jus2shy wrote:
Hybridhunter wrote:
No one questions the reliability of OTR trucks, and all of them are turbocharged, and DI, so the engineering and application far outweigh any potential complexity concerns IMO.
There's a few differences between a diesel and gasoline engine though that may have some core issues to sort. The transit industry has had similar challenges with natural gas engines versus diesels (nat gas motors don't last as long though they tend to be based on the diesel engine block). Some of these special considerations would apply for engines such as the ecoboost and any DI+Turbo gasoline motor are as such:
1. Hotter exhaust temperatures. Though Diesels have more BTU content per unit of fuel, gasoline motors with their stoichiometric burn get much hotter on the exhaust side. Diesel owners start worrying when they break 1,250 on exhaust, and really worry at 1,400 degrees F. Gasoline engines can tap 1,800 on sustained hard pulls, and just for kicks, nat-gas motors are nearly knocking on 1,900 on the exhaust side during a hard pull. Metallurgy becomes far more critical at those temps. So really the head, exhaust manifolds and turbine are subjected to harsher conditions in a gasoline/CNG motor than a diesel.
2. Ignition events. Gasoline motors tend to typically run nearly double the RPM of most diesels out there when there's a need to produce more power when not at a constant state of cruise (grade towing, accelerating, etc.). So you have more stroke events on a gasoline motor than a diesel typically over the same given period of time in those cases where power is needed. So potentially there is more wear. However, most people don't keep their rigs past 150k miles, so this will most likely be a non-issue except for possibly the used market.
3. Gasoline doesn't serve as much of a lubricating function as diesel in a fuel system. However I've personally never seen a DI injector fail at a certain mileage universally. So maybe the lower pressures and injection setup doesn't really rely on the fuel to serve as a lubricant and coolant.
These are just some of the special considerations that I'm aware of that can have some impact on reliability. However, any impact will should be felt much further down the road. However, I do find it funny that the GDI engines are allowed to put out a little soot while the diesels have to run squeeky clean. I wonder if the EPA will ever crack down on that.
Holy Krikey. Forest for the trees man!
My point was that the technology is not inherently unreliable, it's all in the execution, and even the simplest technology done wrong is unreliable!
