How much psi can i 1.8l handle?

1099 Views 6 Replies 4 Participants Last post by SoCoNoHa, Sep 2, 2021

h3xic

Discussion Starter · Aug 30, 2021

So i just bought a 1995 Subaru Impreza L Coupe. I was wondering how much psi of boost can a 1.8l EJ20 handle with stock internals.

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A 1.8l is actually an EJ18, the number stands for the displacement. Ive seen people run 5-10psi on here but the engine isnt really designed for boost. I read somewhere on here that the early ej18s had either forged internals or forged pistons or something but Ive never taken a block apart so I cant confirm that.

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mike-tracy

· #3 · Sep 1, 2021

You need to pick a turbo as well. Because 10PSI on a TD06 is not same as 10PSI on a TD04!

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h3xic

Discussion Starter · #4 · Sep 2, 2021

mike-tracy said:
You need to pick a turbo as well. Because 10PSI on a TD06 is not same as 10PSI on a TD04!

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Thanks, but what would you recommend?

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SoCoNoHa

· #5 · Sep 2, 2021

I believe the EJ18 is the strongest non turbo EJ bottom end. I ran almost 18 psi on an EJ18 bottom end with EJ22 heads, and I bet it would've taken more with better boost control and tuning. The larger combustion chambers of the 2.2 heads dropped the compression ratio a bunch to make boost safer. Definitely read up on things like engine management, injector options, gauges, lowering CR, etc. if you're gonna push it.

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h3xic

Discussion Starter · #6 · Sep 2, 2021

SoCoNoHa said:
I believe the EJ18 is the strongest non turbo EJ bottom end. I ran almost 18 psi on an EJ18 bottom end with EJ22 heads, and I bet it would've taken more with better boost control and tuning. The larger combustion chambers of the 2.2 heads dropped the compression ratio a bunch to make boost safer. Definitely read up on things like engine management, injector options, gauges, lowering CR, etc. if you're gonna push it.

will the EJ22 heads fit or will it need some modification

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SoCoNoHa

· #7 · Sep 2, 2021 (Edited)

rs25 ej22 heads ej18 block - Google Search

www.google.com

Here's the PRIMARY thread that I followed for guidance:

Project EJ18T

Project EJ18T: Transforming one of the weakest EJ's into an STI killer... MODS: 1993 EJ18E shortblock 1994 EJ22T heads with EJ18E roller rockers 2004-06 IHI VF39 turbo (now IHI VF34 turbo) AEM dryflow filter (now APEXi Power filter) WRX turbo inlet positioned under EJ18E intake manifold...

www.rs25.com

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How much psi can i 1.8l handle?

h3xic

stalkergc

mike-tracy

h3xic

SoCoNoHa

h3xic

SoCoNoHa

rs25 ej22 heads ej18 block - Google Search

Project EJ18T

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