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Old 07-12-2010, 10:20 PM   #5
Back Road Runner
Scooby Guru
Member#: 60082
Join Date: Apr 2004
Chapter/Region: MWSOC
Location: Minnesota
2004 Forester STI


I wouldn't worry about anything. I've done +100 <1500rpm pulls to redline just datalogging my car through various engine mods. What breaks engines is knocking. This happens when just pushing tunes too hard. It's not what really happens just by running a stock engine. The knock sensor is there to keep the engine from doing something bad anyways. If you have concerns, I can suggest that you do certain preventative actions. You could run a higher octane. You could run a higher rated oil (going from 5w30 to 5w40). These help prevent knock and prevent wear if it does happen. Are these things you need to do? No, not really. Can you do them anyways? Sure, if you are really concerned. I'll tell you I'm running double the timing you do running my I-Speed SRS-20 tune, but I'm also running 91 octane, and I run more viscous oil, although I do these things because I use my car for sport. I do auto-x and rally-x, so I've done things to make it go faster. My stock internal are getting pushed more than yours. I just doubt you're doing enough with your engine to really care. You may think about downshifting though if you do want to romp on the car some. It's just that a lower gear and higher rpm gives you more power to the ground. While there might be some fun playing with low end grunt, there's just a little more fun blipping the throttle, dropping down a gear or two, and getting on it hard.

By the way, if you're looking to gain some bottom end power, I have a few suggestions. One cheap one is Grimmspeed's phenolic intake manifold spacers. While they don't technically do much for their thermal intent (intake manifold still gets hot from radiant engine bay heat), the do oddly add a bit of low end torque for some not really known reason. I could guess, but that's all it is. It seems to have something to do with air flow, offsetting the injectors, or something along those lines. All I can say is the low end gain is noticeable and proven with data logging. It's just a cheap plop on item that gives you some more low end. I personally have been curious what more than one spacer would do, but I've never attempted adding a second and seeing what happens.

If you seek more torque, I-Speed's SRS reflashes do work and add power across the board. The SRS-10 is a stock engine upgrade and does add 5-10 ft-lb across the board. The next major upgrade is a full exhaust, and you'll be spending a good $1k plus for a quality setup. Gains are again sizable with 10 ft-lb across the board easy plus noticeably improved throttle response. This would let you step to the SRS-20 tune instead which adds more timing and torque across the board. Beyond this, you have cams. There are a couple low-midrange torque geared cams from delta that act much like stock but just make more torque overall. You could upgrade the fuel pump and injectors and step to E85 and make a sizable gain in torque. Lastly, you could redo the internals and up compression and again gain torque.

These are the sort of things you're going to do when shooting for more torque, at least outside of forced induction.
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