oh you guys are too funny!, lol.
Ok here it comes;
Given in Ica or intake closing angle and lets just stick with the afore-mentioned 272/278
if you put that on a 106LSa cam, that is to say, one on which the offset between the intake lobes and the exhaust lobes is 106degrees, then you get the cam I described, namely one with events as follows;
intake/compression/power/exhaust/overlap
272/120/114/278/64. Installed at 104LSA (lobe center-Angle), aka +2, or 2* advanced; then the Ica will be 60*
now
lets open the LSA to 114 cuz you will instantly see what is going on; your new events are;
272/120/97/278/47. To get the 60* Ica, you would need to install this at 104* same as before. But this steals a bunch of exhaust duration (now just 97*), and it messes up the overlap. In the first instance, the overlap is split at 32* to intake and 32* to exhaust, so split overlap. In the Second instance 32* still goes to intake, but now the exhaust is closing at just 15* ATDC. So the EFFECTIVE overlap cannot be more than twice the smaller number, which then comes to 30*, instead of 64* as in the first example.
Nobody would install this cam in such a manner. If they did, it would suffer a severe loss of power from the mid rpms to the peak and over the top; because the overlap is as good as gone, so the headers cannot do what they are designed to do.
Furthermore; with just 97* of power extraction, the exhaust leaving the chambers will still have a lot of energy in it, that could have been used to propel the vehicle. This will be especially noticeable at low to mid rpms.
To make this cam work, it would need to be retimed to something like in at 113*. The new events would be;
272/111/106/278/47. The overlap is still 47, but the Effective overlap is now up to 46*. And the Ica is no longer 60*, but rather, it is 69*! But it's the same stinking 272/278 cam, just on a new LSA with an accompanying later Ica.
But there is something else to consider;
The compression degrees have shrunk from 120* to just 111*, which being a loss of 9 degrees. This will manifest as a loss of CCA, in the amount of perhaps 11 to 14 psi. These are huge numbers, particularly if you have modest pressure to start with. It can easily ruin your low to midrange driving experience.
But it gets worse;
With just 97* of power extraction,
