Tuesday, November 21, 2006

VW - Slip-in 88's

Slip-in 88mm ‘big bore’ jugs

Don’t bother. ‘Slip-in’ 88's are a sucker-bet, intended for the ‘kiddie’ trade.

Slip-in 88's are in fact stock 85.5mm jugs that have been over-bored by 2.5mm, which means the walls are thinned down by 1.25mm or about fifty-thou. The resulting sealing surface is barely a tenth of an inch wide and experience has shown that simply isn’t enough to maintain a reliable compression seal.

Indeed, the stock 1600 is little more than a slow leak, compared to the 1500, which in turn was a notorious dripper compared to the stone-reliable, leak-free 1300. Which is no mystery because the jugs in the 1600 started out as the 77mm jugs on the 1200 engine :-)

Increasing your displacement is always the most reliable means of increasing the engine’s power but that assumes you don’t break any rules along the way. Slip-in 88's are little more than a built-in headache, resulting in compression leaks, warped barrels and scuffed pistons. Enormously popular among the kiddies, of course, giving them bragging rights to a ‘big bore’ engine.

-Bob Hoover

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