how does hi cam work?

[retrofit1]

camshaft more overlap more power,lift hi to open valve more take air and fuel

Hi, what i understand is if the duration is high,say 272 above is good for higher rpm or top speed not for pickup right?

 

[SkYwAlKeR]

long or short duration cams lor

oso got retarded cams, advance cams

even got "low" or "shortie" cams

all sort of cute names to make it interesting to potential buyers lor

That's y i tot hi cams will exert more force to your valve.. cause the profile is more sudden.. sharper peak and the curvature more curved.. if you get wat i mean..

thats why u need stiffer valve spring...

What degree will give most good pickup increase?

272 will be reasonable for street use while giving u reasonable driveability....

but if u are those gets vr irritated even ur dashboard vibrate 0.001 scala richter, den dont use highcams....

camshaft more overlap more power,lift hi to open valve more take air and fuel

yeap.... high valve lift allows more air/fuel to enter... longer durations allows air/fuel to be delivered at a longer duration...

both increases power output...

Hi, what i understand is if the duration is high,say 272 above is good for higher rpm or top speed not for pickup right?

if want pickup, rev higher and launch lor...

 

[retrofit1]

thats why u need stiffer valve spring...


Where can i get this stiffer spring ar?:hmmmm:

 

[SkYwAlKeR]

thats why u need stiffer valve spring...


Where can i get this stiffer spring ar?:hmmmm:

depends on what engine u using... if u using those common ones such as evo and so on, stiffer valve springs usually available from performance firm such as HKS and so on...

if u using proton, most prolly u can get from RPW....

 

[Choon]

wat's the stock duration for exhaust and intake angle? anyone noes? for wira se i mean..

 

[khoyos]

Hi, what i understand is if the duration is high,say 272 above is good for higher rpm or top speed not for pickup right?

depends on ur gear ratio (how big ur final drive is) and ur launching rpm (depends on traction - tyres).

if ur gear ratio teruk, n cant launch at hi rpm (as what sky said) then of course 272 n above are lousy. but most of draggers chose very high lift cams, and their pickup are simply out of this world...

 

[CarroTT]

That's y i tot hi cams will exert more force to your valve.. cause the profile is more sudden.. sharper peak and the curvature more curved.. if you get wat i mean..

yalor, tats y lor, so clever

 

[CarroTT]

What degree will give most good pickup increase?

woooo, u must go to uni and ask what kind of degree course they offer lor
u wan bachelor in wat ?
or u wan doctorate ?


hehehee, kidding, i siao siao today :stupid:

 

[retrofit1]

woooo, u must go to uni and ask what kind of degree course they offer lor
u wan bachelor in wat ?
or u wan doctorate ?


hehehee, kidding, i siao siao today :stupid:

Hehe..degree in doctor ayam...my hand are itchy to get this hi cam for my car.Can anybody suggest a good workshop in JB to tune it.:hmmmm:

 

[Choon]

clever leh me.. haha.. of coz, i'm the finest breed of my parents

 

[SkYwAlKeR]

Hehe..degree in doctor ayam...my hand are itchy to get this hi cam for my car.Can anybody suggest a good workshop in JB to tune it.:hmmmm:

viswork??...

wat's the stock duration for exhaust and intake angle? anyone noes? for wira se i mean..

240 intake
244 exhaust
0.24 intake valve lift
0.24 exhaust valve lift

 

[Choon]

wow, that mean 272 is already alot of gain.. let me count.. *reaches calculator* 13.3% longer duration for intake.. but long duration normally only good for higher rpm because the overlap would be more..

 

[Joeker]

Every engine mod has to complemented.

In the case of "hi-cams", you'll also need matching gear ratios to fully harness its power.

most Modern day engines are 24x ~ 25x degrees cam profiles.

For street use, 26x~27x is enuff. I don't think you'll need stiffer valve spinrgs and retainers unless you plan to rev to the moon and the stars

For SOHC 4G13~15 engines, wat we use to do was grind the heel of the lobe by a couple of mm and then compensate it from the rocker. We get slightly more valve overlap and thus, a DIY-ed "hi-cam" Abit more OMMMMPPPHHH!!!

 

[SkYwAlKeR]

For SOHC 4G13~15 engines, wat we use to do was grind the heel of the lobe by a couple of mm and then compensate it from the rocker. We get slightly more valve overlap and thus, a DIY-ed "hi-cam" Abit more OMMMMPPPHHH!!!

how to compensate it from the rocker??... closer valve clearance??..

i've heard of mechanics grinding a few mm off place where the rocker arm shaft sits... this lowers the rocker arm and hence allowing higher lift on standard cams....

 

[Joeker]

i've heard of mechanics grinding a few mm off place where the rocker arm shaft sits... this lowers the rocker arm and hence allowing higher lift on standard cams....

Yes, it works just as well. either grinding the, as you say it, "rocker arm shaft sits" or grinding the cam's lobe heel, will result in higher lift & more overlap and you have your DIY-ed "hi-cam"

When the cam lobe heel is grounded off, there will be a larger clerance between the heel and rocker arm.

Using a feeler blade, you need to close down this clerance as you would do when you adjust the rockers arm screw to get rid of the irritating the infamous "tappet noise" problem of 4G15/13

 

[SkYwAlKeR]

Yes, it works just as well. either grinding the, as you say it, "rocker arm shaft sits" or grinding the cam's lobe heel, will result in higher lift & more overlap and you have your DIY-ed "hi-cam"

When the cam lobe heel is grounded off, there will be a larger clerance between the heel and rocker arm.

Using a feeler blade, you need to close down this clerance as you would do when you adjust the rockers arm screw to get rid of the irritating the infamous "tappet noise" problem of 4G15/13

means i can jz increase the lift of my cams by adjusting the valve clearance closer together la??... of coz not too close till piston clashes with the valve...

 

[Joeker]

Yes, slight longer valve open duration and higher lift. if not mistakne, we grounded 2mm off the cam lobe's heel.

 

[SkYwAlKeR]

Yes, slight longer valve open duration and higher lift. if not mistakne, we grounded 2mm off the cam lobe's heel.

icic.... in fact there are many innovative modifications can be done on the valvetrain to increase the duration and lift without changing to high profile camshafts...

malaysia boleh... wuakakaka...

 

[Choon]

wah.. pakai grind grind oni ah.. dangerous leh.. all diy king here..

 

[SkYwAlKeR]

wah.. pakai grind grind oni ah.. dangerous leh.. all diy king here..

i dunno how to do one ler... its one of those legend stories made up / created by local malaysia boleh mechs...