escort1989uk

as above was think on buying a -34 over a -31 and was wndering when it would be needed what what sort of spec you would need

escort1989uk

what no one know can't any one help

RSrussell

a -31 will be enough

a -34 has a stronger spring, therefore able to hold the gate shut for longer until the boost level is reach (starts progressing at 14psi i think), this actuator also has a "snappier" on/off response.

Jim Galbally

-31 will hold about 7psi IIRC
-34 will hold about 14psi IIRC

(the rest of the boost is acheived from bleeding off air, or by adjusting the actuator WRONG

youd probably want to be running somewhere in the region of about 20+psi before you should think about moving to a -34

a -31 and -34 are not "uprated/better" as such, theyre just different...

escort1989uk

ta jim and RSrussell good to know people are there to give good advice

RSrussell

Jim, i was running a -31, and it was holding 20psi, no bleed valve either, so my car was setup wrong

hooked_on_boost

I had a -34 fitted to my old erst and it did have a "snappier" response!

I will admit to wanting just the extra bling factor of having a -34 rather than a more normal choice of a -31.......sad I know!

p.

edd

no jims talking bollocks

RSrussell

fpmsl, i was trying to be subtle

Wazzzer

I've got a -34 on mine, came with the turbo, damn is it snappy

Jim Galbally

no im not talking bollocks...

you you were not running a bleed valve (or amal valve/boost controller as these are forms of bleed valve) then in order to acheive 20psi held on that actuator you would have to set it with WAY too much preload.

sideeffects of this would be the actuator wearing out a shitload quicker than it should and eventually not holding boost properly... and also the actuator can quite easily cause the car to overboost as the revs/gasflow rises and melt your engine.

so guys as i KNOW i'm right :P

doing 20psi on a -34 wouldnt be so bad as you're not giving it as much preload (still too much, but not as bad as putting the same thru a -31)

do you also know that a standard actuator will give about 2-4psi of boost when set up CORRECTLY? the car AS STANDARD acheive the extra boost with a bleed valve (amal valve)

Karl

Jim,

Although I can see you're trying to be helpfull, you do not have enough experience to give accurate advice on these issues.

The choice of actuator is relative to engine and turbo spec, so unless we know all the factors it is impossible to say which actuator is required!

Jim it simply is'nt as simple as saying this actuator is rated to X psi and thus if I want XX psi I need this one with this bleed! It's all about turbo size and engine spec, not to mention the different methods of boost control!

For example Jim did you know that when I map a RS500 T4 car at 35+psi I use a -31 actuator? Do you know why I use this?

Jim Galbally

karl, i ASSUME its becasue you like your cars to peak and drop so they give better midrange punch, which would be done via crrectly jetting the amal valve and matching this to actuator preload.

i remember you writing a long post about something similar on Tim's car back when the RSOC BB was being used. infact its from yourself and stu's writings that i have gained 99% of my knowledge (limited i admit, but still better than most of the population)

Karl, i also agree with you on what you wrote about speccing etc. (well it was you that taught me in the 1st place rememebr ) it was just that i was attempting to be vague in the 1st place, and then when i had holes picked in the post i was unable to completely remember the tech reasons behind what i'd written so became even more vague

i do hover know that that 20+psi ona -31 with no other form of boost control (ie str8 from compressor housing to actuator) is not a good idea

kay2

didnt read the posts very well then jim

Jim Galbally

i read them fine, but try remembering every exact detail of something you read 2 years ago is quite difficult

i do understand how boost control works tho and thats the main thing

kay2

so do i, bleed valve turn lots, big boost, big smile, big bang, big loan

Damo V

https://passionford.com/forum/viewtopic.php?t=24096

John Laverick

Oranoco

Got a -31 on mine and it was running 25psi. Was kinda wondering whether a -34 might be better. Saddly I don't know enough to risk getting it horribly wrong

Jim Galbally

good find damo... i forgot about that thread

ps i forgot to come over to you lastnight n show u that dash install gonna havea crack myself tho i think n see how shit i can make it look

Keith B

One thing I considered on my S2 was that due to the spring stiffness on a -34 I couldnt run my 2 stage boost effectively. Low boost was 15psi and high was 18psi. With a -31 I hit almost the same peak boost but low boost was around 8psi or so.