Slight piston problem....pics
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From: Norn Iron
Slight piston problem....pics Bores look ok, albeit with a slight burn mark where top ring gap sits.
Some of the top rings are burnt around these edges too. Ring surface is blackened. Gap when I built it was circa 23 thou I think.
Number two piston has a bit of the 2nd ring broken.
These pics are of piston No1. EVERY piston has this damage. The pistons do have light scuffing, nothing major IMO. Although the top ring land area isnt too pretty on some of them, but it is not damaged.
When viewing the engine from the front, the cracks are on piston are on the right side of the engine ( ie not the thrust side ? )
Any ideas as to the cause ? We could take my recent lack of meth into consideration, but I think this has been going on for much longer than this. This damage didnt happen overnight ?
Any vendors reading.... Anyone have any stock bore pistons in stock, for a 6.125" rod, 4.0" stroke, and as close to a 25cc dish as possible ?
AARRRRRRRGHHHHHHHHHHH
Some of the top rings are burnt around these edges too. Ring surface is blackened. Gap when I built it was circa 23 thou I think.
Number two piston has a bit of the 2nd ring broken.
These pics are of piston No1. EVERY piston has this damage. The pistons do have light scuffing, nothing major IMO. Although the top ring land area isnt too pretty on some of them, but it is not damaged.
When viewing the engine from the front, the cracks are on piston are on the right side of the engine ( ie not the thrust side ? )
Any ideas as to the cause ? We could take my recent lack of meth into consideration, but I think this has been going on for much longer than this. This damage didnt happen overnight ?
Any vendors reading.... Anyone have any stock bore pistons in stock, for a 6.125" rod, 4.0" stroke, and as close to a 25cc dish as possible ?
AARRRRRRRGHHHHHHHHHHH
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From: Norn Iron
Havent a clue...Ross supplied them for my bore, stroke, rod, and dish requirements. I told them it was for a highish powered supercharged application.
Its leaving me in a rather sticky situation for the event I wanted to race at on the 29th :S
Looks like I might throw my stock crank back in, with my old Mahle pistons for a 346 until I can sort something out here, unless I can source some pistons in time.
Its leaving me in a rather sticky situation for the event I wanted to race at on the 29th :S
Looks like I might throw my stock crank back in, with my old Mahle pistons for a 346 until I can sort something out here, unless I can source some pistons in time.
I would call ross with the job number, it could be they just made them a little too thin where they are cracking. You probably were a little harder thenmost and if they are just NA pistons with a dish they really arent made for the kind of power you were making most likely.
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From: Norn Iron
I have emailed Moe who had them made for me.... oddly, after the first pistons I had bought, had a faulty one.
So they made me this set to suit the stroker ( original ones were 0.944" pin, stock bore )
So they made me this set to suit the stroker ( original ones were 0.944" pin, stock bore )
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From: Norn Iron
Whats the time in California ?
I'll let the email run today, if I dont get a response, i'll call him tomorrow. Just wanted opnions here too...
In case there is anything I might have done to cause this. Although I cant think what. Unless I can get a set of pistons by say the 20th...it becomes irrelevant how long I have to wait after that.
I can do a forged 346 from old parts I have sitting about though. I'll probably just need to slow down the blower a little ( or maybe not ? )
I'll let the email run today, if I dont get a response, i'll call him tomorrow. Just wanted opnions here too...
In case there is anything I might have done to cause this. Although I cant think what. Unless I can get a set of pistons by say the 20th...it becomes irrelevant how long I have to wait after that.
I can do a forged 346 from old parts I have sitting about though. I'll probably just need to slow down the blower a little ( or maybe not ? )
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From: Norn Iron
I was hitting 19/20psi on 8.7:1 CR....
I'll have the same CR with the 346 combo. But yes, it would be interesting....
Do you think 25psi is do-able on pump+meth with my CR? Probably is...but its getting a little silly perhaps ?
Wonder what boost it would actually hit ?
Other option...
I have a Tig welder...shall I try and weld them back together
might be worth noting, my welding is crap lol
I'll have the same CR with the 346 combo. But yes, it would be interesting....
Do you think 25psi is do-able on pump+meth with my CR? Probably is...but its getting a little silly perhaps ?
Wonder what boost it would actually hit ?
Other option...
I have a Tig welder...shall I try and weld them back together
might be worth noting, my welding is crap lol
if you can heat treat them at home give it a shot lol.
Just put a lot of meth in and keep your fingers crossed at 25psi. I dont think it will pick up that much boost though.
Just put a lot of meth in and keep your fingers crossed at 25psi. I dont think it will pick up that much boost though.
not impressed, see below
after i sent kurt a bunch of broken pistons he got these made to suit my abuse (new piston on left)
that gusset could be helpful to you
after i sent kurt a bunch of broken pistons he got these made to suit my abuse (new piston on left)
that gusset could be helpful to you
Last edited by MIGHTYMOUSE; Nov 30, 2009 at 07:58 PM.
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From: Norn Iron
I see it...with hindsight, my pistons do look a little flimsy. But I can honestly say Ive never broken a piston before, that wasnt down to detonation, or simply melting it.
This is the first piston.....or rather 8 that have simply broken.
The Mahles I have from my old 346 look stronger. If I use them I end up with a forged 346, with same CR as before.
Im reluctant to go with any oversize pistons, as I dont trust anyone here to bore the block, more so considering its a totally stock LS6 block.
Might be time to invest in a new block soon....
Maybe a LS2 block this time ?
Although getting my CR down is awkward. Heads are 66/67cc
This is the first piston.....or rather 8 that have simply broken.
The Mahles I have from my old 346 look stronger. If I use them I end up with a forged 346, with same CR as before.
Im reluctant to go with any oversize pistons, as I dont trust anyone here to bore the block, more so considering its a totally stock LS6 block.
Might be time to invest in a new block soon....
Maybe a LS2 block this time ?
Although getting my CR down is awkward. Heads are 66/67cc
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From: Norn Iron
Originally Posted by MIGHTYMOUSE
not impressed, see below
after i sent kurt a bunch of broken pistons he got these made to suit my abuse (new piston on left)
that gusset could be helpful to you
after i sent kurt a bunch of broken pistons he got these made to suit my abuse (new piston on left)
that gusset could be helpful to you
One way or another, Im going to need new pistons. Or if I do decide to get another block, block and pistons.
That will only happen if I cant get pistons to suit a stock bore size.
Im not spending money on a complete new short motor though. Even buying and shipping a block from the US will cost enough..
Ross have received my email ( read request has been acknowledged ) but I have yet to get an actual reply from them.
The moly flaking off the rings is either detonation, pretty obvious by your plugs it was detonating.
Or the ring gap being too tight and butting together when they get hot.
I would guess detonation
Or the ring gap being too tight and butting together when they get hot.
I would guess detonation
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From: Norn Iron
possible...although I didnt hear anything...not that that means much given the damage.
Ring gap was as reccomended by ring manufacturer, for the application, maybe even a thou or 2 more. Definately not on the tight side though.
The joys of motoring
Ring gap was as reccomended by ring manufacturer, for the application, maybe even a thou or 2 more. Definately not on the tight side though.
The joys of motoring
I'm sure mightymouse didnt hear anything either when he melted holes in those pistons in the pic. Hell I've tossed connecting rods out of a motor 3/4 of way down the track and thought it was still pulling enough to stay in it