GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: Ben Lessani on 15 January 2009, 00:20
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would that work? Again, taking the 2.0l block up to 2.1 and running it on a std 8v K-Jet head?
I imagine it would be torque central, but would the crank actually fit?
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Just fit an ABF and stop mithering about things.
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:tongue:
Just wanted to see my options ;) It's easy to hide a crank from the insurers, not so much a 16v!
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problem with 2.1 is and allways has been the con rods or pistons. for true 2.1 you use a short nose mk3 diesel cranckshaft and bore to 83.5mm that gives you 2092cc
you and use stock pistons but then need spectial rods ( shorter ), or use stock rods with custom pistons ( higher pin )
a tall block ( eg 2E ) useing std pistons and rods when fitted with a 95.5 mm cranckshaft is going to push the pistons 1.35 mm to high,
you chould mill the pistons down 1.35 mm with the shape of the 8v pistons this is possible but it'll bring the cr up as it effectivly reduces the dish in the piston by 1.35 mm so compression will be off up a fair bit, also the capacity has increased.
3A pistons have a lower compression hight so that helps it is also possible to offset the littel end bush to drop the piston in the bore relative to the cranckshaft, meaning combustion chamber stays the same size and increases in compression ratio are minamised
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That's an answer ;) Thanks very much! You've officially scared me enough to not bother.
I sat and read a thread on cGTi that was around 30 pages where the fella had a 2.0 block, bored to 83.5mm, uprated rods, knife edge balanced crank and mucho's more. Then it died 1,500 miles later, from what looks like either oil starvation at the shells or overtightened oval shells.
Brilliant engine, but I don't think I could take the risk on spending a small fortune on an engine that could so easily catastrophically fail :sad:
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Personally, I don't believe in knife edging a crankshaft unless the engine is race tuned and is stripped down frequently. The cylinder bores rely on splash lubrication. Less splash, less lubrication. Probably why it failed.
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Danny - have seen many people talk and a few do the 1.35 mill down thing.. but they always, always say, you must keep the dish the same.. effectively keeping the entire top half the same as it should be.. to keep CR etc
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That would depend on what you want from the engine TBH. First concern is valve to piston contact. Do the pistons have valve recesses in them? What CR do you want? etc.
When I rebuilt my Chevy engine for my Cobra, I replaced the dished pistons for flat top for two reasons. The first was to increase the CR. The second was to maintain an even burn of the charge accross the crown of the piston.
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http://clubgti.co.uk/forum/showthread.php?t=176252
http://clubgti.co.uk/forum/showthread.php?t=94198
http://clubgti.co.uk/forum/showthread.php?t=161285
few bits read previously :smiley:
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well barn door method of working out if 3a piston will work
3A and PB both are same hight block and both have same length rods.
PB :- piston compression hight 32.2 mm
86.4 mm stroke, / 2 = 43.2 mm
1/2 stroke + rod length = 43.2mm + 144mm = 187.2 mm
block hight ( 220 mm ) - 187.2mm = 32.8 mm for compression hight of piston if comeing flush with block deck
actual compression hight is 32.2 mm, so piston comes 0.6mm shy of block deck
3A :- piston compression hight guestimated at 29.0 mm
92.8 mm stroke / 2 = 46.4 mm
1/2 stroke + rod length = 46.4mm + 144 mm = 190.4mm
block hight ( 220mm ) - 190.4mm = 29.6mm compression hight if piston comes flush with block deck. if the 3A pistons are .6mm shy of the deck like PB, compression hight is 29mm
now take a tall block with a block hight of 236mm and a 95.5 cranck and 159 mm rods
95.5mm/2 = 47.75mm
47.75 + 159 = 206.75
236mm - 206.75 = 29.25mm compression hight to bring piston to face of block, guestimated compression hight of 3a pistons = 29mm so 3a pistons should come 0.25mm shy of deck.
gustimation say 3a pistons in 2e block with 2e rods and a 1.9 d cranck will work, rods may need bushing down have feeling there 21mm grudion pins pins
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Just read through those three articles on cGTi. Even more confused that when I started, one thread its not possible to transfer the toothed wheel on the ABF to a 1Y or 1Z crank, and then Dex's thread he's got the diesel crank (doesn't mention which) and an ABF - but its so vague!
I'm in two minds, the gains from the RR from the 2042cc conversion seem negligible over the standard ABF or ABF/KR head combo.