please look at this log, Engine let go #5 piston

[98hc4mula]

can you please look at this log and see what you can tell me if anything about the engine burning a hole on piston 5.
As i went through the runs, the AFR stayed pretty rich at 11.8 at some points, the sparks was also 26.5 during the WOT runs.... I am speculating that the fuel pump is to blame since im still running the 98 ls1 OEM one. the thing is I cant see this in the logs....
I already have an upgraded fuel pump from racetronix and their harness to install it once the motor gets back to me. what bothers me is that the AFR looked great during the runs and so did the timing. the car was running very strong and was super peppy.

please look at this and speculate from what you see....I need to get to the root of this bc I cant be going through pistons like this.

[98hc4mula]

I am also thinking about sending out the injectors to a reputable place to have them flow tested and see if that may be the problem, I want to know if injectors on 5 and 7 are not flowing correctly....
any place I should contact for this???? I live in Dallas if that matters

[wyochimneysweep]

is your wide band on bank 1 or bank 2? could be injector or how about a blowen intake gasket on number 5 or a vacuum leak near number 5 leaning it out?

[98hc4mula]

its on the same bank this happened....on the passenger side. no problems with gaskets but I am definitely going to replace them.
it didnt feel like there was a vacuum issue....
did you look at the log and tune? does anything pop out from them?

[98hc4mula]

Anyone care to give me some input???

[JoeyJoeJoe]

Number 5 should be on the drivers side, or bank 1. B1: 1,3,5,7 B2: 2,4,6,8 for chevy anyway.

[mecanicman]

Post up the rest of the engine combination. I dont think its the fuel pump. when you go wide open the afr falls down into the 10s at 6000 rpm. You have a interesting map fluctuation, and one bank is running leaner then the other, o2s totally opposite in spots, and wide open large differance in injector pw. See combo before I speculate any further.

[edcmat-l1]

Post up the rest of the engine combination. I dont think its the fuel pump. when you go wide open the afr falls down into the 10s at 6000 rpm. You have a interesting map fluctuation, and one bank is running leaner then the other, o2s totally opposite in spots, and wide open large differance in injector pw. See combo before I speculate any further.

The one bank running leaner than the other only looked like it happened on the first WOT pull. The other ones the NBs looked identical.

IPW is the same after that first WOT pull.

The B2 NB has a more pronounced jagged downward spike pattern, indicating there is probably a misfire on that side, puffing raw O2. That pattern is indicative of a cylinder problem. It is consistant. Something was definitely happening on that side.

[98hc4mula]

the engine specs are this:

408 Iron Block LS1 Shortblock
6.0 GM Iron Block

Eagle 4.000 Stroke 4340 Steel Crankshaft (freeze plug replaced Jun 7th 2010 with GM PN 24502262)
Eagle 6.125 On-Center 4340 H-Beam Rods
Rods Feature 7/16 ARP Cap Screws
Wiseco 8cc LS1 2618 Pistons (11 to 1 w/ 66cc)
Total Seal Plasma Moly Rings
Federal Mogul 152M Race Main Bearings
Clevite CB663H Race Rod Bearings
Federal Mogul 1888M Cam Bearings
ARP 234-5608 LS1 Main Studs
GM Factory Side Bolts and Plugs Installed
AFR heads milled to 62cc for 11.5:1 Compression, .610 dual springs, Harland modified stock rockers, 7.325 long pushrod, LS7 lifters
60 lb racetronic injectors, TR6 NGK plugs installed from the box...dont remember the gap.
Powerbond UD pulley
Fast 92 intake, Nick Williams 92 TB
ARH 1 7/8 x 3” stainless steel Headers and Catted Y pipe
Transmission Specs
Circle D 4L80E, vacuum modulator installed, transgo shift kit and full rebuilt with their specs.
Circle D 4l80 Pro Series Stage 1 245mm 5C torque converter 4200 stall
4l80 SFI flex plate with wide bolt pattern.

do you think having the injectors flow tested is a good idea? and also I am planning on putting the fattest ones on cyl 5 and 7
the fuel pump is going to be swaped as well.
intake gaskets are being replaced.
dont know what else to look for.
I thought the tune looked pretty safe for the combo, no sign of detonation since KR was reporting 0.

can someone verify my knock sensors are not desensitized and able to report knock if present.

[98hc4mula]

also the WB is located in the position of the front O2 on the Drivers side Bank 1 since I knew that side has the highest potential of running lean. the O2 is on Y pipe about 6-8 inches downstream of the WB....is that sucga a bad idea? Im also going to be welding in a bung on the collector just in case that makes a difference with the O2 readings.

[mecanicman]

Dont suppose you have any pictures of #5 piston?

[98hc4mula]

im uploading the ones I took to photobucket hold on a min....

[98hc4mula]

this is one of the #5 piston photos I was able to take before I went nuts...lol
[IMG][/IMG]

here is another one of the same piston
[IMG][/IMG]

number 7
[IMG][/IMG]

[mecanicman]

Have the injectors flowed and let us know the results.

[98hc4mula]

cool, will do

[mecanicman]

Widebands are better installed 6-8" from the collector, not right in it. You tend to see more of each cylinder pulse in the collector and a less stable reading, moving it back a little farther you get a more stable reading.

[Nitroused383]

Look at your map sensor in your WOT runs, its going ape shit. This is either from valve float or a misfire. That hole in your piston is right next to your spark plug any coincidense? Projected tip spark plug that turned into a blow torch maybe?

[mecanicman]

My next suggestion depending on how injector flow comes back would be lost oil control. The afr gets to rich for n/a, start having low octane oil entering cylinder and your blow torch analogy is pretty good.

[Vetal]

OP, did you find the cause?

[98hc4mula]

We think it was a combination o the old 98 fuel pump and the injectors on five and seven not flowing the same as the rest. In fact they were the lowest flowing ones out of the eight. The engine is arriving to us within next week and we will begin installation. I got flow matched injectors. And a new raxetronix pump and harness to install. Also a fuel pressure gauge to keep an eye on that issue.
Then I will start it and see what we can tell at that point