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4g63t engine failiure rod snapped

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I recently did an engine, customer was satisfied, initial start up was good, checked compression before starting dry and wet. Engine was broke in and wasnt seeing boost, no knock, no irregular noises. Setup was je pistons with manley rods on stock crank, .002" bearing clearance, .0035" ptw clearance. Car went on the dyno, saw 600hp on c16, up to this point no noises again, no knocks, running well. He tuned with a haltech elite if i rem correctly. He sent a video of the car setup on the 2step and launching, car seemed great. Another vid was sent later the car was breaking up whilst running. Cam angle sensor was faulty and caused car to misfire whilst on the run, tried to rectify the problem with the tuner and kept melting the sensor due to the heat from the exhaust. Had a wiring issue due to this. They said they sorted it out and the car was parked for some time afterwards as the owner work offshore and returned to give the car a run approx after a month and was driving on pump gas and accelerated and the rod came through the block. Our pump gas is 91oct and it was sitting parked. I explained to the customer there are too many variables to pin point and say that the engine build was compronised due to negligence. I explained that it could have been detonation that caused the problem in addition with the ignition problem he had which could have resulted after numerous times trying to resolve the issue and run the car. The rod snapped jus below the piston skirt, also the intake valve was bent then the rod came pff the crank. Any advice on this matter will be appreciated

Attached Files

Any pics of cylinder wall?

It's most unusual for connecting rods to break there, without there being some other issue - can you get decent pictures of the breaks?

Is there any sort of log you can check, preferably with rpm? My personal suspicion is a 'money shift' with a drastic over-rev' of the engine.

Ah, had another look at the pic's, there is clear discolouration of the connecting rod near the big end, suggesting that may have failed first before breaking it close to the top. It's certainly possible the poor tuning and detonation/pre-ignition caused damage to the big end bearings, leading to the failure.

I'd suggest pulling the other rods and bearing shells and having a close look at them - both for discolouration and damage. You may also see discolouration on the crankshaft.

My personal opinion is the tuner and/or owner stuffed up with the tune and caused the failure - if it were something you'd done I would have expected it to have shown up during the break-in and initial tuning.

Gord i was trying to explain to the customer that detonation does not necessarily mean your pistons will melt. One theory we had was that the detonation broke the rod first and by spinning on the crank at high rpm cause the bearing to spin and when the rod locked on the block it ripped the big end off. All other bearings were in great condition no signs of wear or oil clearance issues

Cylinder wall still maintained cross hatching. In my experience if a bearing has excessive clearance u will experience knocking and there was also no signs of bearing material in the sump to assume that the bearing was wearing prior to this

Ok. Did he tell you how high the engine was revving? And when you say it was making 600 hp - what kind of dyno it was measured by?

He was in boost on pump gas, he was pulling the car hard

How hard? The reason I'm asking is that particular type of Manley rods on the picture are not that strong especially when used in conjunction with manual transmission. If they were pushed to the limit (600 hp by Mustang dyno) by high revving and hard gear shifting or severe detonation it was likely to break.

Manley turbo tuff rods. The customer does not want to understand and is being very ignorant

Oh, sorry - I was wrong. Turbo tuff series is quite strong. It couldn't not be caused by overrevving or detonation. I thought those were Manley H beam rods - the weakest withing Manley rods for 4g63.

Understandably but even in instances of detonation it can snap. Like i stated excessive bearing clearance will knock prior to anything this extreme.

If the big end starts to fail, yes, one would expect it to be audible - but that's assuming the driver/owner actually knew enough to stop and not ignore it. I'm suspecting it would be the latter.

Again, my thoughts are that you provided a product and it was tested without problems before passing on to the client. THEN the client decided to 'improve things' changing it from the product you supplied and so incurring the risk on himself. It's EXACTLY the same thing as someone buying a new car and 'chipping' the engine - it voids any warranty/guarantee on that engine.

Think of it this way - if you built the engine and the client decided that he could get more power by dropping the oil level for less windage, would you be liable for failure from a lack of lubrication? If the owner increased the RPM limiter (checked it?) would you be liable for a dropped valve from valve float? The answers are, of course, NO!

Once again, NOT your problem!

Gord you are a legend. I wish ppl could have a reasonable understanding in these matters. This is the game of speed.

So update, ive learnt that there was a tps issue with the car and also an injector seal leakage issue which he failed to mention ti me