Engine Ops with No exhaust system. facts wanted.
A question was posted somewhere else about operating an aircraft engine less the exhaust system, or just straight pipes, out and down, for each individual cylinder, and how would this effect the engines performance?
I found the question interesting, as i am unsure of the answers even though i have done some well respected courses on engine ops and management, but of course, a lot of responses dont make logical sense, and the number of OWT's soon swamped discussion, so i decided to post here, knowing the background and expertise of some contributors here in engine ops, LOP, etc etc, in the hope some will answer using Scientific fact and repeatable observations..
So i guess the questions are, will no pipes/straight out pipes, (no Muffler) result in damage to valves? is back pressure really required to ensure smooth operation? will it effect mixtures?
from my understanding, it will effect nothing other than ones ears.. nothing more, am i correct? (no references to 2 stroke engines, i know it matters in those engines)