LMM: LMM with 222,000 tear down rebuild

[malibu795]

Is your oil filter pre cooler then?

Lower main bearings will also get beat up from too much timing, but IMO would take more than what you had posted that you're running now.

Right now I think your best bet is new rings/ bearings and hit it with a precision hone, get pistons recoated, put that new cam in and hope for the best.

And with running that much main timing in the midrange, maybe try to reduce pilot timing and see how mpg/ egt compares.

Yep filter is pre cooler just like factory

 

[duratothemax]

Why didn't they drop CR between lmm and LML?

They did.

 

[malibu795]

I was unaware they dropped it from 16.8 to 16.0

 

[bmc1025]

Right... But you're not considering the down time. We can't call our customer and say your parts (that you need right now) won't be on time because our truck is down for repairs, it will be a few weeks before its running again. We would be out of business overnight... There is a lot of things to consider, of course. But down time is HUGE esp when you take it to the next level with regard to size of company and your brand recognition (word of mouth). IMO

Just trying to show the flip side of the coin

I understand the downtime issues of a larger company. I don't know Adam's contract, but I have experience subcontracting snow work from larger companies. Downtime isn't as critical if you have pleanty contractors in your rolodex.

The way we do snow removal is very similar to logistics. First you have large maintenance companies even some national then a broker and finaly lots of subcontractors with their own rigs and insurance. If one of the trucks go down (even new trucks) there is always someone to fill their spot and keep the customer happy. Obviously this works much easier on a local level but can be applied to logistics as well

 

[malibu795]

Quick search for NOx emissions and high compression
I find it rather interesting that drop in CR is realy close to the next lower NOx regulations

I've worked as a Performance Development Engineer on diesel engines. While the other answers contain parts of the story - here's the real reason that diesel engine exhaust contains more NOx than gasoline engines.

First we'll take a look at the combustion process, and then we'll take a look at emissions control strategies.

The Combustion Process in Diesel and Gasoline Engines

As mentioned in other answers, NOx is primarily produced during combustion by a combination of time and high temperature. Nathan Kaemingk's answer explains this particularly well.
Nathan Kaemingk's answer to Why does diesel exhaust contain more nitrogen dioxide than other combustion engines?

Gasoline engines also produce NOx during combustion through the same principles - time and high temperature. However, gasoline combustion is different. In a traditional gasoline engine (not one of the new direct injection engines) the gasoline is perfectly mixed with air at the stoichiometric ratio prior to entering the combustion chamber. This means that there's precisely the amount of fuel necessary in the cylinder to burn all of the oxygen. This is different from a diesel engine in two major ways.

1. The diesel engine burns lean and power output is controlled by the amount of fuel injected into the cylinder. The gas engine always runs at the stoichiometric ratio (except for Wide Open Throttle and Deceleration Fuel Cutoff, which are exceptions) and the power output is controlled by throttling, reducing the pressure of the intake air, and thus the amount of fuel and air in the combustion chamber. Since the diesel engine burns lean that means there is always excess oxygen in the exhaust.

2. Since the gasoline is "perfectly" premixed with air before entering the combustion chamber the flame front is much different as there are no rich/lean areas of combustion as there are in a diesel engine, leading to much more uniformity in the resulting byproducts.

Also note (while not as important for this discussion) that diesel engines typically run higher compression ratios, around 16-18:1, vs. gasoline engines, typically running 9-11:1. Diesel engines are also compression ignition, relying on the high temperature generated by compression to ignite the fuel, whereas the fuel in a gasoline engine is ignited by a spark.


Emissions Control Strategies

Since gasoline engine exhaust contains no excess oxygen, gasoline engines can use a 3-way catalytic converter, which can reduce the NOx emissions in the exhaust by 99%. These catalytic converters have been in use since the early 1980s. If excess oxygen is present this reaction is much less effective and therefore much more NOx passes through unconverted. Since diesel engines always have excess oxygen in their exhaust they are unable to use the same 3-way catalytic converters that gasoline engines use.

The primary emissions controls strategies of diesel engines in the past have generally evolved from:

No emissions control (early 1970s)
Combustion control (mid 1970s)- lowering peak combustion temperature by lowering compression and retarding timing
Exhaust gas recirculation (2002/2004) - further lowering peak combustion temperature by displacing oxygen and reducing the speed of the flame
Higher pressure fuel injection (2000s) - better atomization and control of the fuel plume allowed for tighter control of the combustion process
Diesel particulate filters (2007) - didn't do anything to reduce NOx, but required to reduce emissions of particulates
Urea SCR systems (2010) - a selective catalytic reduction system relying on urea/ammonia to convert NOx into N2

The Urea SCR systems use a fluid that needs to be refilled at regular servicing intervals. Some of these fluids go by the name AdBlue, BlueDEF or DEF Fluid.

NOx emissions were regulated by the US Federal government for heavy duty diesel on-highway engines as follows:

1974 - 16 g/hp-hr (grams per horsepower-hour)
1979 - 10 g/hp-hr
1988 - 6 g/hp-hr
1991 - 5 g/hp-hr
1998 - 4 g/hp-hr
2004 - 2.5 g/hp-hr
2007-2010 (phased in by 2010) - 0.2 g/hp-hr

While diesel engine exhaust has historically contained more NOx, advances in aftertreatment and regulations in recent years have greatly reduced the amount of NOx (and particulate matter) that come out of the tailpipe of the newer diesel engines.

https://www.quora.com/Why-does-dies...itrogen-dioxide-than-other-combustion-engines

 

[Chevy1925]

Is your oil filter pre cooler then?

Lower main bearings will also get beat up from too much timing, but IMO would take more than what you had posted that you're running now.

Right now I think your best bet is new rings/ bearings and hit it with a precision hone, get pistons recoated, put that new cam in and hope for the best.

And with running that much main timing in the midrange, maybe try to reduce pilot timing and see how mpg/ egt compares.

I did this when i was running 45% over injectors on my old lb7 top end. mpg didnt suffer but engine quieted down, spool up was better and EGT didnt suffer much but its hard to get an exact number on EGT since there are so many variables. same with MPG. i jsut never saw them turn for the bad.

Adam, i dont think trash was your only issue on those bearing. they look like they were somewhat starved of oil as well. im sure the pressure bleed off of the hose coming off did not help the situation.

im with Pure on this though if the cyl are honeable without putting too much ptw in there. i think your eyes are playing tricks on your as far as the taper you think you see. if you can see the taper, its well beyond the service limit of .0006.

 

[malibu795]

Well pistons and bores measured
Bores measure at thrust and 45° off left and right and top middle bottom of bore.
Bores gained .0025-.003" ranging from 4.0975-4.098" on a 4.095" initial; bore
#8 was the largest at +.003" everyone else was +.0025"
Less then .0005" taper vertically
Pistons run 4.091" +/-.0005" measured 1" up from bottom of the skirt
Making current PTWC .0065-.007"
service limit is .010"

What i dont know is what piston diameter was prior to going in these assembly with ~30k on them..

Verdict..
Worn but not dead.. and should have a short block at minimum ready by end of the year.

 

[malibu795]

Adam, i dont think trash was your only issue on those bearing. they look like they were somewhat starved of oil as well. im sure the pressure bleed off of the hose coming off did not help the situation.

The mechanical gauge (pluged into #2 main) was bouncing between 20-30psi at 2200rpm when i caught it, from 60-70psi it normally runs pending oil temp
The dash guage had not even recognize the oil pressure drop

 

[Chevy1925]

Well pistons and bores measured
Bores measure at thrust and 45° off left and right and top middle bottom of bore.
Bores gained .0025-.003" ranging from 4.0975-4.098" on a 4.095" initial; bore
#8 was the largest at +.003" everyone else was +.0025"
Less then .0005" taper vertically
Pistons run 4.091" +/-.0005" measured 1" up from bottom of the skirt
Making current PTWC .0065-.007"
service limit is .010"

What i dont know is what piston diameter was prior to going in these assembly with ~30k on them..

Verdict..
Worn but not dead.. and should have a short block at minimum ready by end of the year.

You need a better gauge that reads .0001 +-, not the .0005 +- you are using if you really want the best readings on the bores. You will have a hard time making sure bearings are matched to the mains or rods without it.

Assuming decent accuracy of the gauge as well, by the time you hone, you will be .001-.002 above what you have now and that's if the machine shop will take the time to really get you the specified clearances you want. She's gunna be loose on that ptw clearance and close to service limit

 

[IOWA LLY]

Adam did I read that right???? Your not gonna have this done until the end of the year? Are you going to buy an engine to run in the meantime or something?

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[malibu795]

Bore gauge has .0005" graduations
the outside mic reads .0001" graduations

There is less than .0005" difference between top and bottom of the bore.. and with a minimum of .0065" ptwc i have no risk at sticking a piston.

Funny how 8 months ago some of you guys busted my balls about refusing to run a loose block..

Now you want to bust my balls about getting a gauge that doesnt read small enough... On a block that is now loose the graduation doesnt really matter..

While it's not "perfect/pretty" it will work and i know the condition of it and can plan accordingly.

 

[malibu795]

Adam did I read that right???? Your not gonna have this done until the end of the year? Are you going to buy an engine to run in the meantime or something?

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Read that wrong hoss... New fresh block ready to swap in at the end of the year, to replace current one

This one will be back together in couple days

 

[Chevy1925]

Bore gauge has .0005" graduations
the outside mic reads .0001" graduations

There is less than .0005" difference between top and bottom of the bore.. and with a minimum of .0065" ptwc i have no risk at sticking a piston.

Funny how 8 months ago some of you guys busted my balls about refusing to run a loose block..

Now you want to bust my balls about getting a gauge that doesnt read small enough... On a block that is now loose the graduation doesnt really matter..

While it's not "perfect/pretty" it will work and i know the condition of it and can plan accordingly.

Uh.... I never gave any opinion on your initial tight clearance back then.

I won't give anymore suggestions

 

[malibu795]

I won't give anymore suggestions

I used multiple versions of "you" there.

And some reason i have a feeling you wont stop throwing your $0.02 arounds:thumb:

While id like to recoat the pistons light hone the walls. It was runing as is.. it will run as is.

Yes id like a dail indicator the reads .0001" for bore guage... Currently wasnt an option

 

[DAVe3283]

Funny how 8 months ago some of you guys busted my balls about refusing to run a loose block..

Now you want to bust my balls about getting a gauge that doesnt read small enough... On a block that is now loose the graduation doesnt really matter..

But that's what we do on here :rofl::hug:

Can't please everyone. Hope you get back on the road ASAP and don't have any more problems with this motor for so long you wonder why you built the spare :thumb:

 

[IOWA LLY]

Read that wrong hoss... New fresh block ready to swap in at the end of the year, to replace current one

This one will be back together in couple days

Gotcha.

You like swapping engines a whole lot more then I do. Lol.

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[malibu795]

But that's what we do on here :rofl::hug:

Can't please everyone. Hope you get back on the road ASAP and don't have any more problems with this motor for so long you wonder why you built the spare :thumb:

At least be consistent :rofl:

Gotcha.

You like swapping engines a whole lot more then I do. Lol.

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Not really like doing.. but seam to have gotten decent at it..
As for building a spare short/long block.. has been a goal..had to get boss paid back first.. to free up that monies.
Ive got almost complete engine here at home. Got a LMM block that split a piston.
Be 5-6k to bore balance with LML crank and oval pistons in parts and machine work..
not sure i want to use the lbz junkyard crankshaft again..
Basically duplicate current engine with all new stuff with zreo miles on it.. might reuse the lbz rods though

 

[Digmax]

Hey just for kicks and giggles build it with 15.5 CR and a little tighter exhaust housing on your charger , ya never know!

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[Gmclbz]

At least be consistent :rofl:


Not really like doing.. but seam to have gotten decent at it..
As for building a spare short/long block.. has been a goal..had to get boss paid back first.. to free up that monies.
Ive got almost complete engine here at home. Got a LMM block that split a piston.
Be 5-6k to bore balance with LML crank and oval pistons in parts and machine work..
not sure i want to use the lbz junkyard crankshaft again..
Basically duplicate current engine with all new stuff with zreo miles on it.. might reuse the lbz rods though

You should buy my lb7 block

 

[malibu795]

You should buy my lb7 block

I was planning on buying some stuff off you till this sacre happened