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Old 07-18-2012, 03:46 PM   #3726
Fierysun
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Quote:
Originally Posted by mrxr250rider View Post
Go v7 single scroll. Forged and should beable to handle plenty of power. My 05 wrx is v7 swapped. You can use your current turbo or the vf30 or 34 it comes with. Whichever would be better.
V7 has it's own issues with it's tight (than desirable) piston to wall clearances.
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Old 07-18-2012, 04:31 PM   #3727
Zaider
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Quote:
Originally Posted by Fierysun View Post
V7 has it's own issues with it's tight (than desirable) piston to wall clearances.
Could you elaborate on that a bit? First I've heard of it.
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Old 07-18-2012, 05:01 PM   #3728
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Quote:
Originally Posted by Zaider View Post
Could you elaborate on that a bit? First I've heard of it.
The way Subaru got the V7 forged pistons to pass regulations was to run tighter (than ideal) piston to wall clearances. Add manufacturing tolerance to that, you end up with some motors on the even tighter side and those engines ended up scuffing (ie poor sealing, lower compresion, higher oil consumption, etc...) it's walls. It's a crap shoot. I think some people resolve this issue by taking apart their engine, honing the cylinders to the ideal clearances, and then putting it back together with the original pistons.

Nothing is perfect. You have to pick your poison.

Last edited by Fierysun; 07-18-2012 at 05:09 PM.
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Old 07-18-2012, 05:53 PM   #3729
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Quote:
Originally Posted by Fierysun View Post
The way Subaru got the V7 forged pistons to pass regulations was to run tighter (than ideal) piston to wall clearances. Add manufacturing tolerance to that, you end up with some motors on the even tighter side and those engines ended up scuffing (ie poor sealing, lower compresion, higher oil consumption, etc...) it's walls. It's a crap shoot. I think some people resolve this issue by taking apart their engine, honing the cylinders to the ideal clearances, and then putting it back together with the original pistons.

Nothing is perfect. You have to pick your poison.
your facts are partially incorrect, its the v8 forged hypereutectic pistons are what was mandated to run tighter tolerances for stricter emissions standards. Its common even in domestic pistons now. V7 forged pistons take a little while to expand from a cold start. V7 pistons will over expand and get tight under harsh conditions such as road racing, under normal circumstances they are fine.
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Old 07-18-2012, 06:24 PM   #3730
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Originally Posted by todeswalzer View Post
After reading up it seems the only difference between ej205 and ej207s is the case being semi vs open.....rods piston and crank are the same, how is this able to handle more HP than a dumpy 02-05 ej205 with the same bottom end? There has to be a bigger difference
Rods are not the same as the 205, they are the same as the 255/257.
Pistons are essentially the same design, but EJ205 has more dish and smaller piston to deck, overall CR is pretty close, but the squish design ends up different.

The rods and the semi-closed deck is all there is.

The "magic" of the EJ207 isn't in the shortblock so much as the heads. AVCS adds off boost torque and aids spool some, and the heads are made to rev out where the rod ratio has the shortblock wanting to go. You end up with gains on both high and low vs. an EJ205.

When you analyze the engine design, you come to the conclusion that the EJ205 is a bastardized engine that is nothing short of a bad design. The shortblock (with better rods) will rev to 8k+ no problem, but the heads are done at 6.5k. The EJ207 fixes the mismatch by using heads that are good to the high high revs. that the shortblock loves.
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Old 07-18-2012, 07:05 PM   #3731
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Quote:
Originally Posted by fastnoypi View Post
your facts are partially incorrect, its the v8 forged hypereutectic pistons are what was mandated to run tighter tolerances for stricter emissions standards. Its common even in domestic pistons now. V7 forged pistons take a little while to expand from a cold start. V7 pistons will over expand and get tight under harsh conditions such as road racing, under normal circumstances they are fine.
You have your facts mixed up.

I am referring to the v7 forged pistons, which are the ones that have scuffing issues, and not the v8+ (which doesn't have an issue with the tighter clearance, because of the expansion rate of the hypereutectic pistons).

Last edited by Fierysun; 07-18-2012 at 07:11 PM.
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Old 07-18-2012, 07:51 PM   #3732
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Quote:
Originally Posted by Fierysun View Post
You have your facts mixed up.

I am referring to the v7 forged pistons, which are the ones that have scuffing issues, and not the v8+ (which doesn't have an issue with the tighter clearance, because of the expansion rate of the hypereutectic pistons).
okay which is it? i know they went to cast back in the v8 for cost and clearance issues. being the forged pistons didnt expand fast enough there was emmision problems under light loads. and would then over expland under higher than optimal conditions. hence the scuffing.
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Old 07-18-2012, 07:54 PM   #3733
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Originally Posted by WhiteBgeye02 View Post
okay which is it? i know they went to cast back in the v8 for cost and clearance issues. being the forged pistons didnt expand fast enough there was emmision problems under light loads. and would then over expland under higher than optimal conditions. hence the scuffing.
^ This is correct.

I think we are all talking about the same thing, but differently.

Last edited by Fierysun; 07-18-2012 at 08:03 PM.
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Old 07-18-2012, 09:48 PM   #3734
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Quote:
Originally Posted by Fierysun View Post
You have your facts mixed up.

I am referring to the v7 forged pistons, which are the ones that have scuffing issues, and not the v8+ (which doesn't have an issue with the tighter clearance, because of the expansion rate of the hypereutectic pistons).
my facts are fine, i was speaking to your comment of

Quote:
Originally Posted by Fierysun View Post
The way Subaru got the V7 forged pistons to pass regulations was to run tighter (than ideal) piston to wall clearances.
Subaru passed regulations by using the V8 pistons which addressed the cold startup emissions issues, not by running tighter piston to wall clearances on V7 pistons. During the V7 years, the emissions standard was much lower and not a concern.
Emissions at normal operating temperature for V7 was never an issue since the forged pistons expanded to spec. Past normal op temps, such as generated in road racing, V7 pistons will expand and scuff a wall.
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Old 07-18-2012, 09:53 PM   #3735
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Correct

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Old 07-18-2012, 10:04 PM   #3736
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Quote:
Originally Posted by fastnoypi View Post
my facts are fine, i was speaking to your comment of



Subaru passed regulations by using the V8 pistons which addressed the cold startup emissions issues, not by running tighter piston to wall clearances on V7 pistons. During the V7 years, the emissions standard was much lower and not a concern.
Emissions at normal operating temperature for V7 was never an issue since the forged pistons expanded to spec. Past normal op temps, such as generated in road racing, V7 pistons will expand and scuff a wall.
You are going off on a tangent, both confirming what i'm saying and saying something else, which wasn't what i was saying. The only point i was trying to make was, the V7 piston has scuffing issues as a result of the tight clearances set at Subaru. Be it from normal use or not.

Last edited by Fierysun; 07-18-2012 at 10:43 PM.
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Old 07-18-2012, 10:55 PM   #3737
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anyways guys..... for the tuners out there what kinda taper for afr's do you do given normal load condition for a third gear pull per say. 2000rpms and up. i am no sure but i think from what i am doing on my OL table i might be dipping rich too quick causing a complete fuel dump prior to needing 11.1 afr. all of this i am refering to a normal pull. not cruising at 2500 rpms and putting the pedal down in 5th like some ppl like to do.
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Old 07-19-2012, 09:42 AM   #3738
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Hey what are some of you running for oil brand weight and filter for the ej207 just tying to see if mobile 1 5w30 with a K&N filter Is still good option
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Old 07-19-2012, 09:50 AM   #3739
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Quote:
Originally Posted by NwGc8
Hey what are some of you running for oil brand weight and filter for the ej207 just tying to see if mobile 1 5w30 with a K&N filter Is still good option
Rotella T6 w/ OEM blue filter.
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Old 07-19-2012, 09:51 AM   #3740
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On the cheap: Rotella T Syn 5w40

If you have money: Redline 10w40 in the summer, 5w30 in the winter. Many reports of this making turbo's spool faster, etc.

Is any of this true I just seen this on bob is the oil guy

Last edited by NwGc8; 07-19-2012 at 09:53 AM. Reason: Price for oil is not a concern of mine I rather buy the best if I know it's going to keep my motor running to the peak perfor
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Old 07-19-2012, 11:17 AM   #3741
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Hmm. Ok, maybe I had heard about the scuffing issue, just didn't remember it. In any case, thanks for the info. Is the results of this something that would show up in a compression/leakdown test?

As for oil, currently running Amsoil SSO but will switch back to Rotella after I've used up my case of Amsoil. Both of them got good results from my UOA's and the Rotella is cheaper.
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Old 07-19-2012, 11:34 AM   #3742
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Clark reccomends castrol 5w40. I use castrol edge 5w40 and k&n filter. Only other oil I trust for the 207 is rotella syn t6 5w40. I was going to use that but they sell it in gallon bottles instead of quarts or 5 quart bottles. I used redline 5w30 once and from what I read it was a bad idea and is very thin.
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Old 07-19-2012, 11:37 AM   #3743
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Don't forget about German Castrol 0w30, that is if you can find it. I actually run Rotella T6 5w40, as GC is impossible to find in stock locally without special ordering it from O'Reilly's.
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Old 07-19-2012, 12:11 PM   #3744
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Damn so sounds like mobile 1 not the best anymore. That rottela can you find that at autozone? The filter is any filter from ej205/wrx sorry for all the questions just making sure I'm up to par on this stuff and don't want to blow it
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Old 07-19-2012, 01:40 PM   #3745
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walmart^ they sell it by the quart as well but a gallon is 22 and a quart is 7. might as well buy two gallons and buy another gallon on the next oil change. it will get used up so i dont worry about it.
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Old 07-19-2012, 01:55 PM   #3746
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Do not under any circumstances but 0w motor oil in your Subaru.

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Old 07-19-2012, 02:19 PM   #3747
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Thank you for the heads up Clark..What weight would you recommend 5w30 5w40 10W40

Last edited by NwGc8; 07-19-2012 at 07:21 PM. Reason: Sorry I missed that you said castrol 5w40 I was reading on my phone at work
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Old 07-19-2012, 03:21 PM   #3748
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Has anyone purchased anything from user/vendor jdmnagoya?

They seem to have the good prices but have 0 feedback that makes me iffy


I'm up to post 1001 reading this thread....only 3000 more to go!


What I learned...v7 spec c/v8/v8 spec c/v9/v9 spec c motors are all the same except v7 spec c has forged pistons. In regards to just the longblock, everything else is identical.


Is this correct?

I don't really care about anything else because I'll be selling any add ons I.e turbo/exhaust/intake/injectors etc I'll toss a 30r kit on this thing if the money allows it
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Old 07-19-2012, 03:37 PM   #3749
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Quote:
Originally Posted by WhiteBgeye02
walmart^ they sell it by the quart as well but a gallon is 22 and a quart is 7. might as well buy two gallons and buy another gallon on the next oil change. it will get used up so i dont worry about it.
Ah cool.Maybe a gallon and a quart would do. Just don't wanna go through the extra hassle of measuring it out. That's why I didn't buy two gallons. Ill prob try rotella next time since its cheaper. And whoever asked about the filter yes its the same as the ej205
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Old 07-19-2012, 03:40 PM   #3750
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And for the v7 I belive both regular v7 and v7 spec c are forged. But the spec c had better heads and vf34. Is this correct?
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