Direct injections effects on police and service vehicle engines

[64bawagon]

Why would the out of spec. oil [HDEO 15W-40] damage an engine it the cold start temps weren't an issue?

They often sat outside for periods of time in harsh winter conditions, cold start temps were an issue. These cars were not garaged and many were only used periodically or for only one shift at a day. I am not an engineer but I think if Ford and GM thought 15W40 diesel oil was a good idea they wouldnt have specified 0W20 seeing as they are the ones that designed, built and warrantied the engine. This is aside from the cumulative loss in MPG running thinker oil. In the end it wasnt my monkey so it really didnt matter what I thought. It was one of those "thats the way we have always done it" justifications.

 

[IndyIan]

I'd love to know the 'top 5 bad things' a carbureted engine did compared to direct injection.

The carb on my 1981 Omega was not great, but we also had an 1985 Corolla and I remember the carb worked flawlessly for near 200k miles until it got smashed. It also made 68hp out of 1.6L so it probably was just running a bit rich most of the time unless it was -30C.
I guess a healthy well tuned carb isn't really bad, but probably half the cylinders are running a bit rich and the outer ones are good, its not as efficient of course.
IMO port FI is "good enough" and at 10+ years, that's what I want in my cars. KISS is better than chasing the last 2% of efficiency.

 

[Kira]

IMO port FI is "good enough"

Yeah. Someone here (I think) mentioned a dual system for DI engines.
It included an additional injector positioned such that it sprayed gasoline down the intake manifold to clean it. It operated only part of the time.

 

[loneryder]

An old bug could even do 70? I was stuck behind one merging onto the highway last week. Not only did it stink but holy cow, I thought I was going to have to dip into my retirement savings by the time we were doing highway speeds.

On topic, I think DI is not going to be an issue in cop cars. I think they are more likely to go out of service due to body damage or transmission failures than engine issues caused by DI. I do think hybrids would make good cop cars though, although that's a different topic.

My gas pedal was on the floor.

 

[Exhaustgases]

They all need to be electric.

 

[SC Maintenance]

Yeah. Someone here (I think) mentioned a dual system for DI engines.
It included an additional injector positioned such that it sprayed gasoline down the intake manifold to clean it. It operated only part of the time.

The cleaning part is the side benefit - is my understanding.

The issue is sizing a DI is difficult. To get it big enough injector to have full power, its too big to be efficient at idle. MPI is actually more efficient at idle and low speed / low loads. DI shines at higher RPM/ higher loads.

So my Toyota uses MPI at idle and just off, then there is a hand off to DI. At the very top end supposedly they can both come on to deliver enough fuel if needed. The fuel mileage on this car, given its size, I find pretty amazing.

 

[meep]

^^^ the ford ecoboost I have uses the port FI more often than one would think, similarly above. It is used under idle and no load. The DI fades in as the engine is doing work, and the port injection eases off. At the top of the power band, the port injections comes back in and adds to the DI. Most of the time, except for maybe 25% of the operating range, both systems are doing something.