MR2 Engine Swaps: Which Engine Is Best?
The MR2 in all its iterations was hugely popular, and although there are still thousands on the roads today, especially in Europe, it is becoming increasingly difficult to find an unaltered example in reasonable condition today. While it is true that the original 1 600cc engine did offer some potential for modification, the appearance of factory-fitted turbo charged engines only seems to have spurred fans of the MR2 on to ever greater efforts to out-do Toyota in modifying their cars with more exotic engine swaps.
Favorite engine swaps include 4A-GE twin cam 20-valve silver and black tops, 3S-GTE, BEAMS 3S-GE engines, as well supercharged 4A-GZE 16-valve engines. However, to die-hard conversion fanatics, these engines are hardly worth the trouble since they fit the MR2 engine bay without any modification at all, simply because in some markets, they were offered as standard. Which means that if you wanted a MR2 with a turbo-, or supercharged four cylinder engine, you could simply go out buy one- no modification required.
Which Engine Then?
There is hardly a four cylinder engine in existence that has not been successfully fitted into MR2’s, but there are some that are best avoided, such as for instance, the 3S-GTE turbo engine that was fitted as standard in some markets.
This engine is widely regarded as unreliable, and the exception to the rule that Toyota makes good engines. Although not all 3S-GTE’s suffered from the same failures all of the same time, some common issues include, but are not limited to, turbo failures, erratic under-, and over boosting, high oil consumption, oxygen-, and knock sensor failures, mass airflow meter failures, and many others.
Fortunately though, the choice of suitable engines with which to swap out the original range of engines is not limited to other four cylinder engines, and many V6 engines from different manufacturers have been fitted successfully. There are even some V8 conversions, including LS1’s and various others, but these conversions all require extensive modifications to the body work, fuel tank, and cross members. Unless you have unlimited time, resources, and exceptional mechanical skills, V8 conversions are best left to professional conversion companies.
Fitting a Camry/Lexus V6.
In contrast to V8 engines, V6 1MZ-FE, and 1MZ-FE VVti engines from respectively Camry and Lexus models are easy to fit, and therefore by far the most popular choice for those who want V6 power. These engines require no modifications to the body work whatsoever, and the only component that needs replacing is the driver’s side engine mount, which is available from dozens of conversion and power development companies online.
From a practical point of view, a Camry or Lexus engine drops right in, and bolts straight onto the existing transmission. Transmissions from both turbo and a naturally aspirated models (and their drive shafts) are able to cope with the added power, but with the advantage of gear ratios that were designed for four-cylinder power.
In practice, this means that it is possible to take off in second gear at only a little above idling speed, and even from speeds as low as 20 m/ph in fourth gear, the car accelerates effortlessly and without hesitation, but at a pace that will leave you speechless. So what is required to make this miracle happen, and what about other issues like exhaust systems and A/C systems?
Will a Camry Engine Fit My MR2?
Any second generation MR2 is a suitable candidate for the transplant, regardless of the engine it left the factory with. All manual transmissions also bolt straight onto the engine, although efforts to mate V6 Camry/Lexus engines with automatic MR2 transmissions have by and large been unsuccessful.
Keeping the A/C?
It is even possible to use the A/C compressor that comes with the V6 engine if you need an air conditioner. However, to do this, some modification to the piping is required, and off course, the system would have to be purged and recharged, which adds to the total cost of the conversion, but in some climates an A/C is a necessity, which makes keeping the A/C a forgone conclusion.
What Exhaust Modifications Do I Need?
The only modification to the engine involves alterations to the outlet manifolds to make it possible to retain the same attachment point for the silencer. Any competent exhaust shop will be able to make the changes, but several conversion companies offer custom made manifolds and down pipes that bolt straight onto the engine.
Will I Have Room to Do Regular Maintenance?
If you are worried about not having enough work room to replace the cam belt on the Camry/Lexus engine- don’t. You will have about the same amount of space as you would have had with a stock 3S-GE engine.
Do I Need to Change Anything Else?
No other modifications are required, but with lots of added power comes lots of added speed, so it might be a good idea to upgrade the brakes as well. It is also recommended that you run 235, or even 245 tires and wheels on the rear to handle the extra torque as well.
Will My Gauges and Warning Lights Be Affected?
No, all the important gauges and warning lights will work as before, including the check engine light because the V6 engine runs off its own ECU. However, since the tachometer works with a four-pulse signal, it is necessary to replace the tachometer circuit in the instrument cluster with one from a Camry or Lexus to provide a six-signal pulse. In addition, if the conversion is performed on a MR2 that ran with a turbo engine, the turbo boost gauge will obviously not work anymore.
What to Look Out For.
Although Camry and Lexus engines are virtually indestructible, it is known that from around 80 000 miles or so you run the risk of experiencing blown head gaskets. Apart from this though, there are no other known reliability issues with these engines, so before you fit one into your MR2, do yourself a favor by replacing the head gaskets and timing belt first, regardless of their condition- or suspected condition.
What Does the Conversion Cost?
Generally well under $10 000, but there are many factors that influence the final tally. For instance, it may be necessary to buy an entire Camry or Lexus just to get the engine, and chances are you will not recover all of the purchase price by selling the remainder to a wrecking yard.
Moreover, you may want to add even more power by installing a supercharger, or other making other modifications, so the final cost is more a question of want you want the final product to be, rather than an absolute, definitive figure.
What Other Engine Choices are There?
While there are dozens of viable choices, one other extremely popular engine for a swap into a second generation MR2 is the high revving 2ZZ-GE that makes 180 Hp in stock trim. The popularity of this engine is due to the fact that complete swap kits (including various 6-speed transmissions) are available on the one hand, and that it is very easy to fit, with no modifications to the body work required.
Parts Required for a 2ZZ-GE Swap.
What to Look Out For.
Celica transmissions require a custom made shifter bracket; without this modification you will not be able to select gears. Suitable brackets are custom made, and available here. On stock MR2 transmissions it might also sometimes be difficult to select reverse, but this is relatively easy to fix by inserting a steel washer between the steel bracket and the shift shaft to move the shift lever to the right. Use this resource for details on this issue.
Is it Worth the Trouble?
Certainly. In both conversions, the added power makes for highly improved driveability. Moreover, neither conversion upsets the MT2’s rather delicate balance, although in the case of the V6 conversion, the car gains a significant amount of weight overall. Nevertheless, the effortless power of the V6 engine more than compensates for the added weight.
So if you have the time, money, and an old MR2 that needs a new lease on live, what is stopping you from joining the legions of MR2 fans that are driving their dreams every day?
Here's a great display of a Camry V6 swapped MR2 in a Smoking Tire video. If you thought an MR2 was fun, just imagine this.