• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

New pre-cup idea?

THEFERMANATOR

THEFERMANATOR

FRANKENBURBAN
Staff member
Moderator
Messages
10,567
Reaction score
5,758
Location
ZEPHYRHILLS FL
With me being at home stuck not working due to my recent hip reconstruction, I have had much time to sit and watch youtube videos and ponder things. For those tha thave seen my link regarding the MERCEDES IDI's and there potential, has anybody considered having a custom pre-cup made for a 6.5 simliar to those of the more modern MERCEDES IDI's? I don't think the precup of the OM604/5/6 would work in a 6.5 as it is a 4 valve per cylinder hemi type head where the injector goes right down through the center of the head. But the OM601/2/3 head design is that of a valve per cylinder offset inejctor design. it would require a custom piston to work, but it has proven to be a MUCH more efficient design. There are people out there with the 3.0L OM603 6 cylinder 2 valve per cylinder engine putting down over 400HP to the wheels. It would seem to me that if this precup, piston, and injector design could be adapted to the 6.5 the possibilities would open up a whole new world of potential.

Heres some links to some pics I found of the OM603 head, and pistons.
http://www.peachparts.com/shopforum...ale-wanted/310990-om603-17-cylinder-head.html
http://www.benzworld.org/forums/sale-wanted-trade-giveaway/1534628-om603-22-cylinder-head-sold.html
 
Pretty much. it is a rather unique design, but when a 3.0L, straight 6, 2 valve per cylinder engine can make over 400HP to the wheels, that is somethin(the 4 valve per cylinder design is capable of 600HP to the wheels). Not to mention the RPM potential of this design. It would seem to me somebody could make a pre-cup that protrudes down into the cylinder that uses multiple holes instead of the single hole, a piston with a bowl in it to accomadate the protruding pre-cup, and a bowl design to direct the combustion event and get pretty dang close to a direct inejction engines efficiency without the needed higher pressure injection and noise associated with it. It's just a thought I had while sitting on the laptop here laid up.
 
I know quite a few guys have asked about converting the 6.5L to DI, a set of pre-cups liek these and a deep dished out bowl would be about as close as one could get on the older 6.2/6.5 platform without completely reworking the injection system, heads, pistons, and everything else to support it. A deep ricardo bowl with a pre-cut designed to redirect the combustion into multiple areas instead of just the one like current pre-cups do could work out well in overcoming the IDI's downfalls. I need to find some of the other links I found showing how these pre-cups and injector combos work. It is quite interesting to see how MERCEDES laid them out.
 
Les, I don't see anything else that could be an injector?
Also about that X pattern, it looks like the metal has been eroded or machined out?
 
Not sure if I'm right but given the title of the thread I'd assume it's some kind of inverted precup with the injector behind it still. Be interesting to know how many miles to get those marks in the head
 
The pre cup, bubble shape with multiple outlet port in x pattern, is held into the head with a funky threaded ringlet nut. The injector threads into it and sprays into the pre cup. When it ignites, it is inside the pre cup first, then the flame fires out those ports you see causing the burning marks on the bottom of the head on its way to ignite the air fuel mixture in the cylinder. The pressure is slightly higher in the pre cup area under compression so it ignites in there first. I wish I could find the factory video on it for you guys that I saw a couple years ago. It was slow motion, you can see the flame front fire out of the pre cup area into the cylinder.

The guys in colder climates showed more burn marks quicker, so glow plug burns cause it to happen quicker. I cant imagine how hot it has to be to fire with out gp because mine is 130,000 miles, great compression and needs gp in the summer here to start.
 
OH Ok so that dome is a cover or part of the precup. I thought it was a nozzle sticking though.

Thinking out loud: On a 6.5 what if you machined the precup so just enough material stayed so head gasket could still seal. Basically hog out the precup so injector fired right into the cylinder. What are the side effects going to be? Seems like a real large precup hole is almost doing that anyway?
 
It is still an indirect injection engine. It uses a rather unique precup design with a bowl that the injector fires into. Then the flame front travels out through multiple openings instead of just a single. The pretruding part from the head is the actual precup. With everybody out there now trying new things, it would seem to me the next step would be to use more modern precup designs.

Hogging out the precup and making the 6.5 moreso into a direct injection engine wouldn't work well as the DS/DB pumps just don't have the required pressure to work well as a direct inejction engine. The 6.5 needs pop pressures in the 2100-2300 PSI range to run well(this mercedes design they say works well at 1950), a direct inejction engine needs to be upwards of 4000 PSI just to run cleanly(a good example is the 12 valve cummins with the P7100 pump runs upwards of 21000 PSI at RPM's over idle speed). I would think one could build a precup that protrudes in and utilize the multiple openings instead of just one large one. The MERCEDES guys are making unreal HP out of IDI's using this technology, it would stand to reason if one could adapt it to a 6.5 it could help bridge the gap between IDI's and DI's.
 
Definatly logical thinking, thanks.

Another ?. Is the Merc's injector directly behind the precup or in its stock location? (mabye that is its stock location). So as the fuel in precup fires the flame is disbursed out those holes. Where does the extra power come from? just due to the difference in fuel placement in the cylinder? or is it because of piston shape? Got any pics of the piston they use?
 
Burning oil said:
Definatly logical thinking, thanks.

Another ?. Is the Merc's injector directly behind the precup or in its stock location? (mabye that is its stock location). So as the fuel in precup fires the flame is disbursed out those holes. Where does the extra power come from? just due to the difference in fuel placement in the cylinder? or is it because of piston shape? Got any pics of the piston they use?
Click to expand...

Heres the best picture I could find of the style piston they use.
51332d1200183589-240d-piston-img_1289.jpg
Heres a general layout of how the pre-cup, glow plug, and injector are layed out inside the head i nthe MERC engine.
91233d1302585637-om603-glowplugs-w-glow-plugz.jpg
You can see here the pieces of them. The pre-cup is installed and set in correct alignment to the chamber and the glow plug hole to match up. Then a locking ring goes in the top to hold it in place, and the injector is threaded into the locking ring.
prechambers.jpg
It would be difficult to make them one off, but it would seem to me that somebody could make a pre-cup that is flat by teh gasket surface, then make a protruding finger sticking down similiar to that of the MERCEDES design to help distribute the flame from the precup over a larger area of the cylinder. Essentially the MERCEDES design moves the injector and pre-cup more to the center of the combustion chamber, and uses multiple holes to project the flame front out of VS just one single opening. The 6.2/6.5 pre-cup design is essentially the same as the one that was in my old 10HP FAIRBANKS MORSE I had from the 40's. if somebody could get a set of precups with multiple opening to distribute the flame front out multiple openeings instead just teh 1 large one, it could help to reach the increased efficiency the MERCEDES design achives in theory.

It's just a thought I've been having, but it is hard to deny that this design WORKS when peopel are getting these kinds of results from IDI's.
http://www.thetruckstop.us/forum/showthread.php?41609-If-I-was-to-buy-a-mercedes
 
You must log in or register to reply here.
Back
Top