meltdown -- common rail style

JasonCzerak said:
So where is this magic formula to set the correct timing? I've recently backed the timing down to #3. a little smokier, but the turbo seems to kick in faster. Less boost gauge flutter as well......

Amount of fuel (some pressure) + amount of air = the amount of timing you should run

dodge + smarty folks have 4 guesses.

With the TST you can add a little timing in 3 degree increments.

Marco/Bob never confirmed where "stock" timing cam into the timing matix. I suppose if Marco said #4 was the lowest on the TNT/R, but never confirmed if that included stock. I'm confused on that based on how I read his posts.

But the reason for this thread, the user was on the "lowest" timing, but lots of RPM. Go figure.
Click to expand...



There was a thread a long while ago where someone (I believe it was Wade) that had a scanner / tool that showed the actual timing of the Smarty setting.....

Don't remember the actual numbers in * , but
2 was the highest
3 next lowest
4 was lower than 3
1 (stock) was the Lowest!!!

Anybody remember that????

I've understood Stock timing to be the lowest!!

Not sure about my Smarty, it Rattles the same on ALL the settings and SW's.
 
So smarty on stock timing and no 4k rpms is less likely to melt a piston than lots of timing on a 4k tune? I guess I'm gonna play with it at the track Friday
 
i never ran over 3300 rpm's and ran stock timing and melted 2 pistons.. theres got to be something in common with these trucks melting.. besides the cr.
 
There was a thread a long while ago where someone (I believe it was Wade) that had a scanner / tool that showed the actual timing of the Smarty setting.....

Don't remember the actual numbers in * , but
2 was the highest
3 next lowest
4 was lower than 3
1 (stock) was the Lowest!!!

Anybody remember that????
Click to expand...


Yeah, this is what I had saved...

TNT Timing Degree's
#4=16* max
#3=18* max
#2=21* max
#1=12* max

ALSO take note added pressure adds approx. 3-5* more.same with water/meth if you use a 50/50 mix less if you use the windshield washer stuff.

--Eric
 
I think I'm going to take the MP-8 off and just run the Smarty TNT-R to get my pressure.
 
Hey guys...

This is a REALLY stupid question I'm sure, but I'm kinda curious what the symptoms of a melted piston are...

I mean, could I have one and not know it or is it obvious when this happens?
 
ENafziger said:
Yeah, this is what I had saved...

TNT Timing Degree's
#4=16* max
#3=18* max
#2=21* max
#1=12* max

ALSO take note added pressure adds approx. 3-5* more.same with water/meth if you use a 50/50 mix less if you use the windshield washer stuff.

--Eric
Click to expand...

How does pressure add timing? Commanded open time is commanded open time. Pressure does not effect that. If pilot is working and you have larger injectors with pressure the pilot can become a power shot but. Pressure does not increase the timing over commanded.

Those timing # seem low to me. If I had to guess that is because of pilot becoming to big. I wonder what the injectoin shot is time wise at make timing.

For example. If you are at 3000rpm with a max timing of 21* and a injection shot of say 2000us(microseconds) then your main shot is centered. Meaning at that RPM your 2000us shot takes 42* of total crank rotation. So you open at 21* BTDC and close at 21 ATDC. If you have a bigger shot it gets worse. 3000us =54* of crank rotation. Which means open at 21*BTDC and closed at 33*ATDC. Now to melt a piston it take heat and time to get the piston hot. If you add both pilot and post injection to the main you can easily be injecting fuel for close to 90* of rotation. With that much exposor it would take less peak heat to melt a piston.

Using my Dmax an example. No Pilot over 2000rpm. No post at all. Peak timing of 35*. EGTs are around 1600 when pulling with no water. I pulled injectors and used a scope to look at pistons last week . Everything looked fine.:rockwoot:
 
jlibert said:
SW9, timing 4, rail pressure 1
mp8 80%, 26k max rail pressure
EGT 1400 MAX
Flux 4
64/S480

Plenty of air, mild injector, mild rail pressure, timing dialed back, conservative egt, no drugs.

video of day it happened.......
my pull at :30 sec. in
YouTube - Ceres Sled Pull 7/11 www.brownsdiesel.com


Thanks in advance for all of your input.

-J.P.

Explain how aftermarket injectors (which add timing) and timing at 4 (most advanced) is mild timing? It's not mild at all.
Click to expand...
 
MoltenRedJD said:
Thanks in advance for all of your input.

-J.P.

Explain how aftermarket injectors (which add timing) and timing at 4 (most advanced) is mild timing? It's not mild at all.
Click to expand...

The timing settings you are thinking about are for the standard revo tune. On the TNT tune, level 4 is the lowest (for use with nitrous or whatever else).
 
JasonCzerak said:
So where is this magic formula to set the correct timing? QUOTE]


Inquiry minds want to know this as well...

we see timing is the biggest culprit... but

Of all the trucks that seem to be melitin pistons they are modded to some point, how many of them actually are stock trucks with NO mods whatsoever?

Leads to two thoughts, is the 6.7 a better engine despite all the epa stuff? and are we better off not modifying common rails anymore to avoid this piston gamble...
Click to expand...
 
TxDiesel007 said:
JasonCzerak said:
So where is this magic formula to set the correct timing? QUOTE]


Inquiry minds want to know this as well...

we see timing is the biggest culprit... but

Of all the trucks that seem to be melitin pistons they are modded to some point, how many of them actually are stock trucks with NO mods whatsoever?

Leads to two thoughts, is the 6.7 a better engine despite all the epa stuff? and are we better off not modifying common rails anymore to avoid this piston gamble...
Click to expand...

obviously you havn't been reading, yes stock trucks have been melting too. Usually the stock ones were on a long uphill pull or had a trace of a bad injector. Not to sure about the 6.7 s but they have went to a piston style similar to the 03/early 04 s which don't tend to burn up as commonly as 04.5 and up.
Click to expand...
 
I meant to put this the other day, but my father just MELTED his 2005 CR, its a completely stock truck, he was towing his 5th wheel from the coast (port aransas) to austin tx, pulled the head at my friends shop and 3 cylinders are toast. Ive got some pictures but im gonna have to figure out how to get them on here.
 
TMONEYDIESEL's pic of the melted piston
IMG000301.jpg
 
How does pressure add timing? Commanded open time is commanded open time. Pressure does not effect that.
Click to expand...

I just copied and pasted this from another post. However, I think this is what they mean.

When a fueling modification increases rail pressure, timing is also being "advanced". This is because a larger amount of fuel is able to be pushed through the same duration of the injector. The same thing happens when running larger injectors...more fuel is being injected in the same duration...which is effectively increasing the timing. This is why on the Smarty programs, they advise you to run less timing with large injectors than with the OEM sticks.

Or, maybe "advancing" timing is not really accurate, as the commanded BOI (beginning of injection) isn't changing. Let's suppose you're running a 15° duration, with stock rail pressure and injectors, and you inject 25mL of fuel during that 15°.

Now, say you're running large injectors coupled with higher rail pressure. The commanded BOI is the same, and the duration is still 15°. However, since you're running higher pressure, and higher flowrate through the injector, the 25mL of fuel gets delivered through maybe the first 9° of duration. So now, you've injected your desired quantity of fuel sooner into the cylinder, even though you didn't advance timing per se.

Is this called advancing timing? I don't know...it kindof depends on if you're looking at it from the front end or the back end of injection. However, it does deliver the quantity of fuel sooner...and therefore, by some, fuel injected sooner means timing advanced.

--Eric
 
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