[WT Ask] About High CamShaft - FUNCTION?

[Veloc]

This is what happened. BTDC setting, the NA cams have overlapping for the following purpose.
1) To cool down the pistons crown that's right after combustion.
2) To allow combustion chamber to achieve atmospheric pressure to allow free flow during the overlapping duration.

The higher duration the cams have, the higher overlapping occur....

For turbo cams, they doesn't have overlapping on stock. even for Evo. Reason is...
1) To prevent boost leak during the overlapping at low flow condition.

But when high boost, then u may allow some overlapping provided the turbo is able to produce the flow and pressure even if there's overlapping, then that's a good thing...

Too bad this thing will never happen during low boost condition. So, low boost will lose some pressure.

Oh yes thank you! Now I'm clear... So you are saying for turbo, the high cams may have higher duration and lift but they try to minimize the overlap is it?

And you are saying that if there is overlapping in turbo, the pressure in the intake manifold will force fresh air & fuel right into the exhaust manifold during the overlap period right? Hmm... I guess this cause boost leak and will waste fuel...

So what to do if I would to turbo a blacktop? Any advice?

 

[speed2horizon]

yes...yes....it's true.......hahahaha

---------- Post added at 12:22 PM ---------- 6 hour anti-bump limit - Previous post was at 12:13 PM ----------

if u want more power in ur engine,comfirm FC is much higher than stock..i'm no SIFU,but that is the rule..now i'm using 300deg cam with 11' lift..hoooliowwww...FC is bad and not street wise..but i'm stick with it..why??coz power lorr...great power gain more fuel..even u using haltech or motec or microtech..it still use the same rule..but all this managemnt help a lot la..anyway,can try watermethanol injection..i never tried it yet..but really want to..i have see the result for turbo car...for NA not yet..have been that it could help reduce FC..

---------- Post added at 01:15 PM ---------- 6 hour anti-bump limit - Previous post was at 12:22 PM ----------

if u want more power in ur engine,comfirm FC is much higher than stock..i'm no SIFU,but that is the rule..now i'm using 300deg cam with 11' lift..hoooliowwww...FC is bad and not street wise..but i'm stick with it..why??coz power lorr...great power gain more fuel..even u using haltech or motec or microtech..it still use the same rule..but all this managemnt help a lot la..anyway,can try watermethanol injection..i never tried it yet..but really want to..i have see the result for turbo car...for NA not yet..have been that it could help reduce FC..

Methanol injection is a method not really to improve on fuel consumption. But to increase fuel efficiency. So indirectly, from better combustion effieciency, U are able to achieve more mileage.

Higher ignition timing produces better power, but the sad thing is when the ignition is advanced upt o a certain degree, it'll combust the fuel before TDC due to the over heated combustion chamber and the natural flash point of our pump fuel. That's knock.

So, when methanol injection takes place, it blends with the intake air to reduce the air temperature. Then it blends with the injected fuel to increase the octance level. By having a cooler intake and higher octane level, there u go... U can advance ur ignition further. And so, it produces better power.

At the same time, methanol injection took place within compressed air line... So, u'll have least worry that it'll damage the injectors internal and the diagphram of ur FPR.

---------- Post added at 07:25 PM ---------- 6 hour anti-bump limit - Previous post was at 07:16 PM ----------

Oh yes thank you! Now I'm clear... So you are saying for turbo, the high cams may have higher duration and lift but they try to minimize the overlap is it?

And you are saying that if there is overlapping in turbo, the pressure in the intake manifold will force fresh air & fuel right into the exhaust manifold during the overlap period right? Hmm... I guess this cause boost leak and will waste fuel...

So what to do if I would to turbo a blacktop? Any advice?

I don't have much experience on BOT a blacktop... Cause black top memang highcam.. But not really alot la...

Okay, here is what u can do...

If u are boosting low, U can use adjustable cam gear to advance the exhaust cam and retard the intake cam. This can overcome the overlapping issue. Up to a certain stage.

Or, U can regrind the cams into a turbo cams. Send it to matspeed.

Or, U can change the pistons and straight go for high boost with a high flow turbo. On a high boost/flow application, overlapping is not a problem cause ur turbo is still able to supply the same pressure even though it's leaking.

 

[sideksepakragabulat]

hi there..

just to clear things a bit for me..i'm planning to run about 1.5~1.8bar of boost in a L2s engine..i've tuned my car before(on dynojet) and noticed that the tuner pushed until 7500rpm..since my turbo start spooling around 3500~4000rpm and achieve full boost around 5500~6000rpm,would there be any significant power change if i start playing with hi cam?can my engine handle more rpm than before?

not making my car to be a drag machine..just like it to be fun to drive on the street what kind of hi cam do you think that suit for my application?prefer the hi cam lift closer to my oem lift,would mild cam is enuff?can the oem valve train handle this kind of cams?

 

[speed2horizon]

hi there..

just to clear things a bit for me..i'm planning to run about 1.5~1.8bar of boost in a L2s engine..i've tuned my car before(on dynojet) and noticed that the tuner pushed until 7500rpm..since my turbo start spooling around 3500~4000rpm and achieve full boost around 5500~6000rpm,would there be any significant power change if i start playing with hi cam?can my engine handle more rpm than before?

not making my car to be a drag machine..just like it to be fun to drive on the street what kind of hi cam do you think that suit for my application?prefer the hi cam lift closer to my oem lift,would mild cam is enuff?can the oem valve train handle this kind of cams?

Haha... The golden question is still, How much is enough..? Regarding on Rev limit, u can set it at whatever u like... It's the hardware that limits the safety margin of a machine...

high Rev causes valve float-counter with stronger valve springs
higher duration cams allow more flow at higher Rpms..

high rev also increase the stress of the conrod bearings. Using a better bearings will only make things slightly better... Custom rods and pistons make things safer... But at a costly price tag...

Able to make rev higher... Is your oiling system capable of delivering oil at that rate... Is your oil drainage to the sump have sufficient clearance to allow oil getting back to the reservoir to maintain the oil level in the sump..?

 

[LittleWhiteWagon]

hi there..

just to clear things a bit for me..i'm planning to run about 1.5~1.8bar of boost in a L2s engine..i've tuned my car before(on dynojet) and noticed that the tuner pushed until 7500rpm..since my turbo start spooling around 3500~4000rpm and achieve full boost around 5500~6000rpm,would there be any significant power change if i start playing with hi cam?can my engine handle more rpm than before?

not making my car to be a drag machine..just like it to be fun to drive on the street what kind of hi cam do you think that suit for my application?prefer the hi cam lift closer to my oem lift,would mild cam is enuff?can the oem valve train handle this kind of cams?

What sort of turbine are you running? Theres no point you get a cam that can flow all the way to 8000rpm but your head can't and neither can the turbine bro. Where do you want the poweband to be at?:hmmmm:

 

[ColdPlay]

hi there..

just to clear things a bit for me..i'm planning to run about 1.5~1.8bar of boost in a L2s engine..i've tuned my car before(on dynojet) and noticed that the tuner pushed until 7500rpm..since my turbo start spooling around 3500~4000rpm and achieve full boost around 5500~6000rpm,would there be any significant power change if i start playing with hi cam?can my engine handle more rpm than before?

not making my car to be a drag machine..just like it to be fun to drive on the street what kind of hi cam do you think that suit for my application?prefer the hi cam lift closer to my oem lift,would mild cam is enuff?can the oem valve train handle this kind of cams?

High cam allow for better flow at higher cam opening. The limitation itself come stock parts which may not be able to withstand the abuse at much higher rpm.
Power is nothing without a reliable chassis to start with. Have you installed at least an all round struts bar and upgraded your brake / suspension system?