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Thread: 4AG headwork, now block too

  1. #16
    anti blasphemy ! Carport Converter
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    Default Re: 4AG headwork

    ahh it means must where "goggles"

    i bought a pack of undies in bali and on the intructions (becuase i forget how they work) they said "do not tumble fry" i thought it was funny.
    i dont have a funny or cool signature.

  2. #17
    Senior ****** Carport Converter Sam_Q's Avatar
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    Default Re: 4AG headwork

    theres very little shrouding on the 20V engines so you would be lucky to get anything out of it even on a flowbench.

  3. #18
    Senior ****** Carport Converter Sam_Q's Avatar
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    Default Re: 4AG headwork

    heres how I was thinking of doing my chamber initually:



    not quite the same thing as the 4ag drawing posted earlier but instead a general deshrouding. I believe one of the thoeries is from the valve to the chamber is 85% of the valve lift and 65% for the exhuast. Quoted from the four stroke tuning guide.

  4. #19
    AGE-16V Automotive Encyclopaedia Dimmy's Avatar
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    Default Re: 4AG headwork

    Very nice! That's the next step left on my 16v Probably do it in a few months.

    Anyone willing? hehe
    I have been pruned by old man river!!!!!

  5. #20
    Junior Member Too Much Toyota oldcorollas's Avatar
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    Default Re: 4AG headwork

    top left says

    の範囲で滑ら
    makes somethings area slippery?

    top right is too small to read

    btw, there are no joggles in japanese... in english it measn "dowels" ? (bits sticking out?)
    "I'm a Teaspoon, not a mechanic"
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  6. #21
    tilting at windmills Carport Converter Ben Wilson's Avatar
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    Default Re: 4AG headwork

    Quote Originally Posted by Sam_Q
    heres how I was thinking of doing my chamber initually:
    Careful, you don't want to take too much out of your quench area.
    Strange things are afoot at the circle K

  7. #22
    Olde mechanic Carport Converter oldeskewltoy's Avatar
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    Default Re: 4AG headwork

    Hahahahahahahaha...... you guys are all engineers... not an artist amoung you!

    joggles means the drawn lines! OR look at the photo and the lined section should be removed and polished!

    Sam.... I'd talk to Bill.... I'm NOT sure you want to remove that much squish area. I was as careful as I could be and I didn't remove any squish area....

    Giving it a brief look....



    The areas with less yellow dots... should be gradually tapered, maybe with a very tiny 1/4 round used on the edge (to try to avoid a high temp spot), the areas showing more yellow dots(areas outlined in purple) are areas I'd "adjust" in the combustion chamber.

    Concerning what to polish on a "F" head..... I don't know..... I didn't have to know on the "G" head... someone, likely an engineer, told me what to do... I just had to follow it
    Last edited by oldeskewltoy; 22-04-2008 at 01:31 AM.
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  8. #23
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4AG headwork

    While we are on topic of de-shrouding and combustion chambers.......

    Here's a pic of the ones i did on my 4a


  9. #24
    Senior ****** Carport Converter Sam_Q's Avatar
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    Default Re: 4AG headwork

    ben: your right, see my comment below:

    oldeskewltoy: even though my research said to do so I was told not to take too much out and I didnt. I ended up doing something very close to what you drew. A little more will be taken out but not too much.

  10. #25
    Olde mechanic Carport Converter oldeskewltoy's Avatar
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    Default Re: 4AG headwork

    30psi 4agte - You're running 30 psi(or so I assume...) a completely polished combustion chamber allows for no area to get warmer then others... I ASSUME that the TRD porting diagram was developed for N1, or group 2 race engines.... all being N/A. I BELIEVE the reason TRD leaves the center dimpled is to allow the center of the CC to retain more heat then the sides of the CC

    Btw... VERY pretty head....

    I've been giving some thought to making desktop toys... one section of a head, one cylinder... fully polished (like yours) with valves fitted... using 2# springs. That way the person can pick it up and play with it while on the phone... or doing some other mundane task....
    Information is POWER... learn the facts!!

  11. #26
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4AG headwork

    hmmmm do i detect some sarcasim ?

    Question: why do you want one area of the head to get hotter than another ? I would think you would want a even spread of heat to deterr detonation from hot spots.

    All the pics i have seen of formula atlantic heads have had smooth chambers........ come to think of it any decent head i have seen has had smooth chambers

  12. #27
    Olde mechanic Carport Converter oldeskewltoy's Avatar
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    Default Re: 4AG headwork

    Quote Originally Posted by 30psi 4agte
    hmmmm do i detect some sarcasim ?

    Question: why do you want one area of the head to get hotter than another ? I would think you would want a even spread of heat to deterr detonation from hot spots.

    All the pics i have seen of formula atlantic heads have had smooth chambers........ come to think of it any decent head i have seen has had smooth chambers
    No sarcasm.... hard work is hard work!

    I did as the TRD manual pictured.... Hmmm I wonder if the reasoning behind it all is the center of the chanbers don't require it.. while the outer edges do, and the TRD manual is showing the way to get the most for the least change. If I'm not mistaken chamber volume must be within -2% and +4%, for one of the racing series......

    Like forced induction, Formula Atlantic is a highly specialized head... I was to Arnie Loyning's shop here in Portland Oregon USA. Loyning has made some of the winning Formula Atlantic engines.
    http://www.loynings.com/

    I know what a finished F/A head looks like he has a number of them along with F/A cranks... and all sorts of goodies!
    Last edited by oldeskewltoy; 24-04-2008 at 05:19 AM.
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  13. #28
    ......... Carport Converter jeffro ra28's Avatar
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    Default Re: 4AG headwork

    Just geussing, but i think the reasoning behind leaving the cast finish in the chamber is because it has more surface area then the polished surface. Can only guess as to why they want more surrface area. Perhaps heat dissapation or insulation?

    Iv seen one off specially developed cylinder heads worth 40k a pair. They had smooth chambers all round!

    Do you think perhaps we have a certain misinterpritation of the japanese language in that TRD guide?

  14. #29
    tilting at windmills Carport Converter Ben Wilson's Avatar
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    Default Re: 4AG headwork

    Could it be because the racing series used stock pistons and they didn't want to lower compression any more than they needed to?
    Strange things are afoot at the circle K

  15. #30
    DIY Bloodline Domestic Engineer Talasas's Avatar
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    Default Re: 4AG headwork

    ^ That would be a more likely reason. It's a trade off between compression ratio and combustion efficiency.

    The problem with all of this is that there is no reasoning for doing only that section so we are left to guess why.
    "In the beginning, the universe was created. This has made a lot of people angry and has widely been regarded as a bad move." -HHGG

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