Prechamber Mod "Flame" Front

OM616

10mm MW

572

12-24-2012, 03:05 PM #246

(12-24-2012, 11:08 AM)MFSuper90 I've got most of my stuff made for my prechamber puller, now just waiting on the shimano crank puller.
om616,
so you are Increasing the holes to .125 or .136 and opening up the tube to 14mm?
What effect does opening up the tube have, and what tool did you use since the PC are so hard?

Many thanks,
Eric

I am not at home so I do not have access to my notes to refresh my memory, so I will not quote any specks, but explain what the thinking was behind them.

Well, I can say that I am currently running .136 dia burn holes on my 616 turbo that uses the old style, (flat bottom) PCs.

Now it is important to note that the 616 and 617 NA PC have a smaller burn tube ID, (the tube that connects the burn holes to the injection chamber), than the 617a. ( I do not remember exactly what the Burn tube IDs are between the two right now).

My goal was to put as much of the pressure head at the Burn tube, as to achieve a higher velocity during compression, (better Swirl).

The .136 Dia burn hole total area, is X% greater than the 616 burn tube ID area. Now the 617a burn tube ID is larger, so to achieve the same % difference, the holes will need to be larger, or an additional hole added, (this would allow all the holes to be smaller while increasing total area).

When I change the injectors out, on my 616 turbo, I am going to increase the burn hole dia again, but again, I do not remember what that will be. Getting old sucks!

Now that I remember, Some one did PM me about opening up the holes and I for got about getting back with them! Sorry to who ever that was.

Anyway, you want to use a carbide reamer and some cutting fluid for steel to open up the burn holes. You will need to go in steps to open up the two little ones on the other side of the three main holes, (leave the bottom drain hole alone). The holes are on angles so be sure to match them when you open them up.

With a reamer, you can only increase a hole so much, it is not a drill, so if you go to, say, Production Tool Supply, or another machine tool supply, bring the PC and they will be able to tell you what reamers you need to open all the holes up, and they will have the cutting fluid as well.

I did not open up the Burn Tube it's self, I only increased the ID of the injector seat as per the MB doc that is in this thread. I tried lowering the seat on the first batch and got a little too frisky by going deeper (quite a bit deeper) than MB called out, and one PC broke when I torque the Injector up. The second batch I only opened up the seat ID, I did not see that it was worth the time to lower the seat .040", when I wanted it a lot lower.

With the PC being able to fill (breath) easer, the air will reach ignition temp sooner, which allows for the injection timing to be advanced more, which increases torque and power. I am at the limits of my pump slots. It will also be able to be filled more completely so you can run more fuel which will increase power. This mod is just like increasing boost, as far a fueling is concerned.

EGTs will be lower and less / no smoke, more power, easer starting, and my engine is quieter as well. Now I ran the engine with the turbo and stock PCs for about 4000 miles so I could tell the difference with the modded PCs, that is why I am going to try larger holes, I am curious to see if there is more to be had!