When multi-valve technology and
turbochargers combined forces in the late ‘80s, Mazda was leading the way. Their
B6 and larger BP series engines combine sophistication with excellent torque and
power for the cubic capacity and, not surprisingly, they performed well in
contemporary Group A rallying.
In this article we’ll look at this largely
forgotten range of hi-po fours.
The first truly high performance Mazda B-series
four appeared in 1987 with the release of the BF-series Familia GT-X.
The ’87 Familia GT-X is powered by the base B6
1.6-litre engine design (a 78mm bore and 83.6mm stroke) having a relatively low
7.8:1 static compression ratio, DOHC four-valve-per-cylinder head, IHI
turbocharger, air-to-air intercooler and multi-point injection. This engine
comes alive above about 3000 rpm and delivers a 186Nm punch at 5000 rpm. Peak
power is 103kW when running premium unleaded fuel. The B6 DOHC turbo is arranged
for transverse mounting and comes attached to a five-speed manual gearbox
delivering drive to either the front wheels or all four.
The Familia GT-X was released locally as the 323
Turbo and a Ford TX3 twin was also available. Interestingly, the top-line Ford
Capri soft-top was also available with the B6 turbo donk. Note that the local
cars are rated at 100kW when using normal unleaded fuel.
A naturally aspirated version of the DOHC B6 was
available in the 1989 released Eunos Roadster (aka MX-5 and Miata). With a 9.4:1
compression ratio, the Roadster’s B6-ZE engine is arranged for longitudinal
mounting and delivers drive to the rear wheels. Manual or auto transmissions are
available. Output is 88kW and 137Nm at 6500 and 5500 rpm respectively. Note that
the atmo B6 DOHC was available in the base-spec Eunos Roadster until 2005.
Australian-spec versions make 85kW and 130Nm.
Atmo DOHC and SOHC versions of the B6 were also
fitted to the FWD Ford Capri, Laser and 323. But, really, you’re better off with
a later model and larger cube BP engine...
In late 1989 Mazda introduced the BP 1.8-litre
The then newly released BG series Famila hatch was
available in turbo GT-X guise boasting the new BP turbo engine. The BP uses
similar design to the B6 but larger bore and stroke dimensions (83 x 85mm
respectively) increase the swept capacity to 1839cc. A DOHC,
four-valve-per-cylinder head, multi-point injection, knock sensor, 8.2:1 static
compression ratio, air-to-air intercooler and electronically controlled boost
pressure give the little 1.8 good torque and power. In Japanese guise, the BP
turbo engine punches out 132kW at 6000 rpm along with 237Nm at an accessible
3000 rpm. Premium unleaded fuel is required to generate this sort of grunt –
expect slightly less on normal unleaded fuel. This engine comes attached to a
standard five-speed manual gearbox with AWD.
The same spec BP turbo engine was also fitted to
the locally delivered KF – KH Ford TX3 AWD turbo. In Australian spec, the engine
is rated at 117kW/206Nm – probably due to lower octane fuel.
In early ‘93, Mazda released a 154kW/250Nm BP
turbo powered Familia GTR homologation special. And it’s a whole lot more than a
higher boosted version... The GTR-spec BP turbo engine was reworked by Mazda's
Motorsport Engineering Group and features reshaped combustion chambers, raised
piston crowns (maintaining the GT-X's 8.2:1 compression ratio), stronger rods, a
water-to-oil cooler, larger sodium filled valves, more aggressive camshafts,
minor cylinder head mods and a match-ported intake manifold. A larger capacity
ball-bearing turbocharger, a 70 percent larger intercooler and more boost are
also added. Of course, ECU mapping is optimised to suit and we believe the
airflow meter and fuel pump were changed. These mods delivered those 154kW and
250Nm maxima at 6000 rpm and 4500 rpm respectively (much later than the GT-X
spec BP turbo engine). Again, a five-speed AWD gearbox comes fitted but the GTR
‘box features shot-peened gears, a strengthened housing and upgraded clutch.
Unfortunately, the Familia GTR was produced in very limited numbers.
A high-performance naturally aspirated version of
the BP engine was also released in the Japanese Eunos 100, Mazda Astina and
Familia GT. The BP-ZE doesn’t score forced induction but it does use a 9:1
compression ratio and can put out 99kW at 7000 rpm and 157Nm at 4500 rpm. Front-wheel-drive four-speed autos and five-speed manuals were manufactured. The
same engine was also fitted to the 1994 released Lantis and BH-series Familia
The 1993 updated Eunos Roadster was also released
with the atmo BP-ZE making 98kW/157Nm. The biggest difference is this engine is
built for longitudinal mounting and delivers drive to the rear wheels.
As far as we’re aware, the Eunos Roadster was the
last vehicle to continue using BP engine power. In 1998, the Roadster’s atmo 1.8
was treated to a slightly higher compression ratio (9.5:1), larger ports and
valves, a twin-tract inlet manifold (with the switch-over occurring at 5500
rpm), revised exhaust, ECU remap and knock sensor. We believe the cam profiles
were also altered. These changes elevated peak power to 106kW at 6500 rpm and
torque swelled to 165Nm at 4500 rpm. Normal unleaded is all that’s needed for
In 2000, the Eunos Roadster received S-VT variable
inlet cam timing. These S-VT equipped engines are labeled BP-VE and the variable
cam timing mechanism can be identified by a bump in the valve cover at the end
of the inlet cam. With an accompanying compression ratio increase to 10:1 (now
making premium unleaded recommended), the BP-VE puts out a tidy 113kW at 7000
rpm and 181Nm at 5000 rpm. Japanese versions use a 10.5:1 compression ratio and
make about 5kW more on higher octane fuel. A close-ratio six-speed gearbox also
stepped in to replace the existing five-speeder.
A return to turbocharged performance was seen in
2002 with the release of the Australian-market MX-5 SP Turbo and, later, the
MX-5 SE Turbo.
The Australian MX-5 SP Turbo is a local
development which is essentially a turbo kit mounted to the existing 10:1
compression BP-VE engine. The SP Turbo package employs a nickel-alloy cast iron
exhaust manifold, a ball-bearing Garrett turbocharger, front-mount air-to-air
intercooler, a carbon-fibre airbox, Bosch blow-off valve and large diameter
exhaust. Supporting mods include bigger injectors, different spark plugs and an
upgraded coolant radiator. The factory ECU has also been re-mapped to suit. With
around 0.5 Bar boost, the turbocharged MX-5 SP cranks out 150kW at 6800 rpm and
a massive 280Nm at 4600 rpm – that’s 39 percent more power and 60 percent more
torque than a contemporary atmo version! This engine is second only to the
rally-bred Familia GTR spec BP turbo.
A ‘world market’ turbo version of the MX-5 was
released in late ‘03/early ’04. The SE turbo engine has almost identical
internals to the atmo version except the static compression ratio is brought
down to 9.5:1, the S-VT system is removed and a single scroll turbocharger with
a air-to-air intercooler give it a boost. Around 0.5 Bar boost is delivered and
breathing is improved with a revised rear muffler. Max output is a relatively
mild 121kW at 6000 rpm with 206Nm of torque at 4500 rpm. This engine was
discontinued for the all-new 2005 Mazda Roadster which uses a different family
In the Japanese importer yards you’ll find a
plentiful supply of ex-Familia GT-X BP Turbo engines available at attractive
prices. These are quite strong engines so long as you don’t expect too much from
them. If you’re after 200+ kilowatts, the Familia GTR spec BP turbo engine is
the one to go for – though these are rare and you’ll pay at least AUD$2000 for
the motor alone. The rear-wheel-drive ex-MX-5 turbo engines are the next most
attractive engines however, given the modest output of the later model turbo
engine, you’d be wise to consider purchasing one of the many off-the-shelf turbo
kits to suit an original atmo engine. There are plenty to suit!