Hi all , I’ve been reading that on road emissions standards for diesels may be relaxing in the US and it made me wonder if this could extend to locomotive diesels .
I keep wondering if something between Tier 3 and Tier 4 standards could allow the manufacturers to produce units with a bit less complexity and increase reliability - and better fuel consumption .
Thoughts …
I doubt you will see any changes. The railroads have found that having their older power rebuilt is cheaper than going new. And the new power that is built, at least on the freight side from Wabtec, is doing just fine reliability wise.
You have to read up on what they are relaxing. It looks to me like a very minor change in minor areas and the strict provisions are still in place.
I was under the impression that the Tier 4 units including Wabtec were having reliability/maint issues and aren’t particularly fuel efficient .
EGR was never going to be friendly to diesel engine efficiency , cooling and filtering exhaust gas is always going to be problematic .
How much is due to reliability, and how much is it due to reduced maintenance and engines being ran a lot harder than in years past? I.e. trains that used to have 2-3 engines normally are now being run with one in the name of fuel efficiency?
It’s not “that” bad as far as the principle of diluting the charge with spent gas on a modern road locomotive goes; even at 1050rpm there is reasonable time for the compression ignition to be polynucleate and for oxygen to combine with fuel-vapor constituents. There is also relatively lavish packaging volume and weight-bearing capability to implement both EGR and charge-air aftercooling on any modern engine that already needs ‘six axles’ to support its weight using one common truck/bogie design. You might think of it as a gas-phase analogue of water injection, producing ‘comparable’ piston thrust from lower actual fuel mass flow and not just keeping peak combustion temperature low. Remember that the ‘edge cases’ where EMD’s cost-effective EGR design failed to reach Tier 4 final were only a small percentage of NOx over a few percent of the duty cycle.
Most of the horror stories with EGR come when you try to use it on high-speed engines developing higher specific horsepower, packaged to fit in light-as-possible road tractors that are then ‘built to a price’. That produces disasters like ACERT that like syphilis are only a gift (in the German sense) that keeps on giving. I have yet to see a compelling reason to use EGR on any small combustion engine (vs. proportional SCR/DEF to accomplish the same NOx reduction) and of course it is not the same as FGR from a combustion-engineering standpoint.
Woke then come to any OTR industry shop and see even with SCR and DPF systems in addition to EGR on these engines what happens when they fail. BTW those engines are the same displacement and weights they were 30 years ago when all of these emissions systems were mandated by the EPA. It’s not just the OTR industry that has massive issues it’s agriculture mining construction it’s everything. Why because EGR in a diesel does 2 things it causes the fuel to not burn completely due to lack of oxygen and creates more soot which causes the intake valves to carbon up. It also creates minute amounts of sulphuric acid in the exhaust which gradually eats the valves the EGR cooler and causes systemic damage over time.
25 years ago the B50 that’s the before 50 percent of all trucking engines needed an overhaul was 1 million miles. Last year it was 600k miles. The Cummins ISX which is the last engine that is still based off the pre emissions systems engine the pre 07 models have a B50 of 1 million miles. The 2022 model year is barely making it to 500k before needing a 50k overhaul.
Detroits 60 series line those that are still out there are running between 1.2 to 1.4 million miles between overhauls from everything I’ve heard from my contacts in the industry. The DD15 it’s replacement from 07 onward they’re lucky to get 700k on one before they either blow head gasket or have a rod daylight the block.
Navistar and Paccar are not even in the picture with reliability.
Even Scania with their V8 775 in Europe that doesn’t require any EGR to run only SCR systems with DPF they can’t get the reliability up to prior to 2000 standards. It’s not just the EGR systems that cause the problem it’s also the DPF and SCR systems added on. DEF is extremely expensive and not something you want around diesel fuel. There’s been times were that fluid has via overpressure found it’s way into the diesel fuel tanks. We’ve all seen that YouTube video of the dexcool mixing with oil that turned into jello. Def in diesel is that times 100.
Harold: With diesel at $5.00 or more I read that OTR is hurting. True?
One my list of things I am concerned about, this one is #842.
There’s no doubt that they are hurting right now. The average time to pay for a bill of freight charges is around 60 to 90 days. So these guys are getting hammered in the wallet with fuel costs. I’m hearing rumors about carriers slowing down trucks imposing idle time restrictions. One small carrier near me has stopped running into California entirety for now. The next few months are going to be utterly brutal for the logistics industry in the USA between the loss of almost 200k non-domiciled CDL holders nationwide plus a 66 percent increase in fuel costs. To put that in numbers per mile when fuel was 3.50 a gallon average it was about 55 cents a mile fuel costs. Now your almost 90 cents a mile.
Yeah. I think it was just greenhouse gases, CO2, being relaxed.