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    kelebihan dan keburukan port & polish Head

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    nomo
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    04062008

    http://i38.servimg.com/u/f3 kelebihan dan keburukan port & polish Head

    Post by nomo

    saya nak tau apa kelebihan dan keburukan kalau kita port and polish head enjin
    Share this post on: Excite BookmarksDiggRedditDel.icio.usGoogleLiveSlashdotNetscapeTechnoratiStumbleUponNewsvineFurlYahooSmarking

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    Post on 17/9/2008, 6:55 am by nomo

    makin ganas pula pakai valve besar. bukan kalau valve besar kaki dia lagi panjang.valve apa boleh pakai.
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    Post on 17/9/2008, 6:57 am by DeDiCooL

    kena cari2 dulu apa yang ngam.. tapi kalau nada org sanggup bikin ni.. x dapat juga buat trial and error.. haha
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    Post on 23/9/2008, 2:46 am by blugu

    DeDiCooL wrote:emm, macam mana pula kalau porting lubang valve kasi masuk oversize valve? ada engineering yang sanggup bikin ni ka di kk?

    extra air flow + extra fuel = extra hp ?

    Kena ada kit utk pakai oversize valve nie, so far resipi ini belum diguna pakai sepenuhnya lagi, kalau ada suda tentu tuannya menjadikannya sebagai rahsia(sisik sorok) untuk kelebihan tersendiri Very Happy

    extra air flow + extra fuel = extra hp < wideband tuning or timing/ignition tuning surely will enhance is capability!
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    Post on 23/9/2008, 4:07 am by tony84

    blugu wrote:
    DeDiCooL wrote:emm, macam mana pula kalau porting lubang valve kasi masuk oversize valve? ada engineering yang sanggup bikin ni ka di kk?

    extra air flow + extra fuel = extra hp ?

    Kena ada kit utk pakai oversize valve nie, so far resipi ini belum diguna pakai sepenuhnya lagi, kalau ada suda tentu tuannya menjadikannya sebagai rahsia(sisik sorok) untuk kelebihan tersendiri Very Happy

    extra air flow + extra fuel = extra hp < wideband tuning or timing/ignition tuning surely will enhance is capability!

    ya btl tu....oversize lubang valve memang bule....tp valve yg besar mungkin xbule masuk sbb valve ada yg panjang ada yg pendek...susah mau dpt yg ngam...klu pakai balik yg asal pun bule bah....
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    Post on 25/9/2008, 9:20 am by DeDiCooL

    very good info.. kalau dapat jumpa valve yg ngam ni confirm cun ni..
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    Post on 25/9/2008, 10:40 am by blugu

    DeDiCooL wrote:very good info.. kalau dapat jumpa valve yg ngam ni confirm cun ni..

    Hanya kedai engineering/tuning saja yang boleh cari O/size valve nie... kita cuma bayar duit saja... Laughing
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    Post on 25/9/2008, 1:56 pm by nitrod

    syabasss inspektorrr blugu. nice info. What a Face

    Post on 12/11/2008, 6:25 am by yoreel

    Jadi bagus x paya port polish la ...nanti semput
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    Post on 13/11/2008, 4:08 am by blugu

    yoreel wrote:Jadi bagus x paya port polish la ...nanti semput

    Porting the intakes to remove casting marks and sharp angles will help create a smoother flow, this will result in slightly better torque, polishing the intake is a waste of time, this only results in better looks, it doesn't actually improve anything (intake air velocity), this is because flow actually becomes slower when there's more contact area, which is why golf balls are dimpled. Any time you enlarge the port however, will mean your powerband will be shifted to the right, thus @ low RPMs it'll feel sluggish-er. Only useful if you're building a race engine, since street driving no-one drives at high RPMs. Also note that if you want to drive @ high-RPMs and not risk anything breaking you're gonna have to speed big money. 2x RPM = 4x more internal forces trying to break something (which is why forged con-rods and cranks cost alot)

    Polishing the combustion chambers, especially around the exhaust valves, will result in less pre-detonation, this will enable you to run higher compression ratios (good for fuel economy and power). This is alot of work however, you'll need to 1st polish all the heads, and then CC and flycut them down to the required height for higher compression ratios, since the polishing and removal of sharp edges in the chamber will result in a slightly bigger chamber and thus lowered compression ratio.

    To answer your question, about blowing your engine, no, porting and polishing your intakes and chamber alone cannot blow your engine. This is assuming everything was put back in right, of course if a valve spring for example was assembled wrong and happens to break or fall off when you're at 3000RPM... it'll pretty much damage alot of stuff inside.

    For all this work. You'd gain very little actually. If you're looking to improve fuel economy and get a little power. You'd be better off going for an ECU remap with a free-er flowing intake setup.

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    Post on 13/11/2008, 8:59 am by Ujang87

    kalau keta semput better port dia cantik2..heheheh
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    Post on 13/11/2008, 3:22 pm by CrazyChild

    jadi so..pnp ni gud taw bad?

    dari segi power?
    consumption minyak?
    ada kesan sampingan?
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    Post on 13/11/2008, 5:34 pm by blugu

    CrazyChild wrote:jadi so..pnp ni gud taw bad?

    dari segi power?
    consumption minyak?
    ada kesan sampingan?

    Kalau bro suka enjin bro ada power, P&P nie antara modifikasi yg perlu, tapi kalu bro prefer jimat minyak & enjin tahan lama(dalam 7-10thn tanpa o/haul) maka tak perlula buat modifikasi ini, mmg ada sedikit kesan sampingannya dari segi fuel cosumption & durabiliti enjin.
    P&P for engine head is good & essential for street & drag racing setup, but very bad respon in daily driven setup especially during 1k rpm to 3k rpm, the engine respon is very sluggish.
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    Post on 13/11/2008, 7:09 pm by CrazyChild

    blugu wrote:
    CrazyChild wrote:jadi so..pnp ni gud taw bad?

    dari segi power?
    consumption minyak?
    ada kesan sampingan?

    Kalau bro suka enjin bro ada power, P&P nie antara modifikasi yg perlu, tapi kalu bro prefer jimat minyak & enjin tahan lama(dalam 7-10thn tanpa o/haul) maka tak perlula buat modifikasi ini, mmg ada sedikit kesan sampingannya dari segi fuel cosumption & durabiliti enjin.
    P&P for engine head is good & essential for street & drag racing setup, but very bad respon in daily driven setup especially during 1k rpm to 3k rpm, the engine respon is very sluggish.

    oooo..nice info..mayb pnp tia sesuai tuk sa ni..hehe
    jadi once suda buat pnp , no turning back suda lar ni kan??
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    Post on 14/11/2008, 3:18 am by blugu

    CrazyChild wrote:
    oooo..nice info..mayb pnp tia sesuai tuk sa ni..hehe
    jadi once suda buat pnp , no turning back suda lar ni kan??

    Yup, kecualila bro sanggup beli spare head utk diprojek/reserve bagi tujuan ini, so far tiada komplen dari member yang suda membuat porting ini, mungkin suda sedia maklum bagi mereka kesan sampingannya itu. Wink
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    Post on 14/11/2008, 3:54 am by tony84

    Very Happy mantap...memang ada kelainan lepas porting ni....feel it.... Yahoo

    Post on 14/11/2008, 7:29 am by ProjectD

    ckupla polish..nyaman sudah itu...
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    Post on 17/11/2008, 6:35 pm by gnonz

    shalina7981 wrote:kwn aku ni banyak bikin keta..sekarang dia tenga pengajar(mekanik) kat ikm kuching..sarawak... dulu kat kk dia pernah test dgn toyota turbo..1.6 keatas..dia pakai toyota 1.3 standard tapi power dia bikin...tinggal ooohh...tak tau..dia bikin mcm mana..

    itu 4k kalo pndi bikin nek kimanis no prob...sa pya 4k 24 taun suda masi mantap...x pya kacau byk..tukar clac pun kala 2 4 wheel nek bukit.. OO"
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    Post on 12/12/2008, 6:26 am by blugu

    CYLINDER HEAD PORTING AND POLISHING

    Maximum engine power depends very much on the rate at which air can flow into the cylinders. Airflow efficiency is dependent on the design of the air intake system and the cylinder head. One of the factors that affect the peak power output of an engine is maximum port flow at the cylinder head.

    However, always remember that peak engine power (max. hp @ RPM) is NOT the most important consideration for a road car engine. More critical is the average power across the working engine speed, usually between 2000 RPM to 5000 RPM for a road car.

    Therefore, gaining more airflow at lower valve lifts and losing some at high lifts is a much better option when modifying cylinder heads. Today's multi-valve cylinder heads are already endowed with large curtain areas (the gap between the valve edge and the valve seat) and hence the ports are the major restricting areas rather than the valve lift.

    Increasing the valve curtain area by increasing valve lift can cause reverse flow of the fuel mixture when the piston moves upwards on the compression stroke in cases where there is excessive valve overlap, thus reducing low end torque.

    Without going into complex calculations to redesign a cylinder head to gain more airflow, it has been proven that targeting the right areas to be ported on the standard modern head can usually improve airflow sufficiently to produce beneficial power gain especially at high engine RPM. This is because most mass-produced cylinder heads are done by computer-controlled machines with high production output as the criterion. Therefore, we see a lot of ports and valve throats that are plagued with rough machining burrs and overlapping edges that impede airflow considerably.


    A head ported for maximum power gain

    By simply cutting away such defects and smoothing out the port walls one can expect some improvements to airflow. Of course, just doing this operation alone is not enough to justify the cost of taking out the cylinder head and putting it back on again. More work has to be done. A series of carefully planned operations at the right places are required to produce satisfactory results.
    What are the right places and nooks and corners that need more attention? Both the intake and exhaust ports and the valves themselves restrict airflow. Enlarging the intake port throughout its whole length from the port opening right up to the valve seat will allow more air volume to flow through. Also straightening up the passage in the process will reduce restrictions due to sharp angle changes. This helps to gain more output at the higher end of engine RPM.

    However, care must be taken not to enlarge too much as excessive intake port enlargement can result in slower air velocity and hence reduces cylinder filling. This in turn reduces low end torque and power. Worse than this, indiscriminate removal of metal can reduce the wall thickness so much that a hole leading to the water jacket will appear, rendering the head useless and good only for scrap metal.

    The exhaust port should never be enlarged unless major modifications have been done on the engine, such as restroking the crankshaft, fitting in larger pistons, putting in new oversized valves that require bigger exhaust ports. Only the wall surface needs to be smoothened out to remove burrs and casting overlaps.

    What Determines Power Output?
    Airflow is tested by using a flow bench that measures the volume of air flowing through the ports and over the valves in cubic feet per minute (CFM) at several settings of valve lift. It follows that a bigger port diameter, larger valve and higher valve lift will result in a higher flow rate. Most people would think that the higher the flow rate the better the engine performance. This, unfortunately, is not so.

    The combustion pressure acting on the piston crown (hence determining the power output) depends more on the rate and characteristic of combustion as well as the amount of fuel charge inhaled by the cylinder. Hence, good airflow alone does not mean the engine has a superior performance. Combustion chamber design plays a more influential role in the final power output of an engine. Characteristics such as swirl and squish are contributing factors. That is why even an eight-valve 4-cylinder engine can produce better output than its 12-valve equivalent.



    A carefully smoothed out combustion
    chamber with minimum valve shrouding offers the least
    restriction to airflow



    Obtrusive areas around the valve seat are cut down to smoothly blend in with the rest of the combustion chamber. As much metal as possible is removed from where the valves are shrouded by the walls of the chamber to increase airflow. All the above processes require great skill and precision handwork that may not be easily carried out by a first timer.

    As mistakes can be costly, it is recommended that porting be done by professional tuning shops with the right experience and skills employing techniques that are found in tuning reference books as well as experience gained over the years and hence are usually kept secret. It is worth paying the price for a properly and well-ported head.

    What About Polishing?
    Yeah, what about it? Most performance seekers want a shining polished head for all the money that they would pay. The truth is a highly polished finish does not add much power gain other than giving the impression that it is a high performance head. What is important is giving it the polish only where it is necessary.

    For this reason, the intake port is usually not polished to a mirror finish. A slightly rough, satin finish is excellent in promoting fuel atomization thereby increasing the combustibility factor of the air-fuel mixture. The slightly rough surface also prevents the fuel droplets from condensing on the port walls while on their way into the engine cylinder.

    However, the exhaust port is given a different treatment here. Exhaust gas is extremely hot and rushes out at very high speeds. A rough surface will cause gas turbulence and hence reduces gas flow. Apart from a clean smooth surface free of protruding metal burrs and ridges, a polished finish will improve flow rate and maintain gas velocity. Also, polishing the surface to a high shine will help reduce the tendency of carbon depositing on the walls making the passage smaller and smaller over time, thus reducing gas flow.

    In addition to the above jobs, the head surface that mates with the engine top deck needs to be checked and definitely requires a light skimming if the surface is found to be warped or uneven. If there is no equipment available to check the surface, it is always a safe practice to have it skimmed anyway. However, be informed that excessive skimming will alter the compression ratio and also cause the timing mark on the camshaft pulley to misalign.

    What About the Valves?
    For most road car requirements, the existing standard valves are good enough. Only in circuit racing would special sodium filled exhaust valves be needed, mainly to withstand the punishment of continuous extremely high temperatures that occur at the exhaust valves and the extra pressure exerted by stronger valve springs that are necessary with high lift cam profiles.



    These
    valves are custom-profiled with smooth round edges that
    maximize airflow.


    For the ordinary man in the street driving an upgraded road car, some modifications to the valve shape will help gain a few ounces of power. Back-cutting the valves will allow more airflow over the valve surface. Alternatively, the back side of the valve can be rounded by grinding and then polished off to promote smoother airflow.

    While doing the valves, it is a good practice to check the valve stem to valve guide clearance. Excessive clearance can cause improper seating of the valves resulting in loss of power and poor idling. If clearance is over the limit, the valve guides must be replaced.

    While porting around the valve throat, it is also worthwhile to reshape the protruding part of the valve guide into a taper in the case of the intake valve. For exhaust valves, if the protrusion is high, it may be ground off to flush with the port wall.

    Chamber Balancing
    This does not refer to practicing walking upright with a book balanced on your head in your own private chamber. It refers to an important, but sometimes overlooked process in cylinder head porting, either deliberately or out of ignorance.



    Chamber
    balancing requires patience and accuracy, not a job for
    amateurs.


    POWERzoneģ Ported & Polished Head

    POWERzoneģ ported and polished heads are done according to their own strict specifications and comply with the care and attention discussed above.

    Every POWERzoneģ head has gone through the following processes:

    1. Complete cleaning and checking for wear and tear, and replacing worn parts where necessary.
    2. Contour porting of intake and exhaust ports with calculated sizes.
    3. Polished exhaust ports and satin finished intake ports.
    4. Custom valve profiling.
    5. 3-angle valve seat cutting.
    6. Chamber balancing.
    7. Chamber detailing and profiling.
    8. Deck mating surface lightly skimmed for perfect flatness.
    9. Exhaust gasket port matching.

    Source; http://www.powerzone.com.my/tn4.html
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    Post on 27/1/2009, 3:33 pm by ikankalui

    injin ku suda skim..pnp pun suda...yg ptg sukatan ngam ... pasti inda akan timbul masalah ....naik bukit atau jalan rata semua d sapu injin ku sama rata.....tp bikinlaa dgn mekanik yg ada pengalaman...jgn yg panamberang Very Happy
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    Post on 27/1/2009, 6:12 pm by blugu

    ikankalui wrote:injin ku suda skim..pnp pun suda...yg ptg sukatan ngam ... pasti inda akan timbul masalah ....naik bukit atau jalan rata semua d sapu injin ku sama rata.....tp bikinlaa dgn mekanik yg ada pengalaman...jgn yg panamberang Very Happy

    Ya, betul tu.... kalau salah buat, buang duit beli enjin head baru lagi Mad
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    Post on 8/1/2011, 7:37 am by DAW303

    Port polish ni ape ya ? sy betol2 tidak tahuu...
    ramai org ckp...ada bajet...buat port polishhhh...huuu apa itu...aku tidak mengertii~
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    Post on 8/1/2011, 10:09 am by DAW303

    Macam x dak sambutan ja topic ini...huhuhu....x dak siapa mau bincang kah ? Kipas
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    Post on 8/1/2011, 11:13 am by keba

    port polish ni dlakukan pd valve..
    utk mbuang carbo n kotoran degil pd valve..
    stiap valve d port n polish utk kmasukn lbih air fuel mixture
    ke dlm enjin..
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    Post on 8/1/2011, 11:47 am by Mazlan85

    bro DAW dah fhm kan mksd PORT n POLISH.......bgus juga topic ni.....sy pun bru taw yang PORT n POLISH ni seperti yang di katakan di atas.........thanks KEBA....
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    Post on 8/1/2011, 1:22 pm by keba

    ad jgk kburukan pnp ni..
    bila port n polish, head akan d port utk mngurangkn geseran udara ngan intake..
    jd udara bleh masuk lbih lancar..
    tp bila head nipis, enjin pn akn lbih cpt pns..
    sama macam rebore blok, blok akn jd nipis n enjin cpt pns..
    ad kmgkinan jgk bila pnp, kreta akn jd lembap d jln bukit..
    kalau jln rata tu bleh la..

    bleh refer kpd thread yg sdia ada>>http://www.sioloon.com/t5663-kelebihan-dan-keburukan-port-polish-head
    p/s: anta kpd bgkel yg btauliah utk pnp..silap ari bulan, pnp mburukkan keadaan..huhu

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