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Old 04-20-2021, 05:16 PM   #1
MasterOfNone_
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Default Seller claims 12:1 CR on built EJ255

I found a seller nearby that is selling an EJ255 block with forged internals. This is all the information I have so far:

Built at Yimi Motorsports
Manley pistons 99.5mm
IAG rods
Block itself has 60k miles

I asked him what the compression ratio was and he claimed 12:1 or 13:1. He claimed he was pushing 350whp @ 10psi prior to replacing the pistons at Yimi. I've done my research and that cr just doesn't seem possible. Especially not in Cali with crappy 91.

Can anyone who is knowledgeable share their thoughts? I'm getting the block at a killer price, but I wouldn't want to run that high of a CR. From what I read Manley pistons have a CR of 8.5:1. So, not sure if he's smoked out or actually is running a high CR.
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Old 04-20-2021, 05:32 PM   #2
umscooby
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No way no how it's at 12:1 or 13:1. I'd say the seller is uninformed. I've got a closed deck fully built EJ257 at high altitude with a CR of 9.5:1 (via JE 9.5:1 pistons). Personally I don't know anyone with a CR higher than 10:1 on a boosted subie motor and that is pushing the limits. For sea level a high CR is not needed or recommended. See if he has the invoice/build sheet from Yimi and maybe contact them directly, they should have a record.

Last edited by umscooby; 04-20-2021 at 05:40 PM.
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Old 04-20-2021, 05:38 PM   #3
pcampbell
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Well it is possible with E85 , the pistons might be custom. You might be knock limited even on E85.

Do you have a picture? It would be fairly obvious, as the pistons would have to have a positive dome to them instead of a dish.
If you do not want 12-13:1 CR then why bother looking at it?
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Old 04-20-2021, 05:41 PM   #4
MasterOfNone_
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Quote:
Originally Posted by umscooby View Post
No way no how it's at 12:1 or 13:1. I'd say the seller is uninformed. I've got a closed deck fully built EJ257 at high altitude with a CR of 9.5:1 (via JE 9.5:1 pistons). Personally I don't know anyone with a CR higher than 10:1 on a subie motor and that is pushing the limits. For sea level a high CR is not needed or recommended. See if he has the invoice/build sheet from Yimi and maybe contact them directly, they should have a record.
Yeah my thoughts exactly! Im going to go check out the block later today. He doesn't have the invoice unfortunately. I know manley pistons have a CR of 8.5 so I'm sure he's just misinformed. If everything checks out with the block I'll give yimi a call to see what CR their blocks are at.
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Old 04-20-2021, 05:47 PM   #5
MasterOfNone_
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Quote:
Originally Posted by pcampbell View Post
Well it is possible with E85 , the pistons might be custom. You might be knock limited even on E85.

Do you have a picture? It would be fairly obvious, as the pistons would have to have a positive dome to them instead of a dish.
If you do not want 12-13:1 CR then why bother looking at it?
I didn't think about custom pistons. I'll take a look at the pistons when I check out the block today and take some pics.
I'm going because he's giving it to me at a really good price, and because maybe he is misinformed since he didn't build the block or maybe he just forgot what the CR is at since the block has been sitting for a few months.
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Old 04-21-2021, 12:40 AM   #6
can250
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Could be a na block motor
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Old 04-21-2021, 02:12 AM   #7
MasterOfNone_
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Update:

ended up being an IAG block with d25 heads. Picked it up for $700.
the seller threw in a vf44 jdm twin scroll turbo, wrx/sti intake manifold, jdm ej20x headers, foreseter blue injectors and fuel rails.
If anyone wants to buy any parts let me know. I only need the block so everything else is for sale. Heads, manifold, headers, injectors, tgvs, egrs, and more.
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Old 04-21-2021, 08:04 AM   #8
benflynn
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Smoking deal, I wonder when u do get knock limited on E85. Also could we chunk the intercooler too?
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Old 04-21-2021, 12:48 PM   #9
BlackFighter
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Quote:
nded up being an IAG block with d25 heads. Picked it up for $700.
the seller threw in a vf44 jdm twin scroll turbo, wrx/sti intake manifold, jdm ej20x headers, foreseter blue injectors and fuel rails.
If anyone wants to buy any parts let me know. I only need the block so everything else is for sale. Heads, manifold, headers, injectors, tgvs, egrs, and more.
Was the eng running when you looked at it, or was it already pulled? It could have a spun bearing or worse and just be a big expositive paperweight. Drain and take the oil pan off. See if there is any glitter flakes in it. Check for ringland failure and head gasket. I would take it apart and have a good overlook before standing the time and money putting it in the neg bay.
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Old 04-26-2021, 08:53 AM   #10
Homemade WRX
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It CAN be done with custom pistons. I have buddy at 14:1 with his 2.5 hybrid autox build. And yes, it's boosted but lives on E85.
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