220TC

is it worth doing ?

I have heard that this will result in the turbo holding boost pressure better at high revs. Mine hits 22psi but will drop back quite a bit at high revs to about 17 or 18psi. Will doing this 'mod' help me hold 22psi all the way ?

Also do you get any other negatives or positives such as, it will make the car more / less laggy etc..? I'm running a stage 3 turbo with a T2 cam so its well laggy anyway, I dont want it any worse

Any advice from anyone that has done this mod will be greatly appreciated

Duncan

CabrioTurbo

im also interested in this.. my basic understanding is that it will help you hold the boost better at higher revs... just like you say but im not sure how to plumb it in or if it really works.
The other thing that could be causing your loss of boost at high revs is a soggy actuator!
CheeRS
Phil

Oranoco

Heard of a few people doing this mod but would love to hear from a techy type what the pro's and cons are of this.

Stu, Karl

Tony Turbo

I had this done on my car to overcome the pressure drop at high RPM. It certainly works.

It uses the pressure in the cross over pipe to hold the actuator open, or something like that.

Jim Galbally

cant understand why it would make you hold more boost

i know a few people do it when theyve got big intercoolers n stuff and theres quite a big boost drop over the coller, so taking the feed AFTER the cooler helps keep the boost the same regardless of other conditions etc.

Jon ERST S2

Block up compressor housing and run that pipe to the crossover pipe.

Basically it gets a more accurate reading of the boost you are running as it's near the inlet. if you have it from the compressor housing it's pre-intercooler so it doesn't see the boost drop over intercooler. So if you do this it will compensate for the boost drop (to an extent)

Jim Galbally

so is the boost drop over the I/C greater at high RPM then?

as this would explain what you're all saying and why i dont understand

220TC

does it make any difference in the way the boost is 'delivered' ie. less laggy etc..?

Duncan

KSA-Cossie

iTrader: (4)

So you run a hose from the middle port of a 3 port bleed valve to the crossover pipe? or am i lost in translation!

Jim Galbally

no no no no no... you run the side port (the one that normally goes the the compressor housing on the turbo) there instead...

KSA-Cossie

iTrader: (4)

Can anyone list a drawing of it for me? Not at my best today!

KSA-Cossie

iTrader: (4)

I only have 1 hose from turbo to actuator with bleed valve in the middle of the hose if that helps.

T28 RST

I also have this mod done to my car

220TC

you block off that hose (from turbo) and run a new hose from the crossover pipe to the bleed valve........so it goes, crossover pipe TO bleed valve TO actuator.

Anyone know if it make the car more laggy etc.. or is the only difference that it holds the boost better at high revs ?

Duncan

T28 RST

I would say it holds boost better at higher revs

KSA-Cossie

iTrader: (4)

now i see it whats the best thing to use to block off the turbo outlet.

morto

t28, thats a lovely engine bay you have , is the turbo from the nissan sx200?

andy

morto

what about if your not running a amal valve?

andy

John Laverick

Mine

T28 RST

The turbo is from a small turbo escort cosworth