I've done a big end before and you will be able to tell from the journal ans it will be out of round. My 2c is that you would have heard a big end failure before it let go. I'm thinking further up the line, gudgeon pin or a lean out on a single cylinder?
Either way Reub, that blow. Lets start a collection to get this fixed?
This is the fear we all have with a fresh performance engine.... It is a gamble.... You never know when something catastrophic will happen....
The heads and valve gear look salvageable, the bottom-end looks toast.... The crank and three of the rods might be ok... The rest of the gear is all there.... Awesome work has been achieved.... Fit the 1776 of your mates, run the efi and cooling system as you have it, and get out on the road asap...
Enjoy it....
The love will return, and you will do it again....
Its always hard to look past the carnage to identify the cause of the problem. After seeing these new pics my thoughts are:
Seeing the camshaft was broken I'd be inclined to think the valve/piston interference happened after the engine let go. Also, the marks look fresh. If they were old there would be traces of carbon hammered into the piston from the valves too. This isnt the case, so there was no issue with interference before it went bang. It wont have been valve float with the valve train setup that the engine was running.
Chances are that the cam was broken by the rod when it parted company with the piston. Once that happened, it all went nasty from there.
The rod bearing isnt a good enough indicator to see if the engines oil pressure surged or not. Its been hammered to death after punching a hole through the block, and after that al the white metal disappeared. Similarly other the rod bearing on number 2 cant be used as an indicator of oil surge, because after the bang that journel will have lost oil pressure and you would expect depris and white metal damage to that bearing as a result. The journels on the crank dont appear to be burnt enough either. Only the mains can tell that story properly, and even then there will be some colateral damage.
Based on these new pics my best guess is a lean out either to incorrect mapping of the ecu, or fuel pressure issue. It appears to have happened on all 4 cylinders, so its not an injector issue (based on what has been shown).
Look at the colour of the spark plug electrodes from head 1+2. While the combustion chambers are all pretty sooty, the electrodes look bone white. The blow up happened at full load/wide open throttle and it was shut down immediatly after that. Having a look at the plugs removed from the left head will tell more of a story.
Chances are the lean out happend that quickly though, that the electrodes won't be melted, and only the colour can be used as a guide. Whats is actually left of the plug from number 4 and if it got an oil bath will also be a factor.
Email me the ecu map Reub, or have a look at it yourself. Fuel values at 7500 rpm + max load should be close too what they are where the engine is making peak torque at 5100 rpm, or perhaps a little less as some tuners tend try to keep the AFR's constant at the top of the rev range. I tend to make it very rich 500 rpm from the rev limitor incase a gear is missed, and to keep temps down a bit.
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
maybe if the conrod was broken, but how does a complete conrod which is attached to the crank swing around and hit the cam.....it can't.
I think you will fine the cam snapped after a chunk of metal tried to go through the straight cuts.
My opinion of the sequence : seizure to the bearing, locks the conrod for a split second, conrod then try's to spin with the crank as its locked, conrod then smashes piston as its next in line, barrel then goes as conrod hammers it......At 7000rpm this would happen very quickly and cause this amount of damage easily.
This motor has forged pistons, and there is no melting of the head or plugs....this canage was not caused by a "split second lean out".
Whatever we agree or disagree on though, the fact remains that Reubs now has a $10,000 pile of scap metal, so what does he do now ?
I think the spark plugs look fine. Certainly not lean enough to cause sudden failure. Running too lean will erode the electrode of the plugs, the electrodes look fine in what pics we can see.
If the cam died first then there should be a very bent valve. Part of the oil ring is up the intake port indicating the motor had turned a number of times after eating the piston before the cam broke.
Does this not make people worry when engines gettin built to have them Engine dynoed?....
Wouldnt it be better for warranty value?
How many builders would garrantee there work?
I ask the question cause there is alot of money put into this motor...$$$$
🙄
the big end is burnt
This engine would have made some nasty noises long before the catastrophic failure
IMO it should have been shut down much earlier
It would have been an easy fix if it wasn't run to destruction
Yep, bigend fed from mains, so second down the line, and first to feel effects of oil pressure/volume loss.
#4 too, which is supplied by center main, which has to feed #4 and #1 bigends, where both #3 and #2 have feed from their own mains.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
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