm doing the same thing Hit's 12psi and settles on 11.8. Then from around 5,000 rpm to redline it drops to around 9.5

I thinking about getting a RB20 actuator cause they are 10psi, but I'd like to price up a custom 12psi one..

J

[Guest Robo's]

Jay

Yeah i hate it, ive watched it on the dyno drop and everytime i rev it out, it would be nice to hold boost for some extra rwkw. I'll try to the intercooler next week to see if thats restrictive!!

[Jay95R33]

Jay

Yeah i hate it, ive watched it on the dyno drop and everytime i rev it out, it would be nice to hold boost for some extra rwkw.  I'll try to the intercooler next week to see if thats restrictive!!

Ahhh, are you still running the stock interheater ??

I've got a FMIC and it still does it

Same with me, that extra few psi would be nice up top

J

[Warpspeed]

There are usually two things that can go wrong with wastegates when you tweak up the boost.

Either the exhaust back pressure rises so high in the exhaust manifold, it can blow the wastegate open too far, and you can then loose top end boost.

Or else the wastegate passage is too small to bypass enough exhaust, and boost rises up out of control at the top end.

[Steve]

I have an external gate, the spring is too soft but it feels quite hard when out of the gate, much stiffer than min boost is rated by the feel of it.

How do you know what rate spring to fit? what is the relation between boost pressure and spring rate when changing the entire spring? do I have any other options

Currently the spring is only a 10psi, I still have the old spring (which is softer), can this be retempered to a new rate? (time to break out the oxy:))

Cheers

[Warpspeed]

Not too difficult to work out really. But finding a suitable spring might be a challenge.

First measure the diameter of the control diaphragm in inches, and work out the area in square inches (pi R squared). Then work out the seating pressure by multiplying the diaphragm area by the reqired boost.

For instance, if the diaphragm has ten square inches, and you plan to run 15psi, the required spring pressure on the wastegate valve seat will be 150 pounds.

When you get to 15psi, any extra boost will be enough to start the valve opening. But you need 150 pounds to hold it shut below 15psi.

The next thing you need to do is measure the installed height of the spring when it is fitted into the wastegate. Suppose it is one and a half inches. The spring is going to be much longer than this when you take it out though.

What you need is a spring that has a height of one and a half inches when it is loaded to 150 pounds (for 15 psi boost) in this example. Or the metric equivalent of 68Kg and 38mm.

Now you start looking at what springs are available from your spring catalogue, and try to find something that has that load at that length. It could be a long soft spring, or a stiffer shorter spring.

The softer spring will control boost better because the wastegate will open further for less change in boost.

for instance one spring might start to open at 15psi, and be fully open at 17psi. A shorter stiffer spring might also start to open at 15psi but need 20psi to fully open it.

Hope that helps.

[Warpspeed]

There are also ways to cheat. You can sometimes place shim washers under a spring to increase boost, but usually the spring coils go solid long before you get to as much boost increase as you really want. It is a good way to make a small adjustment though.

Another way is to leave the original spring in there, and fit a smaller helper spring inside the original. This works really well.

[EnricoPalazzo]

hmm can u explain more about the helper spring I can hold around 12psi, but want to hold 1 bar. Its not that much more

[Steve]

I still have a spare wastegate spring that is too soft, would it be worth trying to get it re-tempered?

[EnricoPalazzo]

no but it would be worth givin it to me