richm

ok, I appreciate it's a bit of an open question, and it will depend on a number of factors....

but does anyone know how far the actuator is likely to have to extend to maintain say 15psi boost at WOT on a stg1 4x4 with std T3, Magnex exhaust
I'm guessing it will probably vary some with rpm too?
Where is it going to be maximum - at peak torque, peak rpm, ...?

Dragon

Rich - you need to get out more

If you need to ask the question then you need a new one lol

richm

i've got a new one

i'm interested to know how a standard -55 behaves over the operating range compared to a -31..

Andreas

Get a ruler and sit in the engine bay taking measures while someone you trust give it large.

Or lets hope someone have checked this on a rolling road or dyno.

Fiecos Dan

if you want to see.

put a boost gauge tee'd off from the actuator, and see how much boost it see's at sed rpm/load (as if your runnin any sort of boost controll, eg amal or air inj, bleed valve, the actuator wont see the same boost as say your engine gets)

then take it home and static pressure test the actuator with a compressor or air/vacum gun, and measure.

but this will only give you a rough idea, as the back pressure will push the wastegate open even more.

richm

of course.. i feel a bit of a twat now for not thinking about doing that!... DOH
Cheers!

alan rainbow

the wastgate on a a t04b travels 10 mm just measured mine as turbo is off the acturator will only travel to keep a given level of boost

Fiecos Dan

nearly all garret actuators i've tested, inc std, -31,-34, 20 and 28 psi. on full travel = 13mm, b4 preload. so if 3mm preload, gonna have 10mm travel.

Stu @ M Developments

iTrader: (12)

You shouldnt, as it doesnt work like that
The turbine speed required to make 15psi varies depending on the amount of air being consumed, and thus varies with engine load.

It also varies with air temperature and EGT.
As the gate opens and the engine speed increases, you naturally run more exhaust gas volume and thus the gate has to open even FURTHER to keep the compressor pressure the same as it has to bypass more gas.

A clue you dont have enough is when you see what we call in the trade "Boost creep" where the more you rev it teh more boost the engine sees. This is due to what ive just described above and there not being enough travel left on teh wastageate actuator so teh extra gas starts to increase the turbine speed instad of bypass it.
Reality... 6KRPM on a -31, around 8mm is the minimum travel allowed on a stage 1.

Hope this helps.

richm

cool explanation Stu!!! thank you
there's a bit to think about there, bit late tonight .. no doubt i'll come back later with some more dumb questions after I've pondered a while