Mechanical piezo injectors would complicate some things, but uncomplicate others, and also remove a lot of issues.

Ceramic coated engine parts would make the engine hard to warm up. I'm sure a exhaust heat to coolant heat exchanger could be used. And that might even be better, as the engine could keep warmer than normal in cold weather. Ceramic coating could boost mileage, and allow for high EGT's without causing heat stress cracks.


The funny hydraulic crap I spoke of.... well what I meant is that the TQ converter could be replaced with a positive displacement pump design, so that it can provide 0-100% engagement by adjusting the flow out of it. In essence the tranny could operate a lot like a manual tranny, engagine every gear fully, instead of the sloppy mush feel that the TQ converter gives you. Whats the point in having a low end TQ diesel, when the TQ converter slips enough that you hit 2000+RPM's without even trying???
Think 7.3 with TC lockup mod, it might feel a bit like that,, but yet with softer shifts.

 

Torque converters give you torque multiplication off the line, and when locked up are more efficient then a hydraulic pump. The only reason these transmissions have soft, mushy shifts is because most users want that. They don't want to feel their shifts. As I said, most modern transmissions are completely locked up in 1st gear, and the cutting edge transmissions (ZF 8 Speed, several others too I assume) keep the converter locked even during shifts.


Injectors with their own mechanical fuel pumps are just a bad idea. Instead of having one central high pressure fuel pump, you now have 8 individual pumps, 8 pressure regulator solenoids, and 8 fuel pressure sensors. Add to that 8 more cam lobes, 8 more rockers, and 8 more pushrods. A single high pressure pump is a far more elegant solution.


You still haven't addressed the fact that constant high combustion temperatures greatly increase NOx emissions - which will need to be addressed with more SCR. EGR wouldn't work because it would decrease combustion temperatures, negating the purpose of running hot. Then you have your exhaust/coolant heat exchanger - adding more complexity to the engine.

 

Sorry, I hacked my comments into your comments; it was easier lol.

 

Quote:

I don't intend to mean a hydraulic pump in the sense I think you are getting... I mean that the current TC is technically a pump, and my idea is that it would be replaced by a positive displacement pump. Blocking flow would lock it up, thus it would not be inefficient. It could operate much like a manual clutch, although the computer could control it to soften shifts as well. All the pickup trannies I believe only lock up in OD.

Then you loose torque multiplication, and all the fluid being bypassed will be lost energy and heat.

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Injectors like this already exist. I read a bit about them, they don't seem too bad.

They're just mechanical unit injectors. They operate at far lower pressures, and they're not piezo. They just have a dump solenoid to dump excess pressure. They've been replaced by common rail systems in almost every application.

You're still not addressing my point about high NOx. No vehicles are expected to output low emissions while wide open. Your theoretical engine would be producing huge amounts of NOx - all the time.

 

http://www.google.ca/url?sa=t&rct=j&...KGPYBvSQYazg9Q


They operate at up to 37,000 psi, and were emission compliant till 2010, i'm sure they could be used further with slight mods.

 

Yes, you would lose TQ multiplication.

Vehicles are exempt from emission laws at high output?

 

I was not aware of those more modern unit injectors, but still. You trade off one high pressure pump, for much more complicated injectors.

Vehicles are not necessarily exempt for emissions at wide open, but for example, most vehicles go into open loop and enrich the fuel mixture while wide open.

 

...more complicated injectors... yes... but if you really think about it, I think a system like this would prove to be more reliable.

The NOX might be able to be controlled with EGR... but POST DPF EGR.
And then DEF injection, also.

I don't know all the answers.

I can't see how these trucks would be allowed to hit 1200 EGT's legally while under heavy loading,
Yet unable to do the same a highway driving engine load, caused by tuning?
Just cut back the boost as far as possible while maintaining allowable NOX levels.

Maybe it might still need a regen cycle, but I imagine this would keep the DPF clean most of the time.


Kind of like 3 modes: regular driving, static regen, and full out regular regen.

 

EGR reduces combustion temperatures, negating what you're trying to do.
Because the average emissions standards allow for it.
Diesels need fuel and generate exhaust heat. Cut back boost and you get less power, more soot, and higher exhaust temperatures.

 

EGR reduces PEAK combustion temperatures.

Before the smoke, you get high EGT's.
That's what I'm talking about.... not choking it right off, but giving it JUST enough air to burn hot as hell and pass emissions.

 

I wouldn't go that far. Remember several engine manufacturers were wanting to use Urea to meet the 2007 emissions level but the EPA nixed the idea because they didn't want a system that relied on user maintenance (adding def) to function properly. Mercedes had their bluetec engines up and running in Europe and were told no by the EPA. All the other manufacturers were also forced to invest in other technology instead of the urea which many though would work the best.

I don't know. Maybe they've just decided it was cheaper to pay the fine and keep one motor in production while working on the next round since the emissions requirements seem to be changing at such a rapid pace now. Instead of meeting every new level, maybe just pay a fine and meet every other one. Parts, service and R&D might be cheaper that way. Besides, how many fleets refuse to buy "unproven" technology like a motor that has only been out a couple of years? With the rate of EPA changes, by the time the bugs get worked out of a platform, it's time to change it again.

Fuel mileage is important, but you can't get good enough fuel economy to make up for down time due to a non-working truck.

Amen. Or at least offer a couple of different diesel motors in these trucks. You can order different diesels in the bigger trucks. You can order different gas motors in these and the smaller trucks. Why not offer 2 different diesels and let the buyer choose what they want?

I agree the horsepower wars are a large reason these manufacturers are doing what they do, but I really wonder what the prize is for winning the war. Diesel fuel now costs more than gas. With the emissions junk, fuel economy isn't high enough to offset it unless you put on a whole lot of miles towing.

The buyers that are left end up being the die hard diesel loyalists who are usually pretty brand loyal anyway. How many will anyone really lose by shaving a few hp to gain in mpg's? The guys who demand more power are likely going to tune them above stock anyway, so what's the big deal?

 

That was mainly because there was uncertainty on what would happen when you ran out of DEF. The EPA was satisfied with the trucks giving adequate notice before hand, limp mode, then eventual complete shut down.

 

The EPA is satisfied with limp mode and shut down currently, for the 07 phase in, they didn't trust it.

 

Great read guys. Keep it going, yall may come up with something.

 

But the 2010 engines aren't the same as the 2007 ones. The Maxxforce 7, for example, used a single turbo for 2007 and a dual sequential setup for EPA 2010. They did spend the dollars to redesign things, and this simply wasn't enough and therefore they had to pay the fines. I don't think it's likely that their engineers were incompetent enough not to foresee this happening; I think they decided to only go half way meeting the standard for some reason.


Agreed, fuel economy means nothing if the reliability isn't there. But from what I've heard they didn't get either of them right.