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Registered
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36 Posts
Discussion Starter #1
Hey, there.

As per the title, I'm wondering which one is a better mod for the K20A3. Increasing the displacement of the lower block or increasing its compression ratio?

Recently I changed my dual runner black abs plastic intake manifold to the RRC intake manifold from a Civic FD2 Type R together with the throttle body from an Integra DC5 Type R. But surprisingly the gain is not like what I expected.

My engine also have BrianCrower's Stage 2 cams with steel valve springs and retainers.

I'd definitely gets better gain with a higher compression ratio. But there is also another option, which is a bigger displacement.

As you know, the K20A3's compression ratio is just 9.8:1 .My options are ;

1) Rebuild my K20A3's lower block with higher compression pistons and such.
2) Get the lower block from a JDM DC5 Integra Type R's K20A. 11.5:1 compression ratio.
3) Get the lower block from a JDM RB1 Odyssey Absolute's K24A2. 10.5:1 compression ratio.

I might not go for option 1 as I've heard that the lower block of the K20A3 is not very strong. Also, the 2nd and 3rd option is cheaper here.

As you can see, both the K20A and K24A2 have higher compression ratio than the K20A3, but should I go for purely higher compression or just slightly higher compression with larger displacement?

Thanks.

*I'm not going to go for a full K20 or K24A2. I want to see what is possible with the K20A3. Even if the head is what's left of it. :D . I can go for a full swap anytime, but it's not what I want. After all, a Type R is pretty common in my country. ;) Thanks. :bow:
 

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Noobie
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50 Posts
if dont want to go a full k24a (CL9) and keep your k20a3 base, you could just get a k20a (DC5r) crank and piston set, the k20a3 block should be able to handle the increased comp. those two block are identical except that the k20a2 has some oil squiters mouled into the block. I've seen someone here in NZ run a k20a3 block with a 12.5 comp ratio, on his track car. ofcouse this is using aftermarket pistons and k20a crank.

there's no sense on getting just the bottom of a k20a/k24a, the k20a3 head doesn't breath too well compared to the k20a.
 

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Dafkup
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2,080 Posts
What he said! K24 FTW
if dont want to go a full k24a (CL9) and keep your k20a3 base, you could just get a k20a (DC5r) crank and piston set, the k20a3 block should be able to handle the increased comp. those two block are identical except that the k20a2 has some oil squiters mouled into the block. I've seen someone here in NZ run a k20a3 block with a 12.5 comp ratio, on his track car. ofcouse this is using aftermarket pistons and k20a crank.

there's no sense on getting just the bottom of a k20a/k24a, the k20a3 head doesn't breath too well compared to the k20a.
Yeah the K20a3 head won't breathe as well but he has a modded head anyway so he'll do ok. As far as the bottom, K24 all the way though. Our heavy RSX likes that TQ
 
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