I stand ever so humbly corrected. So when a diesel engine is under load and over fueled and makes loads of black smoke due to unburned fuel there is still an "excess of air just along for the ride"????
Sorry, with all respect, does not compute in my world of reality and diesel experience. So, if you would be so kind, "splain" to me just how the engine limits the fuel load based on the air charge? What, other than throttle position at the IP, limits fuel volume at the injector for each RPM of the engine? My humble understanding of physics tells me the turbo extracts heat energy from the exhaust path and converts that to mechanical energy resulting in compressing an additional air charge into the intake path. This translates into a more oxygen rich block of air in the cylinder at the compression / ignition stroke. Additional oxygen supports greater expansion and more complete burning of the fuel supplied at injection which transfers heat energy to mechanical and drives the piston down [power stroke]. More oxygen plus more fuel makes more heat energy, thus more power. To support combustion successful engine physics requires a stotsimetric (sp) ratio of 11.2 to 13.6 . Adding fuel or air outside that ratio band will fail combustion, or at least impact efficiency. Please correct me where I am wrong. It's been working for me for about 30 years now with Mechanical Unit Injection. Grant... AZ On Fri, Jul 15, 2011 at 3:41 PM, Fmiser <fmi...@gmail.com> wrote: > > G Mann wrote: > > > With the turbo working correctly you are now getting a much > > increased air charge into the engine. > > Correct. > > > More air in a diesel means more power with a moderate increase in fuel. > > Not so correct. :) Except an wide-open, max power a diesel > engine always has an excess of air. The fuel injected burns > only as much air as there is fuel to burn. The rest of the air > is simply along for the ride. > > Simply stuffing more air into a diesel engine increases the > effective compression ratio. This means it is able to extract a > bit more mechanical force from the fuel it does burn. Running a > turbo-supercharger scavenges exhaust heat to drive the intake > compressor. This compressed intake air overcomes pumping losses > as well as increasing the effective compression ratio. Since the > exhaust heat is otherwise thrown out the tailpipe, using it is > big part of where the _efficiency_ is gained. > > > Less air ment you had to push more fuel into the combustion > > process to expand and drive cylinders but it's a losing > > combination power wise in the Suck, Squeeze, Bang, and Blow > > equation. > > No. Less air means less fuel _could_ be burned because the > engine limits the fuel load based on the air charge. Less boost > means lower efficiency _and_ less maximum power. > > -- Philip > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
