Syncro Vanagon engine swap questions and details
David Marshall
Syncro Vanagon Engine Swap Discussion
The purpose of this rather long write up is so that people can pick
apart my design theories and offer suggestions on how to elegantly
mount a different engine into a Syncro Vanagon, namely my Double Cab
Transporter. Elements that I would like to see in this swap would be:
- Use Volkswagen or Audi parts whenever possible.
- Increase my power and reliability.
- Maintain the ability to be serviced by a Volkswagen mechanic if I'm
travelling and can't do the service work myself at that time.
- The last requirement would be to keep the factory skid plate under
the engine.
Results from this discussion will be posted on my web site at
http://www.volkswagen.org so it may help other people with the same
problem.
SECTION ONE: CHOOSING AN ENGINE
First on the list would be choosing a suitable power plant from a
Volkswagen or Audi. Measurements of my Syncro show 15.5"clearance
between the bell housing and the wasserboxer mounting bracket. It is
necessary to keep this bracket if the engine skid plate is to be
retained. This is why only 4 cylinder VW / Audi engines were chosen,
as the oil pan will be less than 1" away from the engine bracket when
using a 5L oil pan.
Hp /rpm tor/rpm code FI
2.1L Wasserboxer 95 /4800 117/4800 MV Digifant
8 VALVE VOLKSWAGEN & AUDI INLINE 4 CYLINDERS
1.8L R GTI/CAB/SCIR 90 /5500 105/3000 JH CIS
1.8L 85-86 J/Golf 90 /5500 98 /3250 MZ CIS
1.8L 85 GTI/GLI 100/5500 105/3000 HT CIS-E
1.8L 86-87 J/Golf 102/5250 110/3250 RD CIS-E
2.0L Audi 80 115/5500 3A CIS-E
2.0L 93+ J/G/B 115/5200 135/2600 ABA Motronic
16 VALVE VOLKSWAGEN INLINE 4 CYLINDERS
1.8L 86-89 G/J/S 123/5800 120/4250 PL CIS-E
2.0L 90+ G/J/P 134/5800 133/4400 9A
CIS-E/Motronic
With the above engines there is one clear and economic replacement
choice - The +-$500 1.8L JH engine that is found in all 83 to 84
Rabbit GTIs and 84 to 89 Sciroccos and Cabriolets with 1987 and newer
engines being the pick of the litter with self adjusting hydraulic
lifters. The MZ engine is a close second but it has a few ft/lbs.
less torque due to the smaller exhaust valves. Another thing to take
into consideration is wiring the engine and the installation of the
fuel injection components. The electrical system that is found in the
CIS JH engine is very simple to hook up. A small fist sized
distributor control box that requires 12V and Ground is the only thing
that really controls this engine. Engines with 10:1 compression ratio
require a knock sensing ignition which requires installing a computer
that is about the size of two VHS tapes stacked one on top of the
other with a lot more complicated wiring. If you feel up to the task
of the extra wiring and don't mind the torque coming on at a higher
RPM range than a 1.8L 16V might be the ticket. The other thing to
mount is the CIS fuel meter / air filter assembly. This shouldn't
prove to be too difficult if one uses an injection system and intake
manifold from an Audi or VW Fox or the injection system from an 85 to
87 Golf or Jetta.
QUESTIONS:
1 - Is the Vanagon fuel pump compatible with the CIS fuel injection
system?
SECTION TWO: MOUNTING THE ENGINE TO THE SYNCRO TRANSMISSION
Attaching the Volkswagen I4 engine to the Syncro Transmission will
require an adapter plate with one set of holes to bolt the Syncro
Transmission and then another set of holes to mount the I4 engine. In
the center of this plate there will have to be enough room for the
flywheel / clutch assembly. The plate could be made from a flat piece
of steel or aluminum. The problem with a mounting plate is if the
Syncro flywheel is mounted to the I4 crankshaft without a spacer it
will not reach the Vanagon's starter and the push rod for the clutch
will have to go out further to do it's job.
Questions:
1 - Does a Golf pressure plate assembly have the same bolt pattern as
a Syncro Vanagon flywheel? If not is there a compatible VW / Audi
flywheel / clutch setup?
2 - Is the I4 crankshaft that has the same depth as the wasserboxer's
crankshaft? I.e. will the flywheel spacer have to be a different
thickness than the adapter plate?
3 - Would it be feasible to use an I4 VW Automatic or Audi flywheel
and starter (starter mounts next to engine and has more torque) in
conjunction with Vanagon flywheel?
4 - Is the Vanagon starter powerful enough for a 10:1 compression
engine?
SECTION 3 - MOUNTING THE ENGINE TO THE VANAGON'S FRAME
As stated in the opening paragraph, I would like to keep my engine's
skid plate. This means retaining the stock wasserboxer mounting
bracket that the skid plate attaches to. We also have to keep the
engine from moving. There must be a support at the pulley side of the
engine, a mount on the exhaust side and dipstick side of the engine.
So this leaves me with the big question of what to do for a simple and
strong engine mounting system!
The pulley side can be mounted in a similar way as the Diesel
Vanagon's engine is mounted. Bolt a bracket on the side of the engine
in the same manner as a VW Rabbit / Audi Fox and have it extend to the
rear of the engine bay or to the original wasserboxer mounting bracket
below.
The side mounts (exhaust and dipstick sides) are a little more
difficult to design. There is the way a Diesel Vanagon mounts, but
the skid plate would definitely be in the way and it is designed for a
30 deg engine mounting angle instead of the desired 15 deg. After
looking at a four cylinder Audi Fox I saw that there is a sub frame
that the side motor mounts bolt on to. The sub frame goes under the
engine and does not protrude below the oil pan. This is promising in
that I can most likely keep the Syncro skid plate and have a similar
mounting system as the Diesel Vanagon.
Questions:
1 - What is the best way to fasten the Audi Fox sub frame to the
Vanagon's frame?
2 - Are there any other proven ways to mount an I4 into a Syncro
Vanagon and still keep the 15 deg engine angle?
SECTION 4 - EXHAUST
The exhaust can be done in a number of different ways. The easiest
way would be the same as the Diesel Vanagon. An alternative would be
to use a single outlet manifold found on 81 and newer Rabbits and
custom bend some pipes with a resonator and muffler. An alternative
would be to use a Audi Fox exhaust dual outlet manifold and have a
tuned header is a few more ponies are desired.
SECTION 5 - WATER PIPES
Again Diesel Vanagon pipes would be the best solution here.
SECTION 6 - ALTERNATORS, POWER STEERING AND AIR CONDITIONING
The alternators, a/c and power steering would be driven the same way
as they were on the donor car with little or no difficulty.
Questions:
1 - Can the Vanagon accessories bolt on to the I4 engine?
2 - If you have to use a VW I4 power steering pump, will the Vanagon
hoses bolt on?
-- David Marshall Email: da...@volkswagen.org --
-- 78 Rabbit 1.8L, 80 VW Cally 2.0L, 88 Audi 5KQ --
-- 85 VW Cabrio, 88 VW Double Cab Syncro Transporter --
-- Volkswagen Homepage http://www.volkswagen.org --
-- VW Caddy Homepage http://www.volkswagen.org/caddy --