Mike? Is that you? The "real Mike Barnes"? What were you in 1990, SK2 or SK1?
Is your "impossible question" and challenge supposed to be akin to the problem of evolving a four-chambered heart from a three-chambered job? After all, you would argue that while converting the 3-chambered model to the 4, the whole thing would have be shut down, right?
Well, crocodiles do it all the time. They're born with three-chambered hearts and as they grow larger to where they need more efficient oxygen transport which requires a more efficient circulatory system, they switch from three chambers to four
without skipping a heart-beat.
You see, a three-chambered heart has two atria and one ventricle, whereas a four-chambered heart has the same two atria and
two ventricles. The only physical difference between the two is a muscular septum that separates the ventricle into two chambers. In a three-chambered heart, the oxygenated blood from the lungs gets intermixed with the de-oxygenated blood from the body, which is good enough for an animal with a low metabolism, such as amphibians and most reptiles. But in a three-chambered heart, there is not such intermixing, so the body gets the oxygenated blood from the lungs.
You see, Mike, the secret to coming up with a valid analogy is for the processes involved to be the same or very close to the same. Your engine "analogy" is a false analogy which has nothing to do with how evolution works.
Here's the key to creating a valid analogy: evolution is the result of life doing what life does, so your analogy needs to emulate what life does. Car engines do not fit that bill.