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Old 09-05-2020, 02:37 AM   #1
vicious_fishes
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Default ej25 dual vs single avcs

Just wondering if anyone has a dyno comparo of the two.

Yes I've searched.
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Old 09-05-2020, 01:40 PM   #2
igoiks
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Exhaust avcs donít do anything for power it helps to lower emissions . Avcs overall dont pick up peak power just under the curve
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Old 09-05-2020, 04:49 PM   #3
subaru_gc8
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Originally Posted by igoiks View Post
Exhaust avcs don’t do anything for power it helps to lower emissions . Avcs overall dont pick up peak power just under the curve
iver heard that, but the sti of today are making alot more than the sti of yesteryears so Dont really about that. I know the porsches that run lots of timing and high compression use it to stave off some of the cylinder pressure.
and if this is the case the 08 and up shouldnt have a egr valve right?
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Old 09-05-2020, 07:26 PM   #4
subydude
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Exhaust avcs helps spool the turbo and add area under the curve. Intake avcs helps in similar ways and can help power up top “some”. A lot depends on the turbo and it’s power band. On stock and small or medium size turbos avcs pays off. On bigger turbos it can help spoil but doesn’t really help power a lot.

It’s setup dependent, but in general it helps.
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Old 09-05-2020, 08:41 PM   #5
igoiks
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Originally Posted by subaru_gc8 View Post
iver heard that, but the sti of today are making alot more than the sti of yesteryears so Dont really about that. I know the porsches that run lots of timing and high compression use it to stave off some of the cylinder pressure.
and if this is the case the 08 and up shouldnt have a egr valve right?


Not relay they all make 305 hp or so. Talk to good tuners they will tell e-avcs donít really help performance i-avcs on the other hand is great!
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Old 09-06-2020, 01:16 AM   #6
vicious_fishes
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I'm not so concerned with peak power (although it'd be nice if it improves it). Just area under the curve.

I know intake avcs makes a massive difference - my question is reference the effect exhaust avcs makes.
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Old 09-08-2020, 05:19 PM   #7
ether947
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I'm not sure if you have seen this. But in general, variable cams allow for a broader powerband.
https://www.comeanddriveit.com/engin...avcs-explained

I only have anecdotal info, but back when I had my 2005 STi (EL headers, DP, CBE) I would go on full-day touge runs with a friend in his 2012 STi (CBE only). He would consistently pull out of corners much harder than I could. Initially, I just chalked it up to him knowing the roads better than I did. However, at some point, I learned the roads and I could only pull him in on long straights.

I went for a ride in his car and it is still one of the torquest Subaru's that I have ever been in (the other one was a 2012 STi w/full exhaust on e85). Eventually, he sold the car and I helped him part it out. That's when I realized he only had a CBE and a tune. Stock downpipe.

I sold my STi and bought a Bugeye with a v8 EJ207. And while I love the way the 207 revs, I still think about how those DAVCS cars make torque.
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Old 09-08-2020, 06:25 PM   #8
subaru_gc8
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Quote:
Originally Posted by subydude View Post
Exhaust avcs helps spool the turbo and add area under the curve. Intake avcs helps in similar ways and can help power up top ďsomeĒ. A lot depends on the turbo and itís power band. On stock and small or medium size turbos avcs pays off. On bigger turbos it can help spoil but doesnít really help power a lot.

Itís setup dependent, but in general it helps.
I think you have it backwards. intake helps with the low end on a engine where the exhaust helps with more of the breathing on the top end.
on most of the tunes I have seen intake avcs stops goes back to zero when the turbo kicks in
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