Injector Spray Pattern - LMM
- Thread starter kidturbo
- Start date
Those are from a set of +100 or 120% Exergy sticks and 10mm pump running 1700us max PW at 190MPA. Timing was touching 27deg with all 3 pilots ON. Hence the illusion of a stock injector cranked way up...
Engines ran great, with very little smoke. One setup with compounds, another time with single S476. But those sticks and tuning melted the tops out of 8 forged Mahle pistons, and then aerated a cast in the engine pictured above in a short time. All while operating well under 1400 egt. Failures all occurring around 3800-4200R under light engine loads, in a boat of course.
That pattern just looked weird to me in how it's not symmetrical. I had turned all pilots off, but customer hated the noise and switched back to a previous tune with them on and same timing in his cast piston setup. Pistons obviously didn't appreciate this over the lip pattern...
Engines ran great, with very little smoke. One setup with compounds, another time with single S476. But those sticks and tuning melted the tops out of 8 forged Mahle pistons, and then aerated a cast in the engine pictured above in a short time. All while operating well under 1400 egt. Failures all occurring around 3800-4200R under light engine loads, in a boat of course.
That pattern just looked weird to me in how it's not symmetrical. I had turned all pilots off, but customer hated the noise and switched back to a previous tune with them on and same timing in his cast piston setup. Pistons obviously didn't appreciate this over the lip pattern...
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those spots are also right where the valves are. you may be getting more flame in the quench area from it, specially running that much timing along pilot injection.
That's what I was really wondering, if the valves faces are causing that specific pattern. These injectors have more hours on a bench than in a engine... While actual flow rate numbers varied between test platforms, everyone agreed patterns looked normal.
Pilot pulses are bad, Okay.. :roflmao:
Pilot pulses are bad, Okay.. :roflmao:
Driving at the moment. But it's 27 main table above 3400r if I recall.
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I have zero experience tuning a boat, so don't take this as gospel. But 1700 pulse at a sustained 4000 RPMs is way to much in my opinion.
And you should not be running pilot injection at that high of an RPM.
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And you should not be running pilot injection at that high of an RPM.
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But you have to remember, pushing a boat takes all the power the motor can make.... in essence it's the same as WOT in a truck 100% of the time. If that makes sense. (I figure you already know this) but some people don't. They think spinning a prop is like free revving in neutral.
Iirc a 32 sonic takes about 1150hp at the prop to run in the 90s? Does that sound correct kidturbo? So that would mean those dmaxs were being taxed hard with that hull, even running much slower.
Iirc a 32 sonic takes about 1150hp at the prop to run in the 90s? Does that sound correct kidturbo? So that would mean those dmaxs were being taxed hard with that hull, even running much slower.
He was running just under 60mph tops, and I figured 750-800hp range with that compound setup. However the failures all occurred getting on plane when the prop wasn't hooked up yet.
For example, the stroker pistons let go while testing a new prop that wouldn't hook up. It would cavitate bad and run up to about 4200r without nosing over and hooking up on plane. So load wise, it never saw much load then. But on the 4th try, she blew the side out of a piston at around 1400egt.
Then with the cast piston single turbo setup it had been running good, and was getting on plane again when a piston let go about the time it shifted into 4th gear. Saw egts hit 1400 he knew something was up..
If it had been on plane at wot, then I would say the loads were high. But these failures all happened with ecm estimated load under 50%.
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For example, the stroker pistons let go while testing a new prop that wouldn't hook up. It would cavitate bad and run up to about 4200r without nosing over and hooking up on plane. So load wise, it never saw much load then. But on the 4th try, she blew the side out of a piston at around 1400egt.
Then with the cast piston single turbo setup it had been running good, and was getting on plane again when a piston let go about the time it shifted into 4th gear. Saw egts hit 1400 he knew something was up..
If it had been on plane at wot, then I would say the loads were high. But these failures all happened with ecm estimated load under 50%.
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27 degrees sounds like too much timing to me, but I wouldn't swear to it that that is your problem. That's about how much timing I run on my truck with a lot smaller injector and almost 1000 uS more pulse width at the same RPM.
27 degrees at 1700 sounds way to high to me as well. I shut pilot off above 2600 on all of my tunes. Obviously I haven't tuned a boat, but my experience is once you get the timing close, the pilot shot doesn't make much of a difference at those rpm's as far as noise reduction goes. I also cut them all back to 1 pilot shot during cruise. I've found it helps the mpg in pickups anyways. I know pilot plays a pretty big role in turbo spool up, but I found too much pilot can also lead to engine noise as well as a touchy throttle. My 1st thought when I seen your pattern was that looks like alot of timing. I would think 27 degrees would be holding alot of heat in the cylinder as well.
1700 us on 100% overs is alot of fuel! Compared to stock injectors
27° by 3400.. nothing would bother me
What's EGTs and EOTs look like
27° by 3400.. nothing would bother me
What's EGTs and EOTs look like
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We can both agree on that much. Mahle claimed those forged pistons failed due to excessive heat, but she it never once touched 1500F. So I'd call BS.
However Marc and I had a discussion about this setup right before Dave's last piston failure. With an older tune running 15deg max timing the EGT's were easily exceeding 1400F with way less power. But when just timing was bumped up, the EGT's fell off. Same BTU's goes in the chamber, but less heat comes out the pipes. Where does it go? Into more power obviously, but at what cylinder pressure and cost? Neither of us wrote this tune, was actually just working to de-tune it a bit..
Here is a couple screenshots from a log day or so before last piston failure. Max timing is actually capped at 28.7, down 2 from where it was running few weeks before. The first jpg is 3rd gear getting on plane, second pic is on plane and prop hooked up..
Attachments
Guess which major shop didn't drill out the oil squirters in engine above as specifically instructed? See attached.
What really gets me, I personally told the owner to make sure it was done. Who then argued that it should only be done if upgrading to a full dry sump system. BS...
After inheriting two engines now that suffered major oiling related failures, I gotta call it like I see it. PPE is officially removed from my rolladex Joe!!
On a side note, Mahle cast race pistons don't seem to crack. They just blow a holes straight thru the bowl when they go.
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What really gets me, I personally told the owner to make sure it was done. Who then argued that it should only be done if upgrading to a full dry sump system. BS...
After inheriting two engines now that suffered major oiling related failures, I gotta call it like I see it. PPE is officially removed from my rolladex Joe!!
On a side note, Mahle cast race pistons don't seem to crack. They just blow a holes straight thru the bowl when they go.
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What is everyone drilling the squirters to anyways and are guys still doing it on stock and Melling pumps? Does anyone know if the LML squirters are bigger to, I figured it was not worth while unless getting a bigger oil pump such as a LML or a big aftermarket or dry setup.