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"The Rest of the Story"


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All:

 

I hope that the following will bring some positive light to the discussion. Please note neither Shelby American or Quantum Performance were NOT responsible for the problems linked to the faliure of this engine. They were soley caused by the owners modifications.

 

The car in question is a 2008 Super Snake 725. The car had stock plugs in it. This is the guy I mentioned in the initial thread that was running lots of additional boost and had a bad tune. I met the guy that was tuning the car and he point blank told me he had no idea what he was doing with tuning the car. When he shared the file he was using to tune the car it was nothing more than a hacked up version of the Kenne Bell file as is installed on all 725 Super Snakes.

 

So a couple of problems immediately pop up in review of the tune. The gentleman doing the post Super Snake 725 upgrades installed Kooks Long Tube Headers with electric dumps which will cause a lean condition if not properly calibrated for. Long tube headers will cause a car to lean out due to collector scavenging etc.. The tune needed to be richened up to compensate for the long tubes and electric cut outs. It was not. Finally, the car had 72 lb injectors installed on it as well. The injector duty slope was way off and not properly tuned for the 72 lb injectors causing the car to run in an even greater lean condition. The only thing that saved this car from complete and total destruction was the higher octane race gas he was running. (104 Unleaded Sunoco) He was also running a 2.75" Upper Pulley which makes 23 lbs. of boost.

 

I worked with a friend of mine on Saturday and we tore the motor down completely and I took pictures of the damage (carnage) for a complete engine autopsy.

 

The only piston that failed was piston #4. Piston #4 is the last piston to get fuel in the fuel system even though the system is a return less pressurized system. The evidence and conclusion from the autopsy is that the tune was excessively lean and the last piston was starved for fuel and it got incredibly hot due mostly to the information mentioned above.

 

This engine failed because of the following and not due to the spark plugs:

 

1. The customer installed long tube headers (not properly calibrated for in the tune)

2. The customer installed 72 lb. injectors (not properly calibrated for in the tune)

3. The customer was running a 2.75 upper pulley (improper boost A/F calibration)

4. The customer was utilizing a really bad tune (improperly calibrated tune)

5. The customer used the services of an admitted tuning novice (bad Tuner)

 

Here is the good news. When this car was at the Texas Mile I personally pulled the plugs on this car and saw the motor craft plugs. After all of the lean out conditions and reasons above, all 32 intake and exhaust valves were fine and completely intact and all cylinders other than cylinder #4 were fine. Considering how lean this car was it is amazing the extent of the damage is limited to piston #4 only. That speaks volumes in and of itself in that there were so many other factors that caused the failure, the spark plugs were not the root cause of the failure or it would have failed in many other locations as well, particularly cylinder # 8 and would not be an issue on any stock tuned, non modified, Super Snake package.

 

This engine failed because of the tune and the many other issues mentioned above and not the spark plugs. There is no spark plug that could have saved this engine. Also, after storing your vehicle for the winter, in some areas, your fuel loses octane rating while sitting. It is wise to not over tax any engine until fresh or high octane rated fuel can be mixed or added.

 

I have attached all of the pictures from the engine tear down and the autopsy.

 

One picture in particular shows what is demonstrative of all pistons in this motor. All piston heads are fine and all cylinder walls look exactly the same with no scoring of any sort except for that of #4.

 

Because this "topic" has strayed "off topic" on many occasions, and due to my findings, I have asked that this thread be closed immediately after posting.

 

All parties should be contacting Shelby American customer service directly if you have any specific questions regarding spark plugs in your Super Snake.

Shelby American, Inc.

6755 Speedway Blvd.

Las Vegas, NV 89115

Phone: 702-942-7235

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