Duration Numbers
03-03-2009, 09:40 PM
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Duration Numbers @ what point does the idle start to become rough? most of the rough idle cams i've found are in the 234+ range. also, is a 114 LSA as close as it should get for a fair idle daily driver?
03-03-2009, 09:57 PM
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Duration and LSA are contributing factors in the amount of overlap the camshaft has, which creates a rough idle. Everyones idea of streetable is totally different, so you will get many differnet answers.
I always use 230 @ .050 as the point of trading streetablility/idle quality for power potential. 230+ doesnt always mean more power, depends on the engines airflow abilities. Also the tighter the LSA also means more roughness but gives you low end power. A wider LSA typically gives you a slighly better idle and more top end power.
I always use 230 @ .050 as the point of trading streetablility/idle quality for power potential. 230+ doesnt always mean more power, depends on the engines airflow abilities. Also the tighter the LSA also means more roughness but gives you low end power. A wider LSA typically gives you a slighly better idle and more top end power.
03-03-2009, 11:01 PM
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Yes, as SweetS10V8 stated it is all in the total overlap degrees (combination of duration and LSA).
Have ran cams with -4, 0, currently +10 degrees overlap. With tuning today, I would not necessarily describe the idle as 'rough', but it definitely starts getting 'choppier' after ~ 6 degrees of overlap.
It is all about personal preference and what your total engine combination goals are.
With 10 degrees of overlap, I can still idle at 750-800 rpm quite easily (tuning). I would describe it as a noticeable 'chop'. Even staying in the 0-6 degree overlap range will have a 'cam sound', with perhaps less overlap reversion concerns.
What is your goal?
..WeathermanShawn..
Have ran cams with -4, 0, currently +10 degrees overlap. With tuning today, I would not necessarily describe the idle as 'rough', but it definitely starts getting 'choppier' after ~ 6 degrees of overlap.
It is all about personal preference and what your total engine combination goals are.
With 10 degrees of overlap, I can still idle at 750-800 rpm quite easily (tuning). I would describe it as a noticeable 'chop'. Even staying in the 0-6 degree overlap range will have a 'cam sound', with perhaps less overlap reversion concerns.
What is your goal?
..WeathermanShawn..
