OK here are the answers to your queries
Ans 1 :Any Petrol engine can run on CNG so can 4Age.
However due to 4 throttle bodies its not as easy to control CNG flow as its on other cars.
Its a difficult task to run it on CNG. The easiest way to run it on CNG is use the Omi-Gas Kit (the one that comes with Liana) and fit each gas jet in one throttle. However its not possible for you to get the Maps for 4 AGE for OMI GAS as Landi Renzo haven't prepared them.
The second option is that you install the normal CNG Kit and modify the Intake Manifold.
For this you will need the normal Landi Renzo EFI kit and Emulator. The Advancer that is required is Landi Renzo Stap 200.
Now comes the tricky part i.e.
How to supply the gas to the intake. As if you will try to supply the gas through the normal intake it will not reach to all the throttles and your car will not idle properly and will stop down. You can control that by always keeping the throttle little open but effectively not all of your intakes will be working due to the limiting supply of CNG . My Solution was to make an intake as shown in the image
Read the description in the image and this will make your car run on CNG.
Why I am successfully and other didn't succeed cause people dont like to change the Intake of the 4 AGE . Since I was already using a custom Intake (I have the 4 AGE in KE 70) so it was not a problem for me.
Now lets talk about the advantages and disadvantages of the CNG.
Advantages
1- 5 times cheaper than Hi-Octane on which I run my 4 AGE
2-No knocking at all due to hi RON number of CNG . You can run it in 3rd gear at a speed of 40 KM/H. With Pakistani Hi-Octane you have to ensure that your RPM is always above 2k to avoid any knocking.
3-The car can go easily to 130 KM/H.
Disadvantages.
Due to a small intake of CNG and Air the car will not rev above 5 K. And any 4 age that can only rev to 5K is the most pathetic engine as the engine does have very little torque up to this point. It is in the region of 5k to 8 K that you actually enjoy the 4 AGE and where this engine shines
I converted my engine on CNG for only one month as I just want to do an experiment and Alhumdullilalah it was successful. Pakwheels members Ghuncha and WaqarCheema have tested the car on CNG and it works flawlessly.
Ans 2 :As far as the parts are concerned it depends upon the part. I was able to get the original timing belt from Mehran Autos in Rawalpindi for around RS 5500.
The plugs that I am using are Denso IK-20 which are easily available in Pindi for RS 3000 [You can get them from Pakwheels also for 4K search the threads]
For oil Filter use the new corolla 2009 filter it is for 4 age. Before 2009 the same filter was used in Camry and also available. You can get the Original Toyota one for RS 950 and guard one for 250 RS.
For Water Body you can use 4-AFE water body.
If you need some exotic part like VVT pulley or head gasket then you need to look for them on the internet as they are not available in Pakistan (Atleast in Islamabad and Rawalpindi) and need to be imported.
Ans 3: Well I change the oil and filter after 5K and uses ZIC XQ. Havent done any other maintenance beside changing the timing belt and the engine works perfectly fine. Remember its Toyota.
Ans 4:Works like a charm no issue there except the high cost of Hi-Octane.I have not experimented it with E-10 but some people are saying that its RON number is higher than Hi-Octane so I will give it a shot some day and may be if its RON number is higher it will further reduce the knocking.
Ans 5 : A lot of options search the internet.
Ans 6 : Varies from Person to Person. Looking at the capabilities of local mechanics I will prefer a stock car. One of the reasons why I have preferred Blacktop over Silver top.
Ans 7 : No issue beating New Civic or Corolla. Remember its 165 hp compare to 133 and 140 of Altis and Civic.
However for a normal city drive I personally prefer 1ZZFE as it has a lot of torque under 3k and 4 Age cant be compared to it till 5 K. However it will take less than 3 seconds for 4AGE to rev past 5k and Altis will be history but you have to remain in the racing mode all of the time.
Also on the hilly areas 1ZZFE can be a much better choice but on straight roads Altis or Civic cant compete 4AGE