sbmar
Marine/Ocean
- Jan 1, 2005
- 26
I always thought I had a pretty good understanding of exhaust back pressure limits on diesel engine and the reasons why, until a recent dilemma came up.. For most manufacturers of high performance modern diesels, seems most spec the limit the maximum exhaust back pressure to about 3" hg.. Yes, some are a little less, and I have also seen some as high a 5" hg for certain applications ( fire truck applications) .........
I could only surmise that if these pressures are exceeded, performance and engine longevity would or could be compromised....That seems totally plausible to me.....
But here is the dilemma... I found a technical bulletin specific to an engine I deal with quite a bit that listed a MINIMUM exhaust pressure limit, and now, have come upon another manufacturer that also has a "minimum" exhaust pressure limit.................
Yes, we deal with very high performance diesels (most all at 60+ HP per liter, w/ some at close to 80 hp/liter).
Many exhaust systems we design, build, install, and test in the field actually go "negative" at speeds of about 60-80 load because of a suction that must be being created at high speeds and the way the exhaust exit the system.. We use a differential pressure gauge to measure the pressures and are quite sure of our reading.......
I would like some input from some of the real engineering that read this forum... Please do make this assumption.. My reading are correct, the engines are loaded and applied per the manufacturers recommendations and history of these exhausts and engines have show no issues for 1000's of operating hours.........
My question is: Why would there be a limit or requirement as to minimum exhaust back pressure for a high performance turbo aftercooler 60+++ Hp/liter diesel?? My only assumption is that "they" are afraid of "over boost"........
Please help me to understand what I cannot seem to reckon with...........
Thanks, Tony
Tony Athens
I could only surmise that if these pressures are exceeded, performance and engine longevity would or could be compromised....That seems totally plausible to me.....
But here is the dilemma... I found a technical bulletin specific to an engine I deal with quite a bit that listed a MINIMUM exhaust pressure limit, and now, have come upon another manufacturer that also has a "minimum" exhaust pressure limit.................
Yes, we deal with very high performance diesels (most all at 60+ HP per liter, w/ some at close to 80 hp/liter).
Many exhaust systems we design, build, install, and test in the field actually go "negative" at speeds of about 60-80 load because of a suction that must be being created at high speeds and the way the exhaust exit the system.. We use a differential pressure gauge to measure the pressures and are quite sure of our reading.......
I would like some input from some of the real engineering that read this forum... Please do make this assumption.. My reading are correct, the engines are loaded and applied per the manufacturers recommendations and history of these exhausts and engines have show no issues for 1000's of operating hours.........
My question is: Why would there be a limit or requirement as to minimum exhaust back pressure for a high performance turbo aftercooler 60+++ Hp/liter diesel?? My only assumption is that "they" are afraid of "over boost"........
Please help me to understand what I cannot seem to reckon with...........
Thanks, Tony
Tony Athens