Your minivan has different gearing in the transmission for one thing. It is a small difference but you might feel the difference.
The other possibility is how open the exhaust is. I don't know if you are required to have converters on both vehicles, but if one is slightly restrictive, it will feel a bit more sluggish. Since these are old vehicles, one engine may have less compression than the other.
The other possibility is how open the exhaust is. I don't know if you are required to have converters on both vehicles, but if one is slightly restrictive, it will feel a bit more sluggish. Since these are old vehicles, one engine may have less compression than the other.