318 - 340 Same Torque??
Low rpm torque is directly related to TRAPPED pressure and SWEPT volume.
So yes it is totally possible for the EARLY 318 to make 340 at 2400 and the EARLY 340 to make 340 at 3200.
But there is no way for us to know if the 340 made more torque later in the powerband. Maybe Ma just pulled the 3200 number and knew the buyers would figure it out.
If you plug the appropriate stock-cam and Scr numbers into the Wallace calculator, you will find that a
9.2 318 actually compares very nicely to a
10.5 Scr 340 in the lower rpms.
Engines with the same VP index will perform similarly below 3000-ish rpm . Keep your eyes on the Dcr numbers.
Here are the Wallace results;
First the 318
Static compression ratio of 9.2:1.
Ica of 48*
Effective stroke is 2.89 inches.
Your dynamic compression ratio is
8.15:1 .
Your dynamic cranking pressure is
167.57 PSI.
V/P (Volume to Pressure Index) is
........................ 140
Then the 340
Static compression ratio of 10.5:1.
Ica of 64*
Effective stroke is 2.57 inches.
Your dynamic compression ratio is
8.37:1 .
Your dynamic cranking pressure is
173.49 PSI.
V/P (Volume to Pressure Index) is .............................
137
Then the 360
Static compression ratio of 8.0:1.
Scr of 52*
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 6.91:1 .
Your dynamic cranking pressure is 134.82 PSI.
V/P (Volume to Pressure Index) is ............................. 123
the smog 318
Static compression ratio of 8.0:1.
Ica of 48*
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 6.91:1 .
Your dynamic cranking pressure is 134.82 PSI.
V/P (Volume to Pressure Index) is ............................. 123
A 360 with a little more compression
Static compression ratio of 8.7:1.
Ica of 54*
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 150.26 PSI.
V/P (Volume to Pressure Index) is ............................ 137
the Commando 273; I don't recall the 273 cam specs, but here it is with a 52* Ica
Static compression ratio of 10.5:1
Ica of 52*
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 9.08:1 .
Your dynamic cranking pressure is 192.80 PSI.
V/P (Volume to Pressure Index) is ............................ 135
Here is the 440 Magnum of 1968:
Static compression ratio of 10.5:1.
Ica of 72*
Effective stroke is 2.69 inches.
Your dynamic compression ratio is 7.81:1 .
Your dynamic cranking pressure is 158.48 PSI.
V/P (Volume to Pressure Index) is ............................. 150
Just for kicks, Here's my alloy headed 367;
Static compression ratio of 10.95:1.
Ica of 62* @ sealevel, like the others
Effective stroke is 2.84 inches.
Your dynamic compression ratio is 8.89:1 .
Your dynamic cranking pressure is 187.60 PSI.
V/P (Volume to Pressure Index) is .............................. 164
She burns E87 full-time, this, with a cam of
276/286/110+2 advertised; 230/[email protected]
Some people say pressure is not a big deal for a streeter
here is the 340 cam in a smog teener
Static compression ratio of 7.8:1. A more true number with a composition headgasket
Ica of 64*
Effective stroke is 2.57 inches.
Your dynamic compression ratio is 6.27:1 .
Your dynamic cranking pressure is 118.36 PSI.
V/P (Volume to Pressure Index) is ................................ 88
This VP is what a 225 slanty makes............ Do you really want that under your bonnet? Just try driving that with a stock 318 TC and 3.23s,
or worse, with a regular A833
Here's my opinion on VPs
123 is a Reasonable grocery-getter type number
135 is where Performance begins
140/145 are getting to be Tire-friers and Heap-Big-Fun
150 or more is overkill on the street, but it lets you run hiway gears and lo-stalls.
164 in my combo is batchit crazy; but it pulls nice controllable second gear slides without much rpm. (A833). If you combine this with a 224 *or less cam, it's pretty amazing what you can do with gearing; like run 65=1580rpm (overdrive and tall tires), and get phenomenal fuel-mileage. My Barracuda went [email protected] with a 223Cam, on it's one and only run with that cam, on street tires, spinning for a long long long ways out.
