PK numbers
But to get off the line half decently, the bigger your cam is, without a change in compression ratio, the more stall those 3.21s are gonna need. Without a Loc-up I would run at least a 2800 and a big trans cooler. With a loc-up, and a cam, at least a 3200, and the same big cooler.
But I gotta tell ya, you cannot compare a Magnum to a slanty, they are worlds apart. And your 3.687 slanty can never get on the same page with even the 3.9 never mind the 5.2. Your slanty pistons are just 3.400 inches in diameter, and the /6 only fires three chambers per revolution. It wouldn't matter if it had a 6" stroke, if the mixture is finished burning in the first three inches, and finished the big push in 3.3 inches, the rest of the time, the next piston in line and the ones after, have to drag it around until the next time it fires.
Here is a stock 5.2 dyno curve; Check out the torque at 2500, and at 2800. That's what you need to have so you can cruise at Part Throttle.
But check out the power associated with 2800, about 155hp.
Suppose the 5.2M cruises at 40% throttle or say 62hp. That leaves it 93hp in reserve for acceleration, for climbing, and for passing.
But if your 225, can only muster 75/80 hp at 2800, yur engine is nearly at WOT! With very little in reserve. And it's pushing about 32 sq ft of barn-door down the road, with no aero whatsoever.
Now, don't get me wrong, I have never had a slanty in my 84 D-100, and of that I am very glad. Cuz altho the worn out 360 could do 65, it took about 5 miles, I mean a really long time, to get up to speed. And forget passing.
Because your rpm at 65 with 28s is 2500LU/2750 @10%slip, as for cruising, it makes no difference. In fact, for towing, you want the TC to be fully stalled and not slipping, so that it is not producing a bunch of heat.
But to get off the line half decently, the bigger your cam is, without a change in compression ratio, the more stall those 3.21s are gonna need. Without a Loc-up I would run at least a 2800 and a big trans cooler. With a loc-up, and a cam, at least a 3200, and the same big cooler.
But I gotta tell ya, you cannot compare a Magnum to a slanty, they are worlds apart. And your 3.687 slanty can never get on the same page with even the 3.9 never mind the 5.2. Your slanty pistons are just 3.400 inches in diameter, and the /6 only fires three chambers per revolution. It wouldn't matter if it had a 6" stroke, if the mixture is finished burning in the first three inches, and finished the big push in 3.3 inches, the rest of the time, the next piston in line and the ones after, have to drag it around until the next time it fires.
Here is a stock 5.2 dyno curve; Check out the torque at 2500, and at 2800. That's what you need to have so you can cruise at Part Throttle.
But check out the power associated with 2800, about 155hp.
Suppose the 5.2M cruises at 40% throttle or say 62hp. That leaves it 93hp in reserve for acceleration, for climbing, and for passing.
But if your 225, can only muster 75/80 hp at 2800, yur engine is nearly at WOT! With very little in reserve. And it's pushing about 32 sq ft of barn-door down the road, with no aero whatsoever.
Now, don't get me wrong, I have never had a slanty in my 84 D-100, and of that I am very glad. Cuz altho the worn out 360 could do 65, it took about 5 miles, I mean a really long time, to get up to speed. And forget passing.