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Discussion Starter · #1 ·
Hi everyone. I'm in the midst of rebuilding my k20a. Just took out the engine on friday, thought of reverting back stock pistons but unfortunately not possible. there was quite a significant wear sign at the bdc and my builder advises not to use back stock. now we are looking into supertech 86.5mm pistons. Engine block has been sent out for reboring.

Head wise i have also done a cnc port and polish. Thinking to use back the stock cams and valve train due to budget constrain. but yet i'm thinking to upgrade to valve springs and retainers first to supertech double springs so in future if i wanna upgrade the cams it would be much easier and require less down time.

What's your advise?
 

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96 civic HX K24a
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Hi everyone. I'm in the midst of rebuilding my k20a. Just took out the engine on friday, thought of reverting back stock pistons but unfortunately not possible. there was quite a significant wear sign at the bdc and my builder advises not to use back stock. now we are looking into supertech 86.5mm pistons. Engine block has been sent out for reboring.

Head wise i have also done a cnc port and polish. Thinking to use back the stock cams and valve train due to budget constrain. but yet i'm thinking to upgrade to valve springs and retainers first to supertech double springs so in future if i wanna upgrade the cams it would be much easier and require less down time.

What's your advise?
Who did the CNC work ? Do you have any pictures ? I would be curious to see. Supertech valvetrain is widely used, but it’s hard to beat the oem reliability. Not many people have problems with stock valvetrain/cams. In the end it’s up to you and what you want to spend. The stiffer springs with stock cams may net some high rpm power increase from better valve control, but I can’t say for sure.
 

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Discussion Starter · #3 ·
Who did the CNC work ? Do you have any pictures ? I would be curious to see. Supertech valvetrain is widely used, but it’s hard to beat the oem reliability. Not many people have problems with stock valvetrain/cams. In the end it’s up to you and what you want to spend. The stiffer springs with stock cams may net some high rpm power increase from better valve control, but I can’t say for sure.
Thks Kbuilt. Appreciate your thoughts and yeah one of my friend also share the same sentiments. Go harder spring even on stock cams I should be able to pull stable and consistent at higher rpm over 8.5k. I have shared some pictures of the ported head.
 

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Arouse the DAMPFHAMMER!
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Discussion Starter · #9 ·
I would like to seek advise from the more experience guys if by keeping the cams stock for now and upgrade the valve springs and retainers would it do more benefits than harm to the engine.

I use my ride daily drive for work estimated 100km mileage and occasionally track days.
 

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Thks man. Cfm are as below

Intake about 350++
Exhaust about 230++

The company ported for me is confident I would easily gain an estimate of 15hp even on stock
I would like to seek advise from the more experience guys if by keeping the cams stock for now and upgrade the valve springs and retainers would it do more benefits than harm to the engine.

I use my ride daily drive for work estimated 100km mileage and occasionally track days.
drag cartel 2.2 are a pretty common choice for DD cars. If you do a new tensioner with the install I don’t see why it would cause any issues , as long as a knowledgeable person assembles everything correctly and lashes to spec.
 

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Arouse the DAMPFHAMMER!
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350ish...
Slang dictionary says "ish" means "insert sarcasm here". I hope not in the port modification 😉. BTW, what was the goal of the port modification? Where the seats also cut newly? Was the valve size changed?
 

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Discussion Starter · #12 ·
Slang dictionary says "ish" means "insert sarcasm here". I hope not in the port modification 😉. BTW, what was the goal of the port modification? Where the seats also cut newly? Was the valve size changed?
Haha. In that case the ++ after the numbers meant an estimation figure. Goal was to get quicker flow into the combustion whilst staying NA. Seats if I'm not wrong were not newly cut. But the valves were relap to fit the seats. Valve size remain stock so no change. That's what they advise.
 

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Arouse the DAMPFHAMMER!
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Haha. In that case the ++ after the numbers meant an estimation figure. Goal was to get quicker flow into the combustion whilst staying NA. Seats if I'm not wrong were not newly cut. But the valves were relap to fit the seats. Valve size remain stock so no change. That's what they advise.
Ok, thanks for your reply regarding the seat and size.

May you've overseen my question before. Are you going to prove that 15 hp add in an adequate back to back test? Or do they prove it to you already?
 

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Discussion Starter · #18 ·
Hi guys, one year now since I have rebuilt. Now I am thinking to upgrade the cams and have narrowed down to dc cams either 2.2 or 3.2. Which one would be suitable for daily drive and track days time attks?
 

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Arouse the DAMPFHAMMER!
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That moderator guy in the "8 mile" film of the rhyme slam would have said now: "Hola hola hola, what do we've here?". Missing slang caused by missing grown up there ;).

Head wise i have also done a cnc port and polish. Thinking to use back the stock cams and valve train due to budget constrain. but yet i'm thinking to upgrade to valve springs and retainers first to supertech double springs so in future if i wanna upgrade the cams it would be much easier and require less down time.
I am really curious about the torque curve of that build and I would appreciate to see a dyno sheet here. From the port pictures I have made the conclusion that engine will suffer from mid to high engine speed on having a lower air velocity as the 350 cfm were reached by cutting all the port surface. I wait since then to see it, which would be really really great if you would share it. I would be happy if I am wrong and the torque graph wouldn't show a bit depressed torque curve.

Now I am thinking to upgrade the cams and have narrowed down to dc cams either 2.2 or 3.2. Which one would be suitable for daily drive and track days time attks?
What is the CR of the chamber, what H, IM, CAI did you assemble on it?
 

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Discussion Starter · #20 ·
Well my current dyno results is not conclusive hence I feel no point to share. I’m experiencing knocks going into vtec which led me thinking my ignition timing is too advanced. I am planning on seeking another opinion and do a retune first.
 
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