Determining valve events
Originally Posted by Summitracing
G and JKD, this has been an enjoyable conversation. JKD gave us a fun twist on things and hopefully helps people really start thinking in terms of individual valve events and having trust in them. ...Even if the "duration, LSA, advance" etc. all seem to be out in left field.
Originally Posted by JKD
Darth and Summit, thanks for the lesson. It has helped me immensely with my grasp on things.
One additional thing is head selection. In a high torque scenario, you want to err on the small side. That 416, I would to a cathedral head. Something like tfs245. Slightly undersized for the displacement to get great airspeed.
On the 454, I would look at aftermarket Ls3 or ls7 heads in the smaller port range. 255-270. Nothing bigger than that. With that big ls7 valve, you can get far more flow to help out with losing power up top while still keeping the cam small.
On the 454, I would look at aftermarket Ls3 or ls7 heads in the smaller port range. 255-270. Nothing bigger than that. With that big ls7 valve, you can get far more flow to help out with losing power up top while still keeping the cam small.
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They will first determine duration for approximate airflow, and then spec out the LSA/ICL to determine overlap, advance, and ultimately IVC.
The valve events fall where they fall in that situation, and the individual timing events are skipped over in order to size the broad-range cam specs to the displacement and application.
To each his own. I feel like doing it by Duration/LSA/ICL might get you in the ballpark, but you miss out on the fine print and the knowledge of exactly what is really going on with the valvetrain.
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One additional thing is head selection. In a high torque scenario, you want to err on the small side. That 416, I would to a cathedral head. Something like tfs245. Slightly undersized for the displacement to get great airspeed.
On the 454, I would look at aftermarket Ls3 or ls7 heads in the smaller port range. 255-270. Nothing bigger than that. With that big ls7 valve, you can get far more flow to help out with losing power up top while still keeping the cam small.
On the 454, I would look at aftermarket Ls3 or ls7 heads in the smaller port range. 255-270. Nothing bigger than that. With that big ls7 valve, you can get far more flow to help out with losing power up top while still keeping the cam small.
Originally Posted by AwesomeAuto
You would be surprised how many "experts" (and even a couple of cam manufacturers) over the years that I've met that follow the opposite ideology.
They will first determine duration for approximate airflow, and then spec out the LSA/ICL to determine overlap, advance, and ultimately IVC.
The valve events fall where they fall in that situation, and the individual timing events are skipped over in order to size the broad-range cam specs to the displacement and application.
To each his own. I feel like doing it by Duration/LSA/ICL might get you in the ballpark, but you miss out on the fine print and the knowledge of exactly what is really going on with the valvetrain.
They will first determine duration for approximate airflow, and then spec out the LSA/ICL to determine overlap, advance, and ultimately IVC.
The valve events fall where they fall in that situation, and the individual timing events are skipped over in order to size the broad-range cam specs to the displacement and application.
To each his own. I feel like doing it by Duration/LSA/ICL might get you in the ballpark, but you miss out on the fine print and the knowledge of exactly what is really going on with the valvetrain.
