Injector spray angle calculations

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bubba_pa

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Oct 30, 2007
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Trying to determine a tighter spray angle for a 12 valve injector so I can run higher timing with the stock pistons and still keep the pattern in the bowl. I don't want to/can't do an engine rebuild at this time.

Last year ran 26 - 29* timing and truck ran well. Has 0.020 over head gasket, thinnest injector washers. Using a stock spray angle of 145* now.

Can anyone supply me with the measurements of the crankshaft centerline to crank throw centerline; crankthrow to wrist pin centerline; wrist pin centerline to top of piston distance and finally the stock bowl diameter. I figure with a little drafting, math and smoke & mirrors I should be able to come up with an accurate number.

Otherwise if someone knows how tight the angle can be to get into the low 30*'s for timing I could use that as well. I can have a set made up to about 5* tighter. I know this will be a one-truck set up application as far as the injector, but I just don't see myself tearing the engine out to swap pistons.

If I'm crazy too, just let me know.

Thanks
 
Doesnt everyone. Factory bowl is 2" or around 54mm most of the bigger bowled slugs are 2.5" or around 63/64mm. If you started from a blank nozzle I suppose you could make the angle that would allow for what timing you desire otherwise your options are to cut the lip out of your stockers or purchase a set already with the wider bowl opening. FWIW another big advantage of a diff. piston design is to get away from that 8 or 10 mm TRL choose one with a 14mm land it will help protect the top ring.
 
As I understand I can go up to about 5* tighter on the spray angle (that's starting with blank/stock tips).

I know with some good numbers and accurate calculations I can come very close to what I need. Certainly the other way is to just tighten them up 2 - 3*, monkey with the timing as close as I can and see what it does. I don't want to go too tight and concentrate the fuel and worry about excessive heat either.

Not sure if I'm on a wild goose chase or not. But someone has to have the measurements and that at least won't give away any trade secrets on the injector angle.
 
Who is going to tighten them up 5°? How much into the 30's do you want to run? There are a few things you can do.
 
J.L. mach. the 5* is what my brain remembers.

What thoughts to you have otherwise? I know I wouldn't go over 35* and probably stick closer to 33*. I ran the 29* and truck seemed to run the best. It does have full cuts, 0.078 DV holders and stock lines. 5 X 0.016's set with 0.015" lift at 285 bar.

Just seeing what else I can do. Looking very strongly at an s400 2.6 charger at this time.
 
With a 140° pattern 30° would be about the limit without modifying the sleeve nut/nozzle to drop it further in the bore. I would see 32° as being the high side if done properly, maybe a shade more depending on the hone size you went with.
 
Thanks Wesley. Appreciate the info. My plan would be for some 5 X 0.018's that's how they thought the could get close to the 5* tighter.

Is this a reasonable plan or will I be hurting performance?
 
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