Making power with "agressive" cams

[DSC]

I was just wondering about "agressive" cams. The longer the duration the more air can flow...makes sence.
What's "degrees" though? I don't get how an agressive setup makes more power. I mean, more lift makes sence...more air, of course that's always good, but I don't understand the gains from increased overlap or what #'s describe the ammount of overlap. &nbsp;If someone could explain it for me I'd appricate it <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/thumbs-up.gif" border="0" valign="absmiddle" alt=':thumbsup:'> thx


Stock - Intake 251 degrees duration, .415 lift, Exhaust 258 degrees duration, .415 lift

Full race - Intake 300 degrees duration, .506 valve lift, Exhaust .300 degrees duration, .506 valve lift

<OBJECT CLASSID="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" WIDTH=320 HEIGHT=300><PARAM NAME=MOVIE VALUE=http://static.howstuffworks.com/flash/camshaft-cam.swf><PARAM NAME=PLAY VALUE=TRUE><PARAM NAME=LOOP VALUE=TRUE><PARAM NAME=QUALITY VALUE=HIGH><EMBED SRC=http://static.howstuffworks.com/flash/camshaft-cam.swf WIDTH=320 HEIGHT=300 PLAY=TRUE LOOP=TRUE QUALITY=HIGH></EMBED></OBJECT>
You can switch between standard and performance cams under the "play" button.
<span style='font-size:7pt;line-height:100%'>Flash taken from howstuffworks.com</span>

[DSC]

Oh <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/blush.gif" border="0" valign="absmiddle" alt=':blush:'> damn, I can't read. &nbsp;I went back through the article, bigger overlap makes more power because the exhaust is helping to suck in the intake air. &nbsp;I read that, but didn't really get what they were talking about.

I guess I could just delete my post now that I don't need help but I'll leave it up incase anybody else was curious.

Here (http://www.howstuffworks.com/camshaft.htm) is the full article.

If there's more to it than I see or if I've got something incorrect, let me know <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/thumbs-up.gif" border="0" valign="absmiddle" alt=':thumbsup:'>

[boosteds14]

it really has to do with your setup. like my set up, u want less overlap so that the exhaust charge does not got back into the combustion chamber. my setup is
intake cam .390" lift 295 deg dur. plus a 2.5 deg retard
exhaust cam .390" lift 295 deg dur. plus a 2.5 deg advance

i think that is what i got. i always forget

[240sxtreme]

sorry for the OT reply....but you just gotta love that website.

[240 2NR]

That article ws pretty cool. &nbsp;Well mostly the part where it talks about the different variable valve control systems. &nbsp;I always thoughtt he VTEC system employed a solinoid that popped the cam over to use the second profile (in a way closer tothe ferarri system). &nbsp;Which, speaking of is pretty damn cool. &nbsp;I never knew they did that.

Anyone know a good way to contact JWT about their cam grinds? &nbsp;I've emailed them twice with no answer. &nbsp;Guess I'll have to call when I'm closer to ordering.

[bing]

that site is very informative,

i should be reading about busniess law for my midterm but...

[fast-datsun]

JWT call them 619-442-0680. &nbsp; The big overlap is for NA cars !Turbo's what stock or alittle less, as incoming air charge is pressurized and more overlap is bad as the charge is pushed out the exhaust.. &nbsp;Read and good book on turbo or supercharges and the will explan the problems.. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/whatsthat.gif" border="0" valign="absmiddle" alt=':whatthe:'>

[Jim96SC2]

Just remember, having too much cam on a turbo car will decrease the time the pressure can build up in the cylinders, thereby REDUCING power. With a turbo you want high lift and only moderate duration, with very quick ramps.

[luke91]

To DSC:

I don't know this for sure, so anyone, please correct me if I'm wrong:

I believe lift and duration are measured like this:

Lift in a measure, in inches, of a cam lobes height from the center of the cam to the apex of the lobe. &nbsp;.415 lift means the top of the cam's lobe is .415 inches fron the center of the cam.

Duration is the total number of degrees around the cam the lobe is present. &nbsp;

If that is not correst, someone please correct me. &nbsp;
--luke

[fast-datsun]

Lift is the amount the cam lobe is above the base circle in inches or mm ie .455.. Duration is the time the valve is open seat to seat)in degrees of crank rotation, ie 270 deg. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>