Rennmeister Posted August 19, 2017 Share Posted August 19, 2017 I wrote an article regarding the causes, prevention, and theory behind ringland failure on the FA / EJ series motors. http://www.comeanddriveit.com/engine/subaru-ringland-failure Link to comment Share on other sites More sharing options...
solidxsnake Posted August 22, 2017 Share Posted August 22, 2017 Nice article! I'd suggest adding a bit on BtSsm, made by our very own heiche, as another method of "being an informed driver." It's considerably cheaper than an AccessPort, and infinitely more versatile. Link to comment Share on other sites More sharing options...
covertrussian Posted August 23, 2017 Share Posted August 23, 2017 Very informative and useful article, I actually learned a few things from it too (specifically the piston metal to silica composition). I like that you went into very technical details of detonation and other aspects, which most articles simply ignore. One thing that I would add on is stressing how lean the factory tune is, even on 2015+ WRX's. Factory tune causes the car to be dangerously lean (above 13:1) while at peak boost & torque. This further increases the damage to the pistons, rings, valves etc. 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
covertrussian Posted August 23, 2017 Share Posted August 23, 2017 Also your detonation article is top notch! I've not seen an all in one location for all of that information, usually it's a bit here, a bit there. Variable valve timing based dynamic compression ratios have been on my mind for a few months now. I didn't have it in me to figure out the math for our motors, but seeing your EJ note really saves me a lot of time! Intake Cam Advance – This will close the intake valve sooner in the compression stroke. Advancing the intake cam will raise the dynamic compression ratio. This means you need to run slightly less ignition timing. Intake Cam Retard – This will close the intake valve later in the compression stroke. Retarding the intake camshaft will lower the dynamic compression ratio. This means you need to slightly increase the ignition timing. The 30° of intake advance range on the 08+ Subaru EJ257 engine will increase the dynamic compression ratio 1.33:1 at full advance. Just a personal experience note on varying timing based on AVCS, On my 2005 EJ255 (with 8.2:1 cr), I noticed that every 5* of AVCS advance, 2* of timing was needed to be pulled to maintain best torque. 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
Rennmeister Posted August 23, 2017 Author Share Posted August 23, 2017 Nice article! I'd suggest adding a bit on BtSsm, made by our very own heiche, as another method of "being an informed driver." It's considerably cheaper than an AccessPort, and infinitely more versatile. I will add that in. Link to comment Share on other sites More sharing options...
Rennmeister Posted August 23, 2017 Author Share Posted August 23, 2017 Very informative and useful article, I actually learned a few things from it too (specifically the piston metal to silica composition). I like that you went into very technical details of detonation and other aspects, which most articles simply ignore. One thing that I would add on is stressing how lean the factory tune is, even on 2015+ WRX's. Factory tune causes the car to be dangerously lean (above 13:1) while at peak boost & torque. This further increases the damage to the pistons, rings, valves etc. Running a lean mixture doesn't exclusively mean detonation. You have to look at the totality of the tune to see how that plays into it. Although I will freely admit, that you'd ideally want to be on the richer side of things. Link to comment Share on other sites More sharing options...
Rennmeister Posted August 23, 2017 Author Share Posted August 23, 2017 Variable valve timing based dynamic compression ratios have been on my mind for a few months now. I didn't have it in me to figure out the math for our motors, but seeing your EJ note really saves me a lot of time! I've built a model and used the EJ257 DAVCS motor. It's for a future article. Link to comment Share on other sites More sharing options...
covertrussian Posted August 24, 2017 Share Posted August 24, 2017 Running a lean mixture doesn't exclusively mean detonation. You have to look at the totality of the tune to see how that plays into it. Although I will freely admit, that you'd ideally want to be on the richer side of things. Right, though I do remember my FBKC being fairly chatty with the stock tune/setup. It definitely lean hesitated a lot while the closed loop delay was still on. Another big thing that I noticed is how aggressively timed Subaru's tend to be. My old 2004 FXT was running 40* of timing towards the redline, that's NA motor timing . My 2.5i Outback would knock and pull IAM even on 93 gas (sticker says 87 only too), I had to pull about 10* before it finally started loosing torque. 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
Rennmeister Posted August 26, 2017 Author Share Posted August 26, 2017 Right, though I do remember my FBKC being fairly chatty with the stock tune/setup. It definitely lean hesitated a lot while the closed loop delay was still on. Another big thing that I noticed is how aggressively timed Subaru's tend to be. My old 2004 FXT was running 40* of timing towards the redline, that's NA motor timing . My 2.5i Outback would knock and pull IAM even on 93 gas (sticker says 87 only too), I had to pull about 10* before it finally started loosing torque. The big bore and short rods require a lot of ignition advance. The large bore on the EJ25 is an issue for detonation as well. The 2.0L motors are significantly less detonation prone. Link to comment Share on other sites More sharing options...
I Donated Too sigmafour Posted August 28, 2017 I Donated Too Share Posted August 28, 2017 This was my favorite... This doesn't mean it's safe to run 30 PSI with a big turbo. Your shit will explode. Link to comment Share on other sites More sharing options...
vnhqle Posted September 12, 2017 Share Posted September 12, 2017 Noted, buy bigger turbo. Link to comment Share on other sites More sharing options...
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