Technical Pistons Question

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Technical Pistons Question

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Apr 4, 2007
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Hello again,
Still waiting for some money to come so i can update the turbo thread! I do have a question to ask though, the pistons from a 1242 8v SPI engine, could i remove them from the engine and put them on a CNC lathe to skim the required amount off of the top of them for HB? or would i be removing some kind of hardness coating? I thought i better ask the question before i go off on one trying to find information and working out CRs etc.

Many thanks in advance

Lenny

PS - Mods move as applicable didn't know where to put this one. :eek:
 
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Sealand
Hello again,
Still waiting for some money to come so i can update the turbo thread! I do have a question to ask though, the pistons from a 1242 8v SPI engine, could i remove them from the engine and put them on a CNC lathe to skim the required amount off of the top of them for HB? or would i be removing some kind of hardness coating? I thought i better ask the question before i go off on one trying to find information and working out CRs etc.

Many thanks in advance

Lenny

PS - Mods move as applicable didn't know where to put this one. :eek:

I use the 1242cc 16v pistons in my 1242cc 8v turbo and this has shown to be a good sollution.
If you mashine the original pistons make sure you dont mashine down the piston crown so the pistons get a flat top.
 
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SlinkyCinqi
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yea i was thinking of doing that tricker, i may still go that route, just looking at options, i don't suppose anyone has a drawing for the VA pistons in an 1108 do they? just for a rough idea of angles and how much material to take out?

Many thanks again

Lenny
 

arc

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don't use VA as an example, they machined them flat i think. check for pics of emmas hiboost using mahle pistons.
 
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SlinkyCinqi
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ahh okey pokes, thought i'd heard somewhere about flat topped pistons in a cinq tub. Whilst i'm on the subject do the punto mk1s 85 (1.2 16v mpi) and the punto sporting (1.2 16v mpi) use the same engine/have the same pistons?

Thanks again

Lenny
 

arseofbox

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don't use VA as an example, they machined them flat i think. check for pics of emmas hiboost using mahle pistons.

It also stresses the ring lands more - best bet is go for a set designed for a turbo engine with larger and deeper lands. But machining will do if you can't afford those.

I agree with that comment re vAD's kit. Theres something about the vAD turbo kit I just dont like. The fuel controller is bodged for the LB, the lack of an ACOC worries me from standard....it just seems like a parts-bin special.

The Novitec conversion is much cleaner, although much more expensive!

According to my calcs, a 2mm reduction in profile is required (assuming the piston crown profile is duplicated 2mm nearer the gudgeon pin)

Ceramic coating could be expensive but may be a winner, as it should help heat disspiation a bit.
 
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SlinkyCinqi
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thanks arse :)

Whats this i've been reading about the standard pistons don't have enough meat on them to machine them down? also when you say replicate the crown 2 mm down, would i also need to replicate the valve cut outs on the top face of the piston? or just the outer raised crown?

Many thanks again

Lenny
 

arseofbox

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thanks arse :)

Whats this i've been reading about the standard pistons don't have enough meat on them to machine them down? also when you say replicate the crown 2 mm down, would i also need to replicate the valve cut outs on the top face of the piston? or just the outer raised crown?

Everything on top face.

Ive heard that too....but I dont know what constitutes enough meat TBH. Id be interested to run a thermal / stress analysis on a piston if I had the time , inclination and understanding! But I dont really....:(
 

Whiley

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am in talks with a guy about getting forged internals made up for mine at the moment could have a word for you if you want to chuck some money lenny :p
 
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SlinkyCinqi
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hmm, gimme a price and i'll let you know my pistons would be for a 1242 though. So bigger bore than the 1108 i believe. 70.8 to the 1108s 70.0

Still if you can get me a price, wouldn't do any harm

Cheers

Lenny
 
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