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Can't figure it out


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Hi guys 

I got a gtx3071r with the standard subaru housing to fit on my sti, 20% duty cycle saw 1.8 bar and full boost before 4k. I've built a 2.1 stroker engine and everything else is the same. But now 20% duty cycle doesn't do anything and I kept adding to see if it would start boosting and got to 1.8 bar at 80% duty cycle and it wouldn't go above. But doesn't come in until 5k.

I genuinely expected earlier spool and if anything having to run less duty cycle. 

Has anyone else had this? If so what was it and any suggestions would be great. 

 

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So was it a 2.0 or 2.5L originally?  Camshafts and cam timing the same?  Ignition tuned to MBT?  If engine capacity and cams are similar and ign timing is optimised then you are losing exhaust energy somewhere - leaking wastegate or similar.  

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Sorry, it was a 2.0l with uk 2000 heads, now it's a 2.1 stroker with sti heads. It's a road tune, timing down low was pretty similar but has to pull alot of timing up top.

OK, I'll check for exhaust gas leaks pre turbo, I'll go over everything, intercooler piping etc I can't see why the actuator spring would have failed, 

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Thanks for the replies, I think it's the characteristics of the new cams moving the power band further up the rev range, I've checked for leaks, plumbing and wiring and can't find anything wrong. Think I'm limited to the gtx in a standard location housing and 1.8 bar is all she'll flow. Looking into getting a new turbo now

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