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Discussion Starter · #1 ·
so i finally have time to look at my blown rb30 motor closely after a year and a half of being away from it
here are the pistons and rods, can anyone tell me, just from looking at it, what went wrong ??? and what caused the oil pressure to drop to 0 ???

motor was running for aprox. 500kms for break in and then went on the dyno blew up at the 5 pull because the oil pressure was at 0.

motor spec
rb30
spool rods
cp pistons
acl bearings
T78 greddy turbo






 

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pistons have suffered from heat which is what the discolouration is off, i would guess the score marks are also from heat expansion of either the block, piston or both

oil pressure suddenly dropping to zero would be oil pump
 

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Discussion Starter · #8 ·
very good point...i guess i should take a picture of all the pistons but i dunno wat order they are in...i just got them bak in a box
also ....i guess i should stay away from N1 pumps ...?
no it was not a new crank......when we measured the crank after....the it bent in the middle..:(
 

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You'd need to know a few things...

Piston Clearance to block.
Did you plastiguage the mains?
The big ends I take it were std.
What was the torque on turning over the short motor assembly.
Was the crank checked for true.
Are there any scores on the inside of the pump?
Was the block lined bored by any chance?

What was the oil pressure when running btw.

Let me know.
 

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Discussion Starter · #10 ·
You'd need to know a few things...

Piston Clearance to block.
Did you plastiguage the mains?
The big ends I take it were std.
What was the torque on turning over the short motor assembly.
Was the crank checked for true.
Are there any scores on the inside of the pump?
Was the block lined bored by any chance?

What was the oil pressure when running btw.

Let me know.
I cannot answer all ur question....I just hope my next engine built will land on better hands :(
 

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At best, you've got a serious heat build up n what looks like the thrust side of the conrod, so ~I reckon your oil pressure would be generally ok up until it blew, but look as tho the piston to bore clearance is out - is there any pick-up of piston on the bore/ heavy marking?

I reckon the engine would not feel lively, or run poor, was this the reason for pulling it apart?

Shame, some good components there, fit for the bin.

Has the block been overbored by any chance?
 

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The rod shows no sign of the shells spinning in the big end bore, but will almost certainly be oval now, through heat distortion. A brave man might have it re sized and honed, I'd bin it, together with its rod bolts, of course. As to cause it's hard to say, if the piston itself started to pick up it would overload the shells on its associated rod and overheating would occur. That piston certainly looks a little excessively scuffed on the skirt to me, could be dirt in the oil, assuming the thing had enough oil in it at all? Would need to see the crank, and all the other rods and pistons, plus the bores and cam journals. As others have said, a really high resolution photo of the oil pump with its cover off would help. Bore and piston sizes? Bearing clearances on any undamaged big end or mains, properly taken, preferably by internal and external micrometers, Plastiguage at a pinch? Failure analysis can take longer than building the thing in the first place, and be nearly as costly if something doesn't jump out and shout "It's me.....!!". What about the suction side of the pump, is the pickup filter screen clear of debris? Any issues with alignment of oil ways on the RB30 things?
 

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Well i sort of have to disagree. Was the whole set up balanced when built up? ie Pistons, Rods, Crank, Flywheel, Front pulley. If this was not dynamically balanced you are asking for trouble whatever oil pump set up you use

Although i agree some may be stronger than others, R.B motorsport has just built up my engine and i put no price limit on this build but told them i only wanted about 550 bhp from it, they fitted a GENUINE N1 oil pump, (rather than one off of ebay) And balanced the whole assy.

They told me the biggest problem with oil pump failure is bad or out of balance set up. One of the reasons for them getting so out of balance is some great oaf doing the cambelt and beating 10 bails of shit out of the front pulley.

Now i am no expert but as this happened to my engine on a standard oil pump, just after a cambelt change, and at about 7 thousand rpm. would guess a similar thing went on here, oil pump failure and rpm's cause mucho rebuild costs
 
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