What do Cams do?

[JDMShift]

Sorry i'm stupid, i've looked up what cams do and I understand that, now I want to know what effect different cams have, and why some cams (300) aren't very "streetable", i'd use the car as a daily driver but I wouldn't mind an aggressive idle.

[steve shadows]

google

how stuff works

then kill yourself

if you know how cams work as you say, then you would know the answer that

[MomentumGT]

Sorry i'm stupid, i've looked up what cams do and I understand that, now I want to know what effect different cams have, and why some cams (300) aren't very "streetable", i'd use the car as a daily driver but I wouldn't mind an aggressive idle.

An aggressive idle is a by product of an aggressive cam setup. Longevity of the valtrain will come into play unless other wise upgraded accordingly. When I had my ka-e way back when, I had an aggressive nismo race cam on there, great when pushing it, but it moved the power band way up there where I didn't have anything coming off a stop at the light. I had to rev the motor 4k + just to get the car moving or it will come close to stalling being "less streetable". Don't know your set up or what you're planning on doing, but I hope I kind of answered your question on being "streetable".

-Jon

[MURPHY]

^correcto and lack of vaccum is well... bad

no need to be a dick steve

[steve shadows]

^correcto and lack of vaccum is well... bad

no need to be a dick steve

he said he knew how cams work

he doesnt.

Its very simple

If a camshaft moves a given amount of air depending on size.

Duration is the length of time of the valve is open on a scale of 360 degrees (or a circle for the smart people)

The longer the duration the the longer the valve is open.

Cam lift has a deminishing return point depending on the head it is in. On most nissan dual cams its between 11.5-12.8mm lift

after that point, there is no point.

Idle is high because as mentioned more air is going into the engine with the same mech timing etc as before if the computer has not been reflashed.

Vaccum will aslo be higher because the engine sucks less to pull in the same air. Compression obviously doesnt chaneg but your mixture over rpm will if you do not re-tune or add fuel.

thats about sums it i think

edit oh and powerband shifts up because overlap is not efficent on an engine until a given RPM where cans can bee seen. which is commonly referred to when your powerband moves depending on cams.

Big duration higher power capability however and longer torque hold out on a dyno read out.

Lower duration equals more immediate power band, with less breathing thanks to less overlap on high rpm.

I found like 30 extremely good links by googling for 1 minute.

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_06.html

http://www.streetracersonline.com/articles/camshafts/

there just two i found in abotu 3.5 seconds on google

[GabeS14]

Resuming the higher the lift , more power when your are moving, but the crappier it will run when you are stopped or slow.!!!!!!something like that..to make it simple.:bigok:

[babowc]

hm..
steve summed it all up.

google ftw.

[JDMShift]

Thank you for all your answers guys, and I don't mind Steve at all Murphy. Just doin his job, lol.

[SexPanda]

Hey man, we were all new once. hell, I'm still new to this site, but not to 240s. Anyhow, depending on your engine ( I assume a Ka24E/DE) there are a few companies making camshafts.

the Lift of a camshaft is how far the cam lobe opens up the valve.
the duration is the time that the valve is off the seat during tappet lift (how long its open)

A performance camshaft has a higher lift and longer duration, causing more air to enter and more exhaust exit the engine. at high Rpm's this is good, because the valves are opening and closing fast, giving you more power. At idle, however, it has the opposite effect.

PDM-Racing.com has some good cams for the KA.

[k's_silvia2.0]

BOOM!!!.....DONE.:cool:
he said he knew how cams work

he doesnt.

Its very simple

If a camshaft moves a given amount of air depending on size.

Duration is the length of time of the valve is open on a scale of 360 degrees (or a circle for the smart people)

The longer the duration the the longer the valve is open.

Cam lift has a deminishing return point depending on the head it is in. On most nissan dual cams its between 11.5-12.8mm lift

after that point, there is no point.

Idle is high because as mentioned more air is going into the engine with the same mech timing etc as before if the computer has not been reflashed.

Vaccum will aslo be higher because the engine sucks less to pull in the same air. Compression obviously doesnt chaneg but your mixture over rpm will if you do not re-tune or add fuel.

thats about sums it i think

edit oh and powerband shifts up because overlap is not efficent on an engine until a given RPM where cans can bee seen. which is commonly referred to when your powerband moves depending on cams.

Big duration higher power capability however and longer torque hold out on a dyno read out.

Lower duration equals more immediate power band, with less breathing thanks to less overlap on high rpm.

I found like 30 extremely good links by googling for 1 minute.

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_06.html

http://www.streetracersonline.com/articles/camshafts/

there just two i found in abotu 3.5 seconds on google

[daryl337]

well there are alot more items to take into consideration. Lobe separation as duration are to be taken into account when figuring out overlap. Overlap is the amount of time that both the intake valves and exhaust valves are open. You may ask yourself "how can this be good?" Well on a high RPM motor the amount of time (in seconds) that valves are open is very minimal (you are revving to 8,000 rpms after all. So to make up for it you increase the amount of time (in degrees) that the valves are open. That is: you are increasing the duration. However, there comes to be a time where you cannot keep a valve open too long (you will lose compression or worse: smack a piston).. so to get the max duration you can out of a camshaft you have to open the valve sooner and close it as late as possible. When you do this with both intake and exhaust valves you get what is called "overlap". Too much overlap will kill your vacuum as well as decrease low end torque... and if taken to an extreme will result in a backflow of gasses into the intake system. So you want to choose carefully on what kind of RPM operating range you choose.


The higher the duration of the cam, the higher revving capability but with a loss to low end torque.