Undersquare vs. Oversquare Engines

moper said
I think the issues are apples to oranges... By limiting heads to one brand and style, and camshaft, and compression.. and you eliminate maximizing each combo with the available parts for them. The stroke is the key in both cases.

#1....The LA RPMs will feed the 4" crank engine to 6500 with a std CNC program netting 270-280cfm. The suggested cam is smaller in terms or duration at .050 than I'd use. A solid roller would be more like 265-270°@.050 at .600 lift, and with taking out for lash and the nasty pushrod angles, that lift at the valve is closer to .560. Also, carb is on the smallish side. I think performance wise 520-540 at 6300 is close. I built a 416 very similar to that that made 540 with a dual plane and 950 carb, using a smaller solid roller cam. The torque peak will be higher than mine tho. I'd think 470-490tq @ 43-4400rpm would be what I'd expect.
The B wedge with it's shorter stroke and a CNC head in the 310 area will be undercarbed but not by much. But it will make it's power higher in the rpm band. I think the numbers would be similar, but slightly lower even at peak. I'd be looking for 510-525hp at 6800, with torque in the higher rpms too. I'd be looking for peak torque in the 5K area with a peak around 470 pound feet. To get things better, I'd run a higher static ratio, closer to 11.5 and a single plane intake for this one, plus a carb in the 950 area.
I have a program that uses a bunch of data points to approximate frictional losses for an engine... Interestingly, the hp it estimates being lost by the 4" is higher, but at 6600, the B wedge has the same hp loss as the 4" LA does at 6K.

Yep, I probably should have titled this "Stroker vs. B Block", but I was trying to prove a point. I do believe (although I have no way to prove) that the B Block will out power a stroker due to the head configuration more than anything else and that the under/oversquare and rod/stroke ratios have far less to do with creating usable power than gas flow does.

Do rod ratios and bore and stroke issues make a difference? I say yes they do, but I wonder how much of a difference they truly make under 6500 rpm? I'll bet that the difference on two identical engines, with the same heads, cam and intake but different rod ratios or under/oversquare configurations would be in the single digits under 6000 rpm, with that number increasing as the revs rise.

As far as I know, none of us are building F1 engines that spin at 18,000 rpm, nor are we building 7500 rpm Mopars that we drive on the street although I'm sure some of us have built some high revvers for the track. Of course, I've been wrong before, lol.

I'm going to be starting on 2 builds come late summer and both will be LA strokers but each one will have a different purpose. One will be for my Ramcharger and one will be for the Duster. The present LA build in the RC will be dropped in the Duster as I have to have it emission checked just once to get it registered and plated as an antique then I can do anything I want to it.

I will be spending my money on getting fuel/air in and out and making sure that engine holds together at the planned rpm range rather than worrying about r/s and b/s ratios. :read2: