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Mazda 4 cylinder Engine History and Interchangability Guide

By Randy Stocker

Like most auto manufacturers Mazda has a lot of commonality between engines. I get asked all the time what parts interchange between different motors so here is what I currently know:

There are three basic types of 4 cylinder piston motors that Mazda currently produces for the US market. They are grouped into engine families, ‘B’, ‘F’, and ‘G’. The Miata uses the ‘B’ family of motors. The ‘B’ family starts with a 1.3 liter SOHC. It was primarily used oversees but did come to the USA for a short stint in the Ford Festiva (other markets got a DOHC 1.3). The primary example of the early ‘B’ motors in the USA came here in the GLC as a 1.5 liter SOHC, later upped to 1.6 liters for the 323 in the mid 80’s (78x83.6mm). The 1.6 liter version has as large a bore as the block can accommodate and cannot really have it's displacement increased much more, in fact, enlarging the bore beyond +1mm is not advised. A DOHC head was designed for the 1.6 liter for the 1988 323 GTX turbo. Because of the severe duty that motor could see many enhancements were made to it for reliability reasons. A stronger web stiffened block and oil spray cooled pistons were among the changes. See SSS Automotive site from Australia for B6T tidbits.

The 116 HP Miata 1.6 DOHC motor from 1990-1993 is a normally aspirated version of that 323 turbo engine. It mainly differs from the turbo counterpart in higher compression pistons (to 9.4:1), lighter connecting rods and a lighter flywheel. This means that the NA version of the motor is quite over engineered for its applications. (how many NA motors do you know have oil spray cooling for the pistons). The automatic transmission version of the 1.6 DOHC engine has lower compression pistons to 9.0:1 and the camshafts have less duration. These changes were done for the automatic version to gain torque at a lower rpm and minimize detonation from the torque eating trans. The tradeoff is a less peak HP rating of 100. In 1991 a running change was made to the crank design from repeated failures of the pulley keyway. The pre-91 motors had a 22mm crank snout while the late 1991 and later had 27mm crank snouts. The 1.6 DOHC motor lived on in the Mercury Capri and XR2 until 1995.

gtxrod.jpg (12 KB)The rods used in the 88-89 323GTX turbo are beefier. They have a thicker beam, thicker small end and larger size bolts. They weight approx 580 grams (w/bolts and nuts) vs the approx 540 grams of the Miata rod. The GTX rods are no longer available new from Mazda and the Miata pieces supercede it.

In 1994 the need to meet emissions standards and to confront cries for more power in the Miata was answered by using the 1.8 DOHC motor that has been in the Protege since 1990. It is also a ‘B’ family member but has a longer bore spacing to accommodate the larger 83mm pistons. The stroke was also increased to 85mm (both the 1.6 and 1.8 DOHC have the same 221.5mm block deck height and 134mm head height). The 1.8 is the same design and is just as robust as the 1.6. It has the same rods, same oil-cooled pistons, same oil passages, same head design and same crank design (FYI, The Japanese/Austr market version of the Protege got a turbo version of the 1.8, the GTR and GTX 'BPT' motor). Unlike the 1.6 though, the auto trans version of the 1.8 was not changed at all.

Since the 1.8 is really just a stretched 1.6, most everything on the front and back of the motor will interchange between the them. This includes the cam angle sensor, coolant intake pipes, flywheel/clutch assembly, various covers and brackets, cam gears, water pump, and timing belt tensioner, etc. The intake manifold, exhaust manifold, motor mount brackets and camshafts do not interchange because of the bore spacing differences. The 1.8 ‘B’ motor has also seen duty in the 1991-1995 Ford Escort GT/LXE, 1990-99 Mazda Protege, 1991-95 Mercury Tracer LTS and Kia Sephia GS. (FYI, the 90-93 Escort GT and Tracer LTS 1.8 DOHC use the same throttlebody and flowmeter as the 1.6 Miata). There was also a SOHC 1.8 used for a short period in the 1990-93 Protege.

The head of the 1.8 ‘B’ was slightly revised with the stretch job by using larger sized intake and exhaust ports, larger valves, moving the cam angle sensor from the intake to the exhaust cam, and using a 4mm higher lift cam with shorter valve stem lengths and a larger base circle. OEM cams specs. Starting in 1995 the valve springs were revised slightly stiffer. This allowed the thick seat shim (1+mm) that was used on the 94 1.8 motor to boost the installed spring pressure to be removed and was replaced by just a thin metal shim (about .005") to protect the head seat.

95 valve springs. 95valvspringcompare.jpg (26KB)95 valve springs (left) are stiffer compared to 94, 96-00.

In 1996 the peak HP rating of the Miata 1.8 motor was raised to 133 hp from 128. This comes soley from the new for 1996 ODBII software having the ability to lean out the above 6000 rpm fuel curve. There have been rumors that there was a running change to the pistons to up the compression ratio to 9.5:1 during the 3/95 cutover, but I have not seen any documentation to prove it.

The 1999+ Miata uses basically the same 1.8 ‘B’ as the 1994-1997 but it was again revised. The block uses slightly higher compression pistons to 9.5:1 from 9.0:1. The head had the most enhancements, the intake ports were raised from 39 degrees to 51 degrees to create a straighter flow path, the cam angle sensor was moved from the head to the front of the crankshaft, and solid lifter camshafts with advanced timing, more duration and lots more intake lift were introduced. The stock 99-00 cams are actually quite strong from the factory. They will easily support higher hp levels with .4mm more lift (to 8.6mm) than the 90-97 HLA cam and has substantially more .040" duration too. Mazda also makes a cam specifc to the home Japanese market. It has the same specs as the USA cam but the cam timing is advance a few degrees. If is part number BP5A12420).

Japanese spec cam. cam5A.jpg (23KB)Japanese spec cam identifed by "5A" cast into billet.
The 99-00 head will interchange onto the earlier 1.8 block if you also determine how to control the variable intake valve in the '99 manifold (VICS systems, probable a rpm activated selenoid will do it) as well as retrofit a cam angle sensor for the earlier ECU (the cam drive is still there so it just slaps on)

99head4W.jpg (54 KB) 99 head uses blockoff plate for cam angle sensor. 99 identified by '4W' cast on head and cams.
99EXcamangledrive.jpg (47 KB) Interestingly though, the 99 EX cam retains cam angle drive.
99intakeports.jpg (32 KB) 99 intake ports are much higher and angle downward
Intakeports90-97-18BP.jpg (56 KB) 90-97 1.8 'B' intake ports.
99intakeportmismatch.jpg (33 KB) 99+ intake port mismatch with 90-97 gasket.
liftercomptop.jpg (33 KB) Liftercompbottom.jpg (32 KB) 99 uses solid lifters (left) with adjustment disk while 90-97 uses HLA's (right).
intakecamscomp.jpg (42 KB) 99 solid lifter intake cam vs 90-97 hydrallic, visible difference in profile. Mazda reverted back to the solid billet design from the 1.6 instead of the hollow design of the 90-97 1.8.
99piston.jpg (47 KB) 99 pistons produce 9.5:1 compression through a raised dome in the middle. Pronounced valve reliefs.

For 2001 Mazda introduced the 'VVT' vaiable valve timing. It adds 15 additional peak hp (to 155) by dynamically adjusting the intake cam for advance, retard and overlap. The head can be retrofitted to ealier 1.8 blocks but you're on your own on how to control the cam selenoid.

2001VVT.jpg (49 KB) VVT adds 15 peak hp to the 2001 Miata

I get a lot of questions about Miata interchangabilty with the 626/MX6 and B series truck motors because of the larger 2.0 liter displacement. Here's the scoop as I know it.

The ‘F’ motors (F,FE,F2, FS) are larger in both bore spacing and deck height than the ‘B’s are are mostly unrelated. Little to nothing will interchanges between the 'B' and 'F' motors, even the bellhousing bolt pattern is different from the 'B' motors.

The 'F'/'MA' engines were first used in the late 70’s in the 2.0 liter RWD 626 and B2000/Ford Courier. An enhanced version called the FE was introduced in the 1984 2.0 liter (86x86mm) FWD 626 and the B2000 pickup. The stroke was increased in 1988 for the 2.2 F2 motor as used in the B2200 and MX6/626/Ford Probe. None of the Mazda 4 cylinder heads are an interferance fit with the exception of the long stroke 2.2. All the F, FE and F2 motors had SOHC heads with the exception of the 1998+ 2.0 liter Kia Sportage which uses the block from the 1984-87 B2000/MX6 (86x86) mated with a new, very 'B' like, DOHC head. This engine was also in use in the Japanese only market 4wd 626 and European/Austrailan market 626 16V too.

626AWDDOHCFE3motor.jpg (57 KB) 2.0 DOHC 'FE3' motor in European market 1990 626 16V

In 1993 Mazda created a short bore spacing version of the F engine called the ‘FS’. It was used in the 1993+ 626/MX6 (83x92mm) and had a DOHC head. Although it is loosly based on the 'FE/F2' internals it is a new generation and not many parts interchange. The motor mount bosses are in different locations and the bellhousing bolt pattern is different. Same situation as the generation change between the 'F'/'MA' and the 'FE'.

The ‘G’ motors are the 2.6 liter truck motors. All are SOHC. There have been two 2.6's, the 1987/88 was a Mitsubishi built engine and from 1989-93 was a Mazda designed and built motor. It was also used in the MPV.

The common use of the engine types makes for some interesting and easy to do swaps, such as a 1.8 DOHC Escort GT motor in a Ford Festiva, 2.0 DOHC Kia Sportage Head on a 2.2 626/Probe/B2200, and a 2.0 DOHC 'FS' MX6 engine in a 1999 Protege. Hmmmm...

Mazda 4 cylinder engines
Motor Years Bore Stroke CC Models
1.3 B 1988-1993(USA) 71 83.6 1324Ford Festiva
1.5 E/B5 SOHC ? 77 80 1490 GLC
1.6 SOHC B6 ? 78 83.6 1597 323, 90-92 Protege
1.6 DOHC B6P 1988-1995 78 83.6 1597 323 GTX, Miata, Mercury Capri/XR2
1.8 SOHC B8 1990-1992 83 85 1839 Protege
1.8 DOHC BP8 1990-1999 83 85 1839 Protege, Ford Escort GT, Miata, Mercury Tracer LTS, Kia Sephia GS
2.0 F/MA 1978-82 80 98 1970 RWD 626, B2000, Courier
2.0 FE 1984-87 86 86 1998 FWD 626/MX6, B2000
2.0 FE3 DOHC 1998+ 86 86 1998 Kia Sportage
2.2 F2 1987-199? 86 94 2184 B2200, FWD 626/MX6, Ford Probe
2.0 DOHC FS 1993+ 83 92 1991 FWD 626/MX6
1.8 DOHC F? 1999+ 83 85 1839 1999 Protege
1.5 F? DOHC 1999+ ? ? ? 1999 Protege

Much of the credit for the 'F' engine information goes to Mazda Master Technician Alan Johnson of Rosen Mazda in Gurney, IL. Thanks Alan!

UPDATE 9/21/98 As reported in the August 1998 issue of the MCA magazine, Mazdaspeed makes a 3mm stroker crank for the 1.8 'B' motor. This crank is used in the Japanese only market 2.0 liter C-Spec Miata (85x88). It is part number 9E3A-11-300 and costs $2,258.66 USD. It is basically a forged racing prepped unit and that is why it costs so much. It is available for import from Mazda Competition at 800-435-2508.

Also, Toda Racing in Japan offers a race prepped forged stroker crank for the 1.6 'B' engine as well. According to their web page (http://www.todaracing.com), it offers a total of 1854cc. It currently sells for 300,000 Yen which is $2112 @142 Yen/USD.

UPDATE 9/21/2000

(Q)What Mazda engines besides the 12a and 13b rotary can be swapped into the Miata?

(A)

Mazda makes 5 'boinger' [piston] engine families. They are:

  • 'J' 90 degree v6 (as in the 3.0L 929 and MPV)
  • 'K' 60 degree V6 (1.8 MX3, 2.0, 2.3 Millenia, 93+ 2.5 MX6/Probe)
  • 'B' 4 cylinder (323, Protege, Miata)
  • 'F' 4 cylinder (B2000/B2200, 78-92 F/FE/F2/F2T 626/MX6, 93+ FS 626/MX6)
  • 'G' 4 cylinder (B2600, MPV)
  • The DOHC 'J' is generally too wide for the Miata engine bay. Mazdaspeed M2 had done a swap of this engine back in 92 as an engineering exercise and is the only one known to exist. The SOHC fits but why, it's only 165 hp and not really matched to the Miata.

    The 'K' engines are not designed for RWD and not only do the manifolds and plumbing not line up correctly for RWD but it will have oil starvation problems if used as such. MCA tried a swap of it back in 93 but was stillborn. The Susuki variant of the engine as used in the Vitara has real possibilities though! This swap has been talked about at length in the Miatapower list list and 'ask Bob' at Miata.net.

    The 'F' engines are the 'big blocks' of the 4 cylinders. They are long stroke motors and are generally not designed for high revs. All were cast iron SOHC with the exception of the FS and FE3. The FE3 has been used here in the states in the Kia Sportage and has real possibilities for a Miata swap. I'm going to be installing a 2.3 version in a Miata this winter. I have written about it in the Miatapower list.

    Any swap would require a tranny swap (or integrated bellhousing swap) too since none of the other engine families use the same bellhousing bolt pattern. I am using the B2200 truck tranny (w/Miata gears and a Miata PPF tailshaft housing) for my swap.

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