Please consider this. Found it on Airliners.com. It compares not just the engines but also the P-47 to the P-51, but interesting none the less.

"This is a summary of his 12 points (italics are quotes from the article):

1. Air-cooled radial engine was more reliable and could take hits and keep on running, even with inoperable cylinders.

2. The Jug's air-cooled engine did not have the Achilles' heel that the Mustang did: A small-caliber hit on an aluminum coolant line could down a Mustang in minutes, even if the fighter was otherwise undamaged.

3. The P-47's big turbocharger enabled it to fly higher than the P-51 (over 40,000 feet).

4. The Jug could outdive the Mustang.

5. The Thunderbolt had eight .50's. The Mustang had six. That's 33 1/3% more firepower.

6. Later model Jug's could carry 2,500 lbs of bombs.

7. The P-47 was larger and much stronger, in case of a crash landing. The Jug was built like a machined tool. Mustangs had a lot of sheet metal stamped out parts, and were more lightweight in construction.

8. The Thunderbolt had no "scoop" under the bottom, so it handled ditchings and gear up landings much better.

9. The Thunderbolt had a much larger, roomier cockpit. You were comfortable in the big Jug cockpit. In my Mustang, my shoulders almost scraped the sides on the right and left. I was cramped in with all my "gear." I could not move around like I could in the P-47.

10. The Mustang went from 1,150-horse power Allison engines to the Packard built Rolls-Royce Merlin engine that had 1,590 hp. The Thunderbolt started out with a 2,000 hp Pratt & Whitney engine, and ended up with 2,800 war emergency hp with water injection.

11. The Jug had a very wide landing gear, which was especially valued when landing on rough fields.

12. The Jug's record against all opposing aircraft is remarkable. The ratio of kills to losses was unmistakably a winner. Thunderbolt pilots destroyed a total of 11,874 enemy aircraft, over 9,000 trains, and 160,000 vehicles.

But, the big factor, above all else, it saved pilots in great numbers. Ask most fighter pilots who flew both in active combat and they will tell you that, given a choice to fly either one in combat, it would be the Juggernaut hands down.

Now one last thing: the P-51 Mustang was a superb fighter. I am fully aware of that! But, considering that I flew about every kind of mission the Pentagon could dream up, and a few they didn't know about, I will rate that 8 tons of destruction first as long as I live, and no one can change my mind. I was there. Simply walk up to one of them and see for yourself.


I guess that the fact that the Mustang is more aesthetically appealing than the Thunderbolt probably has something to do with its continuing popularity."

So even though the kill ration was not quite as good, you have a better chance of survival, if your plane was mortally damaged, being in the P-47. It saved more pilots and the radial contributed to this.