Re: Eurovan crank in ur-Quattro?

[bbell@csn.net (Bruce Bell)]

>  Does anyone know if the Eurovan crank would fit an ur-Quattro block? What
>  would the resulting displacement be, with no overbore? What other mods
>  would be required? Anyone done this or anything else to increase
>  displacement on an ur-Quattro engine?
>
>  THANKS!
>
>  -glen
>

Hi Glen,

According to the VW parts department at Heuberger VW in Colorado Springs:
Seals and Main bearings for the Eurovan crank carry the same part numbers as
the Quantum Syncro's (2.22L Audi). As I recall all 5 cylinder Audis use the
same mains, and I assume seals too. The rod journals are a problem though
because there are several different sizes. e.g. the Ur 2.1L uses a different
size than the 2.22L in the 4000Q. (according to Chilton)

The Eurovan has a 95.5 mm stroke VS 86.4 mm, I am told the deck height of
the Eurovan engine is about 3/8" taller than our Audi's. Whether this
because they used a longer rod, or to make room for pistons with the
standard compression height (distance from face of piston to top of wrist
pin opening ~30-33 mm) or both, I don't know. Some clearencing of the block
is required to use this crank on a standard block. Much as with the 2.0L
conversion tuners such as tectonics have doing with VW's (although we don't
have to worry about the intermediate shaft as they do).

The Ur with a 79.5mm bore would displace 2370 cc; however I think you might
have problems finding pistons for that bore with the correct compression
height. Especially if you want to keep the static compression ratio low
enough to prevent melting the engine when the boost comes on. e.g if you
could change the compression height of your pistons so that they came to the
same deck height as they do now at TDC, then the CR would increase from 7:1
to a whopping 9.7:1 due to the increased displacement - ouch!

Tectonics has pistons in the 83mm size, and possibly 82.5mm, for their
94.5mm crank that have CR's of 8.5 and 10.1. These pistons are designed to
work with the 144 mm rods with th 20mm piston pins. Using the 83mm 8.5:1
pistons would still yield a 9.4:CR because the piston comes up an extra .5mm
in the bore (95.5mm crank VS 94.5mm). Total combustion chamber size would be
54.7 cc. For you to achieve a reasonable compression ratio, say 8.2:1 you
would need to increase the combustion chamber (I'm including head, gasket
and piston recess) to 63 cc. Several ways you might so dis including
polishing the heads combustion chamber and opening up the area around the
valves (unshrouding), possibly using a thicker head gasket, using a late
model head like Dan did should get you at least 3 cc, and finally, taking
some material off the tops of the pistons. I have not taken into
consideration that turbos may use a head gasket of a different thiskness. 

The problem with increasing displacement in an Ur quattro is one of finding
a piston that will work, as you know the Ur's pistons are "almost" unique. I
say almost because in the mid 70's VW made a European only GTI that had an
80mm stroke, with 9.5:1 CR that used the "Heron head" (combustion chamber
entirely inside the piston) and those pistons,79.5mm, are, at least
visually, a dead ringer for the Ur quattro's! Hmmm shared parts bins?
Speaking of shared parts bins, I noted the a couple of weeks ago that the Ur
quattro has the same size rod journals as the 1.7L VW engine. what I
couldn't determine is whether it uses the same rod (136mm) with the 22mm
piston pin. If it uses the longer 144mm rod with 20mm pins then you could
consider using the 7.8:1 81mm pistons from the late model 2.22L turbo. With
your slightly smaller combustion chamber you would end up with about an
8.2:1 CR.

IMHO 9.0:1 + compression ratios work ok for 20v turbo engins because of
small details like a seperate coil for each spark plug which is centered in
the combusion chamber and dual knock sensors to prevent detonation. If I
were brave and using a cam with a longer duration (reduces volumetric
efficiancy) I might try higher 8.5 or 8.6:1 CR on an 8 valve, but I'd want
to know that the ECU wuold shut down in time if there was a problem. I'd
also add knck sensors.

I don't think anyone has tried the Eurovan crank in an Audi yet. I'm the
only one I know of who's given it serious consideration. I talked to Ron at
Ron's Parts over a year ago and while he was able to provide some info and
even offered to build the engine (for a hefty fee). I still find the need to
know more about the design and construction of the Eurovan motor. I't could
be a better block and head to use as the platform. A mechanic friend has the
1994 Mitchell International data base on a zillion CD ROMS at his shop.
While this system has all the factory service bullitins and specs for most
cars, there is virtually zilch on the Eurovan's 5 cylinder engine.

Glen, you were right, my '87 4000q appearently does have a 3.89 final drive
as opposed to the 4.11 as advertised. What confused me was the difference in
ratios between 4th and 5th gears. I thought they had just changed the 5th
gear ratio for milage and cruising. seems that 5th is about a 0.77 ratio
while 1-4 are the standard 3.6, 2.31, 1.46 and 1.07 ratios.
 








Bruce

bbell@csn.org (Bruce Bell)