another forum brought me to wanting to ask the Tech guru's in here about the desing of the top of the pistons in Diesel engines. Esp. the DI's of the recent past and up to what is in production today.

Im wondering which (if any) have a design on the top of the piston made for enhancing the automization of the fuel... via a cup or some other form of indentation or pocket on the top of the piston. This seems to be the design in the VW diesels and was told also the Ford powerstroke diesels.

Also if anyone knows..... which of any of Ford (or any other diesel engine for that mater) engines have injectors aimed with the intent of keeping fuel from contactiing the cylinder walls. As I understand it; this is the VW design being used in VW diesels with the specially shaped piston tops. I have not confirmed determined if this is also true with the Ford powerstroke. Anyone in here know?

I don't think so, at least on the 7.3, but I'm not sure. I know the idi's (6.9 & 7.3) used an essentially flat top piston, but they have a precomustion chamber, and piston shape would make little difference. I am sure that they put quite alot of engineering into shape, esspecailly on the 6.0
~John

"I took a picture of the "cut away" PSD at the
Detroit auto show last year showing the #8 piston, injector and rear of the drivers side intake. The piston has a round "cup" as you described, looks like the cup is half the diameter of the piston and .150" to .250" deep.

hmmmmmmm

Originally posted by jaluhn
I don't think so, at least on the 7.3, but I'm not sure. I know the idi's (6.9 & 7.3) used an essentially flat top piston, but they have a precomustion chamber, and piston shape would make little difference. I am sure that they put quite alot of engineering into shape, esspecailly on the 6.0
~John

You seem to contridict your own words. Or is the two 7.3's you refer to here different engines; one IDI and one not?

7.3s and 6.9s before 1995 were IDI, while the 7.3 after 1995, aka Powerstroke, a totally different engine, were and are, direct injection.

Nope, the psd and 7.3 idi were both availible in 94.
83-87 used the 6.9 idi non tubo engine, 88-92/93 used the 7.3 idi, which was a bored and stroked 6.9. Some 93 and 94 7.3 idi's were avalible with a factory installed ats turbo system, and are often called 7.3 turbo diesel. These are not the same as the 7.3 powerstroke. Starting in 94, and continuing through early 03, they used the 7.3 psd, which is an electronic, heui turbo diesel. Starting this year, they introduced a 6.0 psd.

The idi engines used a removed combustion cahmber, and run a 21:1 ratio. (I think) The high compression ratio limits them to 10-12 psi boost, athough they seem to hold up with out any trouble. The 7.3 psd is a completly different engine, using electronic direct engine, with a 16:1 compression ratio, and factory turboed. These engines are capable of around 30 psi boost mostly stock, and can hit 100 with some mods.

BTW, all the ford diesel are actually international / navistar engines, and most parts are availible through IH at lower prices than ford.

Any other questions? As you can tell, I know absulutly nothing about these engines. :)
~John

Ok since you know nothing about those..... do you know nothing about International engines too?

Like Im trying to remember which Unimog a guy told me about that a IH 4cyl will bolt up to the Mercedes tranny. It was either a 406 or a 416 Mog.... I cant remember for the life of me and I cant find it in a search. hmmmm then again maybe this is a Mog question not an IH one..... hm :flipoff2:

Back to Swirling piston chambers: So do u seem to think most all DI engines have some type of swirl chamber on the piston head?

Sorry, according to Ford , 1995 was the first year of availability for the 7.3 direct engine, while 94 was the year when they went from the availabilty of the non turbo 7.3 to the turbo'd version, which was only produced for 6-8 months.

Originally posted by liliysdad
Sorry, according to Ford , 1995 was the first year of availability for the 7.3 direct engine, while 94 was the year when they went from the availabilty of the non turbo 7.3 to the turbo'd version, which was only produced for 6-8 months.

nope, you're off by a year...I own a 93 with a factory turbo, and looked at about 15 others before I bought this one, and also looked at many 94's with the powerstroke. My father also owns a 94 with the powerstroke. Finall, it's quite easy for me to go to the dealer, and get parts for my 93 with the IDI factory turbo, and to go for parts for his 94 powerstroke. If on the rare chance that they were converted by others later, ford would not have any parts listings for them...:rolleyes:

I have heard this several times, and we all know how weird ford is, but according to Ford Motor Company, what I said is, in fact, accurate. But, like I said, Ford has been known to deviate from assembly line normalities quite frequently.:confused:

Originally posted by coachgeo
Ok since you know nothing about those..... do you know nothing about International engines too?

Like Im trying to remember which Unimog a guy told me about that a IH 4cyl will bolt up to the Mercedes tranny. It was either a 406 or a 416 Mog.... I cant remember for the life of me and I cant find it in a search. hmmmm then again maybe this is a Mog question not an IH one..... hm :flipoff2:

Back to Swirling piston chambers: So do u seem to think most all DI engines have some type of swirl chamber on the piston head?

No idea.

I'm not sure about the swirl question. All engines are going to attempt to create a very turbulent air charge at the moment of injection, but there are several differnet ways of doing it. The cupped piston is probably most commen, but I'm not sure.
~John