318 Port match heads to Performer RPM Intake

AJ/FormS said
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

This is all new to me and to be honest Im not at all familiar how things are calculated. What I know is 72 and newer engines became low compression due to emissions coming around. After hearing this I looked into this cam that says its a simple drop in with increased benefits based on their claims noted below from there web page. Again this is a 318, if I really wanted power id go with a 360. Like I mentioned I want to see If this might give a little more response than stock and sound nice even if it does not make up for it with the power. Not looking for something to launch at green lights or take to a track. All my components seem to match up except the intake ports being bigger on the manifold than the head.

Here is the info from Hughes engines:

"Whiplash cams are designed for the very low compression Mopar O.E.M. engines such as all the 318's, 360, 400 and all 383 & 440's built after 1971.

The factory built these engines with a combination of low compression and cams that produced very low cylinder pressure and low power (see this tech article CLICK HERE). Normally, to increase the cylinder pressure in these engines you would have to disassemble the engine, buy new pistons & rings (at a minimum), rebore & hone, rebalance and reassemble. And then you would still need cam & lifters. The cost of this build-up could easily be $2,000.00 or more and take 2-3 weeks.

The unique design of the Whiplash cam will accomplish all of the same results for as little as $340.00 (cam, springs & lifters) and take about one Saturday afternoon to complete. The Whiplash cams are designed, like all of our "real" Mopar cams to take advantage of the .904" lifter diameter which increases the area-under-the-curve, for more breathing time. However, with low lifts (yes we consider .520" low lift) so that you do not need to remove the heads and machine the valve guides.

These Whiplash cams have become one of our top selling items and we have customer that want to put them in engines that are not low compression. The problem is that the cam will still raise the cylinder pressure and your engine may then require race gasoline or a mix of pump and race gas. As a general rule of thumb engine with a true measured compression ratio more than 8.9:1 with iron heads or 10:1 with aluminum heads should not expect to be able to run on just premium gas. And, whatever you do, DO NOT retard the timing to "make it work". That will "work" and also reduce your power & torque considerably. You'll be sorry!"