Engine Theory, Build, Etc Discussion.

Discussion in 'Engine & Transmission Mods' started by BlkCurrantKord, Oct 15, 2007.

  1. turboputz

    turboputz Well-Known Member

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    Lower compression is usually achieved through the design of a new cast piston that you buy. It may be slightly dished like a bowl in some cases. This will increase the combustion chamber size and lower compression.

    Compression can also be lowered through the use of a thicker than stock metal or copper head gasket. When the piston is at it highest point it will now be further from the roof of the combuston chamber. Again combustion chamber size increases while bore and stroke stay the same and compression lowers.

    Changing of the headgasket thickness should only be used to achieve a small level of compression lowering. Meaning going from a 26mm gasket to a 75mm headgasket is a poor substitute for getting lower comp pistons.

    8.3:1 to 8.5:1 compression is ideal for turbocharging above 15 psi on the F23. What that means is that with a good tune at this comp level you will be able to eliminate detonation and protect the longevity of the engine. Detonation is when the gas and air mixture explodes before the spark plug fires. This can cause knock and ping, which are both very bad things. Before this goes way over your head I will just mention three ways to combat detonation.

    1: Adequately cooling the intake charge
    2: Lowering compression
    3: Tuning, tuning, tuning
     
    Last edited: Oct 15, 2007
  2. Kid2000EX

    Kid2000EX Well-Known Member

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    I know ive been giving a couple answers but heres a question I have, Ive heard that by claybarring the motor, and running RSX-S pistons, compression should be in the 11:0-11:7 range. Is that true?
     
  3. Roadrage

    Roadrage Well-Known Member

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    yes its a A5. thanks for the info BLKCurrantKord:thumbsup:
     
  4. BlkCurrantKord

    BlkCurrantKord Super Moderator

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    Are you talking about claying the motor or extrude honing cause I think you kinda combined the two with "claybarring".

    Here's how to play around w/ the compression w/ K20 pistons...

    K20a3 - dome = 2.5cc - should give around 11:1 compression
    K20a2 - dome = 4.25cc - mid 12's to 13:1 compression
    K20a - dome = 6.6cc - highest compression 13-14:1
     
  5. Sonnick

    Sonnick Well-Known Member

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    Lol...are you talking about waxing your car? :talk-punch: Hahaha just playin' man.

    Hmm..so Jackhunt runs 11s and has over 400whp on stock rods :confused: :confused:

    But anyway..........anything under 9:1 should be great for the F23 in terms of turbo. However, you can use the stock pistons/rods as well, along with ARP H23 head studs and ARP F22/23 rod bolts, just don't be silly with the amount of boost.

    N/A..with the K20 pistons, etc, etc, you should be looking around 200whp, maybe a little more. See, the problem with these assumptions on 'how much horsepower' the F23 can achieve N/A with a mild build is that no one, at least from my knowledge, has done a true all motor F23 build.

    But by the looks of what PirateMcFred did with the DOHC H23 and F22 heads on our block, 200+whp seems feasible.
     
  6. xci.ed6

    xci.ed6 Well-Known Member

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    everyone does. e85 = 105 octane, and cheaper than 91/92.
     
  7. DarkSideAccord

    DarkSideAccord nadeshiko fobz ftw..

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    i never understood how one crank is better than another... more agressive? but how do i look at the numbers (if there are numbers)

    also, not motor related, but how do i tell if a clutch is still good or not? :thinking:
     
  8. BlkCurrantKord

    BlkCurrantKord Super Moderator

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    What do you mean by the crank Roy? Like as far as stroke?
     
  9. DarkSideAccord

    DarkSideAccord nadeshiko fobz ftw..

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    crank... as in the actual crank... i know it lifts the pistons, but tht's abt it :hide: i guess it is the stroke lol





    i'm an crank noob :lawl:
     
  10. Kid2000EX

    Kid2000EX Well-Known Member

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    I would kind of like to know that too. At least knife-edging to increase stroke, I think!
     

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