I have been away for quite a few weeks and I apologise for not responding earlier to all the replies for your needs.
An engine conversion in a lot of countries is a cheap way of getting more HP without any serious modification and lowering the life expectancy of the original engine. Some countries will have harder rules on conversions due to the strict exhaust fume regulation. Generally, it is fun, but costly and will take up a lot of time and personal effort. Not to mention the ability to run the vehicle and servicing it. I have noted down problems and tips that may be able to help you all as I may not possess the 4.1 RAV4 soon(my baby).
1. Fuel consumption.
As more HP means more fuel consumption and it is a fact in every part of more HP either with or without engine conversion. You will notice a lot of difference in fuel consumption and I will list what Andrew and I have came across. All units are in Metric as I do not know what the imperial measurements are.
Andrew made a 3S-FE to 3S-GTE(gen II: ST185) conversion. He once said the most he ever get was 8km/L and in worst case, 6km/L. Also, he couldn't run any low octane gas, but must be above RON96.
I made a 3S-FE to a 3S-GE(gen III: ST202) conversion. I have highs and lows depending on the weather, fuel pressure regulator pressure and driving conditions. Generally, in summer, it uses less gas and uses more in Winter. In summer, I have managed to get a maximum of 9.3km/L and 8.5km/L in winter. Standard Toyota fuel pressure regulators(fpr) run at 2.5bar(35psi) on idle even they claim to run 2.1bar(30psi). This contributes to a lot more fuel consumption when idling after the conversion, hence an after market will be needed to lower this tolerance. Leaning the fuel out may be good for economy, but if you run too lean, you risk of over heating your pistons and kput them.
When starting up the 3S-GE engine cold, starving the fuel system will give your engine jolts on idling and will not settle until water temperature reaches above 60 deg C. Running rich is good, but you will barely make 350km/tank of petrol.
During racing, I have had the worst fuel consumption ever. I fill half of my tank ~27L. This will provide me with less than 100km or track mileage. Which works out to be 3.5-4km/L or more. Also you must set your fpr to above 2.5bar during idling with vaccuum on. I normally set it to 2.8 bar as this will run richer and prevent overheating of the pistons.
2. Engine mounts.
As you all know, all the engines above I mentioned starts with the 3S, whether it's a FE, GE or GTE. They all share the same engine mount(ahhh.... the greatness of Toyota). So they will bolt on perfectly to the existing engine mounts.
3. Gearbox and clutch.
As you all will know the history of the 4.1. It comes out of the corolla, Celica GT4 and Camry platform. Pretty much anything goes on it, and Toyota shares all it's components on similar vehicles. So any of the 3S engines will bolt onto the existing gearbox. However, how you transfer all those power depends on your clutch and pressure plate. As with the standard RAV4 gearbox will handle up to 250HP, but the rear diff will need a lot more attention once you are able to get those HP to convert to the wheels.
4. Fuel system.
The standard RAV4 fuel pump is not that dissimilar to the existing MR2 or Celica fuel pumps. It has plenty of flow, even for the standard 3S-GTE motor. There is one thing you will need to change. This is the fuel filter located on the bottom of the engine bay. As you require more flow, you will need to allow the filter to filter more fuel.
Changing a more powerful engine requires a more stable platform, hence the suspension upgrade. This will not only keep your vehicle balance, but more managable under unexpected environments. Having a tower bar is a must to minimise body and chassis flex. Another tip is inserting foams in chassis to give it more rigidity. use those self expanding foams.
The faster you go, the more stopping power is required. I had a few ideas in the past and since I'm not much going to use it, I might as well post them here.
The SXA10 and SXA11 chassis uses a single port brake caliper on the front brake setup. The rotor is 302mm in diameter and a thickness of 18mm with minimum tolerance of 16mm. The cheapest way to gain more brake is change to a slotted rotor and better braking material. But for those who were thinking of changing the brake calipers, there are two options:
a) Do not change anything and settle for the slotted rotors and good pads.
b) Out of my many days and weeks at wreckers, I have realise the ST206(Toyota Curren) brake caliper share the same bolt dimension as the SXA10 and SXA11 brake caliper. This is a direct bolt on, but will require new brake lines as the stock RAV4 hose line bolts on opposite direction to that of the ST206 calipers. Another problem is, the ST206 rotors have a 275mm diameter and a thickness of 28mm and minimum tolerance of 26mm. The center hole is 55mm while that of the RAV4 is 62mm, so you will need to shave it out.
As with heat capacity, the thicker the rotor, the more volume and better heat capacitor it will be. As with simple volume calculations, it comes out that the ST206 rotors have a mere 30% more volume than that of the RAV4 which means it can handle a more more braking power. Setback is, the thick rotor will dissipate heat less faster than that of the 18mm rotors.
7. Tyre choices and alloy wheels.
Once you all have an engine swap, there is a major thing you must know about the RAV4's standard wheel and offset. The standard alloy wheel vary in offset from continent to continent and generally, the stock 4.1 215/70R16 tyres will be sitting 10mm inward the guard in front and same as the rear. If you all are able to get alloy wheels with a +32mm or less offset with either a 6.5" or 7.0" width, you will be a more stable platform at higher speeds and better cornering.
As with tyre choices, all of us will have a different opinion, and this is mine. It may not be correct, but at least this is based on New Zealand condition.
Choose tyres with a directional pattern as this will help better aquaplaning. Also, they will have less road noise, but these tyres are poor on off road performance. I do recommend the BFGoodrich Macadams, but they are not so great during rain as they could give you a glide across high speeds and medium to low grip on wet surfaces.
8. Exhaust system problems.
I have been through 2 full setups before I am satisfy with the flow, back pressure and noise level inside and outside the vehicle.
If you transplant a 3S-GE into your engine bay, you will need a minimum 2" exhaust system to get a good flow, but I would recommend a 2.25" - 2.5". There will be major work needed on the 4WD SXA11/10 mid section as the setup will need to go near the 4WD viscous cupping. It will involve some experience exhaust welders to get this right, do not try to do it yourself as it will take up to 2 hours just on that section alone.
As with materials for exhaust, do not use thin materials. I would recommend materials thicker than 1.5mm as this will create less reconance inside the car. More comfy driving. The 3S-GE is notorious for their noise, hence you will need at least 2 resonators and a huge muffler to get the noise to an acceptable level. I am sure for the SXA11, you can fit 2 12"-14" resonators, 1 medium after market muffler and another silencer. This way, you will have the pleasure of low end power as well as high end flow without the annoying noise.
As with 3S-GTE exhaust setup, I prefer you all to ask Andrew in www.rav4oz.com/forum
or some others here who might have the experience.
9. Engine movement.
When you put a 3S-GE/GTE into the RAV4 engine bay, you will realise a lot of movement in these engines. I'm not talking about transverse movement, but lateral movements. This will create some unpleasant vibrations at high speeds or engine loads. Simple solution is to get an engine suspension. If you have the money, you can buy them for around US$200.00 plus fittings. If you are poor like me. I made one out of a gas strut with high pressure. One end mounted on the engine with some durable metal and the other on the tower bar with some custom fittings. DO NOT drill on the tower bars. Also, DO NOT fit the shock on the firewall nor the rosecut(front of the engine bay).
This is for now.