Sjobing

I have done some mod's to my 03 STi and the latest is changing turbo from stock to a Turbonetics hybrid. I didn't gain any power with this turbo (280 hp compared with 307 hp on stock turbo)
I thougth this turbo didn't suit this engine so I changed it to a Garrett GT3076R .63 turbo + external wategate and this gave the same result....

I use a Motec M800, 800 ccm injectors, 2 fuelpumps, costum made up-pipe with rotated turbo mount, 3" turboback exhaust without cat's.

The guy that mapped this car has been building racecars for 28 years, and worked with Subaru and Motec for the last 10 years in rallying so I think he knew his stuff.

Do anyone have any sugestion's for whats wrong?

jaytc2003

iTrader: (1)

do you have ways of monitoring boost? could be up pipe blown/leaking

Sjobing

Yes, I'm monitoring the boost and I get over 2 bar if I want to...

The uppipe did I weld the day before I started it so I know for sure that this is ok.

Is there any other suggestions?

jaytc2003

iTrader: (1)

Daft question, but was it remapped with each of the turbo changes or was it left on the stock turbo map?

Sjobing

Yes, it was remapped after each turbochange. We have tryed some diffrent setting's in the maps, but is seem's like the problem has to be mechanical and not in the map.

jaytc2003

iTrader: (1)

It sounds to me like some kind of restriction somewhere and I would look at all pipework leading to and from the turbo

Sjobing

I use the same exhaust (3" decat) from turbo and back as i used before and I can not measure any backpressure in it.

I have measured if the was any pressurefall from turbo outlet to intake manifoil (loss tru IC) and I meassured the same pressure each place.

The only thin I've changed is the up-pipe, but I think it's wierd if there is in this pipe the trouble is. This is an 2,5" pipe with no restriction in it.

JohnD

iTrader: (5)

Is the variable valve timing working OK?
JohnD

Henrik

iTrader: (5)

Hmm, aren't up-pipes usually a smaller diameter?

I'm sure someone knowledgeable on here said a smaller diameter will spool faster on most set-ups (Can't remember who it was, though), but I'm not sure if it's just the spool or even top end power that is better with smaller diameter up-pipe?

The theory is that the gasses flow faster due to the tube being smaller, so it spins the turbine faster.

Don't quote me, though

Sjobing

Yes, this is working ok.