Does anyone know for sure whether or not I have to increase or decrease the size of my restrictor (inside small pipe that comes of turbo into the t-piece which goes to boost control solenoid and wastegate) to cure the overboost I have?

Basically due to this cold weather up here, the car 9in 4th or 5th gear) boosts to 1.05 bar then settles down to the correct figure of 0.9 bar (MY97 with full scoobysport exhaust and panel filter). It was even worse when using SUL (1.25 bar then overboost protection cut in!)

Eagerly awaiting your replies,

Russell

 

On MY00 you increase the size of the orifice by 0.1mm (from std 1.2 to 1.3mm) to drop peak boost by a couple of PSI in my experience. Someone said earlier models are the otherway round. If you got a valve as per our other discussion I'm sure you could fix it - but you have to adjust it gradually and press the throttle gently and get a feel for how high it is going to boost so you don't get some stupid figure.

 

Had the same prob.... overboosting that is.

Take it down to your local Subaru dealer they will sort this in about 30 seconds. little restrictor, done and dusted!

Hope you get it sorted!

 

Trouble is that most Subaru dealers will not take you out with a Select Monitor plugged in and try three difference sizes - I insisted they did as I had just coughed up £1763 for a PPP and it was overboosting. Many dealers will put a size in to stop it overboosting but your car will feel slower and it will indeed be slower. They will not push the envelope like you can armed with a boost gauge and a suitable valve.

They have 0.1mm increments in drill sizes. This is just not fine enough IMHO unless you are lucky - 0.1mm difference on my car is 2-3PSI difference - ie 20-30bhp!

 

Got some drills bits last night and drilled out the hole slightly. Took it for a run and ...........................................0.7 bar!
(F##K! drilled the hole too big) So, out came the soldering iron and solder, filled the hole and started again

Driled hole to original size and am removing a wee bit at a time and then going for a run (time consuming or what!)

Still, I will not succumb, no, no, no, no, no!

Russell

 

You will succumb. You will go mad. You will hate it. You will get it right and then it will be foggy and you will be so wrong. Sorry. Get a valve.

 

Don't be so soft get the hole blocked up and wire the waste gate shut and run as much boost as possible.

I own a version 5 STi and have had to have a GEMS engine management system installed to overcumb my standard ECU cutting it out. I run 1.6 bar and I'm a girl!!!!!!! It goes like F**K!!!

Impreza Babe.

 

I used solder to plug an over-sized restrictor once....but what's the melting point of solder? How hot is the air coming through the restrictor?

I couldn't remember the answers - but the thought scared me enough to remove it, pronto

Richard

 

I have been running 17PSI and a lot of WOT testing and the solder on mine never melted. According to temperature mapping exercises on I-club, the temp around that pipe can reach 150F, and the restrictor removed after a hard blast cannot be held in your hand for long. But neither can a soldering iron!

Typical solder has a MP of 188 deg C - so around 100 C of leeway. obviously it has different expansion properties to brass.