LS6 Piston failure Cylinder #7 ST 2 Race car
 

Hey guys,
Was at the track heard what I thought was a bad lifter later to find that I did have a lifter go bad but also found a huge chunk out of my pistion when i pulled the head. All in cylinder #7. I have a Stock powered LS6 and want to purchase a new shortblock. The car is a race car and will see 8-10 events per year. I want to stick to the stock power ratings.

What type of short block should I purchase and from who? What are your recomendations.

I would contact DRM Motorsports and can see what they can offer. They have always done well for me with their products. You might also look at Texas Speed - they build a wide variety of engines on the LS platform.

When I do my next one, it will be the spare LS6 block I have. But after that, it'll be LS3 I imagine.

Did it kill the bore? Lots of options depending on what broke.

Randy

That is the same piston that was eaten in mine at VIR. Was only able to salvage the camshaft. Had only a little over 2 hrs on brand new AFR heads. Some folks put a little richer injector in that hole. Conservative AFR is the order of the day. Just make it better next time around.:thumbs:

well I had same problem on my LS6 I went with a shortblock from http://www.schwankeshortblocks.com/ They seemed to have quite a bit of knowledge on the LS motors for racing applications.

Clean your fuel rail and turn the injector upside down and tap it on a paper towel.

Sediment settles in the #7 area in the rail.

I have a 26k mile LS6 for sale if you're interested. Complete top to bottom...2500 + shipping.

Not sure if anyone has gotton the bottom of the #7 ills, this post HERE is the closest I've seen to any insight.
As mentioned, another guess is crud due to the rail design, either in the rail or in the injector.
Another idea floating around is the intake manifold design, but Kurt's testing seems to disprove that.
Would be great if we had cylinder-specific tuning ability, but you'll need to dish out for an aftermarket piece for that, or at least a piggy-back injector controller.

I have read it is a combination of the rail clogging up in that area and coolant having air pockets and moving to slowly around the cylinder.

These two tied together will for sure do it.

Water wetter help hot spots?

Generally, yes. But this is a specific (localized) problem. My guess is that the World Challenge cars that had the issue were running wetter (or the cheaper drop of dish soap) and still had the problem.

So even if you sent your injectors out for clean/blueprint, you need to address thr fuel rail?

:thumbs:

Not necessarily, I would pull and clean it from time to time, once every two years or so. Keep fresh fuel filters on the car will also help.

if its a steam pocket issue, does venting the head at the back help?

I have seen high compression LS1 engines tap the back of the heads ala LT1 and T them together and run it to the radiator.

The heads are tapped already. just have to pull out the block and replace with something else. I did that a few years back using something like this: http://www.kurturbanperformance.com/...-adapters.html

I thought there was one stock that connected all 4 together and sent out to the coolant hose
...

All of them were that way 97-00ish. The Z06 intake got in the way and they switched it over to the current setup.

Randy

Seems like someone dropped the ball. Typical of engineers to change something to solve a problem without looking at the reasons WHY it was there in the first place.

I would know because I've worked with those kind of engineers and I try to remember the lessons I've taken from the past so I do not make the same mistakes.

With that said, some seem to be going overkill on the vent sizes. I've seen an3- an4 lines coming off the 4 corners. This to me is marketing.

Do most people run a lower thermostat to combat the issue?