Pre Cups

[nmb2]

The IDI Ford cups.. Did they see sort of an evolution through the years similar to our 6.2/5's? Any pics floating around?

Not really. There is the first 6.9 cup which lasted for a year, and was changed to the cup that all 6.9's have after 83. Then the 7.3 came out and it uses a cup with 2cc more volume and that was the cup used, even on the turbo engines.

 

[buddy]

You would need to change the piston to match it. Also, you do not get your power from the flame front coming out of the pre-cup and hitting the piston. You get your power from the 'secondary' combustion that takes place in the main combustion chamber.

I dont think the piston needs to change just to use a wider flame front, and I am basically saying I dont think velocity is the key to great mixture in the cylinder. I would prefer great dispersion, distributed pressure across the piston rather than hoping the swirl thing works at elevated fuel volumes. And GM actually did this, not me or a science experiment, ran production that way for 4 years before switching to the DMax.

 

[nmb2]

I dont think the piston needs to change just to use a wider flame front, and I am basically saying I dont think velocity is the key to great mixture in the cylinder. I would prefer great dispersion, distributed pressure across the piston rather than hoping the swirl thing works at elevated fuel volumes. And GM actually did this, not me or a science experiment, ran production that way for 4 years before switching to the DMax.

and ford/IH didn't.....

If ford/IH did as well, I would be more on board.... but you have one company that changed cups 5 times.... and you have another that had 1-cup for the 6.9, and 1 cup for the 7.3

The design on the piston changed when the cups changed as well.

 

[buddy]

So, you think GM does stuff willy nilly, but Ford not taking action proves something? I dont buy that, and I dont think every company has the same level of expertise and R&D for all the platforms. GM makes some crappy engines and Ford makes some great ones, and then Ford makes some bad choices where GM makes good ones.

One thing Ford didnt have, was the US military buying them and footing the bill for some of the R&D.

 

[nmb2]

So, you think GM does stuff willy nilly, but Ford not taking action proves something? I dont buy that, and I dont think every company has the same level of expertise and R&D for all the platforms. GM makes some crappy engines and Ford makes some great ones, and then Ford makes some bad choices where GM makes good ones.

Its a two way street. You guys strongly base your opinions on the subject based on the fact that detroit changed the pre-cup design so many times. I say that if it was such a big deal, a company such as international/navistar would of done the same

One thing Ford didn't have, was the US military buying them and footing the bill for some of the R&D.

No, International didn't have the military buying their IDI's, but the 6.9/7.3 was used largely in Fleet applications, both medium duty, and light duty, as well as Ford pickup trucks. Uhaul being the biggest fleet probably... and I'll note that the engines had no design flaws or failures that required a redesign of anything after the very first year of production. The 1983 blocks crack around the block heater if its used, and they have less support in the casting on the front of the valley.

These problems in the 1983 6.9 can simply be avoided by not using the block heater.

There were never overheating issues, head cracking issues, broken main caps, broken cranks, worn out dampers.... ect. International got it right the first time is my take on it.... maybe it just took GM awhile.

 

[buddy]

Gm didnt have issues until they put a turbo on it, and even then it wasnt so bad if you kept the turbo boost at stock levels of like 6psi. They didnt do their systems engineering at the time, they didnt over engineer. Then they found out that more fuel needed wider precups Well and that higher cylinder pressure and temperatures required a better block. And then GM led the way in electronic diesel injection that contributed a lot of the other issues.

 

[nmb2]

Gm didnt have issues until they put a turbo on it, and even then it wasnt so bad if you kept the turbo boost at stock levels of like 6psi. They didnt do their systems engineering at the time, they didnt over engineer. Then they found out that more fuel needed wider precups Well and that higher cylinder pressure and temperatures required a better block. And then GM led the way in electronic diesel injection that contributed a lot of the other issues.

Its the difference between a medium duty engine, and a very light duty engine. The International was a work horse. International could not afford to have problems, since they were in service in such large fleets that needed a bulletproof engine. It needed no changes when a turbo was strapped on.

As for the Military helping with R&D... that's not good. The Military will take the cheapest route possible in my experience.

My point still stands.... if the pre-cup was such a big deal and needed to be modded as you claim, and as GM thought. International would of addressed this. I think you are just struggling through the dozens of other design flaws that are not fixable.

As far as GM leading the way with electronic diesel injection... that's a big negative. The T444E would be that creature, and although I hate HEUI, its a fact.

EDIT:

There are also rumors of a few 93/94 model 7.3 IDIT's that were test fitted with a DS4... Ford was getting desperate as the powerstroke was already 2yrs late into production.

 

[buddy]

Well, its not a big deal, but GM released the 1994 models of the 6.5 with DS4 in 1993 before the PowerStroke electronic direct injection came about.

Its also completely possible that Ford left well enough alone that worked like it was supposed to at stock fuel levels. Would you get any haze from a stock trim truck pulling along with boost?

 

[Twisted Steel Performance]

I wouldn't think that piston would work too well just by looking at it, but I'm not an engineer.

Whats the results of this piston in the engine its running in?

Just out of curiosity nmb2, what about these pistons makes you think they won't work very well ??

I'm not looking to say anything out of order either, just would like to hear your thoughts is all... and the build they are going in can be seen here...

http://www.thetruckstop.us/forum/showthread.php?35785-Yet-another-6-5-build-this-one-for-towing

I have just started the thread and only a few of the mods are shown , there will be more showing up later...

 

[ak diesel driver]

I think one of the factors concerning the precups is that the ford engines produce their power at lower rpm and don't need as much velocity thru the precups

 

[nmb2]

well, like I said, I am NOT an engineer.... but I just can't picture that piston working spectacularly. I am picturing the fuel droplets blasting the middle of the horse shoe on its face, spittling left, and right.... and instead of a clean uniform burn.... a dirty burn focused on the outside of the piston.

Once again, I could be out in left field... but that was my first thought.

 

[buddy]

I think that piston is the perfect design for this setup. Because it provides more surfaces to create turbulence and then a better containment of the combustion force before pushing into ring land. If you look at direct injection pistons, a lot of them are dished or bowls to create the combustion chamber. that will help keep heat and force from the piston edges, protect the rings.

 

[nmb2]

I think that piston is the perfect design for this setup. Because it provides more surfaces to create turbulence and then a better containment of the combustion force before pushing into ring land. If you look at direct injection pistons, a lot of them are dished or bowls to create the combustion chamber. that will help keep heat and force from the piston edges, protect the rings.

If you have good pistons, you don't have to worry about your rings.

Again, I don't know. It would be cool to see what happens with them.

 

[buddy]

If you have good pistons, you don't have to worry about your rings.

Again, I don't know. It would be cool to see what happens with them.

6.5 pistons dont have a lot of ring height. And not much a flat top piston can do about helping the situation.