Toyota MR2 differences – Seperating each revoution

The SW20 model mr2 was in production for almost 11 years with 5 major revisions in that time. This can make finding the right parts or information tricky. In this post I will try to briefly explain the differences between each revolution.

Dates of Each Revision

  • Revision 1, (and the first appearance of the mk2 mr2) begins late 1989
  • Revision 2, starts early 1992
  • Revision 3, starts late 1993
  • Revision 4, starts 1996
  • Revision 5, starts late 1997 and lasts in to the year 2000

The most notable revisions were going to revision 2 for chassis development and revision 3 for engine and ABS, revision 4 and 5 were mostly cosmetic changes.

Engine differences, before and after the revolution 3.

  • Oil filter position changed
  • Engine internals upgraded
  • Different turbo-charger, (previous Toyota CT26 to the new CT20B).
  • Boost pressure increased from 10 to 13 PSI.
  • Horsepower increased from 220 to 240 BHP (depending on which market)
  • Lowered compression ratio
  • Air flow meter removed from turbo-charged models, n/a models never had them
  • Bigger injectors (Up to 540cc from 430cc)Kouki Tail lights
  • Larger throttle body
  • Higher lift intake camshaft lobes
  • New, more modern ECU
  • Fuel cut off threshold increased.
  • Cylinder head and inlet design changed, 8 ports reduced to 4.
  • Engine sump design changed
  • The newer ECU now can now modulate the turbo VSV, enabling variable control of boost pressure rather than a choice of open or closed.
  • A coolant drain plug / bung was added on to the cylinder block
  • Air temperate sensor (intake) added in after the intercooler
  • First compression ring now made from stainless steel
  • Oil ring (from piston rings) now made from stainless steel.
  • Not an engine difference but, almost all revolution 3 and above cars came with a limited slip differential whereas any previous models did not
  • Late revolution 5 cars in Japan eventually came with an option of the “Beams” engine, this was a limited production car so is very rare

Chassis Differences Between Revision 1 and 2

  • Front brake upgrade! The diameter of the front brake discs was increased from the earlier 258mm to 275mm and the thickness up from 25mm to 30mm
  • Rear brake upgrade! The diameter of the rear brakes were increased from 263mm to 281mm and the thickness from 16mm to 22mm
  • Speedometer now uses an electronic sensor rather than the older mechanical type.
  • Bigger and better wheels and tyres. The front tyre size changed from 195/60/14 to 195/55/15 and the rear tyres from 205/60/14 to 225/50/15. The spare wheel also was also increases.
  • New front strut bar, this actually stopped the adjustabililty of the caster angle.

Main Aesthetic changes

  • Round tail lights known as “kouki” tail lights
  • New one piece rear wing
  • New colour coded centre panel, side skirts and front lip
  • Rev 4 models now came with 5 spoke alloys
  • Indicators mounted on the wings (Rev 4)
  • Clear indicator lenses (rev 5)
  • New alloy wheels (slimmer spokes, rev5)
  • Larger spoiler (Gen 5)Generation 5 Spoiler

Japanese, UK MR2 differences

The biggest differences tend to be the trim level and extra toys that the Japanese models had / could have. Head-unit and speakers systems are slightly different, electric folding mirrors came on the Japanese cars as well as climate control, the seats are different and the headlamps are tiny bit different but can still be swapped. Front wingers are different as well with the side strip being higher up on UK models than Japanese. On the whole though the chassis are fairly similar as far as I am aware

End Note

Something to note that this post was just based from my experience of what I have seen on certain model cars and from internet research. That cars I have seen may have had previous part swaps and internet research can sometimes be from questionable sources so the information here is only as a guidance, not 100% definite facts

 

 

 

Benefits of premium fuel – is it worth it?

Everyone sees it at the fuel station, but how often do you use it? How beneficial is it? What does it actually do?

How it can increase power and fuel efficiency

Engines are desgined to run as close as they can to knock. This simply means the ignition timing is set or constantly monitored to be set as advanced as it can before the engine begins to show signs of knocking.

This “knocking” phenomenon is created when fuel / air self-ignites, the type of fuel changes at which point this happens greatly. The octane rating of fuel is sometimes wrongly known as “how flammable” it is. A better description of this is how resistant to self-igniting or causing knock it is. The premium petrol have an octane rating of between 97 – 99 depending on brand where as standard petrol is 95 (RON – research octane number, United Kingdom. If the fuel you see at your local fuel station is massively different than it will be because you country measures it in a different way)

Using this higher octane fuel the engine will be able to run with a more advanced ignition timing, this potentially allows more power from the same amount of air and fuel in theory without any more risk than using regular fuel.

The way of gaining more miles per gallon using this is from the fact that the engine is possibly creating more power from the same amount of fuel and air. This also creates the situation where the same amount of power – as made using reguar fuel – can be made from using less fuel and air. So with less fuel you can create the same amount of usefull energy to move your car along the road.

This works best if your car has a sensor to listen for knock (nicely named a knock sensor) so it can determine the furthest advanced point it can use for ignition, other wise the higher octance fuel wont be able to used to its full advantage. The mk2 mr2 does use a knock sensor but many older cars do not.

 

What is knock? (the technical part)

Knock is a very important factor on this topic, it is associated heavily with igntion timing and can also cause very expensive damage to your engine.

Knock (or detonation) occurs when pockets of fuel ignite in the combustion chamber but they are not ignited by the flame front propogating throughout the chamber, instead as the flame spreads it builds up pressure in front of it, squeezing the air / fuel mixture thats furthest from the first point of ignition (spark plug gap) as the pressure increase, the temperature increases and can reach a point where the air / fuel mixture ignites itself. This creates a “pinking” sounds as shock waves are created from the exploding fuel pockets. This can also cause extremely high localized cylinder pressure which can also cause extreme engine damage.

The more advanced the ignition timing the more likely this is to occur as the pressure is still being increased as the piston is compressing the contents of the cylinder.

Detonation is sometimes associated with pre-ignition. However these are actually different terms. Pre-ignition is similiar but this is when the air / fuel mixture is self-ignited before the spark plug ignites at all. A result of this is uneven and several pockets of fuel then self-igniting which is detonation but the initial flame was not cause by the spark plug. This can be caused by hot spots around the combustion chamber, usualy from carbon deposits or around the hot exhaust valves, as they are rarely exposed to fresh intake air temperatures to cool down, which raise the air around them enough to ignite. Engine cylinder

Does it clean your fuel system / engine?

Petrol is not as simple as just hydro-carbons, there are many additives put in to it which can make each supplier of fuel differ from each others products. The more expensive fuels are said to have better cleaning additives with in, however petrol is a pretty clean fuel to be using anyway so the difference is argueable

After looking in to the differences of using higher octane fuel the only real evidence of benefits is when used with older engines that have “gunk” present in the fuel system and injectors and “carbon-y” cylinders, after testing many manufacturers claim that the premium fuel was actually much better ad cleaning out and dissolving gunk or cleaning off carbon deposits.

Is “cheap” fuel bad?

This is highly debated from both sides and even i occasionally will use the cheaper supermarket fuel for ease and time saving if there is one close by. On the other side i have friends who would never touch the stuff, not for any amount of cost saving, plus after several years working in a garage i have personally seen a couple cars running rough that where in regular use but always filled up with supermarket fuel and ended up with a gloupy mess that was fixed with simply good new fuel and advised not too use supermarket fuel.Branded Fuel

Including all the different uncertanties in my experience the fuel is not completely bad, especially if your not always using it. Older engines are not refined anywhere near enough to not be able to run on it, and if that was the case then surely millions of people would of caught on by now and none of it would sell. Used once every often i dont see any harm done.

There are downsides as the fuel will have less additives to it than branded fuel but at most the noticeable differences would only be minor performance, efficiency and emissions readings would be slightly worse. Maybe 0.1% of the time i would say it would actually be the root cause of a problem and the other fuel options can’t be completely perfect either. My verdict is cheap supermarket fuel in general is not great for a car but if it was as bad as people say then it simply wouldnt sell.

Conclusion

Overall the benefits of premium fuel do seem to exist and it does have true facts of to why it should work on most engines, but the benefits over stadard fuel are fairly small and in my opinion you are not going to feel a larger benefit in comparion with the extra cost that is charged for it.

Personally, i use standard branded fuel for 80% of the times i fill up, if i need to then i would use supermarket fuel but only on rare occasions and once in a while i treat my car to the expensive fuel to give me peace of mind that if any gunk is building up then pretty soon it should be flushed out, without always having to pay the high price of paying premium every time.

In the case if buying a “new” car like a 20 year old Toyota mr2 for example that you are not too sure of the history of, then putting a good amount of premium petrol for the first fill up i personally think would be a good idea.

I would like to hear from you, have you ever experienced any issues with cheap fuel or/benefits of premium fuel? Has your local mechanic ever mentioned it to you or advised you on the issue?

 

 

 

 

Toyota MR2 Oversteer – how bad?

There is many parts to the suspension layout in a car, in this post i wll discuss the handling characteristics of an mr2 and what is fact or fiction.

The Mid-engined Myth

What i am going to start with is what sometimes really annoys me. A lot ofthe time when I hear people talking about mr2s they always mention snap oversteer. This is a phenomenon that causes cars to suddenly “snap” in to oversteer, this is common with mid-engined cars, particularly mr2’s, particularly mk2s, particularly early turbo models. So i feel the need to explain this as its not all as it seems and no where as near as some peoplw will tell you!

Snap oversteer occurs when suddenly the rear loses grip, cars can be prone to do this if:Modified suspension MR2

  • They have a high percentage of weight over the rear tyres (as a lot of mid-engined cars have) The sw20 mr2 has 44 front /  56 rear % weight distrobution so can be succeptable to this, but overall 44/56 is very good.
  • They have turbo lag. On exit of a bend, you put your foot down to power out, you get the feel of how much throttle you can use, after accelerating and the revs begin to climb, the turbo is now “on boost,” suddenly the engine is putting out a lot more power unnexpectadly, this can cause a number of situations to encourage oversteer, wether it be the rear wheels trying to spin and losing grip or through the driver suddenly backing right off the throttle and causing the front to dip, weight transfers to the front, the rear goes light and begins to slip outwards in to oversteer. Modern turbos are clever and have little lag, but older turbos in times of the mr2 did suffer from turbo lag and cause this.
  • Inexperienced drivers – Every car handles different, the low price of an mr2 in comparison to most mid-engined cars allowed almost any driver to be able to own one. A young person with little experience going straight from a 60hp front engine front wheel drive hatch back in to a 200+hp mid engine car and having a little fun on a twisty section of road could easily end up in disaster.

So yes an mr2, especially a turbo, will be prone to snap oversteer but! everyone ive known to own one and race them always claims there are not as bad as the internet will have you beleive. This was not toyotas first mid-engined car and many adjustments where made to the suspension for the revision 2 and 3 cars onwards to limit this problem, someone who will treat these cars as a mid engined sports car and expect them to handle as one always credit how they handle. I personally find they people who say the problem is massive have either never driven one or doesnt understand what not to do in a car similiar to an mr2. Many unexpecting journalists have got in to a mess with an mr2 and written reviews on the snap oversteer to emphasize the problem, road testing a more expensive mid-engine car they would be expected to handle a bit more “on edge” so stayed far from there limits.

Concluding my small rant, my opinion is the snap oversteer does exist but only as a small aspect and you should expect that in any similiar layout car, the fact that its “only a Toyota” and a small 2l engine should not mean the driver shouldnt be careful. Snap oversteer in an mr2 is not as bas as people say.

All Round Independant Suspension

Even today its common for cars to not come with independant rear suspension, usually front wheel drive cars but even high power performance FWD cars such as the Honda civic type r (FN2) where still using basic rear suspension. In the case of the civic, many road tests came back with the opinion that the older civic type r’s where much more fun because of the more expensive independant rear suspension that had been dropped for the FN2 model. This doesnt mean cars without this can’t be fun, old hot Peugeots didnt use them, neither did the AE86 Corrola and there where all legendary handling cars, but it does play a benefit.

An mr2, being mid-engined and rear wheel drive is a much more obvious car to find independant suspension, but it is still a clever set up they have.

The benefits of having each wheel react independantly to the other is mostly improved grip. This is achieved by using lower suspension arms and strut bars connecting the hubs to the chassis, allowing them to pivot still but resists all forces to keep the wheel in the desired place. As one wheel goes over a dip for example it will be forced down the dip by the compressed coil spring in the strut while not affecting the other wheel. Another benefit is that there is less unsprung weight, this keeps more weight pushing the coil springs down and less weight to react to suspension movements. This keeps the tyre in contact with the road properly and keeps as much grip as possible.Independant Rear Suspensio

When wheels are linked through a torsion bar or live axle then as only one wheel goes through the dip, the other wheel will remain at a higher height, as they re both connected the tyre over the dip will either skip over the dip or not have as much weight pushing it onto the surface of the road while in the dip. Without much weight or with uneven weight over each wheel it will create a situation where there is low grip levels on certain wheels and lower the overall cornering forces that the car can handle as well losing the “feel” the driver has of the car.

Having this indepenant set up on your MR2 will make it much more stable on predicable over the public roads, there will still be benefits on tracks, but being so much more smooth and level it is not as noticeable a difference.

Weight Distrobution

When it comes to weight distrobution ive heard many say that the mr2 has way too much over the rear wheels. In fact its not too far off 50/50, 44/56 is fairly close and better than the vast majority of cars.

A good way to think of it is that a lot of the weight over the rear comes from the engine and gearbox. A lot of mid-engined performance cars have engines as big as v8s or v12s, the 3s-ge is only a little 4cylinder in comparison. Theres many more cars out there that will have a harder time getting the weight distrobution near to 50/50.

Aftermarket Parts

This is another area where there is a massive amount of choice, i will go in to detail of in later more specific posts as each revolution does occasionaly use specific parts to other revolions. Parts such as coilovers, polybush kits, lowering springs, dampers, tension rods, anit-roll bar kits and more can all be found by performance part manufacturers such as Bilstein, Tein, BC and Cusco etc

So should you worry?

After doing some reading and more importantly, careful driving of an mr2 to find its characteristics and limits, no you shouldnt worry. This should be done with every new or different car you drive honestly. It drives different to most cars in the same price range being mid-engined so can catch people out if they dont pay attention to that, But differently is by no means badly or to the extent that the snap oversteer stories are told.

 

 

 

 

MR2 Catalytic Coverters – Explained

A post to clear up if your car should have a catalytic converter and what they do.

First, what do they do?Exhaust Tips

Catalytic converters where first introduced to treat and monitor the gases emitted from the engine and remove certain harmfull pollutants before they are let in to the atmosphere.

As an enigine is running a number if gases are produced as exhaust.

  • Carbon dioxide – Carbon deposits that have mixed with the oxygen in the combustion process
  • Water vapour – Hydrogen from the fuel that has bonded with oxygen
  • Nitrogen gas – An inert gas that makes up the mix of gases found in the air
  • Carbon monoxide – Formed when there is not enough oxygen, this is colourless, poisenous and odourless
  • Hydrocarbons – These are particles of fue that have not been fully burned, they can be broken down by sunlight later and then turn in to oxidants which contribute to the break down of the ozone layer
  • Oxides of nitrogen – This contributes towards acid rain and smog and can cause irritation to people breathing
  • Particels of fuel – These have not been burned in the combustion process and cause breathing problems

The first three in this list are the main outputs from the exhaust and are mostly harmless, the last 4 or aimed to be vastly reduced by the use of a catalytic converter.

How they work

Modern units use 2 different catalysts to lower the harmful emmisions: a reduction catalyst and a oxidation catalyst. Each type uses a” honeycomb” structure inside, coated with a metal catalyst – platinum, rhodium and/or palladium

Reduction – This part uses platinum and rhodium inside the unit. As the oxides of nitrogen in the exhaust gas pass through they will attach on to the elements mention previously, this will then cause a chemical reaction to occur and break up the oxides of nitrogen in to nitrogen gas and oxygen.

Oxydation – This second stage targets the unburnt hydrocarbons and the carbon monoxide, which flow over a membrane made up of platinum and palladium. As the gases flow over the membrane a chemical reaction occurs which converts the carbon monoxde and hydrocarbons in to carbon dixode and water.

Technically speaking there is a third part as well. This is an oxygen sensor(s), older cars used just 1 sensor fitted upstream of the catalyst, this monitored oxygen content in the exhaust. The readings from this are sent to the ECU which adjusts the air/fuel ratio to compensate for the lean/rich mixture. Ensureing that the engine is running at the ideal stochiometric point while recieving enough oxygen to burn off as much of the hydrocarbons and carbon monixide as pssoble. Occasionally newer models use a secondary sensor after the catalytic converter, this largely is used to monitor the performance of the cataytic converter itself.

This then means the harmfull pollutants are massively reduced. The material in the catalytic converter is not used up during the chemical reactions.

Should your MR2 have one?

“Back in the day” cars could get by emmisions laws easily without a catalytic converter, but with ever stricter laws coming in, they began to be fitted as standard to common production cars. After 1992/3 it became near impossible to pass the new regulations without the use of one (UK).

This means that a lot of revolution 1 mk2 mr2s did not have one fitted in the exhaust as standard, and as they where built before the updated regulations they do not need one still for passing MOT’s and staying legal.

In the revolution 2 models this did lower the power output to 156hp (N/A), though by the time the revolution 3 was introduced in 1993 the power was back up to around 173hp for most naturally aspirated 3s-ge models even with them all including the catalytic converter.

Aftermarket parts

Alot of aftermarket or performance manufacturers that either build complete exhaust systems or simply just the catalytic converter section do commonly use a “de-cat” system, This is basically just not using a catalytic part as there main goal is to build an exhaust system to give as much extra power and toque as possible, not emmisions. This design is offered by Japspeed while they do also offer an option to include a “cat-back” option, something that Mongoose offer as well.

A cat back is basically everything in the exhaust system after the catayltic converter. These are usually installed straight after the exhaust manifold as the extra heat in the gases will heat the membrane up quicker than if it were further down the exhaust. The extra heat is beneficial as it will begin the reaction quicker to reduce all of the harmful emissions.

 

 

 

 

 

The MR2 mk2 – Reasons to buy one?

My first post! So the best place to start, why should you choose the mk2 mr2

There has never been a better time.

Starting production in 1989 and an ending 10 years later, these cars now ageing gracefully. The popularity and long production run means that getting a hold of one is not too hard though, a fair condition n/a model can be picked up from £1000 with the more desireable turbo models now fetching around £3000.

On the other side though, the early ones are now 29 years old. Meaning a lot of them will have their share of problems, the main killer being rust and with that, many are being used for donor cars or scrapped. This does mean though that the lucky models than have been looked after and maintained over the years are finally starting to creep up in value, especially the turbo charged models. These are now coming on for classic car status and can be considered an investment. Why spend £20,000 on a dull box on wheels and lose £3000 each year in depreciation alone when you could buy an MR2 turbo (a car that when new could out accelerate a Ferrari 348 TB) and likely sell for 50% extra in only a few years?

Smiles per GallonToyota mr2 sw20

You may have heard the reviews saying that the sw20 mr2 is the least fun, least sharp and heaviest of all the generations. Which yes, is a fair point. I have driven all of them, the mk1 has an amazing driver feel to it, you know exactly what’s going on as you drive and the mk3 which yes does lose some feel due to power steering but other than that is simply amazing around some bends. So saying the mk2 is not as sharp or responsive as them does not mean it’s a bad or numb feeling car in any way.

The second generation may be the heaviest but all in all, it’s still a fairly light car, especially considering with the higher power, they can compete with the likes of Supras or Skylines in many ways, both of which weigh around 200kg more.

Being mid-engined, well-balanced and only a few driver aids, they are still definitely “drivers cars”. What other choice can you get if you want a reasonably quick, fun mid engined car without having to spend tens-of-thousands of pounds?

Even an n/a 3s-ge can be quick, higher powered revolutions came with around 173hp in the UK. That’s a lot of power for an old 2.0 engine even for todays standards and for the mid 1990s is around twice as much as an average family car! Put that in a well sorted solid chassis and for as little as £1k, i cant think of many cars in that price range that are half as fun.I

Old cars are unreliable?Toyota Mr2 mkii

Nope. Toyota are well-known for the reliability, especially the 1990s. There was a couple problems with early models as every car will have but mechanically you can certainly do much worse!

Main things to look for on them are as with most cars. Timing belt needs replacing every 60,000 miles or 5 years, rust spots tend to be the sills, arches, around the bottom of the doors, if you go for the t-bar (especially) the seals will have a good chance of being worn enough to let water through and into the cabin and with the layout of the engine far from the radiator the cooling systems are more complex than a standard FF layout, so make sure signs of new coolant and a properly bled system are present. Earlier revolutions did have a weaker transmission and developed synchro mesh problems on occasions but as a whole the cars are generally above average for reliability.

If you are the kind of person who is looking to modify and work on your car, don’t be put off by the mid engined lay out. Access is hampered by the engine being in the middle and there being a large storage area behind the engine bay but not an issue worth talking too much about, especially if you have a two or four post ramps at your disposal.

Modification wise, there is a massive amount of parts to choose from so that is not a worry at all! The 3s-ge was used in many other awesome cars like the Celica and Altezza, both of which are also big with the modification scene. Hopefully in the weeks to come you shall see that choice on this very website as well!

The followingToyota mr2 mk2

There is a vast following for these little Toyota almost worldwide and access to information is always available online or even better through books!I

The downside of owning the first and last model MR2 is that when looking for parts / information / online fan groups, you will always get excited and think you have found what you are looking for, then 90% of the time it will be all Mk2’s you have found.

The fan base is huge and although the cars themselves becoming rare now are still a regular sight on the road today, this means you can meet your new friends and discuss with them their own ideas, information and feelings of MR2 ownership life.

What do you think?

Overall, my opinion is it’s never been a better time to buy a fun, cheap, reliable car. With new cars becoming ever more similar to each other and losing character and older classics shooting up in value and near impossible to get a hold of a good example, a Japanese 90s icon offers all you need, a low risk car with plenty of parts and available knowledge around with the reality of appreciating in value.

The mk2 MR2 is not too complex or complicated, not too rare yet still a head turner all with that Toyota badge to show it’s been designed and built properly and when looked after will always look after you in return.

 

 

 

 

About Stewart

 

MY STORY

Hi everyone and welcome to my website “sw20 modified”. For years cars have been a massive interest to me, mostly cars between 1975 and 2005 and once I was old enough to drive I went straight to buy my first car, a 1989 mk1 Toyota mr2. (Which I realize is not an sw20).

Being involved with all 3 models of mr2 I developed a particular interest and respect for them. However, finding the correct parts can be frustrating to say the least with all the small upgrades through the production age of the cars and the fact good, clean parts are getting hard to come by now-a-days.

 

WHY I WANT TO HELP PEOPLEMe

I have created this website to help MK2 MR2 owners find good quality parts as well as for advice in the differences in parts between the various revolutions and the 3s-fe, 3s-ge, 5s-fe and turbo-charged models in the hope of making their ownership of these awesome cars easier and simpler.

Also, with the creation of this website I hope the new owners of these cars also gain much useful information of the cars they own and optimize how useful the money they have spent becomes.

 

THE GOAL OF MY SITE

When I purchased my first MR2 I would sometimes spend hours online looking for which part I needed, usually to find one, place an order and find their was several variations that either were not listed or not available so would not fit my car. This is what I hope to minimize.

If you ever need a hand or have any questions, feel free to leave them below and I will be more than happy to help you out. All the best, Stewart

 

Stewart Richardson

Founder of sw20modified