Lowering compression on the ALH engine

leon10tagg

leon10tagg

Veteran Member
Joined
Sep 26, 2003
Location
Northern Ireland
TDI
2001 Golf 90bhp ALH tdi, 2002 Golf PD100, 2004 Passat 1.9PD AWX, 2001 Golf 4-Motion, 1997 Audi A4 1.8t sport, 1998 Subaru Impreza 2.0t WRX
IF I were to fit the pistons from an AJM/ATJ/AUY to my ALH engine would they be strong enough to run with a set of Hi-FLO .272s, an 11mm pump, uprated cam and gtb2260?
 
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p0wer

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May 21, 2009
Location
Jyvaskyla, Finland
TDI
Golf 3 -94 1Z 377hp, Golf 3 Cabrio 4-Motion 1.8T 620hp, Golf 3 Syncro 2.9 VR6 HX52, Bora AJM 4-Motion 2260vk +120% Firad, Passat 3B Syncro AFN 2260vk
Yes .
 
Hasenwerk

Hasenwerk

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Nov 28, 2003
Location
Quesnel, BC
TDI
1982 Cabriolet (BEW|VNT17|Stage4), 1989 VW TriStar Syncro soon-to-be CR TDI (CBEA), 2001 Ford Ranger Edge 4x4 (ALH|VNT17|R520|Stage4)
Way back when, the 11mm|GT2052V|Race520 ALH that was in my VW Westfalia had the pistons machined to lower the compression ratio. We remove the lip that goes around the combustion hole so that the hole was straight up and down. Apparently this makes 18.5:1 and is what Volkswagen Motorsport did with the RTDI engine back in the late 90s.
 
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