Low power + Dyno caused piston slap on STi MY02
14 May 2004, 12:26 PM
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Low power + Dyno caused piston slap on STi MY02
Facts
1) We have STi MY02 engine placed into UK turbo wagon (MY99). Engine comes from USA without original ECU. We decided to run it on GT (UK turbo) electronic . We locked camshafts in basic position. The car runs well.
2) Then we decided to swap electronic to Haltech programmable ECU (for the safety and to get more power) Results on dyno were poor. 195kW/265hp and 340N.m (250lb.ft) = original values). Good power and torque till 4500 rpm , then we loose power on the top.
I checked all running conditions (water temperature, correct fuelling (Lambda = 0,77 on 1,4 bar pressure, no knocks). But at end of the tunning day on the rolling road, the 3rd pistons starts slapping. Problem was piston parts on the cylinder side. Piston wasnt burned , other pistons and conrods and bearings were ok. It doesnt seems like fueling problem
1) We have STi MY02 engine placed into UK turbo wagon (MY99). Engine comes from USA without original ECU. We decided to run it on GT (UK turbo) electronic . We locked camshafts in basic position. The car runs well.
2) Then we decided to swap electronic to Haltech programmable ECU (for the safety and to get more power) Results on dyno were poor. 195kW/265hp and 340N.m (250lb.ft) = original values). Good power and torque till 4500 rpm , then we loose power on the top.
I checked all running conditions (water temperature, correct fuelling (Lambda = 0,77 on 1,4 bar pressure, no knocks). But at end of the tunning day on the rolling road, the 3rd pistons starts slapping. Problem was piston parts on the cylinder side. Piston wasnt burned , other pistons and conrods and bearings were ok. It doesnt seems like fueling problem
Questions:
a) could Sti original camshafts in locked position interaction on the loosing top end power?
b) Is there any known problems with MY02 Sti pistons (bad material or clearance) and running on the higher pressures and temperatures?
c) I heard about non serial pistons homologated into group N Subaru engines. Is it because of problems with serial pistons ?
d) Have Subaru due this piston problem replaced it with hypereutic in new engines?
What next?
- Cams from GT (turbo UK) ? Adjustable cam position wheel (adjustable cam pulley?) for different timing (position between intake and exhust valve.....) ?
- Leave it as it is and look for other engine?
- I plan do it with another engine STi3 MY97 with 2,5USDM short engine and 550 injectors and 20G TD05 turbo (with original cams :-)
a) could Sti original camshafts in locked position interaction on the loosing top end power?
b) Is there any known problems with MY02 Sti pistons (bad material or clearance) and running on the higher pressures and temperatures?
c) I heard about non serial pistons homologated into group N Subaru engines. Is it because of problems with serial pistons ?
d) Have Subaru due this piston problem replaced it with hypereutic in new engines?
What next?
- Cams from GT (turbo UK) ? Adjustable cam position wheel (adjustable cam pulley?) for different timing (position between intake and exhust valve.....) ?
- Leave it as it is and look for other engine?
- I plan do it with another engine STi3 MY97 with 2,5USDM short engine and 550 injectors and 20G TD05 turbo (with original cams :-)
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