LS1 Piston and Bore after 78,000 on M1

[Ryan00TJ]

Found this over at LS1tech.com and thought you guys might like it. Looks pretty darn good to me! Car had used Mobil 1 for it's life.

Quote from actual owner........
I installed my new heads/cam/intake this weekend and when I pulled the heads off I was surprised to see that you could still see the original crosshatching in the cylinder sleeves.
My car has 78,000 miles on it and has pratically lived at 6k RPM. I am very pleased. I have pulled cams outs of cars that use regular non synthetic oil and after 5k miles it looks worn.

 

[Patman]

I just saw that thread over there a few minutes ago myself! I think that is very impressive, but at the same time, this doesn't necessarily mean Mobil 1 would protect the rest of the engine as well. I still think someone running 5w30 M1 in a hard driven LS1 will see more bearing wear and more valvetrain wear than they would with a slightly thicker oil.

 

[buster]

I think what this website has shown is that while oils are important, we tend to over emphasize them a bit. We've seen all the people with 200K + miles on various oils that aren't impressive on paper and 1/2 the time on UOA's, yet there engines last.

With an LS1, Patman is right, a thicker oil is better. However, you might be talking about 400K miles vs 300K in the end. No one can predict such a thing. I think using a high quality oil will determine how much better your engine will be running at high mileag, more so then determine how long it will last.

 

[Michael SR]

i used to be in the performance industry, and probably did 50 heads/cam jobs on american V8s. i never saw a single one that didn't still show the crosshatch and/or look virtually new.

in other words, this says nothing to me.

-michael

 

[Rick]

Wow it had's flattop pistons

 

[cryptokid]

those piston tops are WAY too clean. either he is lying about the mileage or ir a mobil salesman or somthing.

 

[KW]

I'm with M SR on this one. The cross hash is still in most of the motors I pull apart. I'd think that if the bore was smooth that the rings were to tight. Makes the bores look like chrome.

 

[KW]

quote:

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Originally posted by cryptokid:
those piston tops are WAY too clean. either he is lying about the mileage or ir a mobil salesman or somthing.

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Nice carbon ring at the top of the bore. Super duper clean piston. Hum?

 

[Patman]

Yep, you can clearly see the carbon on that piston. Carbon buildup on the pistons is extremely common on the LS1, which is why so many guys swear by seafoam and GM's top engine cleaner.

 

[Last_Z]

Pat,
Is this a slapper? Can you post the link to the post?
Thanks

Rick

EDIT: Thanks for sharing Ryan!

 

[Nosmo King]

quote:

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Originally posted by Michael SR:
i used to be in the performance industry, and probably did 50 heads/cam jobs on american V8s. i never saw a single one that didn't still show the crosshatch and/or look virtually new.

in other words, this says nothing to me.

-michael

---

Same here. Any VW with dino oil will still clearly show cross hatch at 80,000 miles.
It has more to do with the new air cleaners than oil.

On my BSA 500cc Gold star, with single AMAL trumpet ( no air cleaner ) the cross hatch is gone in under 10,000 miles

 

[Ferb]

quote:

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Originally posted by Patman:
Yep, you can clearly see the carbon on that piston. Carbon buildup on the pistons is extremely common on the LS1, which is why so many guys swear by seafoam and GM's top engine cleaner.

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Is that related the the lack of an oil separator on the PCV?

I'm starting to get into the LS1 (saving up for a new GTO) and noticed that it seems a pretty easy mod to put the LS6 valley cover on which features the oil separator. Just didn't know if it made a big difference at all.

ferb!

 

[Patman]

quote:

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Originally posted by Last_Z:
Pat,
Is this a slapper? Can you post the link to the post?
Thanks

---

We can't post links to other boards from here, but if you go to LS1Tech and check out their internal engine section, this thread should be close to the top as it's getting a lot of replies there.

Don't you visit LS1Tech regularily? What about the new LS2 site?

 

[Patman]

quote:

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Originally posted by Ferb:

quote:

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Originally posted by Patman:
Yep, you can clearly see the carbon on that piston. Carbon buildup on the pistons is extremely common on the LS1, which is why so many guys swear by seafoam and GM's top engine cleaner.

---

Is that related the the lack of an oil separator on the PCV?

I'm starting to get into the LS1 (saving up for a new GTO) and noticed that it seems a pretty easy mod to put the LS6 valley cover on which features the oil separator. Just didn't know if it made a big difference at all.

ferb!

---

I'm honestly not sure why the LS1 builds up so much carbon. I'm gonna post the link to this thread on LS1Tech and maybe one of the guys from over there will join us here to explain.

 

[Motorbike]

The lack of piston ring groove on top of the bore shows probable combination of hi-nickel content of the sleeve " ie old Oldmobile 455's " , the ultra low tension of the ring sets used in the LS-1 is not tough on the bore and a reasonably good detergent/dispersant package that takes the junk to the oil filter and good oil change habits .

That's my take on it anyway ..........

Need another pic to see lower in the bore where it tapers and the piston would be prone to slap . Need a pic of the piston too . I've often thought some of the noise fron these came fron the wrist pins .

 

[MolaKule]

quote:

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I've often thought some of the noise fron these came fron the wrist pins .

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The offset wrist pin design and short piston skirt usually means the piston skirt slaps the cylinder wall. No indication of wrist-pin problems in any of these engines.

 

[Patman]

quote:

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Originally posted by Ryan00TJ:
Our LS1's run very rich on the factory GM PCM tune which may help contribute to these engines carboning up so quick. When I first had my 02 SS dynoed with 1500 miles on the dash it had an air fuel ratio of 12.0-1 which is pretty rich for a NA application. This also hurts performance. Either way it still put down 315rwhp @ 326 rwtq stock. A good LS1Edit tune on a stock car is good for 10 rwhp especailly on the 01 and up cars with the different Factory PCM tunes. My current AFR is 12.9-1 across the rev range when the PCM switches to closed loop.

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I wish I still had my LS1, as I think it would've been interesting to do oil analysis on, and to inspect after driving it a long time. I think mine ran more on the lean side of things. I never had an air fuel ratio test done, but according to Autotap, the o2 sensor readings were in the .870 to .885 range down the entire quarter mile. So it ran more on the lean side, but not too lean. This was acheived with the HPP3 tuning, a ported stock maf, and a homemade timing tricker. I bet I didn't get much carbon buildup on that engine, especially since I drove it so hard. It made 320rwhp and ran a best ET of 12.68 at 110.6 mph. Never should've sold it.

 

[JohnBrowning]

When I used to do import tuneing I would routinely pull apart a 4 cylinders with 70,000-100,000 miles with the cross hatching still pristine. When I first started doing this the machine shop I used was new to imports. At first they would call me up and ask me how many miles were on a given engine. On two occasisons after I cleaned a block up and measured everything they thought I sent over a new block to see if they were honest!

They were amazed when I told them the engine had 80,000 on it and had been run on conventional oil. It was my personel engine. The engine measured to factory spec.'s and the cross hatching was beatiful! They all but called me a liar. I invented the owner down to my shop for a beer and to check out the odometer on the truck in my shop!

It does look nice though. The top of the piston looks like it has been cleaned though. It would have been nice to see it dirty to check out the carbon deposits. The lack of a ridge is also nice to see. If the piston was out of the bore and we could get a shot down the bore that would have made my day!

If you look over at the other cylinder in the top right of the frame you can see the carbon deposits.

To day itis common to see the crosshatching well into a vechiles life cycle. In the old days this was not the case! I think a lot of this has to do with less bore polishing due to better fuel control over the life of the engine. Combine that with low tenion rings and better materials and you have longer life cycles.

 

[darkdan]

My guess would be he was cleaning off the piston and stuff and noticed the crosshatching. That's why he took the picture. If it was really dirty you wouldn't be able to see it....so he cleaned it.

 

[Ryan00TJ]

Our LS1's run very rich on the factory GM PCM tune which may help contribute to these engines carboning up so quick. When I first had my 02 SS dynoed with 1500 miles on the dash it had an air fuel ratio of 12.0-1 which is pretty rich for a NA application. This also hurts performance. Either way it still put down 315rwhp @ 326 rwtq stock. A good LS1Edit tune on a stock car is good for 10 rwhp especailly on the 01 and up cars with the different Factory PCM tunes. My current AFR is 12.9-1 across the rev range when the PCM switches to closed loop.