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-   -   Whats a worst-case scenario that can occur with slipped timing? (https://www.dieselbombers.com/5-9l-12v-performance/48687-whats-worst-case-scenario-can-occur-slipped-timing.html)

85_305 04-13-2010 09:55 PM

Whats a worst-case scenario that can occur with slipped timing?
 
Just curious. What can happen? Truck impossible to start? Truck starts but runs rough? Truck will NOT go past 1800rpms? Sucks down fuel? Etc?

My throttle response is AWESOME but people are telling me my timing may have slipped. Trying to figure a worst case scenario that can occur with slipped timing.

Matt

dan33klein 04-14-2010 08:22 AM

um re time it? hello:w2:

12vcummins96 04-14-2010 09:01 AM

blow a head gasket truck wont run it will pop out the exhuast ect

wisconsin redneck 04-14-2010 12:31 PM

with slipped timing it was start amazing... check your last thread... entiled "why does my truck start so good? seriously" :tu:

guhfluh 04-14-2010 01:00 PM

The only thing I can think of is high EGTs.(Yet another reason you need gauges)

I'm not very knowledgeable about the effects of timing on diesels and why, but just from an internal combustion engine standpoint, the later the timing event, the closer to the exhaust stroke peak cylinder temps occur. This pushes EGTs up and makes exhaust valves more prone to heat damage. Over a certain point the excessive EGTs won't melt the pistons because the chamber temps arent that high because the timing is so retarded. The temps in the exhaust will be through the roof, turbos will glow, etc., but the peak combustion temp point has moved from in the chamber through the valves to the exhaust ports in extreme cases. Good for turbo spool, bad for power.

As far as why the lower timing helps lower rpm power in a diesel, I'm still kinda in the dark. I'm guessing it's just because the timing is fixed, that all you can do is move the peak power point around and stock is too much timing down low, but perfect in midrange and too low up top. Lowering it makes peak power down low, but still nothing up top because its too low up there. I guess its why guys bump there timing to move the peak up there where their turbos spool, can really fuel it and make big HP numbers, but cyl pressures skyrocket because then the timing is really too far advanced on the low end. Just guessing.

---AutoMerged DoublePost---

Another thing too low(or high) timing could do is hammer the rod and main bearings. The combustion even is still trying to push the piston down when the crank is already at its lowest point and getting ready to come back up on the exhaust stroke(late). Too early and the piston is still coming up when combustion is trying to push it back down or at least the crank has not started back down and is straight up without any leverage to rotate.

85_305 04-14-2010 01:22 PM


Originally Posted by wisconsin redneck (Post 537654)
with slipped timing it was start amazing... check your last thread... entiled "why does my truck start so good? seriously" :tu:

It actually starts like a normal diesel now. It was 27* the other day and I had to cycle the grids twice and still had to lay my foot on the throttle so the truck would start. Took a few seconds of cranking to start.


Originally Posted by guhfluh (Post 537669)
The only thing I can think of is high EGTs.(Yet another reason you need gauges)

I'm not very knowledgeable about the effects of timing on diesels and why, but just from an internal combustion engine standpoint, the later the timing event, the closer to the exhaust stroke peak cylinder temps occur. This pushes EGTs up and makes exhaust valves more prone to heat damage. Over a certain point the excessive EGTs won't melt the pistons because the chamber temps arent that high because the timing is so retarded. The temps in the exhaust will be through the roof, turbos will glow, etc., but the peak combustion temp point has moved from in the chamber through the valves to the exhaust ports in extreme cases. Good for turbo spool, bad for power.

As far as why the lower timing helps lower rpm power in a diesel, I'm still kinda in the dark. I'm guessing it's just because the timing is fixed, that all you can do is move the peak power point around and stock is too much timing down low, but perfect in midrange and too low up top. Lowering it makes peak power down low, but still nothing up top because its too low up there. I guess its why guys bump there timing to move the peak up there where their turbos spool, can really fuel it and make big HP numbers, but cyl pressures skyrocket because then the timing is really too far advanced on the low end. Just guessing.

---AutoMerged DoublePost---

Another thing too low(or high) timing could do is hammer the rod and main bearings. The combustion even is still trying to push the piston down when the crank is already at its lowest point and getting ready to come back up on the exhaust stroke(late). Too early and the piston is still coming up when combustion is trying to push it back down or at least the crank has not started back down and is straight up without any leverage to rotate.

Awesome explanation for a terrible situation :tu:

Red_Rattler 04-14-2010 02:14 PM

Get it timed... Mine was at 6* and the truck was totally stock. It slips over time or due to added hp boost like u did.

85_305 04-14-2010 02:24 PM

6*???? Whats stock on those, the same as on 12v's?? Jeez dude was it even running lol

But I called the local diesel shop and the dude said he's nearly positive its the timing. Gonna do the timing bump for 180$ :rocking:

Red_Rattler 04-14-2010 02:32 PM

It was my 12v and stock is 12.5. I got it bumped to 16* and it ran fine just no top end and would sputter and smoke at high rpm or any rpm besides idle when cold.

85_305 04-14-2010 02:41 PM

So which rpm did it start the sputtering stuff begin?


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