It depends on a fair few factors of how these super powers are shaped. Given the average human (male) size of 1.8m and 70kg, if you scaled the height directly (factor of 1.7) you'd get a human sized 3.2m and 120kg. This means your supers have a lot of increased mass, this is to be expected as they need more muscle to keep up with their increased size, but the increase is almost a factor of 3 higher than expected.
Now I'll compare your super soldiers to strongmen like Hafþór Júlíus Björnsson, one of the heaviest strongmen recorded, with a height of 2.05m and a top recorded weight of 205kg. This is already closer to your numbers, and scaling this up gets very close.
Now how does this translate to speed? Hardly, I'm afraid. There are records of strongmen reaching sprint speeds of roughly 26kmh, but this is over very short distances. Long distances aren't done by strongmen for various reasons, but mostly because of my next point.
Scaling up muscle length diminishes their usefulness tremendously, so the concept of bigger = stronger doesn't really hold up. This will be paired with the fact that more weight needs more energy to move, so large muscles are needed. And more muscles equals more weight, meaning even more muscle power is needed, and so on. A lot of the muscle mass of one of these supers will be needed for simply moving around, and won't help for athletic feats like running.
Due to their size, and the fact that they are created from ordinary humans, I'd expect your supers to have the following issues:
- Brittle: Their bones will be elongated and out of proportion, the average human skeleton simply isn't built for the strain put on by such a tremendous size. So either their skeleton will need to be reinforced or they would simply pull themselves apart. This adds a lot of weight, which isn't muscle mass.
- Tires easily: Moving a large amount of weight requires a large amount of energy. Moving a body of the size you describe will require an exponential amount of energy, which the body stores mostly as fat, which is once again, added weight that isn't muscle mass.
- Weak: Over all, I'd expect these supers to be weak in comparison. They will indeed weigh a lot, and a lot of this weight won't be in the muscles needed to move, and the muscles will have already diminishing returns. This means that they won't be nearly half as efficient in movement as a regular human, for an increased amount of effort. I don't mean they are weaker than a human, but they won't be "Twice as big and twice as strong", rather they might be twice as big and only 1.25x as strong.
Of course the question was about speed, and this is a tough one, as speed does not scale at all like strength does. Rather as I displayed above, the increased weight would diminish speed rather than increase. The only positive thing about their physique would be their increased stride length. You state that longer distance running is 15-18kmh on average, but I think this is already generous. A 10km run is more often done at roughly 10kph. With the added weight and energy requirements of your supers, I would expect this to be more like 8kph or slower for a trained super. Also, I would question whether they have the energy to do such runs often if at all.