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Basic camshaft installation guide
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<blockquote data-quote="drexchan" data-source="post: 1063750119" data-attributes="member: 6936"><p>Dude, overlapping between the exhaust and intake stroke is the basic event what a cam modder is looking forward to change lah... What those numbers 262/288/2xx mean when we talk about cam profiles? It's the overlapping duration in cam degrees. If there isn't any overlapping the engine is useless in automotive term.</p><p></p><p>Higher degree of overlapping is what making all the extra horses even the standard camshaft has overlapping. Performance cam overlaps more for longer intake and exhaust event. Exhaust scavenging will aid intake charging so having overlap is good.</p><p></p><p>More overlap makes high rev power, less overlap makes good low rev torque and best idling quality is with minimal overlap. Therefore VVT/CVT/VTEC/MIVEC/etc are invented to change the overlapping at different rev range and engine load.</p><p></p><p>The problem here is not with the camshaft or the tuning of it.</p><p></p><p>When we talk about knocking, the 4G15 is one of the most robust engine running around with knocks. Seen those Iswara/Wira that are being driven by lazy drivers who never bother to drop shift after a corner around a taman?</p><p></p><p>I personally think that all he need is increasing the fuel pressure. 4G15 is known to burn lean, too lean. Lean burning + blow back contamination is what causing the knock. Not the cam profile.<span style="color: Silver"></span></p><p><span style="color: Silver"></span></p><p><span style="color: Silver"><span style="font-size: 9px">---------- Post added at 09:28 PM ---------- 6 hour anti-bump limit - Previous post was at 09:20 PM ----------</span></span></p><p><span style="color: Silver"></span></p><p><span style="color: Silver"></span></p><p></p><p>As long as the cam lobes are reprofiled to the specification with accuracy in control, and the surfaces are treated by either nitriding or brickering then a reprofiled/reground camshaft is as good as a billet. After all, it's the same grinding and hardening process that they use to make the so-called billet shafts out of a blank shaft.</p><p></p><p>A poorly made 'billet shaft' with base circle too big or lobes too high, without precision is even more dangerous to use.</p></blockquote><p></p>
[QUOTE="drexchan, post: 1063750119, member: 6936"] Dude, overlapping between the exhaust and intake stroke is the basic event what a cam modder is looking forward to change lah... What those numbers 262/288/2xx mean when we talk about cam profiles? It's the overlapping duration in cam degrees. If there isn't any overlapping the engine is useless in automotive term. Higher degree of overlapping is what making all the extra horses even the standard camshaft has overlapping. Performance cam overlaps more for longer intake and exhaust event. Exhaust scavenging will aid intake charging so having overlap is good. More overlap makes high rev power, less overlap makes good low rev torque and best idling quality is with minimal overlap. Therefore VVT/CVT/VTEC/MIVEC/etc are invented to change the overlapping at different rev range and engine load. The problem here is not with the camshaft or the tuning of it. When we talk about knocking, the 4G15 is one of the most robust engine running around with knocks. Seen those Iswara/Wira that are being driven by lazy drivers who never bother to drop shift after a corner around a taman? I personally think that all he need is increasing the fuel pressure. 4G15 is known to burn lean, too lean. Lean burning + blow back contamination is what causing the knock. Not the cam profile.[COLOR="Silver"] [SIZE=1]---------- Post added at 09:28 PM ---------- 6 hour anti-bump limit - Previous post was at 09:20 PM ----------[/SIZE] [/COLOR] As long as the cam lobes are reprofiled to the specification with accuracy in control, and the surfaces are treated by either nitriding or brickering then a reprofiled/reground camshaft is as good as a billet. After all, it's the same grinding and hardening process that they use to make the so-called billet shafts out of a blank shaft. A poorly made 'billet shaft' with base circle too big or lobes too high, without precision is even more dangerous to use. [/QUOTE]
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