Gsi_Ire
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Registered: 9th Aug 04
Location: Republic of Ireland
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My mechanic reckons i need to replace a piston, he cant be sure till he has a look at it ofc, but assuming he is right it will cost bout £200.
I plan on doing some work in the future on the engine, so was thinking maybe of upgrading all the pistons while he is at it.
What would ye recommend and how much you talkin?
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James R
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Registered: 4th Feb 03
Location: 205GTi16/306GTi16
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You can't really tell if they need changing till they are out rhe block and measured to see how worn they have become.
Forged pistons are about £400 with rings, but you need to modify the rods to accept the different small ends used on them.
But unless you're running lumpy cams your engine will be in trouble as they are high intruder type normally, and unless you have high over lap cams the dynamic CR will be too high and it will pink badly.
Your best off just having the std pistons pocketed, that will be ok to up to 285mm 11mm dur/lift cams, although std ecu can't cope.
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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uprated pistons... well SBD ones cost the earth  if you find cheap uprated ones though let me know....
[Edited on 28-10-2004 by Siberia]
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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quote:
Originally posted by j1400
You can't really tell if they need changing till they are out rhe block and measured to see how worn they have become.
Forged pistons are about £400 with rings, but you need to modify the rods to accept the different small ends used on them.
But unless you're running lumpy cams your engine will be in trouble as they are high intruder type normally, and unless you have high over lap cams the dynamic CR will be too high and it will pink badly.
Your best off just having the std pistons pocketed, that will be ok to up to 285mm 11mm dur/lift cams, although std ecu can't cope.
 some people may not understand all that... if you had of said all that to me a few months ago wouldnt have know what the feck yer on about
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Gsi_Ire
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Registered: 9th Aug 04
Location: Republic of Ireland
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well i dont understand a word, so basicly, its not worth it or neede unless i do a sh*t load of work to the engine, and the mechanic said he couldnt be sue till he took it out.
[Edited on 28-10-2004 by Gsi_Ire]
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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i'd just use standard parts there good up to 7500-7600RPM.....
uprated internals just cost to much..... and as j said yer gonna have to lots of things at once...... mega €€€
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Stu_22
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Registered: 25th Mar 02
Location: Luton
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quote:
Originally posted by Gsi_Ire
well i dont understand a word, so basicly, its not worth it or neede unless i do a sh*t load of work to the engine, and the mechanic said he couldnt be sue till he took it out.
[Edited on 28-10-2004 by Gsi_Ire]
Yeah.
What your mechanic saying are you sure its not just the rings.
But as J1400 said while its all out the standard pistons can have the valve cut outs enlaged for slightly lumpier cams ca they dont crach together
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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quote:
Originally posted by j1400
Your best off just having the std pistons pocketed
how is this done????
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Gsi_Ire
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Registered: 9th Aug 04
Location: Republic of Ireland
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Well, i got a tap, bad in the mornin, not so bad as the day goes. he is fairly confident its the piston, so he wants to drop the sump out and check. dont ask anymore, cause i just dont know 
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Greasemonkey
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Registered: 17th Apr 02
Location: Drives a Tractor
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you can cut 2mm valve pockets into the standard pistons to accept the lift J1400 was talking about, it might be worth sticking some oversized pisons in 79.5 ones, this will give you about 25cc extra which means more tourqe, my C16XE managed 139lb of tourqe and that was with oversized pistons with 2mm valve pockets cutin to em
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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what size are standard c16xe pistons?
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Stu_22
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Registered: 25th Mar 02
Location: Luton
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79mm
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James R
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Registered: 4th Feb 03
Location: 205GTi16/306GTi16
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78.95mm 
The std internals are only good for 7200rpm!!
however if you replace the rod bolts for ARP items then you can go to 8k, past that the pistons laff apart.
Then past 8200rpm the rods can't take it.
Then 9k the crank isn't strong enough.
Oh and the oil pump would really need dry sumping when the steel crank goes in.
Anyway, you basically have the piston pockets that are already in the pistons milled deeper to allow the pistons to get higher up it's stroke before hitting the valves (defineately a bad plan)
Oh Grease monkey, you also had a powerbox thingy annnndddd a gas flowed head which will obviously bump up torque significantly as it increases VE and hence torque.
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James R
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Registered: 4th Feb 03
Location: 205GTi16/306GTi16
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Oh and it's gonna be cheaper to buy a lower milage bottom end £100 and swap it than a £400 rebuild
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Greasemonkey
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Registered: 17th Apr 02
Location: Drives a Tractor
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aahhh, yeah forgot to mention that, but think thats a decent figure to have even with them mods, seems it gets a little expensive after 8K, lol
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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Soooooooooooo standard internals except some arps and 7500 is ok?
doesn anything need doing in the head for this RPM?
[Edited on 28-10-2004 by Siberia]
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miles
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Registered: 25th Mar 02
Location: plymouth Drives: Astra Sport
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Head is fine.
My bottom end was al standard parts except the arp bolts.
Just get a secondhand block as said, cheapest and easiest way.
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ainsley_brader
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Registered: 24th Mar 02
Location: Tattershall, Lincolnshire
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Hmm
I dont think its a piston, I think you have a little end gone! I have exactly the same problem with a customers tigra atm.
Does it tap on tickover or only as you increase the revs!
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Gsi_Ire
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Registered: 9th Aug 04
Location: Republic of Ireland
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with tick over, seems less with revs, but that might just be cause its tapping faster
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ainsley_brader
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Registered: 24th Mar 02
Location: Tattershall, Lincolnshire
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What makes him think its piston? i'm sceptical
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Gsi_Ire
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Registered: 9th Aug 04
Location: Republic of Ireland
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couldnt tell you, i aint the most mechanical minded person.
but i have been told he knows his stuff, might try for a second opinion.
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ainsley_brader
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Registered: 24th Mar 02
Location: Tattershall, Lincolnshire
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mmm i'd like to know how he came by the diagnosis!
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Siberia
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Registered: 9th Oct 03
Location: Leprechaun Land Drives : Zafira GSI
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hmmm... i dunno my engine makes noise taps when its started i just dont bother looking at it... arnt c16xe's suposed to make a certian amout of noise?
of and another question... my engine has about 90k on it... it the much point in sticking arp's in it now?....
[Edited on 28-10-2004 by Siberia]
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