Ivylog wrote:
"A H" you might want to look at my post on 08/27/15 at 01:24pm... 7th from the top.
I do not put my Allison in N while moving and I did not miss your question nor the edits to your post.
Your still not paying a lot of attention to what I am writing. The ISL 400 uses a C Brake. It is a Combination brake that raises boost with the VGT to enhance the compression release brake. The boost increasing is not a function of the compression brake which is what I have said since my first post. Re-read all of my posts. You keep telling me to look at your post over and over, yet there isn't anything there I haven't addressed. Not sure where your comprehension issue lies.
It sure looks like you are missing something, such as how the different type of brakes work and their effect on the engine/airflow.
Go run those tests and report back.
JetAonly wrote:
A compression brake forces the engine to do work. The air exhausting the engine is hotter than the air entering it by the amount of work done in compressing the air. Adiabetic heating. The turbine continues to extract work from the exhaust gases which produces boost.
Fuel, after all, is just a way to heat air so it expands.
Compression does increase temperature and the rapid pressure drop as the ~500 psi leaves the cylinder will then cool the air and reduce its velocity. Some of the energy is also used to make the nice sound we all either love or hate.
7-15 psi of boost takes a lot of turbine flow to sustain.
