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Short Deck 2.6 20vt Build

2664 Views 1 Reply 2 Participants Last post by  varia
I am currently building a 2.6L short deck stroker for a '90 90qs.

This thread will be for just documenting what I see or come across as I build. Just an exercise in using modern(optimized) Audi/VW engine internals in an old lump.

In the past you automatically use the 2.5 AAF block but would need to machine in oil squirters and most likely bore the block .... and would need aftermarket rods and pistons. Also has 24mm wrist pins. If you want to use an 7a/3b/aan you may need bore it and add aftermarket rods/pistons, then some griding to clearance the block for the rods. 20mm wrist pins. So all the newer TSI 2.0 engines are short deck strokers with 92.8mm cranks and 82.5mm bores 21 or 23mm wrist pins. FSI was the same bore/stroke but with 20mm wrist pins. Starting from scratch I would buy BPY FSI rods and pistons, but I already had 3-4 sets of TSI CCTA internals to play with. A takeout set of TTRS rods pistons would be fine too.

AAF vs 7A/3B/AAN stroke
95.5 - 86.4 = 9.1mm huge amount to soak up in custom rods/pistons

AAF vs TSI/BGP stroke
95.5 - 92.8 = 2.7mm added stroke overall.
2.7mm / 2 (radius of the stroke = 1.35mm
1.35mm is all the extra clearance that is needed on the short deck. It may be a non-issue anyways.

-Starting out with a Non-turbo 7A 220mm short deck block with 82.5mm bores
-Eurovan AAF 95.5mm crank
-Mk6 CCTA TSI Rods 144x21mm and the matching 82.5mm pistons - so far rod big end needs block clearance
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7A rod/piston TDC on stock 86.4mm stroke.
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TSI rod/piston TDC on stock 86.4mm stroke.
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TSI rod/piston TDC on 95.5mm stroke.
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7A piston vs TSI piston wrist pin heights
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Piston skirt and ring comparison
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All 144mm rods. X-Beam TSI vs H-Beam 1.8T vs TSI vs 7A
Rod widths on the big end 77.9 vs 77.9 vs 77.3 vs 73.2mm
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Drilled some holes to help see what needs ground away in the block.
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Since the 7A block is non-turbo. You need to drill the block for a turbo oil return. The 8mm bolt holes are already drilled and taped. I was able to use an aftermarket universal 10an oil return adapter and bolted right up as a guide for drilling. Will most likely use a similar adapter when its turbo time
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you can use the turbo oil return to the pan, just like the later S2 cars.
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