Lets start with the Head.
A standard cylinder head is OK for the job and if you have a gas flowed one so much the better. Try to find a head that
has not had too much skimmed of it as this will push up the target compression ratio. Make sure that the valve seats are cut
nice and wide to give a good contact area to help dissipate some of the heat .
The compression ratio has to be kept fairly low so Simon Atherton used Marina van dished pistons which gives
a compression ratio of 7.44:1 (8.5:1 being the norm).
Good results can be had from the standard pistons and compression ratios as long as you do not use more than about 0.5
to 1 bar of boost. You could get away with more boost if you had an inter cooler fitted.
The standard oil pump does not need up rating. There are various versions of the standard oil pump around. Both I
and Simon have around 20 psi idle and 40+ psi while driving and engine being hot
The Metro Turbo oil pump will not fit.
The turbo needs its own oil feed for lubrication and to some extent for cooling, this feed can be taken off the oil pressure
gauge line using a T piece or from some other convenient point. (In this case both me and Simon have taken it from the
same place but using slighlty differrent ways, I have taken the oil from the big screw that holds the banjo connection pipe
that goes into the oil filter and have placed a fuel filter into this line to create an inline oil filter. Simon's is
also taken at the same place but as can be seen by the photo on the photo's page is where his oil filter actually is.
The oil has to return to the engine some how. Some but not all A series engines have a hole cut in the block for this (it's
sometimes blanked off). It used to be for the petrol pump drive on early engines. This may need breaking through and a couple
of studs fitting. Or some other way found to return the oil from the Turbo to the sump. In my case I used a pluming
attachment in the sump to allow my oil to return to the sump from the turbo.
An Oil cooler might be needed, you will have to run and see. Mine hasnt got an oil cooler, but does have a
kenlow fan and appears to be fine
The standard camshaft is good enough; (it is retained by the Metro Turbo cars). You can fit 1.5:1 ratio high lift rockers
to give you that extra valve lift, but this may lead to a little extra turbo lag. You should be aiming to lift the valves
about 400 thou.
The standard water pump is OK but you may need to play around with the drive pulley size to help cooling. Simon used
a 3 1/2" dia pulley combined with a 6-blade fan which has proved adequate for UK weather conditions. You could fit an electric
fan like me instead of playing with the static fan.
The thermostat should be a summer one as it opens a couple of degrees lower than the winter one. Or you could use
the special tuning blanking sleeve. Part number (AJJ4012) and the bypass hose blanking kit part
number (AJJ4013). But again mine is a standard one
Standard bearings and rods are good for about 7500 rpm so you do not need to worry too much about this. It may be a good
idea to have the crank and Clutch dynamically balanced to reduce vibration.
Use good synthetic oil Mobil one is what I recommend. Although it is a little expensive.
The breather system for the block needs to be improved; adding an extra breather pipe in the Rocker cover can do this.
The 3 way (red) crankcase breather valve from a Metro Turbo is a must if you are using a servo on the brakes. It allows a
vacuum to be formed in the crankcase regardless of boost conditions. Essential if you do not want your dipstick shooting out
due to high internal engine pressures caused by the rings passing little. I have on mine taken this pipe from the rocker
cover and fitted it to the air intake to the turbo pipe by placing the a T piece connection into the pipe and bonding it in.
A high pressure fuel pump, a return line into the tank and boost sensitive fuel pressure regulator are needed to supply
the Correct volume and pressure of fuel and dump the rest back to the tank.
As can be seen by one of the photos both me and Simon have a standard fuel tank, and on the fuel filler line have placed
a small piece of piping into the filler pipe to return the fuel straight back into the tank.
A good air filter for easy breathing is needed, K and N or similar.
A 1 7/8" to 2" single box free flow exhaust (twin box if you like very quiet). You may find it a bit tricky
creating the inital downpipe mine took about a day of cutting and welding to create an S shape to get it out the car in the
usual place. Where as Paul Dorner has taken a different route and cut through the passenger footwell and sill and routed
the exhaust cobra style down the side.
One of Simons additions is the Inertial cut out switch from a Montego. This cuts off the fuel pump and
ignition if all goes Wrong.
Do away with the Metros Boost modulation device, this was a gearbox protection device for the Metro. This device limits
the amount of useable boost to 4 psi at around 4000 rpm and we do not want any restrictions.
The Three way fish tank valve fits in the signal pipe from the waste gate actuator and is used to bleed air off the waste-gate
and fool it into thinking that there is less boost than there actually is. This is because the standard waste-gate is set
for a max boost pressure of 7 psi. You could always change the Waste gate actuator spring for one that is stronger to get
higher boost pressures as many have.
The Distributor is standard just set to give about 20 deg advance. You need loads of advance with low compression engine
to get the fuel burning early enough when the motor is off boost.
