Here's a guide I wrote for the racing series
- will probably help you choose a track car too!
The mk2 MR2 had a ten year production run spanning from 1989 to 1999.
During this time, Toyota revised the car five times
- roughly every two years.
The revision dates are as follows:
Revision 1: December
'89
- August
'91
Revision 2: August
'91
- November
'93
Revision 3: November
'93
- June
'96
Revision 4: June
'96
- December
'97
Revision 5: December
'97
- May
'99
Chassis
There were four different version of the MR2 chassis, designated SW20, SW21, SW22 and SW23.
The SW21 and SW22 chassis' were designed for the left hand drive American market and were fitted with the 2.2l 5SFE and 2.0l turbocharged 3SGTE engine respectively.
Neither are currently legal for the MR2 Championship.
The SW23 chassis was available in the UK only and was outfitted with the lower powered 3SFE engine.
The SW20 chassis is by far the most common and was available with the 3SGE engine in the UK and the 3SGE and 3SGTE engine in Japan.
For the purposes of this article the SW20 and SW23 can be considered identical and are both suitable for use in the MR2 Challenge series.
I will refer only to SW20 from this point.
The SW20 chassis was available in three forms, depending on whether it was purchased in the UK or Japan.
Both regions received the T-bar model which has two removable glass panels in the roof.
The UK had the alternative option of a
"Moon Roof" which was a single large glass panel in the centre of the roof which could also be removed and stowed under the bonnet, while the Japanese market had the option of a
"Tin Top" fixed roof.
Tin Tops were not available in the UK and Moon Roofs were not available in Japan.
The T-bar version of the SW20 chassis is generally accepted to be heavier than the Tin Top or Moon Roof versions due to the extra strengthening in the roof area to combat scuttle.
Other than that, weight differences between different versions of the mk2 MR2 are explained by variations in engine package, trim levels and options.
The only known change to the SW20 chassis was the introduction of two
"dimples" in the rear panel at revision 3.
This was to allow space for the reverse lights to be installed in the centre panel.
Since MSA regulations forbid glass positioned above the driver, the most suitable chassis would be the Japanese market Tin top SW20.
The UK Moon Roof model would be a reasonable second choice, with the T-bar model coming in last.
Engine and Gearbox
The mk2 MR2 was available with a choice of four engines:
3SFE: UK Only
- 118BHP
- Not currently allowed
3SGE: UK, Japan
- 158-200BHP
- Championship legal
(except BEAMS VVTi)
3SGTE: Japan, USA
- 200-241BHP
- Not currently Allowed
5SFE: USA Only
- 135BHP
- Not currently Allowed
The lower powered 3SFE engine was only available in revision 1 and some very early revision 2 cars in the UK.
It was also the only model that could be equipped with an automatic gearbox.
Although low-down torque is said to be very good on these engines, it is unlikely that anyone would want to consider them for race use.
Revision 1 and 2 3SGE engines are essentially the same 158BHP output, regardless of whether they are Japanese or UK market cars.
The 3SGE engine in the corresponding Toyota Celica of the same year is also
(as far as is required) identical to it's MR2 twin and can be interchanged.
All Japanese versions of the 3SGE engines are available with an automatic gearbox.
Toyota improved the 3SGE at revision 3, increasing power to 172BHP, although there are many conflicting reports of this figure rangine from 172
- 176BHP.
Other changes such as oil squirters below the pistons
(as found on turbo models) help to cool the engine and increase it's longevity.
Again, UK and Japanese models are the same and can be interchanged with the same engine from the Toyota Celica.
At revision 4, Toyota made some significant changes to the UK iteration of the 3SGE, while the Japanese version remained unchanged.
UK cars were fitted with a system of exhaust gas recirculation in an attempt to bring down emissions.
This in turn brought overall engine power down to 168BHP.
The EGR system can be removed
(or blanked off) under MR2 Championship regulations to bring power back up in line with the earlier model.
UK cars were also equipped with transponder immobiliser systems making it very difficult to transplant the engine into another car
(There are ways around this).
Revision 5 engines remain unchanged from the previous revision in the UK market, but changed radically in Japan.
There, Toyota introduced a variable valve timing head, distributorless ignition and increased the compression amongst other tweaks, bringing power up to 200BHP and achieving the magical 100bhp/litre.
Since only a limited number of these BEAMS VVTi engines were produced
(rumored to be 1,000 installed in MR2s) and they change hands for in excess of
£2,000 they are currently banned from the MR2 Championship.
Also of note, some late revision 5 cars were fitted with a limited slip differential which are not permitted.
The weapon of choice would therefore appear to be the higher powered revision 3+ engines, but real world experience would suggest that all versions of the 3SGE are very closely matched.
Suspension, Brakes, Wheels, Steering
All mk2 MR2s were equipped with power steering with the exception of revision 1 UK models which were not.
Selection here is a matter of personal choice, although the non-power steering version is lighter.
Revision 1 MR2s have smaller brake calipers, disks and front pads than revision 2 onwards cars.
Revisions 2 to 5 remain unchanged.
Revision 1 MR2s were fitted with 14" wheels as standard, and with slightly narrower tyres than later models.
Due to the increase in disk and caliper size at revision 2, all later models were fitted with 15" wheels and wider tyres.
While 15" wheels and tyres can be retrofitted to revision 1 cars, 14" wheels cannot be installed on revision 2+ cars.
14" wheels are not permitted in the MR2 Chapionship
- this is to ease tyre supply rather than for any technical issues.
Standard shock absorbers and springs remain unchanged throughout the lifespan of the normally aspirated mk2 MR2.
Japanese turbo models were equipped with uprated Bilstein shock absorbers
(made by Toyota under license) from revision 2 and these make a good upgrade for n/a cars.
A limited run of 500 normally aspirated
"Anniversary Edition" cars split between UK and Japanese markets were fitted with Bilstein suspension as standard.
Revision 2 also saw some suspension geometry changes over revision 1, including a completely different rear subframe.
Apparently this was in response to early criticism that the MR2 was tail-happy, although many consider that this was because people were unfamiliar with the mid-engine, rear wheel drive layout.
Later cars are understood to be more predictable, though some claim that they've been
"dumbed down" for the masses.
Anti-lock brakes were optional on all revisons of mk2 MR2.
The system installed in Revision 1
-3 cars was fairly basic and
(in my opinion) not well suited to racing
- I would recommend disabling this system.
Revision 4 and 5 cars benefitted from a more sophisticated setup with seperate channels to each corner
(rather than one to each wheel at the front and a single line feeding both rear wheels), a deccelerometer and more sophisticated software.
This system would be more suited to racing but I suspect that most race cars will be earlier models.
Other Considerations
All Japanese model cars came with climate control as standard.
This is not a problem, but it will give you more components to remove when preparing the car.
By law, aircon gas must be vented and disposed of professionally.
All Japanese vehicles are limited by law to 180kmh
(~112.5mph).
This can be disabled by either converting the speedo signal to read in MPH
(essentially moving the speed limit to 180mph) or by simply cutting the speed input signal to the ECU
(though this will illuminate the engine management light).
Revision 3+ MR2s command a significantly higher price than previous revisions, due to improved styling and power.
T-Bar models are more sought after and typically fetch up to
£500 more than other types.
Japanese normally aspirated models are known as
"G" or
"G-Limited".
UK models are known as
"GTi-16" for 3SGE engined cars or
"Coupe"
(no badge on the rear) for the 3SFE engined version.
Turbo models are
"GT" or
"GT-S".
All versions of the MR2 were supplied with a rear spoiler with the exception of the 3SFE Coupe model.
Revision 1 and 2 cars had a three piece spoiler that extends along the rear wings.
Revision 3 and 4 cars had a single piece spoiler of a similar design but without the wing extensions.
Revision 5 cars were fitted with what is affectionately known as the
"Comabt" spoiler, consisting of two side supports and a central adjustable
"blade".
This can be positioned to
(allegedly) affect downforce.
Exhaust systems vary between engine versions as well.
Revision 1 and 2 engines have the same manifolds, while the revision 3 is different but shares the 4-2-1 layout.
revision 4 and 5 cars have a 4-1 exhaust manifold design.
All japanese model cars have a catalytic converter, as have revision 2+ UK cars.
De-cat pipes are available to remove them.
Revision 3+ cars are fitted with a different design of rear light
- they are more rounded and have the reverse lights in a colour coded centre panel.
Revision 1
"G" grade Japanese model MR2s were available with manual wind-up windows.
Internal side impact door bars were installed in all models from Revision 2.
