raising the boost

[rxtoy]

ok, i'm not looking for anything major but i've got a boost gauge on my 8V 4g63t and she's only running 5 psi. first, where should i look to see if i'm losing any pressure (wastegate actuator? what operates this and what should it be set too and how can i check it?) and then once i've found any lost psi where should i look to start improving it.

ie, can the wastegate actuating rod be easily extended (i'm running a tc05, i assume its a 12a) or can the spring rate inside the actuator be easily changed (if yes, what sort of spring should i use and where can i get it?) any other ideas?

i've heard of people using a t piece with one side venting to atmosphere to stop the factory boost cut cutting in, what pressure is this meant to cut in at? and is there a better way than this? because i'd like to keep my boost gauge reading at least semi accurately? can the boost cut just be disconnected or a 'trick' signal be sent to the computer?

cheers
Matt

[tmz_99]

boost cut out is at 12 or 14 psi, more then enough without intercooler...
you hould be able to run about 10psi safely, turn it down a touch on hot hot days.. easiest way to do this is to get a boost control valve from turbosmart or someone, allows easy adjustment...

leaks can be pretty much anywhere and effect your boost in some way..,:( take a few hrs and look over everything.. heh.:P

[CussCuss]

1st thing you should do is buy a boost guage even if you dont intent to put it in the factory location it is essential, the factory guage is way off and its pretty much impossible to see what its going up to. My factory guage reads around 10-11 psi when its really at 14psi according to the microtech.

Upping the boost can be done with a simple t piece out to a bleed valve, the GFB style ones that sit inline have a smaller diamater to try to get rid of wastegate creep, but this induces a massive spike, you will probably hit boost cut if it is installed like that. What i have dont is tee'd a line off the vacuum hose that goes too the wastegate actuator, put the bleeder on that and capped the end of it. Doesnt spool up mega fast like it did with the spike but it holds proper boost. Basically it spiked about 4-5 psi, so if i wanted to run 14 it would be spiking to 19 wich is very bad, so it was a choice of lower boost with a high spike but faster spool or a proper holding boost with a normal spool (wich is still a little faster than 9psi).

[SpidersWeb]

Also something to keep in mind, these engines limit boost to only a few psi when cold then raise to 7-8psi when warm. You may just find you're missing the second vac hose on the wastegate actuator - have a look.

I dont think my turbo actuator had this, but since its sold and gone I can't look for you sorry. Just going off what Ive read on this forum in the past.

The twin-injector ECI unit doesnt like going much over 12psi . Its more of a case of the equipment not being able to provide the fuel than an actual boost cut.

Anyway its why many people here have chosen to go aftermarket ECU and four point injection - or as we like to say 'MPI'. Its easier and will prevent detonation and leaning out.

[CussCuss]

well not quite, it can provide the fuel just fine, its just set in the ecu that 50% duty cycle is the max it will allow.

[rxtoy]

i know what you mean about the factory boost gauge's, the lancer ones only have a picture for vacuum or on boost and a needle that flicks inbetween. i've got an autometer boost gauge in there anyway so that should be pretty accurate.

i'll have to check out that second hose to the actuator (the cars not here atm) but i'm pretty sure there's only one hose going to it so maybe thats one of my problems. where is the 2nd hose meant to come from? don't suppose anybody's got a pic they could put up/send to me please????

and i'll start looking for an adjustable boost controller but first how exactly do they work? do they just meter the pressure going to the wastegate to decide where it lifts? that would be pretty easy to set up at least.

cheers
Matt

[Chris 83JA]

DIY boost controller
http://www.autospeed.com/A_0670/page1.html

[SpidersWeb]

Well mine didn't have it

But Im told the second pipe comes from the the termostat (so when it opens - e.g. car is warm, it puts a second vac pressure on the actuator). Dont hold me to that though.

Anyway a bleed valve type boost controller (the cheapo ones), work by leaking air just before the actutor pipe - for example if its set to leak 3psi, then at 8psi your turbo actuator will read it as 5psi Unfortunately its not always that reliable and/or accurate.

A decent electronic boost controller (Turbosmart eBoost, APEXi AVC-R etc) does this with an electronic solenoid bleeder and an electronic sensor.

[rxtoy]

cheers for that wastegate article, might have to give that a go.

how would this compare for accuracy in installation? ie: would an electronic boost controller be any more accurate? or would this do the job just as well.

cheers
Matt