BP turbo information

[Okibi]

Although I don't have an MX-5 currently, spose I'll still post some details as the info might come in handy to others, maybe for a engine swap or the like.

I have a variant of the BP engine named the BPD (nicknamed "The Big Turbo" back in the day & superior to the more common BPT found in Mazda Familia GTX's/Ford Laser TX3's) which is Mazda's factory produced highest power BP Turbo engine. Production of these BPD engines were limited to 5000 & were fitted into Group A rally homologation 2200 Familia GTR's & 300 Familia GT-Ae's, 2500 being the minimum number made & sold to consumers required by WRC racing rules. These road legal rally cars were only made from 92 to 94. The engine itself is forged by Mazda's Motorsports Engineering Group, these are the guys that do Mazda's competition engines. For example the racing RX-7's at Bathurst & the 787B quad rotary of the 1991 Le Mans 24hrs where Mazda won (& remain the only Japanese motor co. to do so).

So the specs (now quoting data found at fordlaser.com)

Engine model.....................................BPD
Engine type.......................................Turbocharged, in line 4 DOHC, 16 valves with front mounted intercooler
Displacement.....................................1839 cc
Max power output (Euro version)...............210 hp (156 kw) @ 6000rpm (185ps @ 6000rpm)
Max torque (Euro version).......................25.5kgm @ 4500rpm (235nm @ 4500rpm)
Redline (Euro version)...........................7000rpm (6500rpm)
Bore & stroke.....................................83 x 85 mm
Compression ratio................................8.2:1
Turbo IHI RHF6CB (ball bearing)................62mm Turbine, 62mm Compressor (VJ-23)
Control system...................................Electronic Petrol injection


Some of the main changes from the BPD to the BPT engine

--Intake Manifold--
With the "Big Turbo", it has become critical that boosted air is distributed to the individual cylinders in equal volume and pressure. Likewise, the energy of exhaust gas must be fully exploited to quickly "spin-up" the big turbine in order to obtain high power and minimum turbo lag.

The Mazda engine design team has perfected a unique manifold system, combining the air volume and pressure equalizing intake and exhaust extractor manifolds.

It was Mazda's finding that with more a more commonly used equal-length intake manifold, the tract nearest to the air entry received the least volume/pressure, and the farthest tract the most. By trial, measurement and testing, the engine team perfected a cast aluminum manifold that has intricately curved and sized "walls" between the individual tracts leading to the intake ports to equalize air volume and pressure. A bonus is that the manifold's swirl generating effect contribute to efficient combustion. The equalizer intake manifolds have shown its effectiveness in improving torque from idling to the Group-A 300-bhp-plus output level and all the way up to maximum revs.

--Turbocharger--
The turbocharger was specifically developed for the GT-R application by IHI. The RHF6CB turbocharger has a 62.0mm turbine and a large 65.0mm compressor. By comparison the turbo for the type BPD 1.8-litre engine that powers the 323 4WD GT-R has a 52.5-mm diameter turbine and a 52.5-mm compressor. It is commonly believed that a big turbo is employed for high rpm power. The Mazda and IHI teams have proven with the GT-R turbo installation that this is not necessarily so. They have sought and achieved an optimum balance between high power and quick mid-to-high rpm response. A relatively small "A/R" ratio, a value of 16 to the GT-X's 15, was one of the means they adopted to assure these desirable characteristics. "A" is the turbines smallest scroll area and "R" the distance between the turbine-shaft center and the center of area "A", the two factors used in calculating turbocharger's performance characteristics.

The turbocharger employs a steel turbine wheel for its proven reliability under the rigors of competition. In Mazda's testing it suffered little in responsiveness when compared with a unit fitted with a experimental ceramic turbine; the latter may be decelerating too quickly for any appreciable difference in pickup that follows.

The turbocharger shaft is supported by ball bearings, which improves turbo response by as much as 7 percent by Mazda's testing.The turbocharger is watercooled. Boost is controlled by a dedicated computer map, and it s maximum pressure is 450mm of mercury(Hg).



--Exhaust Manifold--
The exhaust manifold has individual tracts collecting at the turbocharger entry. These tracts are in two groups; the tracts from cylinders 1 and 4 are routed to the center, and those from cylinders 2 and 3 to the outside. This routing allows nearly equal tract length. The complex manifold is made of cast ferrite steel, for which the lost-form casting method is employed. Not only is this about 20 percent lighter, much stronger and its passages much smoother than a conventional cast iron one, but also its surface finish is much smoother.

The exhaust manifold's extracting ability precludes an unwanted rise in exhaust back-pressure, which would cause the dilution of the combustion chambers with exhaust gas. This would, in turn, raise cylinder temperatures. Enriching the fuel/air mixture to lower combustion temperatures would obviously deteriorate fuel economy.

The GT-R exhaust system adopts a 3-way catalytic converter with larger capacity but a reduced number of cells, and a new main silencer that assures reduced resistance to gas flow.



--Pistons--
The aluminium pistons are squeeze-cast with a cast-in cooling channel. With this technique, molten metal continues to be pressurized while it cools in the mold. Blow-holes that might otherwise form during cooling contraction are dríven out by pressure, and a denser, stronger casting is formed.

Further, the pistons top ring groove area is reinforced with integrally cast nickel-based "metal foam". The nickel foam is produced by electroplating urethane foam, which is then melted away, leaving porous metal "foam". The foam ring is integrally cast in the piston by the squeeze-casting method. The metal reinforced, squeezed-cast piston with cooling channel was first adopted in Mazda's direct-injection diesel engine, whose pistons are subjected to extremely high thermal load during the combustion process. the metal reinforced piston is about 10 percent lighter as compared with an aluminium piston with Niresist top ring groove, and according to Mazda's testing has an extended piston life by threefold. The piston's skirt is also zinc-plated for improved wear resistance, and its inside is cooled by an oil jet.



The forged steel connecting rods have a larger section for added strength. The connecting rod's big-end bearing is fully balanced with counter weights and is supported by five main bearings, again of competition grade kalmet metal.



--GTR Valves--
Superior heat dissipating metallic sodium-filled exhaust valves are adopted. During engine operation, the metalic sodium inside the valve stem melts. As the valve moves up and down, the sodium splashes around inside the valve and helps to absorb heat from the cylinder head and to transfer it back to the engine coolant through the valve guide. In this way, the combustion chamber temperature is reduced, reducing knocking and improving fuel efficeincy.



The engine in mine hasn't had too much done to it. Only a full 3" mandrel bent exhaust system incorporating a highflow cat, resonator, muffler with 3" tip. A Turbosmart Kompact adjustable recirculation BOV has been fitted. Walbro in tank hi flow fuel pump.A K&N pod air filter is on the AFM till I change it to something nicer.

The previous owner had an adjustable Boost Pressure controller fitted & the car made 155 kw at all 4 wheels with 16psi boost. I think they usually do about 135 kw at 4 wheels for a stock standard Familia GTR.

An MX-5 with one of these engines could be quite the special project.

[VroomVroomBlackSheep]

So where am I going to source one of those engines?
there is a familiar gtr for sale atm.. buy it and dump the body and drop the donk into mx5

[SuperMazdaKart]

Well, there's only 2200 Mazda GTR's made (technically, with the other 300 homologation being GTAE's). So no, don't do that unless the car is a scrapper...

[alexbwang]

So where am I going to source one of those engines?
there is a familiar gtr for sale atm.. buy it and dump the body and drop the donk into mx5

Is this what you're after? http://www.carsales.com.au/private/details/Mazda-Familia-1992/SSE-AD-2171445/?Cr=0&sdmvc=1

[4sfed5]

i have been in a GTR engined MX5 and it was "HOLY sh*t" fast. It was dyno'd at 200RWKW (not sure the boost level).... of course running a custom exhaust manifold and i think microtec EMS.
it was prett laggy though and di ruin the drive through the curves... i preferred my low power 140 ish RWKW setup for driveability