Swapping K20z3 engine into 9th gen SI

R

RedSI

Well-Known Member
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Hello everyone,

Obviously I am new to this forum and I am a proud owner of a red 2014 civic si sedan, hence my username. I been enjoying my SI for over a year now and I absolutely love the way it looks. Without sounding bias, I believe the 2013-2015's are among the best looking honda civics ever made, especially the sedans. Also when it comes to the interior in terms of material quality, technology, and a bit more leg room, this is where I truly feel the 9th gen leaves the 8th gen completely behind in the dust.

With all that said, I have been reading a lot about how the 9th gen lost its "soul" with the introduction of the K24z7 engine, as I am sure all of you have heard. Now the general consensus seems to be that the K20z3 engine was the best engine built ever for honda driving enthusiasts.....and with the apparent end of naturally aspirated engines for sporty, compact, FWD cars......and everyone going turbo, including honda (10th gen)......I feel like if I want to enjoy the glory days of honda's VTEC engines, I need to replace my engine with the K20z3.

I was wondering if anybody had thought about doing this or has done this before? Any pointers or recommendations to help guide me? I truly appreciate any feedback and I did not mean to write a mini novel...lol.
 
a lot of people on the 8th forums wanted more power and went with what they called the "k24 frankenstein" swap. They'd use a k24 bottom end from an accord/crv to gain extra torque and used the k20 head off their k20z3 engine.

the race vehicle honda uses is a k24 bottom and the k20 head -
http://9thcivic.com/forum/threads/k20-head-swap-parts-list-needed.6612

it's not a simple/cheap swap though. Truthfully, you'd be better to go with a CT supercharger or something along those lines for upgrades. You can do extra mods to run aftercoolers and e85 gas to be in the mid 300's for power to the ground.
 
If you want the high revving character of previous honda engines your better off doing the rbc intake manifold swap, tunning, and upping your redline to 7500. The reason everyone is going turbo is because in general people enjoy mid rpm power to top end power. Thats why honda went with the k24 for the 9th gen in the first place.
 
webby said:
a lot of people on the 8th forums wanted more power and went with what they called the "k24 frankenstein" swap. They'd use a k24 bottom end from an accord/crv to gain extra torque and used the k20 head off their k20z3 engine.

the race vehicle honda uses is a k24 bottom and the k20 head -
http://9thcivic.com/forum/threads/k20-head-swap-parts-list-needed.6612

it's not a simple/cheap swap though. Truthfully, you'd be better to go with a CT supercharger or something along those lines for upgrades. You can do extra mods to run aftercoolers and e85 gas to be in the mid 300's for power to the ground.
Click to expand...

That's interesting because it sounds like a lot of the ppl that were complaining about the 9th gen engine being "soul less" are the same ppl that were asking for more torque on the 8th gen engine. One thing I been constantly reading about on why you don't hear and feel the VTEC crossever on the 9th gen to the same degree as the 8th gen is because on the K24z7, there is only one VTEC lobe on the exhaust cam. Wheres as the 8th gen have two VTEC lobes, one on the exhaust cam and another on the intake cam.

Forgive me I am a noob when it comes to engines, but if I do the k24 frankestein swap, will that engine give me the torque of the 9th gen, but with the VTEC crossover and rpm range of the 8th gen? Am I understanding that correctly?

I am not really looking to have 300 horsepower, it's more about the driver engagement I'm looking for and it seems the 9th gen has lost a step in that regard.
 
Bulkybear said:
If you want the high revving character of previous honda engines your better off doing the rbc intake manifold swap, tunning, and upping your redline to 7500. The reason everyone is going turbo is because in general people enjoy mid rpm power to top end power. Thats why honda went with the k24 for the 9th gen in the first place.
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What about the lack of a VTEC lobe on the intake cam for the 9th gen? You don't feel the 9th gen engine has lost a step in terms of driver engagement?
 
MuBGFK3.jpg


The lack of torque made 8th users want to do the k24 bottom end if they didn't want to go turbo/supercharger. See the huge spike when vtec engages. Yes, they had a vtec intake and exhaust cam. The 9th doesn't have that, but it does have more consistent torque down lower in the rpm range. The 8th gen required you to rev it out much higher to get that torque.

the 9th gen has totally different power output - significantly more torque in the lower rpm range.

12_Civic_HeaderDyno.jpg


The vtec crossover isn't that big of a deal. People like the sound of the 8th vtec point. You can achieve a bigger vtec engagement sound by changing the intake/downpipe/exhaust etc on the car.
 
I understand now. The VTEC crossover on 8th gens is basically all sound. I thought it also affected the pull of the car as well as the overall feel/connection with the driver.

So basically 8th gen owners switched to a k24 engine when they did the frankenstien swap. What is the purpose of putting a k20 head on a k24 block though? What are the benefits to that versus a k24 head like our engines?
 
RedSI said:
I understand now. The VTEC crossover on 8th gens is basically all sound. I thought it also affected the pull of the car as well as the overall feel/connection with the driver.

So basically 8th gen owners switched to a k24 engine when they did the frankenstien swap. What is the purpose of putting a k20 head on a k24 block though? What are the benefits to that versus a k24 head like our engines?
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The vtec crossover on the 8th gen isn't all sound. Notice the big bump in hp & tq where the vtec crossover occurs. The K20Z3 head flows great for higher peak hp. The K24 block has a similar bore size as the K20Z3 (87 vs 86 mm respectively) but it has a higher stroke, 99 vs 86mm. This is where the increase in torque comes from. When you combine the torque of the K24 with the high-rpm attributes of the K20, you get the best of both worlds known as the frankenstein swap as mentioned by webby.

At the end of the day I don't feel like there's a lack of soul in the 9th gen. The increased torque is much more practical for daily use, you never need to go above 5000rpm, hell I can keep up with traffic keeping it under 4000rpm with no issue. That leaves 3000rpm+ for play time.
 
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'13_Si said:
The vtec crossover on the 8th gen isn't all sound. Notice the big bump in hp & tq where the vtec crossover occurs. The K20Z3 head flows great for higher peak hp. The K24 block has a similar bore size as the K20Z3 (87 vs 86 mm respectively) but it has a higher stroke, 99 vs 86mm. This is where the increase in torque comes from. When you combine the torque of the K24 with the high-rpm attributes of the K20, you get the best of both worlds known as the frankenstein swap as mentioned by webby.

At the end of the day I don't feel like there's a lack of soul in the 9th gen. The increased torque is much more practical for daily use, you never need to go above 5000rpm, hell I can keep up with traffic keeping it under 4000rpm with no issue. That leaves 3000rpm+ for play time.
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Thanks man! I finally get it now lol. It sounds like I def want to go for the k24 frankenstein swap, but I will look more into that as webby mentioned it wasn't cheap nor simple. The fact that you can still have lots of torque, yet still make power while revving up to 8300 rpms (safe zone from what I read on other sites) is beyond sweet.

I never really got into turbocharged engines, because I would read how a lot of them had low rpms due to how quick they made their power. That right there detracted a lot from the driving dynamics for me. Before I make any move for a frankenstein, I think I will to see how the new engine for the 10 gen si will be like first, since it will be honda's first turbocharged engine.

Going back to the frankenstein swap, can it be any k24 block? I ask because I see the k24a4 block mentioned a lot on other forums. Once thanks a lot to everyone in this thread for taking the time to answer my questions.
 
k24a4 is one of the cheapest k24 blocks to find used. That's why most k20 owners buy them. You already have a k24 though, so you're not buying a k24 block. You need the head from the k20 - rsx-s, 8th si, or whatever you want.

RedSI said:
I never really got into turbocharged engines, because I would read how a lot of them had low rpms due to how quick they made their power.
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tell that to all of the k20 turbo/sc guys. They can rev to 8k and beyond. Still building power above 8k here -

dyno.jpg


  • ~23psi on E85 made ~670hp — the car went 10.5 @ 139mph on ~26psi and set the new 8th gen turbo street car record
 
the same will happen with turbo/sc on the 9th gen - they build power till the top.

rob.jpg
 
The K24Z7 in our cars can be equipped with the K20 head, the difficulty seems to vary depending on the source. Some say it's not too bad while others suggest it is a more intense process. Someone mentioned swapping the older K24 into the 9th gen, but I know for sure the oil filter locations are different and who knows what else so that may not even be possible. I'm 100% in favor of a 250+ whp NA 9th gen with mostly OEM parts, that would satisfy my hp needs.
 
Full bolt-ons and some higher compression pistons should get you close. Maybe lighter flywheel, pulleys, and ultra light wheels as well. No point in dealing with the hassle of trying to get the head to work.
 
@webby, that's great to learn a turbo/sc k24 engine will continue to make power till the top end. The only thing is it still won't be able to rev to 8300 rpms( I don't want to make it sound like a deal breaker, but being able to rev up to 8300 rpms is pretty cool).

@13_Si, right now I am doing more research on the net to see if I should put a k20 head on my engine or go with the turbo/super charged route. It might better to wait until information on the 10 gen Si engine comes out. That way I don't miss out on what Honda's new engine technology will be like.

At this moment, I am leaning more towards putting a k20 head on my engine and keeping it naturally aspirated. Why? Because I keep hearing about how a turbo/super charger will kill half the lifespan of your engine. Also with a turbo charger, I hear there is lag time before the full power is delivered.
 
Lol well I be damn, 10-11k rpm civics, that should satisfy my inner racer. I just love the sound of the exhaust as the rpms continue to climb and more power is being made, you really feel like your car is becoming alive.

How do you think the 10 gen si engine will turn out to be? You think it will be a turbo charged version of the k20? It might be Honda's approach to bring back the high revving nature of their engines, combined with getting with the times in terms of turbo charging and being able to provide enough practical torque in the lower rpm range. The focus ST and golf GLI are already turbocharged. Even BMW moved to turbocharged for their M series.
 
RedSI said:
Lol well I be damn, 10-11k rpm civics, that should satisfy my inner racer. I just love the sound of the exhaust as the rpms continue to climb and more power is being made, you really feel like your car is becoming alive.

How do you think the 10 gen si engine will turn out to be? You think it will be a turbo charged version of the k20? It might be Honda's approach to bring back the high revving nature of their engines, combined with getting with the times in terms of turbo charging and being able to provide enough practical torque in the lower rpm range. The focus ST and golf GLI are already turbocharged. Even BMW moved to turbocharged for their M series.
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Well the new type r is a 2 liter and redline at 7k rpm. The new civics we don't know what engine will be in the Si. We have only heard about the 1.5 liter turbo. All I can say pretty surely is the high revving Hondas (stock anyways) are a thing of the past.
 
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