Questions on free boosting in a twin turbo

[scoobygt]

I have unplugged the vac line on the wg on the primary turbo, still only get 12-14 psi on primary but secondary goes past 20psi, does any one know how you actually get the primary to free boost or just get higher boost?

[Marky]

thats how you do it, boost control is same as anything else on these, just that one wastegate

are you sure its just not slow to spool up, like load it on the brakes at 3k and it should keep rising, not just flooring it and seeing how high it goes before changeover

also maybe try to avoid letting it go to ridiculous numbers when freeboosting maybe

[scoobygt]

yeah put it back to normal now as didn\'t really gain any thing, it just pulls like a mofo, will try the brake idea

[telemekas]

 scoobygt said:

I have unplugged the vac line on the wg on the primary turbo, still only get 12-14 psi on primary but secondary goes past 20psi, does any one know how you actually get the primary to free boost or just get higher boost?

Some of the primary boost is being diverted to prespooling the 2nd turbo. Disconnect and plug line No:5 that goes to the top port (positive pressure) of the large ECV actuator.

[scoobygt]

so then you will be boosting on primary only?

[telemekas]

No. Boosting both primary and then twin turbo mode.

[scoobygt]

ohh yeah I see

[Marky]

Ha

That got me thinking so went outside and looked - some gremlin had gotten under my bonnet at some point and gotten hose 5 and 8 swapped over

I think the gremlin may have looked a bit like me

It might explain a few things

[Guest]

 scoobygt said:

yeah put it back to normal now as didn\'t really gain any thing, it just pulls like a mofo, will try the brake idea

Yea um adding boost doesnt add power magically. As with anything as you get more of something you need to balance everything else in it. Sorta like making a thickshake with 200ml milk and 2l of ice cream in it. That shit aint ever gonna work.

[scoobygt]

I know more fuel and timing is needed when adding more boost other wise it won\'t make a big diff

[rex-leggy]

 scoobygt']

I know more fuel and timing is needed when adding more boost other wise it won\'t make a big diff

itll make no difference other then your pistons vaporizing.

[quote name='scoobygt said:

yeah put it back to normal now as didn\'t really gain any thing, it just pulls like a mofo, will try the brake idea

/quote]

Yea um adding boost doesnt add power magically. As with anything as you get more of something you need to balance everything else in it. Sorta like making a thickshake with 200ml milk and 2l of ice cream in it. That s*** aint ever gonna work.

that would be a tasty thickshake! ;D

[scoobygt]

and running lean, checked my up pipe out the other day and its almost white in side, shouldn\'t it be black?

[kamineko]

 Marky said:

thats how you do it, boost control is same as anything else on these, just that one wastegate

are you sure its just not slow to spool up, like load it on the brakes at 3k and it should keep rising, not just flooring it and seeing how high it goes before changeover

also maybe try to avoid letting it go to ridiculous numbers when freeboosting maybe

for the sake of discussion, with the wastegate actuator unplugged you will be relying on the wastegate spring to hold the gate closed. wouldn\'t it be better to block the vac line to the actuator so the vacuum (generated by the actuator diaphram being forced open) contributes to the spring pressure?

[Marky]

yeah i guess so, more academic than anything though i guess - itd have to be a reeeal soggy wg spring to get forced open with solely exhaust pressure on it. they normally creep open early from having that part pressure still being applied to the diaphragm as soon as you get positive pressure fed to it, along with the exhaust pressure on the flapper as well (hence why using an ebc or relief valve improves spool up, the gate does creep a bit)

The logic makes sense for sure