M_DOS86

Hi all,

I am from Durban, South Africa and I recently got my first Subaru. It is a 2007 STI (2.5 Hawkeye). The car was completely stock when I bought it. Last month I fitted a full 76mm turbo back exhaust. The stock VF43 turbo went from 0.7bar to 1.1 bar boost just because of the full exhaust.

I then needed to replace the clutch (not fun) whilst I had the motor out my mate noticed the turbine housing on the exhaust side of the turbo was cracked. I thought about just welding it up and throwing it back on but then I managed to come across a 2nd hand TD05 16g. The turbo was in pretty good condition so I went ahead and put it on. When I compared it to the original VF43 turbo the inlet and exhaust turbines looked the same size. the only difference to me was, the 16g turbine housing looked a bit bulkier and the inlet turbine or impeller (not sure what they called) had like a twin blade design... other than that it looked almost the same as the VF43.

I got everything up and running but I have noticed that the car is pretty sluggish now. it feels like the timing has been pulled back or something. I have yet to tune the car. I also noticed that this 16g is only boosting 0.7bar max. I am too scared to play with the actuator and ill leave that up to my tuner when I do get it tuned. what concerns me is that although it is at 0.7 bar, the car is not pulling as well as my VF43 did at 0.7 bar.

There are no boost leaks.. Iv gone over everything more than twice. The only thing I can think of is because the ECU is not tuned for that turbo? the reason I have not taken it to be tuned yet is because I don't want to tune the car and there happens to be something I have missed that is causing the "sluggishness" I would just like some reassurance from fellow Scooby owners that it can only be because it needs a good tuning. I have a little fault finder scanning tool and it comes up with zero errors.

Any advice will be greatly appreciated.

rob84

iTrader: (5)

You cannot just replace a turbo and expect it to work as the old one did. air flows will be completely different on those two turbo's.

when you mention it being sluggish the reason is the engine will be picking up detonation and pulling the ignition timing back and adding fuelto prevent it from destroying itself. you need to get the ecu remapped to suite the new turbo you have fitted. I must say that it was an incredibly brave move running it un mapped on a 2.5 chocolate engine, they blow ringlands at the slightest hint of detonation..

M_DOS86

Thanks Rob. Hope I haven't blown ringlands yet. I haven't been flooring it to much and its only making 0.7 bar boost so I hope everything is still okay. There is no smoke coming out the exhaust but there is a smell of fuel which is probably from runing rich

scoobysteve1983

out of curiosity, what fuel are you using? what octanes are available in SA?

M_DOS86

Im using 95 unleaded. For older cars we have 93 LRP (lead replacement petrol). Even our 95 octane is a poorer quality compared to European 95 octane. Cars imported here have been detuned to compensate for the poor fuel quality. We can get 98 octane, avgas and ethanol but it is not easily accessible for the public. As far as im aware, the STI's boost at 1bar in stock form for the overseas market. I was told the ones we get only boost at 0.7 bar. So I fitted a boost gauge and it was right on the money at 0.7bar. Tuners here recommend not going any higher than 1.2 bar and as soon as I did the exhaust the bloody thing shot to 1.1 bar without me touching the boost. Anyway ill get it tuned to 1.2 bar or maybe less if it runs lean. Allot of the guys here will have 2 maps. One for pump fuel and for pump fuel with some form of additive.