HIGH-END TORQUE ON CNG

Home > Gari Forums > Others Forums > Others Other Forums > Others Other Fuel Economy Forums

HIGH-END TORQUE ON CNG

Hi Guys,
I recently bought CITY 99 (CARBY ENGINE) with preinstalled CNG. The problem is that though it has great low end torque (from 2k to 3k rpms) but it is hopelessly poor at high rpms.
The cng is directly injected into the carby ( by drilling it and fitting a pipe directly into it instead of a mixer placed between carby and filter housing). The top speed is never more than 120 kph. I have sufficiently advanced the timing but no improvement.
My guess is that since this system can only installed in one of the two barrels of carby, it behaves well as long as secondary barral dosent comes into play. As soon as the throttle is opened wide enough , the second barral starts playing and the mixer becomes lean and hence no power beyond that point. What u guys think?

Gari.pk User 950 asked on 18 Jun 2010 13:18:55 pm

1 Answer

339 views |

Aryan - on 18 Jun 2010 13:19:15 pm

well i converted my carb from a nozzle drilled in it to venturi and i dont tune my car from cng specialists and i have never done that either, pal i am the guy u need first thing is u cannot advance ur vehicle more then 15 to 20 degrees max believe me cause i am a mechanical engineer who is in love with cars and work on them all the time if u advance the car to much it will stall on hi r.p.ms, the second thing is check ur plugs, power leads the ideal value for them lies between 10kohms to 20khms but less then 20kohms and above 10kohms ur filter needs to be clean! now we move to the carb remove the nozzle asap or close it in order to get more power we need to activate the second butterfly asap to get that u have to get a venturi the venturi should not have numerous holes in it just one rectangular opening which u would place such that half of it is on one barrel the other half on the other barrel, remove any tape the damn cng mechanics have placed over the filter to control the amount of air!!! then u reduce the intake cng pipe as short as possible and the power T as near to the carb as possible clamp the ends so that no cng leaks and tune ur car make sure when u tune it see if the second butterfly opens or not automatically the vacum operating it should work do this and report to me the venturi will cost u no more then 150rs max