things you need to know,
I dont have a vario, i have never driven vario with cng installed, I do have honda civic 2002 1.5 exi prosmatec which is auto transmisiion on cng ..
Honda City VArio has a Continous Variable Transmission CVT, which means that there are unlimited Gear combination that it can make , it mostly drives by keeping the engine at a constant rpm where it shud get best economy and it keeps on changing gears to accelerate..
Which means that the gearbox has to do a lot of work.
i am sumwat a petrol head myself, and i tune all my cars myself, having the civic automatic on cng taught me a few lessons by experience which are...
The best the car tuning, the easier the work is for the transmission and torque convertor,
if the tuning of the car is messed up, and its not generating good power, the tranmission will be unable to change gears at the right time, and more often it will be found in the wrong gear with the orque convertor trying to compensate for it,
the kick down time affect increases, as first the torque convertor tries to change the ratio and deliver power out of the same gear...causing excess wear and tear,
THe better the engine tuning, the easier it is for the tranmission to do its work.
All the above experience is from a 4 speed prosmatec transmission wiht a 1.5 liter engine on cng.
The CVT transmission is a lot more complex and it has to do a lot more work, as it makes and changed between many many more gears as compared to just the 4 gears of a conventional automatic tranmission.
in city idsi vario, this complex CVT transmissin is coupled to a 1246 cc engine, which obviously is not known at all for its power generation ailities for a big car like city, so the engine is already on the sluggish side ,
when this sluggish engine will be forced to run on cng, there will be a further power loss of around 20% on average.. and it might increase with the usage as the car will need tuing from time ti time...
so the transmissoin would lierally go bizzare with changing too many gears... and will wear out.. as there are no metal gears in the gearbox, and there are pulleys and belts making gears with oil pressure.... the tranmission is very likely to say bye bye...
How can it be saved, and why some people have no complaints?
1.It is very common that automatic trasmissoins are not used as they are supposed to be used, this is the major reason that people dont like automatic transmissoins, it is because they dont know how to use t properly, if used properly, in the right selection as the situation needs, you prevent a lot of wear and tear in the suspension.
making sure that your engine is producing the maximum power all the time, getting very regular tuneups, or getting a Lambda control kit fitted to manage CNG input. This will result in reducing the powerloss as compared to petrol.
The driving habbit, routine and route, Auto transmissions are very hapy when they are driven at constant speeds for long interval of times. not stuck in bad traffic at school or rush hours. if you are a freeway driver then your car and its transmissoin will last long.
My suggestion: Get a 2003-2006 Exi prosmatec 1.5 liter, CNG fitted. to be in absolute peace of mind.
hope this helps you to understand some issues regarding auto transmissions n cng