318 Port match heads to Performer RPM Intake
since it relies on stock low compression
I think that's a bit of a stretch.
The specs on that cam are 213/
[email protected]/109LSA in at 104
If I gross that up, by a typical acceleration ramp for Hughes, of 46*, I get an advertised of ~260/272. Don't worry about the accuracy of this. Just watch what happens as I go thru this exercise.
Ok so; in at 104* per the card, the Ica becomes 54*. Lets install this into a TRUE 7.8 Scr, 318 at sealevel. I get
Static compression ratio of 7.8:1.
Ica of 54*, elevation 0
Effective stroke is 2.78 inches.
Your dynamic compression ratio is 6.70:1 .
Your dynamic cranking pressure is 129.38 PSI.
V/P (Volume to Pressure Index) is 104
The Wallace Calculator predicts a cylinder pressure of just 129psi and a VP of really lousy 104.
I gotta tell you this is a catastrophic situation.
I processed the number 3 times to verify these numbers, the numbers are right.
Read about VP here; V/P Index Calculation
What does it mean? A box-stock Non-Magnum 318LA posts a VP of 115, see below
Static compression ratio of 7.8:1.
Ica of 48*/ sealevel
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.94:1 .
Your dynamic cranking pressure is 135.60 PSI.
V/P (Volume to Pressure Index) is 115
As you can see; you are giving up 6psi and 11points of VP. 11 may not sound like much but in this case that represents almost 5% performance loss at the lower rpms, where you will be doing the vast amount of your driving, namely below 3000 rpm.
What that 318Whiplash cam wants is
Static compression ratio of 9.2:1.
Ica still 54*/@sealevel
Effective stroke is 2.83 inches.
Your dynamic compression ratio is 7.88:1 .
Your dynamic cranking pressure is 160.34 PSI.( to burn 91gas at WOT)
V/P (Volume to Pressure Index) is 131
131VP is 14% better than a stock low-compression 318LA
Now yur talking!
IDK; maybe you already have a pre 72 Hi-Compression 318, in which case you'd be right in sticking with less than 9.2 Scr