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newb boost worries


kirky1
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Hi i have recently purchased a turbo 2000 1998 'S' reg impreza it has a turbo back sports exhaust and a k and n air filter. It has an 8S ecu and it is boosting to around 14psi sometimes in 4th gear it goes over 14 nearly reaching 15psi is this a safe level of pressure to run at? i have read on the net that 13psi is standard boost and that the 8S isnt mappable so it cant have been remapped. i think it has had a slightly smaller restrictor pill fitted. I think a standard pill is 1.2mm the one in my car looks like a 1.1mm is this safe on a standard 8S ecu map?

Another question i have is about stock components power output ie: injectors, fuel pump and what the clutch can take? im not even sure what clutch i have in mine but i want to get an esl daughter board, bigger turbo and a remap but dont know how far i can take it before the clutch will start slipping and the injectors/fuel pump will run out of steam

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Wotcha and welcome Kirky - a lot of questions there and some more experienced classics owners will be along in a while to put your mind a rest - hopefully

 

13 - 15 psi is around 1 bar - that is fine running as standard

 

I dont know about the pill

 

or the ECU

 

wrt the other standard components - as you havent had the car from new it will be hard to say at what point the standard components will give out due to wear blockage etc.

 

WhatI would suggest is if the car is running fine as is and you want to spend money ensure the car has been serviced - good oil filter, possibly injectors clean, plugs swap,clean the K&N and then look at handling - brakes and suspension

 

then plan upgrades in power

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I have a UK 2000 wagon on the 8S ecu too, I have a full larger bore stainless system with only a back box as a restriction, and that's straight through too, it has stock ecu, stock td04 turbo and stock injectors, I have an HKS fcd, a manual boost controller and forge dump valve, my boost gauges reads 1.4 bar (20 psi) when on full chat and has been like this since I got it, I rarely drive sensible and the cars covered over 150k miles, I haven't run into any problems at all at the moment but I am looking at getting more power in the future, I too will be getting a new ecu as you have read correct and the stock pre 99 can't be mapped, the esl is very limited in functions though and I can only assume you don't wanna spend too much money on a bit of circuit board, I'm the same but as I know i will probably keep adding to the mods I want an ecu I can keep with me through the mods and I'll be going for the ecutek or simtek when the time comes

Hope that's answered some bits for you, if there's owt else I can help with please just ask

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wow didnt think a td04 could run that much pressure how long has it been like that?, makes me feel safer with my car tho thanks for that, ill probly just get a td05 and an esl for about £700 dont want to spend any more than that. Ive been told ill need to upgrade the fuel pump, injectors, intercooler and the boost solenoid but i dont think i really need all that

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It is generally agreed that the maximum safe level of boost for a standard Subaru turbo bottom-end is 1.4 bar, assuming everything is in good working order.  Once the engine starts getting a bit older (say over 10 years) I would drop that down to 1.2-1.3 bar to be safe.

 

The reason you get higher boost in higher gears is simply because the engine is under more load in higher gears, and therefore producing more exhaust gases to drive the turbo.

 

If you change your turbo (or any other major upgrade) you MUST get the ECU re-mapped.  If you don't you risk long-term damage to the engine.

 

Depending on the size of turbo you fit you may need a new fuel pump and injectors too.  This is because you will be forcing more air into the induction chamber and to keep the correct fuel/air mix you may have to upgrade these to be able to provide the correct amount of fuel.  Personally, I would say always upgrade the fuel pump as the standard one hasn't got much room for upgrading, but the standard injectors should be OK unless you plan a huge upgrade.  Either way, if your injectors are not up to the job it will show up when you get the ECU mapped so upgrade then if needed.

 

You do not need to upgrade the boost solenoid, but I would.  It won't make your car any quicker but it will give the ECU more control over the boost levels so you will get quicker response and a smoother power curve.

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When the ECU decides the boost level has reached the limit it will party open the turbo wastegate to hold the boost at that level.  This is totally normal and very smooth so you probably wont notice it as you drive.

 

If the boost continues to rise, the ECU will not cut the fuel but it will then open the wastegate fully to fully bypass the turbo and reduce the boost.  This is usually quit rare unless the engine has been "tuned" without being mapped for the modifications.  I do know some people who bypass the boost solenoid to stop the ECU from opening the wastegate, and thus letting their car overboost.  If you do this you will not get fuel-cut, but obviously you run the risk of your bottom end giving up.

 

If you are getting fuel-cut it is much more likely the ECU has detected knocking and has cut back to prevent damage, so make sure you always use the best quality fuel (highest RON) you can get.  Or it may be that your fuel pump is getting old and not able to supply petrol quick enough at the higher boost levels.

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I've had the car as a daily runner since Xmas last year the guy I got it off had it a few weeks of his mate before he got an insurance quote, before that his mate had it for 4 years, 3 of which it was running as it is now, I'm not to bothered about the car, if it fails it gives me scope to get a white saloon I've been wanting for some time, if it keeps going until I have some decent money coming in I was going to get a cdb and build that to a custom spec then paint the wagon white and fit the new engine and bits

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