Paul_13 212 1 Cars Posted July 30, 2009 I thought I'd start a new thread I will be using a GTI 6 block and a diesel crank in this conversion, unsure about pistons as I will probably buy some forged/custom ones. Just a project to do over time really and then drop the engine in and sell the old one Recently bought this off a member the 306gti6 forum: Includes: Exhaust/inlet gasket Valve stem seals Thermostat gasket Headgasket three layer (the layers seem to be separate and not joined apart from around the piston, is this right?) Headbolts Exhaust fitting kit (with two sets of bolts?? Bit generous of Peugeot) And a circular rubber seal which I am unsure what it is for Bit of a bargain at £130 And my diesel crank I will be using. Going to take it to an engine shop and see if it needs a regrind or could do with a polish. Going to be picking up the block, head and sump this weekend or next. Any advice/support is welcomed Share this post Link to post Share on other sites
Anthony 1,000 Posted July 30, 2009 You're definately going to need different pistons in my opinion, as valve clearance is tight at TDC on GTi-6's with a standard 86mm crank, and moving the piston a further 1mm up the bore is going to leave you almost no clearance, and given how thin the pistons are I'm not sure that I'd be wanting to cut deeper pockets either. If you're not going to overbore the block, you'll need to find an unworn one, as any wear lip is going to ruin the rings in no time at all as the piston repeatedly goes back and forth over it. Also, whilst I've not worked it out, I suspect that you're going to be looking at very (too?) high compression - over 12:1 I'd guess. I've done a 2045cc (86x88) S16 before now, which feels very strong, but that's got the advantage of different pistons without the valve clearance issues, and the head has a 4cc larger chamber which kept compression at a sensible(ish) figure - something around 11.5:1 from memory. Share this post Link to post Share on other sites
Paul_13 212 1 Cars Posted July 30, 2009 (edited) I was expecting to get new pistons to be honest, I've heard the clearance is bugger all and I may install cams at some point later on in the build. Money permitting lol I was planning on boreing the block, not sure wether to go for the full whack of 88mm or 87.5mm. 88mm has problems of the cylinder breaking through to the water jacket I believe. I understand what you were saying about the wear lip near the top of the bore, my old S16 engine had a humungous lip. I haven't a clue about compression ratios, but i'll learn at some point Oh yeah Anthony, my mates says a big thankyou for the engine. He's enjoying it... i'm not I need to get mine on the road Edited July 30, 2009 by paul_xiii Share this post Link to post Share on other sites
welshpug 1,621 Posted July 30, 2009 (edited) yup, definitely different pistons required, standard gti6 pistons are dished and come up to deck. what you could use is S16/2.0 MI16 pistons, they are flat-topped and sit about 1mm below deck, drop them straight in and you'd have about 13-1 compression they'd still have a decent valve cutout too, maybe a bit too much compression though, skim them down a touch? of course, you have the big bore option and custom pistons, though they're not cheap. looooads of maths and figures here, though "disclaimer" please check them to be sure! http://forum.205gtidrivers.com/index.php?s...=105736&hl= Edited July 30, 2009 by welshpug Share this post Link to post Share on other sites
Paul_13 212 1 Cars Posted July 30, 2009 (edited) I just sent a set of S16 pistons to a bloke in Portugal who's on here. But i'd rather get the block rebored = new pistons I had a look at that thread ^ What do the figure mean with compression ratio, getting a bit confused with it all Edited July 30, 2009 by paul_xiii Share this post Link to post Share on other sites
welshpug 1,621 Posted July 30, 2009 (edited) not sure what's ideal but you need to work out what cams you're going to use too, I think for a road car between 11 and 12-1 is good. speak to an engine builder I think, as they'll be able to assist with choosing cams and the design of the pistons. edit, plenty of reading on the internet http://en.wikipedia.org/wiki/Compression_ratio Edited July 30, 2009 by welshpug Share this post Link to post Share on other sites
James_R 3 Posted July 30, 2009 I'd have a look at 16v205's engine build he got wossner pistons for his engine on an 88 crane, mighty nice items aswell Share this post Link to post Share on other sites
richsmells 2 Posted July 31, 2009 Gti6 / 88mm crank build: http://forum.205gtidrivers.com/index.php?showtopic=90889 Share this post Link to post Share on other sites
Cameron 16 Posted July 31, 2009 Don't take this the wrong way, but I think its probably a good idea for you to get a grasp of the basics before you go any further with this. Learn what a compression ratio is and how to calculate it, and learn how to calculate how far up the bores your pistons will need to sit in order to get the compression you want. Otherwise you're going to seriously piss off whoever makes your custom pistons, and probably have them come back wrong. If you put all your faith in somebody else doing the work for you, and just bolting it together and hoping it works, you're going to end up with a bunch of expensive swarf. Share this post Link to post Share on other sites
Paul_13 212 1 Cars Posted July 31, 2009 Don't take this the wrong way, but I think its probably a good idea for you to get a grasp of the basics before you go any further with this. Learn what a compression ratio is and how to calculate it, and learn how to calculate how far up the bores your pistons will need to sit in order to get the compression you want. Otherwise you're going to seriously piss off whoever makes your custom pistons, and probably have them come back wrong. If you put all your faith in somebody else doing the work for you, and just bolting it together and hoping it works, you're going to end up with a bunch of expensive swarf. I see what you mean Cameron, was going to sit down and have a read through and try and suss it out. I did engineering at college 2 years ago but it went in one ear and out the other... Just got to learn maths again Share this post Link to post Share on other sites
welshpug 1,621 Posted July 31, 2009 this might help http://www.pumaracing.co.uk/CAPACITY.htm Share this post Link to post Share on other sites
Paul_13 212 1 Cars Posted July 31, 2009 Cheers, thats put it in simpleton terms for me I'm going to have a go at doing a few sample calculations to get the knack of it Share this post Link to post Share on other sites
Paul_13 212 1 Cars Posted July 4, 2010 Got this and the roll again, going to start checking things over/mocking things and do a few calculations. Of course i'll keep you posted Got the: Block Crank Pistons Need: Gti6 sump Oil pump Possibly a head... Or rebuild old one Only bit i'm unsure of is the thrust bearing. Spoke to Miles and he believed this would the main problem. I'm trying to find the topic where Sandy modifies one!? Share this post Link to post Share on other sites
ryan_stdt 2 Posted July 20, 2010 I see what you mean Cameron, was going to sit down and have a read through and try and suss it out.I did engineering at college 2 years ago but it went in one ear and out the other... Just got to learn maths again i wonder why lol Share this post Link to post Share on other sites
