Date: Tue, 3 Jan 1995 14:12:08 -0600 (CST)
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Gerald Skerbitz <gsker@lenti>
Subject: Re: motor swapping
>From schwarze@superc.nosc.mil Tue Jan 3 13:06:34 1995
>From: David Schwarze <schwarze@superc.nosc.mil>
>Subject: Re: motor swapping
Christopher Bridge writes:
>
> We would all like to get our VW's greater hp with the least effort.
> To build this size ( 1835cc 92mm X 69mm) engine you must split the case to
> have the case bored. It is true that there are "slip in" kits for 87mm and
> 88mm bores. With a stock crank, this gives 1641 and 1678cc. The 87mm is a
> safe way to go- altough there are as many opinions about motors as there are
> people. The 88mm is generally not recomended. There is some confusion on
> what flycutting is. Flycutting removes metal from the large flat area on
> the heads. This is done to either increase compression ratio or to flatten
> the heads-cylinders mating surface. Under no circumstances have your heads
> flycut to increase your compression ratio- this is a great way to burn up a
> motor. To fit the case and heads with the 92mm jugs both the case and the
> heads will have to be machined.
Thanks for the correction Chris. I didn't mean to imply that the compression
ratio should be increased - merely that the diameter of the combustion
chamber be increased. I was also wrong about not having to split the case.
I forgot about having to widen the holes for the cylinders... DOH!
As for terminology, I always thought "flycutting" referred to the use of a
circular lathe to widen/deepen the combustion chamber, whereas "milling"
refered to removing metal from the large flat area on the heads, usually
done by running the head across a different type of lathe which removes a
couple of thousandths each pass. Milling doesn't do squat to VW heads
though, cause the mating surface is recessed. In any case, you are correct
on all counts.
-David
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David Schwarze '73 VW Safare Custom Camper (Da Boat)
SAIC Comsystems, San Diego '73 Capri GT 2800 (Da Beast)
schwarze@nosc.mil '87 Mustang Lx 5.0 (Da Bruiser? Soon...)
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