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Hey guys I had a few question regarding the k20a3.

Now before you guys bash on the engine i know it's garbage, I should swap it out for either a k24a2,k20a2, k20z3 or hybrid k20a3 head with bottom end k20a2. I considered all of these
options but i had a question regarding the true nature of the a3. I can't seem to find someone who built this engine completely, everyone has done an all motor build on it and got no further then 330hp ( i think ) at most !
what about fully built a3 with turbo ? who has the fastest a3 out here ? was it worth it ? what kind of issue did you guys have ? Before i jump on this long gruesome journey i wanted to reach out to see if you guys have any feedback.
The car itself will be used for time attack& circuit racing. I know the more ponies under the hood the less likely she will be reliable -___-...

thank again for you answers

 
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You might want to look around on K20.org or EPhatch.com. There is a lot more info specific to the K series engine and EP3 on those forums.

Is there a reason you want to keep the K20a3 instead of upgrading before boosting?

 
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Hey thank you for your reply,

To be honest theirs no particular reason, i mean everyone swaps for either an 24a2 or 20a i wanted to do something different? I'll definitely look into the website
you forwarded over to me. Just exploring the different avenues on the a3 xD

 
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The a3 isn't garbage. It just doesn't make as much power (160BHP/141ft-lb) as the k20a2 (RSX-S, 200HP/142ft-lb) or k20a (JDM ITR/CTR, 212-221bhp/149-159ft-lb depending on gen/model of the vehicle its in). Big factors there is head flow/build, compression ratio, and tuning/redline. The -a3 has a 9.8:1 CR and a 6800RPM redline, the -a2 has an 11.0:1 CR and 7900RPM redline, and the -a has an 11.5:1CR and 8400-8600RPM redline. Otherwise, the k20 series are all solid engines.

People go with the k24 due to torque down low, but sacrifice power on the top end. Then some people get a happy medium by doing a K20 block and k24 head k24 block and k20 head (I always mix those up). The k24 is something like 4cm taller though. That might just be the head being 4cm taller, hence why people don't do straight up k24 swaps in EM2s, but I haven't looked into it that hardcore.

 
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I have a K24a2 block with a K20a2 head in my Civic. The K20a2 head is supposed to flow better plus it doesn't have EGR. Unless you specifically like revving higher there really isn't a reason to stay with a K20. It's easier to make more power with the increase in displacement of the K24.

Like Riceboy said, there's nothing really wrong with the a3. It doesn't have the 3 lobe VTEC like the a2 but it's still decent. If you're boosting the lower CR would be better than the a2. It's really up to you on how much power you want to make and how much you're willing to spend.

It's either 18 or 19 mm taller, I can't remember which. And the entirety of that is added on to the top of the block. The heads are the same height.

 
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how did I not know you have a franken k-swap in your civic?

 
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Never really posted anything about it. It's been there since last winter

 
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Hey guys thanks a lot for the info! @ xRiCeBoYx that my friend is valuable knowledge i wasn't aware i'd loose top end power on the k24a it would make sense why most people would rather go for a k20a2 xD
@BrotatoChip that hybrid swap did it mess up your reliability ? how much power did you really gain ? how much higher can you rev? I'm still doing research but i hear the 5speed tranny will be great for boost. again my question may sound stupid but do you guys think it be worth to swap the 5 speed for the 8th gen 6 speed si?

Thank you for you replies much appreciated

 
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on a street car, torque talks louder.
Have you ever driven a s2k without revving higher? pitiful.

 
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Pretty much this. Track racing, you'll spend more time down low and get up to speed faster coming out of turns. If you're building a drag car, sure, the torque down low will help you get to speed faster, but you spend more time in the upper range, so that's where you want more power

I always defer back to a segment I saw on SpeedTV back in the day. They had a team of lower powered Hondas with torquey setups and built suspensions vs a team of high horsepower Nissans on a road course. Despite being out-powered by the team of Nissans, the low end torque and suspension setups gave the Honda team the win with an average lap time 1-2 seconds faster than the Nissans.

 
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actually, track racing needs a lot more gear shifts to keep the engine where its happiest (like the s2k comes alive at tracks and other venues that you can unleash it.
daily driven streets, you are not gonna hit the rev limiter most of the time. So torque is preferable.

 
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K24 doesn't really lose power up top, they both make ~200 HP stock. The K24 just makes a lot more torque down low and doesn't rev as high (500-1000 rpm less).

I swapped a K20a2 into my EM2 back in 2016 and then did the K24/20 about a year ago. The car got noticeable quicker in all areas. With the K20a2 I was using a stock tune, with the K24/20 I was using a stock K24a2 tune. All parts are OEM so reliability is still there.

Here's a dyno graph I found comparing a K20 and K24. Not a direct comparison because the K24 was tuned but you get the idea. In my opinion, there is no reason to use a K20 unless you want to rev to 8k+ with a stock engine.