Just so you guys know, I had the original 7.3 IDI non-turbo before my V10. I have always wondered why Ford or Navistar got rid of the 7.3 Powerstroke. Is there a reason they didn't just produce some 4 valve heads and a higher PSI injection pump and call it good. It seems like it would cost a lot more money to make a completely different engine then to just upgrade the tried and true 7.3.

 

I think it has alot to do with our government's emmision requirements.. the 7.3L would not meet the new requirements.

 

Good question. I've often wondered the exact same thing. One of the gurus will surely chime in here.

 

It was mainly the new Diesel Emissions standards that killed the 7.3.

 

By the time you bolted all of the crap onto it to make it cleaner, it would bear little resemblance to the 7.3 that we all trust.

 

So why were other OEMs like Cummins, Isuzu (Duramax), Caterpillar, etc... able to incrementally upgrade their proven designs to meet the increasingly strict emissions requirements, while Ford/Navistar thought it necessary to start with a clean sheet of paper?

And just look what Ford/Navistar came up with, an engine that was so bad it had to be scrapped and completely redesigned a few years later to meet the next tier 2007 emissions, while the other OEMs just made another incremental upgrade to their tried and proven designs!

I think the Navistar dream of a "Camless Diesel" that's discussed here... http://findarticles.com/p/articles/mi_m3012/is_5_180/ai_62685781 is what drove the "clean sheet of paper" approach to meeting the 2003 emissions requirements!

Also, vendors have built in conflicts of interest that push them toward new designs because they need to keep their engineering staff fully employed and abreast of the latest technologies, and that requires billing their customers (that's us BTW) for non-recurring development costs, as in new engine designs.

 

Great answer, ernesteugene.....The 7.3L was still around (2003) long after the duramax had made it's debut (2001).........You still have the duramax (6.6L), which has been upgraded several times since then.......(increased hp and tq)......

Could they not have done the same with the 7.3L? Personally, I like the larger displacement engines.....Could they have incrementally increased the hp and tq of the 7.3L to remain competitive with the cummins and the duramax, and also increased the emission standards? BTW, how much does the ENGINE have to do with 'cleanliness'?.....Seems like a stupid question, I know.....But they made the fuel itself cleaner already (ULSD 15ppm) and put particulate filters on the exhaust......

COULD they create an efficient, reliable, relatively powerful 7.3L compliant with the current standards?

Oh, if only........I just don't trust the new 6.4L.....Sorry.

 

Gene you are right, the others didn't change the size of the moter but they all redesigned didn't they? The Dodges when to the new style CR, the Durmax's went with the new design, and Ford downsized displacement for the emissions equipment. I just can't imagine a 7.3 with a EGR.

 

The "Navistar Unveils Camless Diesel" article was written in May, 2000. Very interesting. They were shootining for 2003 production and 8 years later they still haven't figured it out. Doesn't bode well for the future of Ford/Navistar cooperation. Wasn't Ford thinking about building its own diesel? And what about the F150 diesel, any more recent news on that?

 

Because none of them were 7.3L. They were all under 6.6 (I guess Cummins managed to squeak out a 6.7)... I think the raw raw displacement was a huge problem to overcome even with 4V heads, EGR, etc, etc.....

Didn't Cummins just get their peepees slapped because of sending a detuned engine for testing but had a different tune in their actual production engines?? I think it was them, but it was the big truck engines, IIRC.

Anyway, it was the emissions that did it in. I think it's goofy that they took the 7.3, which gets a solid 16-20mpg depending how you drive it, and gave us the 6.0/6.4 that gets 12. Does all that extra fuel not equal diminishing returns??? I'd like to know why we have to keep kissing the tree-huggin' peace queers' asses. Does nobody have the testicular fortitude to tell them to stick their caribou, global warming, and offshore "eyesores" up their well-worn kiesters??? I guess not. They even have GW talking about this stuff. The last thing he needs to do is cave to these loons in his last few weeks in office. I'll get off my soap box now. I think I've probably crossed the line already anyway...

 

The easiest way to meeting the emissions standards and remaining competitive in the horsepower department was to build a higher revving engine. The 7.3's weak bottom end was it's downfall, it can't handle the rev's so they needed an engine with a stronger bottom end (the 6.0).

Everybody also seems to forget that the vt365 had already been successfully in service for a couple of years in medium duty applications before Ford got a hold of it.

 

I won't bore you with too many details, but the 5.9L Cummins and 7.2L Caterpillar didn't need or use EGR to meet the new 2003 emissions spec, and the 6.6L Duramax added EGR to get ahead of the curve prior to 2007. They also both strengthened their short blocks without a complete redesign using stiffer base plates, etc...

Sure there's been some changes over the years, but in the big picture the current 2007 6.7L Cummins is just a bored 5.9L, and the 2007 6.6L Duramax and 7.2L Caterpillar are also the same as their older pre 2003 emissions engines. Even though CAT discontinued their HEUI for 2007, it's still the same basic engine as the old 3126! BTW, the CAT C7 was still venting their crankcase to the atmosphere as late as 2006, because until 2007 the crankcase emissions weren't counted in the EPA spec.

Now the 7.3L vs 6.0L vs 6.4L ARE completely different engines, and for no good reason other than inept decision making at top management levels!

 

I thought the 6.4 was a slightly bored 6.0 with common rail fueling... Am I wrong? I read somewhere that the base engine was basically the same, and I can't recall where.

 

I disagree with you there Gene. Navistar's real mistake began with the 7.3 and their choice to go with the dead end technology of the HEUI fuel system.

The duramax was designed with tier II emissions standards looming, they built the engine from the ground up to be cleaner. The cummins and your cat being an I-6 are just a much stronger and more versatile block than the v-8's.

The 7.3 was going to need new castings for the block and completely new heads to remain usable under Tier II emissions standards. The VT365 was already up and runnings successfully and was a much more suitable platform for the emissions equipment.

The 6.4 is a variant of the VT365 block.

 

Thanks for confirming -- that's what I thought...