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Old 04-25-2013, 02:00 AM   #1
warmup
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Member#: 233425
Join Date: Dec 2009
Default 10% - 15% Power loss on JDM V7 swap, bad leakdown?

Complete JDM V7 EJ207 swap on 2004 wrx, all are stock subaru parts including oem eql header and twinscroll vf37. 3" catless turboback taper to 2.5". AVCS is working.

Open source tune on a 4wd dyno. Stock STi read 215-225HP on this dyno.

Running 22psi at 3800rpm taper to 16psi at 6500.

Expecting 260-270WHP but got only 235, running 10.5 AFR.
Wont get more than 5HP when lean out to 11.5 and pull some timing, if I lean AFR out without pulling timing it will knock. So I guess it is not problem of tunning.(another proof is same day same dyno same turbo, almost same tune another V8 EJ207 yield 278WHP)

And power dropped dramatically after 5500, should those 207 engine's power go straight up to at least 7000?

Compression test is ok on all cylinders. But leakdown is not.
Cylinder #1 has 15% leakdown at beginning and middle of compression stroke, at TDC it is as good as other three cylinders.
Other three cylindes has less that 5% leakdown at any position of compression stroke. Since cylinder#1 leakdown is good at TDC of compression stroke I guess valves are good.

So what's wrong with this engine? An oval cylinder #1? Wore piston ring? broken ring land? Or V7 STi(non Spec-C) has this kind of power characteristic natually?

Any suggestion will be appreciated.
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Old 04-25-2013, 02:53 AM   #2
Torquey
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Member#: 175334
Join Date: Mar 2008
Chapter/Region: TXIC
Location: Dallas, TX
Vehicle:
2003 Impreza WRX
JDM v8 EJ207 WRB

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v7 EJ207 had UEL and VF30/VF34... sounds like you may have a v8?
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Old 04-25-2013, 04:08 AM   #3
warmup
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Quote:
Originally Posted by Torquey View Post
v7 EJ207 had UEL and VF30/VF34... sounds like you may have a v8?
Sorry, I'm not so sure it is a V7 but from what I read in nasioc, it has LHS20V and RHS20V on the head and S20C 701 on the block so I think it is a v7?

So that might be a v7 long block + v8 header and turbo, but all are oem parts.

But from my experience the HP number of an EJ207 with downpipe should not lower than 270.
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Old 04-25-2013, 12:00 PM   #4
warmup
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Any more opinions? Please?
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Old 04-25-2013, 12:57 PM   #5
Shortpersonbk
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Member#: 319017
Join Date: May 2012
Chapter/Region: MWSOC
Location: Michigan
Vehicle:
12 sti 700+whp
it wants to be a evo

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Did you ask your tuner? He tuned it he should know more about your car then some people on nasioc taking pop quiz guesses....
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