MGTurbo

I am about to purchase a -31 actuator for use on my cossie 4x4 turbo (which didnt have one with it)

I need to know if they made them with different spring ratings. My plan is to have a base setting of 14psi going up to 18psi.

The part number (garrett) that i am about to buy is 430099-0031. i have been told that they did them in 4psi, 7psi, 10 and 1 bar, bit confused to be honest and a search doesnt reveal the specific information i'm looking for.

TIA

Gareth

CosRush

Not sure about some of what you say, the -31 is approx 7psi on half a hole preload and the -34 is approx. 14psi.....

Im assuming you have a suitable chip to allow the boost over standard?

Ive heard it reported the -34 tends to bring the boost in with more of a punch as the wastegate stays closed longer. Bare this in mind.

Stu @ M Developments

iTrader: (12)

Whoever you spoke to hasnt a clue what he is talking about.

The -31 is the part number of the SPRING and they lift around 8psi.

You want a -34 if you want a lift rate of 14 psi.

Also be aware that there are different shaft lengths and threads available.

wilky

iTrader: (1)

are you running some sort of bleed valve or are

you running direct off the inlet manifold to actuator

MGTurbo

Direct off of the plenum chamber to actuator. I may be using a GBE boost control valve after setting the actuator to 12 psi.

CosRush, Turbo is going on a Maestro Turbo which has a 1.5 Bar map sensor and no boost cut You should remember me as you sold me your old T3 4x4 turbo

MGTurbo

Have now purchased said -31 and look forward to the results..

Stu @ M Developments

iTrader: (12)

MGTurbo

General opinion of the -34 is that its too aggressive coming onto boost.

The gearbox is the weak point on my car and anything i can do to smooth out the power delivery is going to help long term. A softer actuator which the -31 appears to be, will give me steady boost (i currently have dropping off problems except in 5th where i get boost creep )

To be honest my current actuator is 15 years old and well past it. I just wanted something thats going to do what i want with some added flexability, say, if i want to run 10psi and increase the boost to 15psi with a Dawes type device.

CosRush

MgTurbo,

Yes i do remember, hows things???

Personally i would have followed stu's advice, as the -34 should will allow you to bleed less air off to get your desired boost.

Otherwise with the -31, you'll be wasting 11psi or so bleeding it away....

Why dont you get the -34, and try it....if you dont like it, i would swap my new -31 Garret for it, as i'd prefer a -34 myself.....as im running 24psi held......

Let me know what you think...

Stu @ M Developments

iTrader: (12)

Thats because youve added too much preload, so that your wastegate cannot pass enough volume of air at high RPM, thus the turbine speed begins to increase.

That is EXACTLY why you i said you dont want a -31 for 18psi with no additional boost controller as 14psi requires around 18psi base load and a -31 is no good at all for that. Also, how do you plan to use a Dawes device to make your boost LESS aggressive? Its whole point is to make the boost come in harder with no gate creep.. same as fitting a -34 as its simply a pressure relief valve.

MGTurbo

Well we shall see how i get on. The actuator i have bought is brand new and i could get my money back on it if need be, if i decide not to use it.

I wasnt saying the Dawes device would make the boost less aggressive, i have had experience of a few before and found very little if at all detectable difference in the way boost comes in. I suspect the boost still wont be quite as aggressive as a -34 outright though?

I guess the use of a bleed valve would eliminate this problem, however i have no way of fitting one without also bleeding off the air going to the fuel pressure regulator so thats a no no. Last thing i want is higher boost and LESS fuel

svony

iTrader: (3)

Not trying to hijack this post but how would an electronic boost controller figure into this? I used (Greddy Profec B) them in the past with very good results but never on a Cosworth. What is the advantage/disadvantage to using an electronic controller rather than an uprated actuator?