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New Project Suggestion on Head

Discussion in 'Engine Building' started by unix4linux, Jun 23, 2010.

  1. unix4linux

    unix4linux Senior Member

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    Ok, here is what I have gathered so far from doing a little reading. From what I understand, a K24A2 head vs K24A4 head stock to stock, you'll see significant changes as far as power numbers is concerned. So, when trying to output the most power based on stock internals, it is wise to swap the k24a4 head for a k24a2 head due to the cam profile and better head airflow.

    Now, if you are going to run a turbo setup and plan on changing the internals of both the block and the head, it makes sense to just keep the k24a4 head. If you do a port/polish/valvetrain job to the k24a4, you can expect the same performance as if the same is done to a k24a2 head. In summary, if staying stock and want to gain more performance, then a head swap is the way to go, if building the entire engine from head to bottom, then keeping the k24a4 head instead of swapping it out for a k24a2 head doesn't matter.

    That is what I have gathered from my research so far, can someone shine some light on this subject? Am I on the right track?

    I am also curious to know if I can order parts (internals) for a k20a1/2/3 head to use on a k24a4 head? The reason I ask is because I am having a hard time finding parts specifically for a k24a4 head. Everything seems to be for a k20a1/2/3
     
  2. unix4linux

    unix4linux Senior Member

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    Anyone with thoughts?
     
  3. newb

    newb phresh VIP

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    Im no K series expert, but Im gunna take a shot in the dark and say you can most likely pick up the A2 for cheaper than you can get the A4 ported (just to even match the flow of the A2 head) and decked out with internals that are worth anything. So, Id pick up the A2 head and save some coin ny having a better starting point.

    Someone correct me if Im wrong.
     
  4. unix4linux

    unix4linux Senior Member

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    Well, porting it is not going to cost me anything. I have a brother that works at a machine shop and porting/head mods won't cost me a penny. I just have to spend the funds on getting the new valvetrain that I would like. This is why I am wondering if getting an A2 is worth it if I am going to change the valvetrain regardless if it's an A2 or A4 plus the porting will be no cost.
     
  5. RoughKnight

    RoughKnight Christmas Car

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    If you wanna get head, get a girlfriend or stripper
    /thread
     
  6. unix4linux

    unix4linux Senior Member

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    RoughKnight,

    No offense, but I mentioned in my first line that I have indeed researched, google, search, and no answers that have been useful. In many forums, I have received the same answer you posted, "Did you search?".

    I know you are trying to help but it is frustrating to find the only reply to be "did you search". All of the info I have ran into just talks about how the A2 head is better than the A4 but that's stock comparison. I am looking to see if when you build any head and port them out, does it matter which of the two you choose and why. Besides one being able to offer the 3 lobe vtec mechanism (A2), is a three lobe vtec head really gonna be that much better than a 2 lobe vtec (A4) when you fully build them?

    Since I have the A4 head, I want justification as to why the A2 would be best besides just gaining 5-10HP more just because of the 3 lobe after fully building either of the two.
     
  7. RoughKnight

    RoughKnight Christmas Car

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    Unix4linux,

    No offence, but my comment was aimed purely at entertainment as the act of fellatio is a welcome part of my life. Thus, you ignoring that simple fact of humour and jumping into an analysis only concures my hypothesis that you have not experiened said act. That being said,

    take a joke please, no need for the essay response.

    Somebody with knowledge will chime in soon enough, in the mean time sit tight and enjoy.
     
  8. unix4linux

    unix4linux Senior Member

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    RoughKnight,

    None taken. It has just been upsetting to find the same responses in 4-5 different forums so I am sure you can understand the frustration.

    Either way, I can take a joke :)

    On another note, I am going to answer my own question if for others who may wonder the same when they do this setup:

    Ok,

    After hours of reading, looks like I am going to search for a K20A2 head instead of using my k24A4 head. Here is why:

    The A4 head seems to open up only 1 intake valve per cylinder when not in vtec. When vtec engages, it opens both valves on the intake side. On the K20A2 head, when vtec engages, the valves open on both exhaust and intake side (4 valves). So, the 3 lobe vtec mechanism is definitely a huge factor besides just head flow and the power gains would be a lot more than just 5-10HP. The A2 head will also allow a larger turbo setup to spool faster because of the 3 lobe vtec mechanism (since more air is flowing).

    All in all, if porting and completely building a K20A2 head and K24A4 head, the K20A2 head will perform better anyway because of the 3 lobe vtec engaging all of the valves.
     
  9. newb

    newb phresh VIP

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    Wait, so youre saying the K24A4 only works 3 valves when not in VTEC and the fourth just stays shut?
     
  10. unix4linux

    unix4linux Senior Member

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    From what I gathered, yes
     
  11. newb

    newb phresh VIP

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    Im thinkin you should dig a lil more. That doesnt seem right to me.
     
  12. RoughKnight

    RoughKnight Christmas Car

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    Sounds to me like the difference is going to end up almost negligable if your going for a port/polish, matt or somebody on the board (I forget) has a ls head and has flowed it and it ends up almost exactally as flowed as a vtec head.

    I could be wrong though
     
  13. unix4linux

    unix4linux Senior Member

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    Roughknight,

    That is what I thought. I thought that since I am going to be porting out the head (A4), that at that point it was pointless to get the A2 head. But, apparently, the A2 head uses a different vtec mechanism (true vtec) where all valves open.

    Newb,

    According to what I have read and asked in a few places, vtec on the k series is very different between some K engines. One of the sources is here: Short Block with K20A2 VTEC Cylinder Head - Tech - Sport Compact Car Magazine
     
    Last edited: Jun 25, 2010
  14. unix4linux

    unix4linux Senior Member

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    Hmmm...the A2 head still looks better than the A4 even if porting. After looking at some pictures and reading some info, the A4 head intake ports seem to have a split in the port wall. The A2 head doesn't. This is because since the A4 head is an economic vtec mechanism, one of the valves on the intake side stays closed during non vtec engagement. If that valve is closed, the air has to go somewhere so that it doesn't produce back gases or turbulence. This is why it has a split in the intake port wall so that when the valve is closed at low RPM, the only open valve can receive the air through the wall split of the intake port from the valve that is not receiving any air through the valve. In other words, it becomes a dead end.

    On the A2 head, the intake port doesn't have this split in the intake wall that separates the two intake valves because both valves open all of the time. So, the A2 head would still be better with any mod because air flow is directed through two intake valves at all time where as the A4 it only happens when vtec is engaged.
     
  15. K2e2vin

    K2e2vin Senior Member

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    Nothing new. Honda has been doing it since 1992 with the Civic VX; it's called VTEC-E...or in this case, "i-VTEC-E".

    A2 uses a head more similar to the K20A heads; but of course K20s are easier to come by and flow more from the factory. The A2 heads will probably net higher low-end torque than the K20A heads.
     
  16. newb

    newb phresh VIP

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    Im not saying its any new concept. Im just saying there might be some misinterpreted info.
     
  17. CAFROG

    CAFROG Honda Minion VIP

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    Hope you figured out he was talking about your signature. I think he didn't know its in your Signature and not wrote to him, specifically
     
  18. unix4linux

    unix4linux Senior Member

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    Ahhh yes, I just realized he didn't write that. Didn't notice it was a sig...oops!!
     
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