Hole size on Marine 370 injectors
01-09-2006, 09:37 AM
#16
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It is cool to see what the sizes etc.. are. I have an edm machine that is made for doing small holes and can also drill and ream down to .012. Anyone around here ever try to make their own????
01-09-2006, 10:03 AM
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Originally Posted by Bobcat698
I'd rather run the correct spray angles though, so things are more efficient. A 215 pump is also in the works 
No problem with doing it that way - efficiency is always good. What I'm saying is to be careful you don't go too big on the injectors if you're planning on running a turbo with a 66mm inducer. 7x.012's and a bombed 215 pump would seem to be too much fuel for a Sledpuller66, I would think. With the plate slid back it might be do-able.
Good luck - sounds like it will be a fun project!
Chris
01-09-2006, 10:38 AM
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Funny that Don hasn't posted on this.
More holes are better, but only to a point. 7 or 8 is better than 5, right, so 12 would be even better, right?
WRONG!
When Don was first doing injectors, he made some with as many as 14 holes! Atomization should be awesome, right? Well, it was.
But they noticed that as boost levels came up, that the injectors would smoke like CRAZY, and power was way down. It was like someone switched on the smoke at 40psi boost.
It turns out that at high boost, the many small holes didn't allow the fuel to "penetrate" the cylinder very well, and the quality of the burn dropped off greatly as boost came up. Of course, the off-boost performance was killer, and very clean.
But it turns out that the actual number of holes in an injector are not as important as some may think. I remember reading an article from Bosch or something saying that they could make a 2 or 3 hole injector actually perform quite well.
More holes are good in some cases, but there's a lot more to it than just drilling more holes. Hole uniformity, smoothness, spray angle, and nozzle sealing all play a huge role in overall injector performance-- more than just hole numbers and diameter.
I thought I read that Mach 6s have fewer holes (6) than Mach 4s (8). If so, you can bet that this is not by accident, or by following what "should" work. It's the result of TESTING and more TESTING.-jmo
More holes are better, but only to a point. 7 or 8 is better than 5, right, so 12 would be even better, right?
WRONG!
When Don was first doing injectors, he made some with as many as 14 holes! Atomization should be awesome, right? Well, it was.
But they noticed that as boost levels came up, that the injectors would smoke like CRAZY, and power was way down. It was like someone switched on the smoke at 40psi boost.
It turns out that at high boost, the many small holes didn't allow the fuel to "penetrate" the cylinder very well, and the quality of the burn dropped off greatly as boost came up. Of course, the off-boost performance was killer, and very clean.
But it turns out that the actual number of holes in an injector are not as important as some may think. I remember reading an article from Bosch or something saying that they could make a 2 or 3 hole injector actually perform quite well.
More holes are good in some cases, but there's a lot more to it than just drilling more holes. Hole uniformity, smoothness, spray angle, and nozzle sealing all play a huge role in overall injector performance-- more than just hole numbers and diameter.
I thought I read that Mach 6s have fewer holes (6) than Mach 4s (8). If so, you can bet that this is not by accident, or by following what "should" work. It's the result of TESTING and more TESTING.-jmo
01-09-2006, 11:44 AM
#19
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Interesting! Up my alley, so to speak.
Justin is right. We built some 12 and 14 hole injectors in the beginning. They were awesome TQ makers. I send them out now as keychains for a novelty.
Comparing to a DD3 our 12 holer made 1326 Ft lbs VS 1000 with the DD3. I have never seen anyone make 1300 ft lbs with a HX40 in my entire career. They flat out rock at low engine speeds!
The 12 and 14 holers made about the same HP, but the smoke was unbelieveable as boost came up. Air density and pressure play a huge part in the process. They were very clean driving until about 35 PSI or so. Then all heck broke lose.
BTW, the 24 V Mach 4 ( 150 HP ) , 5 (200 HP ) 6 ( 220 HP ) and the Mach 7 ( 240 HP ) all share the same hole size and the same number of holes. But are nearly 100 HP apart in power making and smoke production. Hole size is important, but there is much, much more to it. This is why the guys who try and take a stock nozzle and increase the hole size end up with sets of injectors that make power levels all over the place. I see this problem every day as I take in core injectors and injectors that were messed up by others trying to make a larger hole and ended up with a messy, smokey injector. I cant tell you how many so called EDM injectors I get from customers who bought from ebay, a local machine shop that has a EDM machine or a performance shop that sells EDM injectors from a local machine shop. The Common Rail stuff comes here all the time with 8 holes punched out to unbelieveable sizes or some with more holes or whatever the performance shop "thought" would work. I get some back that have broken off. Its actually entertaining sometimes, but in the end I feel sorry for the guys who get ripped off. Buying parts from sources who have no concept of testing before they sell or even if the stock nozzle can take such abuse or modification.
I know it is biased, but I have been preaching the dangers of modifying stock nozzles for years. Some engines have had them break off and cause subsequent damage and a host of other things, not to mention a poor power level.
Don~
Justin is right. We built some 12 and 14 hole injectors in the beginning. They were awesome TQ makers. I send them out now as keychains for a novelty.
Comparing to a DD3 our 12 holer made 1326 Ft lbs VS 1000 with the DD3. I have never seen anyone make 1300 ft lbs with a HX40 in my entire career. They flat out rock at low engine speeds!
The 12 and 14 holers made about the same HP, but the smoke was unbelieveable as boost came up. Air density and pressure play a huge part in the process. They were very clean driving until about 35 PSI or so. Then all heck broke lose.
BTW, the 24 V Mach 4 ( 150 HP ) , 5 (200 HP ) 6 ( 220 HP ) and the Mach 7 ( 240 HP ) all share the same hole size and the same number of holes. But are nearly 100 HP apart in power making and smoke production. Hole size is important, but there is much, much more to it. This is why the guys who try and take a stock nozzle and increase the hole size end up with sets of injectors that make power levels all over the place. I see this problem every day as I take in core injectors and injectors that were messed up by others trying to make a larger hole and ended up with a messy, smokey injector. I cant tell you how many so called EDM injectors I get from customers who bought from ebay, a local machine shop that has a EDM machine or a performance shop that sells EDM injectors from a local machine shop. The Common Rail stuff comes here all the time with 8 holes punched out to unbelieveable sizes or some with more holes or whatever the performance shop "thought" would work. I get some back that have broken off. Its actually entertaining sometimes, but in the end I feel sorry for the guys who get ripped off. Buying parts from sources who have no concept of testing before they sell or even if the stock nozzle can take such abuse or modification.
I know it is biased, but I have been preaching the dangers of modifying stock nozzles for years. Some engines have had them break off and cause subsequent damage and a host of other things, not to mention a poor power level.
Don~
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