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Black GC8
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235 Posts
I do like the whole smaller displacement for higher revs, but all that torque loss is bad in my opinion. To really utilize the higher rpm means you need the Avcs. You might end up damaging your head if it's anything like honda's vtec. What I mean is that vtec is controlled by oil pressure and pushes the pin to lock the cam lobes together. This build is really close to the Honda guys (me included, still rocking my b18c in a eg). I friend blew his b18c type r motor revving it to 8k without the vtec hooked up yet so watch out.
 

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2000 2.5RS BRP
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1,175 Posts
Discussion Starter #62 (Edited)
We've spun these to 8k and so far, so good. I doubt they'd live 300k miles this way, but as a fun throw-around engine this build did just fine. I'll have the built motor done or another spare handy before I raise the redline. This is for some fun, not serious racing. 7k would be a lot more fun. Throwing it around some curvy roads for g-force giggles still nets a smile :).

This is still meant to be mostly a street car, even if it is a bit of a wolf in sheep's clothing, wearing those clothes rather poorly :p.

I installed a washer bag last weekend. It worked right out of the box, rather unexpectedly.



http://www.rs25.com/forums/f105/t229295-diy-washer-bag-kit-install.html

The window regulators are to be replaced sometime soon. I'll also finish making the interior panels and do some more dieting mods this summer. The power is limited to keep the driveline alive while taking more weight out. Once the weight is satisfactory, then I'll worry about the next motor. This is only half of what it can do and still a hoot to drive.
 

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2000 2.5RS BRP
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1,175 Posts
Discussion Starter #64 (Edited)
I did my first autocross yesterday. The tune feels very good. I'm in SM and likely will be bumped into XP due to the mods. My 4yr old Ventus wet/dry tires definitely feel lacking. When pushed, the tires light up into a drift on crappy pavement. On a tight course, there's not much room for sideways antics before changing direction. The excessive weight and poor grip were very apparent. Power feels great, but I need to follow through on chassis work.

I knew there'd be some kinks to work out and some shortcomings would demand money. I would like to run all year long and steadily improve the car and myself. A year after the TBI, I feel pretty good. The dizziness is gone and the heat wasn't too bothersome. Running after smashed cones was harder.
 

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98 impreza outback
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61 Posts
Just out of curiosity why dont you have intake manifold spacers?I've seen most n/a builds that don't run them and I've heard of benefits running but wanted to know whar the guys who don't run them say
 

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2000 2.5RS BRP
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1,175 Posts
Discussion Starter #69
I have apparently maxed out the 440cc injectors, on 93. I wasn't giving it enough fuel at the very top of the revs, making it stumble. There's really no room for E85 at 7k rpm on these injectors. I'm squeezing every drop from these and will see if it pulls clean to 7200rpm. 6800 is what it will do so far on gas with further mapping tweaks.

Maxing out the power fuel map's lambda target is how to get the fuel in the combustion chamber. It's a little ugly, but works. 100% VE on the base map only goes so far. I had to just let the engine have the fuel it wanted. The target was richer than the o2 sensor was reading. The high rpm stumble confirmed it. I added more power fuelling up there, and the stock wideband o2 sensor reads closer to the target lambda while pulling more cleanly to the higher redline. I had to listen instead of telling it what to do. It's commanding an 8.0AFR, but not actually doing it. IDC reads at 12ms up top.

I cleaned the Magnafuel filter yesterday. That helped a lot. It was due for a good cleaning. I should have taken pics. There's a lot of material a fuel filter catches. Dirt, like actual dirt. There was mud in there. I'm not kidding. There were what looked like rock chips, too. Ever seen those larger grains of sand that look more like a little rock chip? Those were in the filter sludge. +1 for Magnafuel's reusable E85 tolerant fuel filter.
 

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Hey ImprezaRSC have you been using a wideband 02 and/or knock sensor throughout all your testing? I'm about to start playing around with my bluessm and ej251 (delta 1500 cams and a few mods). Cant wait to see what can really be done with slightly worked ej25!
 

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2000 2.5RS BRP
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Discussion Starter #72
This thread could use an update.

The car sat most of the summer while I worked....a lot. I've taken up tuning my Chevy with HPTuners as another hobby. My work truck is up from 14mpg to 19mpg on gas. E85 was 10mpg, now up to 14mpg. That was educational. It needed some hardware replaced, like coil packs, plugs, MAF, and o2 sensors, and eventually came the water pump. Mileage was 110k, so it had age related issues. Turns out the RS had some age issues, too.

Over the summer I replaced the front O2, TPS sensor, and MAP sensor. No codes, no hiccups...just running really slow with a pig rich AFR, even after backing fuel out. It should have felt like boost. One day, all the fun just went away with no indication of why. The TPS and the MAP were the oldest sensors on the build. I changed them out, and everything changed. Suddenly, the o2 sensor had a full swing in readings. The sound became unbelievable, and all the performance came back in spades. I could adjust the fuel mapping and the o2 sensor would respond. So, it's back on track. The fuel mapping and cold start needs some further polishing, and then I'll go back to E85.
 

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2000 2.5RS BRP
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Discussion Starter #73
Hey ImprezaRSC have you been using a wideband 02 and/or knock sensor throughout all your testing? I'm about to start playing around with my bluessm and ej251 (delta 1500 cams and a few mods). Cant wait to see what can really be done with slightly worked ej25!
I've been reading both sensors from the stock ECU. If you run it open loop, it will ignore both. That's why I've been working in closed loop first.
 

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Discussion Starter #76 (Edited)
So, yeah...it's fun again. Every gear pulls like mild boost, and that's exactly what I wanted. For a junkyard swap with fab and mods, it's wonderful. The sound is incredible, like a cracking whip and a mini-gun.

The details with the tuning bring the character to life. I'm still working things out on the ProjectLambda software, but the tweaking is finally rewarding. I was getting nowhere with minor tweaks for a while until I changed out the TPS and MAP. I'm working on transitional throttle between tip-in tables and VE throttle compensation. I can see it go a little too rich on tip in and then level out past +20% throttle gain.

I'm basically undoing the tweaks that I made before replacing the MAP + TPS, and trying a different strategy with fuel. I'm also pulling back timing on the top end and it's showing some positive results. The injectors and fuel pump may be getting a little weak. Top end near 6k seems to go between lean and rich. Tuning is conservative, but the giddy-up is plenty quick. It feels like it's headed in the right direction....straight to a blown transmission :p.
 

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2000 2.5RS BRP
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Discussion Starter #78
Have you upgraded the rails yet? Don't remember
Very much so. The injectors are 10 years old, and the Aeromotive 340 pump is about 7 years old. I had the injectors cleaned before I put them in.

The fuel blending trick worked in the mapping. I brought the VE throttle compensation columns over to 25% throttle. The Fuel Acceleration Enrich table ends at 20%, I'm scooting the throttle VE back where the FAE table leaves off. Rescaling FAE's break points didn't really help anything. The trick was more in the numbers used. At low-mid rpm and part throttle, fuelling is very specific for this combo. I get twice the throttle area opening all the time. So, 5% throttle is like 10%. 10% is like 20%, etc. But not from the computer's point of view. That's where the programming comes in handy. It helps for the ECU to be able to see well, instead of through a kaleidoscope :bonk:.

I'll play with E85 next weekend :projectsti.com:.
 

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01 STM RS Sedan & MORE!
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315 Posts
Did you use new OEM Subaru TPS and MAP sensors? I've been looking at my live data, and it seems fine, but I wonder if new sensors could be beneficial.
 
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