one for the fuelling experts

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EssexAaron

Member
this engine was only built about 10k ago but as you can see the fuelling killed it.

but what i wana know is why has one quarter of the piston running lean? this is where the failure is also. isit just the normall spray pattern of the R.why isit no4 piston the same? the exhaust always stunk of petrol too

any ideas lads? need to sort this before next engine





 
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pulsarboby

Guest
how do you know it was running lean and not bore wash thats killed it?
i would say overfuelling is more likely as opposed to running lean.
in which case you may have a dicey injector!
so if i were you that would be the first thing i would get checked out. also check the engine oil for traces of petrol and smelling of fuel.

detting or underfuelling would have led to piston meltdown on top edge so i would say that wasnt your problem, whereas borewash will cause rapid heating of piston and rings and cause them to expand in cylinders and lead to scraping of walls
 
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noriek2003

New Member
there is no sign of any problems with lubrication there at all, any loss of lubrication would show as scuffing to the rings, skirt of piston. Thats not a failure due to borewash, its almost definately suffered from abit of det, not too bad as it hasn't blown the ringland which is where they normally go,

whats the set up on this car ? who built the engine ?
 
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EssexAaron

Member
i thought the lack of burn mark in that 1/4 of the piston would be down to lack of fuel. if you look at no1 in the pic the edge has started to melt. no2 had the same scores but on the opposite side also theres about 7 cracks in no1 and 2's riglands.. the usual.

this is why im asking, obviously new engine will be mapped with bigger injectors, my mate has a flow tester and cleaner so i mith get these tested to see what they come back with, what happened to your engine bob when you had bore wash, was it a similar thing?
 
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EssexAaron

Member
noriek2003 said:
there is no sign of any problems with lubrication there at all, any loss of lubrication would show as scuffing to the rings, skirt of piston. Thats not a failure due to borewash, its almost definately suffered from abit of det, not too bad as it hasn't blown the ringland which is where they normally go,

whats the set up on this car ? who built the engine ?
Click to expand...
nissan rebuilt the engine .5 oversize, still got hone marks, crank and bearings still look new.

it what way do you meen setup? engine, fuelling? car spec?
 
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noriek2003

New Member
its det, forget borewash.

any loss of lubrication will show as scuffing, you dont have any scuffing.

you've lost the edge of the crown, and are now saying the ringland is damaged. All points at det.
 
Fast Guy

Fast Guy

Moderators
Staff member
pulsarboby said:
how do you know it was running lean and not bore wash thats killed it?
Click to expand...

It's been detting, you shouldn't get that running rich. No1 piston has partially melted.
 
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pulsarboby

Guest
EssexAaron said:
what happened to your engine bob when you had bore wash, was it a similar thing?
Click to expand...

nothing like yours aaron, my piston had melted on the gudgeon pin side around half way down and had severe schafing to piston and cylinder.

after looking at photos again i have to agree with noriek (i never noticed the burn on top of piston edge) which as he rightly says does point towards detting, but theres a number of things that could have caused that!
timing out
dicey fuel pump or bad fuel surge
bad mapping
afm probs
knock sensor not working
dodgy injectors
insufficient cooling........the list goes on
 
red reading

red reading

Active Member
Water Leaking From The Head Gasket Will Cause That Kind Of Damage As Well,but Look's More Likely To Be Det Nissan Pistons Are Fine Up To 400bhp With The Right Fueling/ignition Set Up
 
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EssexAaron

Member
MarkTurbo said:
Why on earth did you get Nissan to build it and replace one set of chocolate pistons with a newer set of chocolate pistons :lol:
Click to expand...
trust me mate i would NEVER have done that:lol:

the bloke before me did, new engine will be built properly as all my cars are, im glad its apart now the amount of bits i aint happy with, thanks for the comments i thought it was detting, i understand it can be a shed load of things caused it, i woz more asking about the clean 1/4 of the piston just seems strange.

cheers lads
 
Fusion Ed

Fusion Ed

Active Member
Just like to add, that is 100% det. This pretty much always happens on the intake side of the piston. Due to these extra high temps and pressures it eats away at the piston crowns and cleans the area in question, burning off all the carbon.

Pulsars can take quite a fair bit more ignition with the typical mods we do (fmic etc) than they are mapped for, so my bet is that you almost certainly ran lean on boost.
 
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