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Old 07-16-2020, 03:59 PM   #1
protegejustin19
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Default Ej20x cam timing

Swapping an Ej20x in my 06 usdm legacy I’m planning on not using exhaust avcs. Plan on using aftermarket uel header and vf52. Now I know leaving it unplugged isn’t the best way but it’s the easiest. Could I use my old cams,cam gears(static exhaust), and time it normally. Of course I’d check clearance for the buckets. Or would swapping just the exhaust cam gears from the ej255 to the 20x and timing it normally be okay? Talked to one shop about leaving it unplugged and they said the cam gear moved with it unplugged and valves hit pistons so I’m hesitant to do that. Another guy on YouTube (Subie Sanctuary)said time the Ej20x exhaust cam gears one tooth retarded. Anybody have first hand experience changing the cam timing let me know how it went. Trying to get it figured out before putting the engine in!
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Old 07-18-2020, 12:09 PM   #2
protegejustin19
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Bump anyone
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Old 08-17-2020, 09:18 PM   #3
NSFW
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Join Date: Feb 2007
Chapter/Region: NWIC
Location: Near Seattle, WA
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05 Stage Free LGT
ATP 3076, 6MT, AVO FMIC

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The 08 STI exhaust cam pulleys have springs on them which pull the cams into max advance, which is also max piston-to-valve clearance and zero overlap (best idle). With no power to the AVCS solenoid, the cam angle stays put.

The intake cam pulleys are sprung to go full retard, which also gives best clearance, no overlap, and best idle. In other words, all four cams are mechanically configured to move to the position that gives full safety and best low-RPM performance. Probably because after a cold start, the ECU leaves the solenoids unpowered for a couple/few minutes. In other words, the system was designed to be safe with no power to the solenoids.

I don't know about the 20X, but I'd be very surprised if they were different in this regard. AVCS needs oil pressure to work properly and there isn't any right after startup.

I ran the 08 STI heads in my 05 LGT disconnected for months while I worked on an exhaust cam controller, and there was no harm.

Someone else had a similar setup dyno'd that way, and found it to be down 40whp if I remember right. If I remember right, you'd want to adjust the cams by two teeth in the timing belt to get them back to single-AVCS cam timing. Or at least that was the case for the 272 cams that I used - that was my 'plan B' in case the AVCS controller turned out to be too hard.

For your stock cams you should get the specs to see how much they need to be adjusted.
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Old 08-18-2020, 07:51 PM   #4
Yeltsew
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Chapter/Region: South East
Location: Florida
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2011 WRX w/ EJ20X
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I have an ej20x with a vf52 in my car with the exhaust avcs unplugged right now and I find it to be really laggy and have almost no low end torque. It could be that my turbo is on its way out, but I don't build hardly any boost until 3500-4k rpm. I've seen a lot of people say to retard the exhaust cam by two teeth, like nsfw said.

I do have a hunch that part of why the car feels so laggy is because of the avcs. I'm going to talk with my tuner on Thursday and see what he thinks, because I'd really like to try and make this car a lot less laggy and have more low end, like the 20x engines came in Japan. I'm not searching for crazy high power numbers, just a wide powerband.

Quote:
Originally Posted by NSFW View Post
The 08 STI exhaust cam pulleys have springs on them which pull the cams into max advance, which is also max piston-to-valve clearance and zero overlap (best idle). With no power to the AVCS solenoid, the cam angle stays put.
I really want to try getting your avcs controller working on my car. I know you designed it with a 257 in mind, but I'm sure it could easily be adapted to work with a 20x (or maybe already has and I just missed it). I tried sending you a message asking if it was something you'd be willing to give some advice on, but it said your inbox was full.
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Old 08-21-2020, 12:46 PM   #5
protegejustin19
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I’ve got word to just set the exhaust side back one tooth with jdm Ej20x cam gears which is what I’ve done should have the engine installed by the end of this week so I’ll post back with updates
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Old 09-04-2020, 06:53 AM   #6
NSFW
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05 Stage Free LGT
ATP 3076, 6MT, AVO FMIC

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Quote:
Originally Posted by Yeltsew View Post
I really want to try getting your avcs controller working on my car. I know you designed it with a 257 in mind, but I'm sure it could easily be adapted to work with a 20x (or maybe already has and I just missed it). I tried sending you a message asking if it was something you'd be willing to give some advice on, but it said your inbox was full.
I PM'd you my email address. I'm pretty sure my controller can be adapted.

There are basically three places where the controller touches the engine:

1) Crankshaft position. I was too nervous about wiring into the stock electronics, so I painted a white mark on a quarter of an AVCS pulley and put an optical sensor in the fan shroud. That should adapt to any EJ. If the fan shroud is the same, you can use the same 3d-printed sensor mount that I used, the file for that is on the github site. If not, you'll have to improvise.

2) AVCS Solenoids. I suspect the AVCS solenoids work the same way - it's just a 12v solenoid that takes a PWM signal to control it.

3) AVCS Sensors. I have no idea whether the sensors are the same or not. But even if they're not, it probably won't take a ton of work to adapt to it.

The USDM sensors take 12v and ground and there's a third line that gets pulled to ground when the cam timing trigger goes past (twice per revolution if I recall correctly).

I can do software, but electrical engineering isn't my thing... I was lucky to have a coworker a couple years ago who volunteered to figured out the sensors and the interface circuit for me. If you're good with electronics, or if you have a friend who is, then hopefully you can figure out how your sensors work, and how to interface with them.

Everything I have is on GitHub, here: https://github.com/LegacyNsfw/AvcsController

Last edited by NSFW; 09-04-2020 at 06:54 AM. Reason: GitHub link
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Old 05-07-2021, 10:23 PM   #7
bferrell130
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2004 Subaru
WRX STI

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Quote:
Originally Posted by protegejustin19 View Post
I’ve got word to just set the exhaust side back one tooth with jdm Ej20x cam gears which is what I’ve done should have the engine installed by the end of this week so I’ll post back with updates
How did this work? I have seen mixed responses on if the timing should be retarded or not. I can’t seem to find a straight answer.
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Old 05-10-2021, 12:20 PM   #8
bferrell130
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WRX STI

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BUMP

Can anyone give feedback on this?

I have an EJ20X on the way and need to know how to set up my exhaust timing. My options are:

1. Run the EJ20X cams as they come and leave the exhaust AVCS disconnected

2. Retard the exhaust cam gears 2 teeth and plug the oil ports.

3. Run my EJ257 exhaust cams and re-lash.

4. Run my EJ257 intake AND exhaust cams and re-lash.
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Old 05-24-2021, 06:02 PM   #9
aboveandbeyondohd
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I did the ej257 exhaust cams and phaser gears. My car runs amazing. I have a vf52 bigger intercooler, tgv delete. Cobb sf and full cattles tbe. I've run about 1500 miles at this point on my tune. It runs great and is pretty quick however it lacks punch. I literally just talked to my tuner today about it and he said he had a tough time with my engine taking timing on the higher revs. It does push 21 psi but lacks the punch I'm used to. I'd actually like to know why an engine can't take timing? Also hope some of this info helps someone else.
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Old 06-01-2021, 09:02 AM   #10
bferrell130
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2004 Subaru
WRX STI

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Just to update, I talked with my tuner (Shinji Tuned) and the guys at Subie Sanctuary. From what they recommended, I am retarding the exhaust cams one tooth and NOT plugging the oil ports in the end of the cams. I am going to run the JDM cams in the car. I am about ready to drop it back in and I will keep y'all posted. My tuner said he will be able to get around 300whp out of that setup with a 16gxt turbo and 550cc injectors.
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Old 07-01-2021, 08:50 AM   #11
bferrell130
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2004 Subaru
WRX STI

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My car is up and running. It runs GREAT with the exhaust cams retarded one tooth. It has good torque down low and pulls hard once the turbo spools. It starts building boost right at 3k and is at full boost by 4k. It pulls all the way to redline. I am not sure about power numbers but my butt dyno says around 300whp. I can't say enough good things about ShinjiTuned and Subie Sanctuary for their help on this project.
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Old 01-18-2022, 01:04 PM   #12
jeffambo
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Chapter/Region: BAIC
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2013 WRX Base Hatch
Obsidian Black Pearl

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Quote:
Originally Posted by bferrell130 View Post
My car is up and running. It runs GREAT with the exhaust cams retarded one tooth. It has good torque down low and pulls hard once the turbo spools. It starts building boost right at 3k and is at full boost by 4k. It pulls all the way to redline. I am not sure about power numbers but my butt dyno says around 300whp. I can't say enough good things about ShinjiTuned and Subie Sanctuary for their help on this project.
Can you be a little more specific on how to retard the timing 1 tooth? So if I have both the double lines lined up I move the bottom cam pulley one tooth counterclockwise?

I'm also wondering how the car is still running? I've been really impressed with my 20x especially since I was running with 10psi for a long time and just recently got to 16psi after fixing vac leaks, but like everyone has said, there's no low end power and my vf52 doesn't seem to kick in till way late,

I'd like to test out the vf38 it came with because that's supposed to spool up much faster, but I don't have a downpipe for it and I'm not about to start another project on this car until I've fixed everything and gotten it to pass smog.


Have any ej20x swappers gotten smogged yet? My car was totalled and I need to jump through a bunch of hoops to get it registered, I've been driving it with the registration having been delinquent since May and it's not fun having a heart attack Everytime you see a cop car
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