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Hey y'all. Im sure this topic has been beat to death, but I recently acquired an '03 EP3, and was wanting to build it to around 450hp. Anyone have any good input as to what would be the best way to do that? I was considering doing a K20a2 head, K24 block, but I was wondering if any of you K wizards have any input. Anything useful is much appreciated!!!
 

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Either a k20a2 or a k24a2, or a combination of the two engines with a turbo kit on it will easily get that power. If you’re talking naturally aspirated I won’t even go there as that kind of power NA would be very expensive. Really if you have a healthy engine to begin with they respond very well to 8-15psi of boost and you’ll be at 350-500whp with the right turbo , a sidewinder, big fuel etc
 

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Or if you’re up for building a block, a nice CSS with beefed up rod and pistons with nitrous could net 400+ , but would also be expensive.
 

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I have the same an 03 ep3 and im trying to push 300 n/a im thinking a jdm k24a with the 6 speed it comes w an lsd and 10.5/1 compressions ratio or the jdm k20a and transmission that also has a 6 speed w an lsd but instead has an 11.5/1 compression ratio, a slightly longer duration intake and exhaust cams and dual valve springs on both the intake and exhaust sides and 8600 redline. Which do you think would be better for my build both in terms of how easy it would be and how much it would cost?
 

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Arouse the DAMPFHAMMER!
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...450hp...K20a2 head, K24 block...
You need about 12.5 psi of boost for 450 flwhp with the 87x99 engine on gasonline, if you have an reeeeeally good intercooler, giving you 50 °C MAT (manifold air temperature). Ign. timing might be around max at 18° [email protected] rpm, depending on blowby and intake setup. Still possible with an Rotrex (C30-94 or C38-61) compressor, but turbo would be much more easier. It is all about knock depression with a MAT lower then 50 °C.
 

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Again not really trying to push that much. Id be happy with 280-300 whp trying to go for a n/a build what would be best for me?
 

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Arouse the DAMPFHAMMER!
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Either a k20a2 or a k24a2, or a combination of the two engines with a turbo kit on it will easily get that power. If you’re talking naturally aspirated I won’t even go there as that kind of power NA would be very expensive. Really if you have a healthy engine to begin with they respond very well to 8-15psi of boost and you’ll be at 350-500whp with the right turbo , a sidewinder, big fuel etc
Yeah :)

Or if you’re up for building a block, a nice CSS with beefed up rod and pistons with nitrous could net 400+ , but would also be expensive.
Rooooooaaaaaarrrrrrrrrrrrr...that would be nice. It's a long time ago I have seen here a NA engine with N20 injection. I guess the last I have seen was in F&F 1 LOL :D. With the 87x99 engine you need a very good intake and exhaust to get with a modified head, valvetrain and crank assembly to 300 [email protected] rpm or 354 [email protected] rpm. Adding a 80 hp Nitro Oxide shot will push it to 434 [email protected] rpm. That's, as you said, is much more effort than the turbo setup, which is likely the cheapest one. But definitely not like the NA sound.

I have the same an 03 ep3 and im trying to push 300 n/a im thinking a jdm k24a with the 6 speed it comes w an lsd and 10.5/1 compressions ratio or the jdm k20a and transmission that also has a 6 speed w an lsd but instead has an 11.5/1 compression ratio, a slightly longer duration intake and exhaust cams and dual valve springs on both the intake and exhaust sides and 8600 redline. Which do you think would be better for my build both in terms of how easy it would be and how much it would cost?
The way to 300 flwhp in a NA way is more easy with the 87x99 Frankenstein concept. You need a higher CR (12:1 minimum), forged pistons and rods, stage 2 cams and at least a RRC IM and a nice header. You can find a lot of examples in this forum by search to this.
My 86x86 engine, which will exceed the 300 flwhp, is around 20 k€ (a lot of own designed and built parts), definitely not an easy way to 300 flwhp and only for 2000 ccm class racing your way to go. The easiest NA way would be an 89x99 engine, which will be capable to exceed the 300 whp mark at around 8200 rpm. There are a ton of examples here in the official dyno thread.
 

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Yeah :)

Rooooooaaaaaarrrrrrrrrrrrr...that would be nice. It's a long time ago I have seen here a NA engine with N20 injection. I guess the last I have seen was in F&F 1 LOL :D. With the 87x99 engine you need a very good intake and exhaust to get with a modified head, valvetrain and crank assembly to 300 [email protected] rpm or 354 [email protected] rpm. Adding a 80 hp Nitro Oxide shot will push it to 434 [email protected] rpm. That's, as you said, is much more effort than the turbo setup, which is likely the cheapest one. But definitely not like the NA sound.

The way to 300 flwhp in a NA way is more easy with the 87x99 Frankenstein concept. You need a higher CR (12:1 minimum), forged pistons and rods, stage 2 cams and at least a RRC IM and a nice header. You can find a lot of examples in this forum by search to this.
My 86x86 engine, which will exceed the 300 flwhp, is around 20 k€ (a lot of own designed and built parts), definitely not an easy way to 300 flwhp and only for 2000 ccm class racing your way to go. The easiest NA way would be an 89x99 engine, which will be capable to exceed the 300 whp mark at around 8200 rpm. There are a ton of examples here in the official dyno thread.
Can 89 bore be achieved safely on the stock sleeve ? Or does it need reinforcement to go that big. Sometimes I think I need an 80 shot for my k24 😂 the k series always seem to make very good power on the bottle
 

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Arouse the DAMPFHAMMER!
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Can 89 bore be achieved safely on the stock sleeve ? Or does it need reinforcement to go that big. Sometimes I think I need an 80 shot for my k24 the k series always seem to make very good power on the bottle
One should stop at 87.25 mm which is maximum for the steal inlays. For more you need aftermarket liners. With them you have options up to 90.5 mm for drag, 90 mm for circuit and 89 mm for boost.
 

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Are there any k series that have 89 bore stock? And what size would be best for n/a
the k20 are 86mm bore and the k24 are 87 and that’s as big as it gets unless you move up to J series. Member child star’s build made 300 whp on pump gas with an 88x99 k24 12.5:1 compression with 4piston cams. Stock port type s head.
 

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Are there any k series that have 89 bore stock? And what size would be best for n/a
According to what Markus said 89mm on stock sleeves is too much. But a lot of people go 88mm without problems and always good to make sure the cylinders are perfectly in round with a fresh bore
 

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Arouse the DAMPFHAMMER!
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The 88x99 engine report: Childstar's K24 "gravity coupe" - Honda-Tech - Honda Forum Discussion. Seems like to be a friend of KTuned or he is sponsored by them.

According to what Markus said 89mm on stock sleeves is too much. But a lot of people go 88mm without problems and always good to make sure the cylinders are perfectly in round with a fresh bore
The stock liners of the K20 and the K24 consists of an aluminium wall which has a steal inlay of around 3 mm thickness, at least at the K20 it is like 3 mm. The steal inlay is inserted for better honing structure and form stability reasons. The lower it is the less the later will be stable in size and form. It would be interesting to know the oil consumption and cylinder pressure curve of an 88 mm bore engine with stock and higher CR. The steal inlay at Child Star's engine looks like to be around 1.0 to 1.5 mm thick, not sure about that, just guessing from the picture. The stock oversize piston stops at 87.25 mm if I am correct?
 

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The 88x99 engine report: Childstar's K24 "gravity coupe" - Honda-Tech - Honda Forum Discussion. Seems like to be a friend of KTuned or he is sponsored by them.

The stock liners of the K20 and the K24 consists of an aluminium wall which has a steal inlay of around 3 mm thickness, at least at the K20 it is like 3 mm. The steal inlay is inserted for better honing structure and form stability reasons. The lower it is the less the later will be stable in size and form. It would be interesting to know the oil consumption and cylinder pressure curve of an 88 mm bore engine with stock and higher CR. The steal inlay at Child Star's engine looks like to be around 1.0 to 1.5 mm thick, not sure about that, just guessing from the picture. The stock oversize piston stops at 87.25 mm if I am correct?
I believe you are correct i don’t think I’ve seen 87.5 oem oversized pistons, only aftermarket. Ya I would be curious to hear how his 88x99 longblock is holding up , seems like he put together a pretty efficient engine👍
 
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