NA to Turbo... cams

[barryogen]

Be gentle with me I'm learning(heaps and fast).

Can someone help to explain cams to me... or failing that, just tell me if I am right, wrong or otherwise.I have read and read and read about it, and I see that there is much to learn, but for the moment I'm wanting to know the major differences between an NA and a Turbo cam.

From what I have read, Turbos have little if any overlap, whereas NA engines tend to have a little bit for lower performance engines, and a lot for higher performance engines(for the moment I'm ignoring Vtec and VVTi/Li).

Overlap seems to be bad in Turbo engines as the boost goes straight out the exhaust, which pretty much defeats the purpose of the boost in the first place.


So, to make a car that was NA to turbo, you can just slap a turbo on the side, work the ECU magic(just ignoring explaining component change for the moment) and get it going, but without changing the cams, you're playing second fiddle in the orchestra performance wise, as the cams are letting the boost go straight out the exhaust instead of making useful power for you.

So, if you ship them off to some experts, who make the leading and trailing edges of the lobes steeper, would this reduce the overlap, giving you a more turbo friendly cam grind? or am I looking at this the wrong way?

[AceSniper]

adjust your cam timing.... in doing that if your cam gears are vvt/vvt-i could be an issue

[strx7]

Overlap seems to be bad in Turbo engines as the boost goes straight out the exhaust, which pretty much defeats the purpose of the boost in the first place.

dont be fooled into thinking that, itr actually makes the turbo spool up faster then once into the 'cam range' you're off and away flying. People seem to think you cant run large degree cams in turbo applications. The only REAL difference between a turbo and N/a application running long cam duration is One has to inhale its own air while the other has something hanging on the side forcing air into it, thats it.

Same goes for big ports on rotary's with turbos

[AceSniper]

take it your talking 2zz? from memory there cams weren't overly large duration more the large amount of lift?

[spencer]

yea check out some of the turbo drags imports around most rum pretty big cams 270 degree plus