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Originally posted by ner947
My car has been running very well too under fuel+spark. I really need to find some time to get rid of these 415 cc/min injectors put the 780's back in and turn up the boost pressure on this 16G. I've never gone beyond 200 kPa or so, I think 220-230 kPa would be a good boost pressure for this turbo. Matt, what do you think would be a good advance to run at this boost pressure? If I had to guess, I'd say around 16 degrees at peak torque then slowly increase the timing to around 20 degrees at redline? Also, what are you doing to monitor knock? I don't have any kind of knock monitoring system other than my ears.
Well I can run 15 psi(approx 200kpa) with 17 degrees of advance with no knock, running 93 octane, and pretty rich at around 11.0:1 A/F. It was my goal with the MS to max out the S16G on 93 pump gas, which I think is obtainable with careful spark and A/F tuning. I use a knock meter made by MSD, but it's not the greatest, although it does detect knock. Usually I will just listen for it, since I know exactly what it sounds like. A good place to start for 18-20 psi boost would be an A/F of 11.3- 11.5:1, and maybe 14-15 degrees of timing up to and during peak torque(stock cams- 4k-5k), and after 5k rpm, start adding 1 degree or so up to redline for every 200 rpm. If your A/F is good at 20 psi, and its not knocking, watch the EGT's very closely. If they climb PAST 1600, add 1-2 degree of timing up top. If it knocks a bit, pull 2 dgrees at the rpm at where it knocked. It's really best to do all this on a dyno,where you can easily hear any knock or any breakup of the engine.
Small amounts of knock wont really hurt the forged pistons, providing it only lasts for a second or two. I've had that knock issue before the MS when doing a 5th to 4th downshift at 15 psi, but its not there anymore. The knock lasted about a second, and I've "made" it knock purposely to try and tune it out before with the 8 injector setup. Prolonged knock will be very bad though..You just have to be very carefull, and immediately get off the gas if you hear it. Even with that small amounts of knock I was getting, after having the head off last year, the pistons/combustion chambers all looked just fine.
If your A/F and timing are in tune, your EGT's will be pretty close to 1600 on a long pull at high boost. Not enough timing when running a rich A/F will make for high EGT's, esp at high rpm. A high EGT can also be caused by being too lean. But if you run an A/F of 11.0-11.5, then a high EGT issue will be timing related. The boosted 420a REALLY likes fuel at high boost(15+ psi)
13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)
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