Overheated engine/loss of power

I’m very sorry for all the typos in my above question. I hit send before I proofread it. Here is the corrected version:

So the mechanic that I had do my annual left a radiator hose loose which I did not know about until I was 2500 feet and noticed the temperature gauge was buried. I immediately flew back to the field and made it. I had‘the heads sent off for hardness testing and one of them was compromised and replaced. Now that the engine is back together seems to be making less power than it was . So I have two questions.

1. does anyone have any suggestions on what else might have been damaged to cause a loss of power?

2. this one might seem like a dumb question but if my rpm is the same is it possible to have reduced Horsepower at that same RPM?  Like for example… my airplane used to run 92 kn and level flight at 5200 RPM. 

Now it runs around 82 kn at 5200 RPM In level flight. Does this indicate a loss of horsepower or if the RPM is the same should the airspeed be the same?  I’m a little bit confused and I hope I’m explaining this correctly. Basically I want to know if it is possible to have less horsepower and therefore less airspeed if my RPMs are the same at 5200?

 The reason I ask is that I’m not 100% sure it’s a loss of power because we did replace the prop although we put the exact same prop back on and the degrees are supposedly exactly as they were. it was double checked by two different mechanics and confirmed it was exactly the same setting as the prop that came off.  So the prop setting should be the same. And therefore my speed should be the same unless I’ve lost horsepower. But again I’m not sure how that works if it’s even possible to have less horsepower but still be turning the same RPM?

thank you for your help and have a great day!

Dylan

Dylan,

Perform an engine compression leak down test and compare that to both the Rotax manual requirements and the results from your test at your previous annual.  Confirm carbs are synchronized mechanically and pneumatically if applicable (what engine is this?). Then…Compare your static (aircraft chocked on the ground) WOT prop rpm to what it was before this unfortunate incident happened. Discuss the results with a trained Rotax technician and implement his/her advice as to what to do next. Let us know what you find out.

It’s a 912 ULS. As to my other question about RPM? Is it possible to have less horsepower at the same RPM? Or if the RPM is the same is that impossible? 

It sounds like perhaps the prop is adjusted differently. Do you know what your static rpm was before at full throttle? Is it the same now?

If your prop is now flatter than it was before, that would explain why you are going slower at the same rpm. It would also show up as a higher static rpm at full throttle than what you were getting before.

It would also show up as more power on takeoff and full throttle climb, since you would be getting higher rpm and therefore higher power at full throttle settings.

Yes well that’s the funny thing I seem to have lost performance in both areas. My climb out feet per minute is terrible and I also don’t have any speed up top.