HighCam

[jswong]

I've got a spare 4G15 head complete with cam, rocker, etc. Planning to try some "pocket porting" (basic gasket matching + smoothening of surfaces) on it.. what's the odds of failure for this process? Easy to DIY?

Planning to get it sent to machine shop later for some skimming.. and a mech once told me that skimming the rocker rods' seats will increase rocker arm lift.. is it true? I thought we'll need to change rocker arms for that..

Maybe stick in a Piper cam + ACP after that.. Then only go for top overhaul with a fully tuned up head.. or maybe Guan can give a good price for that.. hehehe..

 

[khguan]

Do not attempt to DIY port n polish if u do not know how and do not have the proper tools.. else u might just wasted a cylinder head...

it is not as simple as u think... all the airways need to be ported evenly for even airflow between cylinders... another thing is if u over port.. u will lose low end torque and power as well...

 

[ettm_14]

heee..sidetrack a little...khguan is one of those members who actually mods the 4g15 plant and it is nice to know if you ask him on how to gain power for you 4g15, he will not tell you:

Swap for a mivec, put in GSR, Vr4....(unless your 4g15 is at the max and you still want more power)

But instead tries to work on the 4g15 plant! Keeps me(or maybe many 4g15s' owners) not wanting to swap my engine for the moment!

:)

 

[khguan]

well frankly speaking.. i do not have the skills to do PnP on a cylinder head either... hehe... cos i have read alot about cylinder head rebuild... but still do not know the exact ways to do it properly... this skill really need to have a sifu to guide one...

 

[SkYwAlKeR]

Do not attempt to DIY port n polish if u do not know how and do not have the proper tools.. else u might just wasted a cylinder head...

it is not as simple as u think... all the airways need to be ported evenly for even airflow between cylinders... another thing is if u over port.. u will lose low end torque and power as well...

yea... polishing the surface can diy la... porting it better leave it to sifoo and mahaguru... better if they are equipped with benchflow test...

 

[tofu_manic]

yea... polishing the surface can diy la... porting it better leave it to sifoo and mahaguru... better if they are equipped with benchflow test...

if not mistaken, exhaust ports should be mirror-finish

while intake ports should be have a smooth, but not mirror-like, still have texture

i guess like sky sed, can do the polishing, and port matching

 

[khguan]

yes.. exhaust mirror finish... and the intake NOT mirror finish... this is bcos we want a bit of turbulence at the walls so that the fuel will not stick to it, otherwise the fuel that stick to the walls will not mix with air for optimum A/F mixture...

 

[jswong]

So, port-matching and polishing can be done, but not porting e.g. enlarging chamber diameters, cutting back the short-side radius, etc?

How do you smoothen out the valve surfaces? I'm under the impression that we can grip the valve stem at the chuck of a powered drill, spin up the valve, and apply sandpaper against the valve surface to smoothen it.. or will that damage the valve stem?

 

[khguan]

some ppl just fit the valve onto a drill n spin it then use sand paper... but there is risk of having the drill chuck deforming or scratching the valve stem surface... which might cause oil leak later on...

for me.. i used a disc grinder with hard polishing cloth... holding and rotating the valve with my other hand while grinding off the deposit...

do not sand the valve stem... u dont need to do that.. otherwise smaller stem will cause oil leak as well..

 

[JINEIL2EN]

Do not attempt to DIY port n polish if u do not know how and do not have the proper tools.. else u might just wasted a cylinder head...

it is not as simple as u think... all the airways need to be ported evenly for even airflow between cylinders... another thing is if u over port.. u will lose low end torque and power as well...

very true statement... as i oso spoiled 2 b16 head for 1st try after 'bai' sifoo..

 

[jswong]

very true statement... as i oso spoiled 2 b16 head for 1st try after 'bai' sifoo..

Ya, that's why I'm trying to source a 2nd 4G15 head for a cheap price.. because I'm experimenting to learn and not to merely save money from sending to professionals.. One option that I have is to buy a head that has been professionally ported & polished, so that I can examine how those things are done, and then try doing it on my existing spare head.

Kalau rosak, I still have my stock head + the modded head, so it should be an adequate learning experience, I hope..

 

[khguan]

well 4G15 head price is shooting up thanx to the taxi drivers... they use NGV which is very dry and the cylinder head very fast get spoilt... so many chop shop head kena sapu...

 

[JINEIL2EN]

Ya, that's why I'm trying to source a 2nd 4G15 head for a cheap price.. because I'm experimenting to learn and not to merely save money from sending to professionals.. One option that I have is to buy a head that has been professionally ported & polished, so that I can examine how those things are done, and then try doing it on my existing spare head.

Kalau rosak, I still have my stock head + the modded head, so it should be an adequate learning experience, I hope..

i dun think 4g15 still can get at cheap price...
other than copy port from the pro, u must know wat u really needs, such how high the cam u gonna plonk & the capacity of ur engine & how high the compress u gonna go on.
all u needs to do a great job, just get a nice Calculator.

 

[jswong]

Ya, it'll be a lot of work.. I have these two software.. Cam Analyzer Pro and Engine Analyzer Pro.. they can be used to simulate flow based on cam duration, what angle the ramp starts and ends, etc. and the projected HP and torque figures based on those parameters.. while it won't simulate exactly and give anything close to ballpark figures, it's a good starting point to learn the effects of cam durations, cam advance/retard settings, increased compression ratios, increased valve flow rates, etc etc.

4G15 head is expensive now, huh? And NGV buggers up the engine heads? Alamak, that's bad..

So, the conclusion is that even for simple job like sanding the combustion chamber to reduce abrupt angles (e.g. edge of valve seats, near sparkplug, etc) and lapping the surfaces to reduce flow friction also have to bring to pros?

 

[FVel]

So, the conclusion is that even for simple job like sanding the combustion chamber to reduce abrupt angles (e.g. edge of valve seats, near sparkplug, etc) and lapping the surfaces to reduce flow friction also have to bring to pros?

khguan's prices reasonable mar.

 

[khguan]

eh??

btw simple job that jswong mentioned can be DIYed la.. no prob... but wun make much difference lo... it is almost same like cleaning the cylinder head niah... as long as we are not removing metal from the head... then it is ok...

 

[JINEIL2EN]

eh??

btw simple job that jswong mentioned can be DIYed la.. no prob... but wun make much difference lo... it is almost same like cleaning the cylinder head niah... as long as we are not removing metal from the head... then it is ok...

if not moving some metal out... better dun do it... ehehehe

 

[juniorkirk]

anyone here know what the price for 4g13 matspeed cam? or other high cam...

 

[khguan]

i got Piper cam... hehe... PM me if interested.

 

[tofu_manic]

anyone here know what the price for 4g13 matspeed cam? or other high cam...

matspeed / powerzone / maddriver cam costs around 1.2-1.3k, have to swap ori cam