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Old 11-10-2018, 04:23 PM   #28 (permalink)
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GasDwarf - '13 Volkswagen up! EcoFuel CNG
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Originally Posted by Big Dave View Post
CNG requires "driveway fuel" to warm up the cooling system to keep the NG regulator from freezing.
It uses the coolant to keep gas regulator from freezing, and requires the coolant to be warmer than about -10

An optimized CNG vehcle would run 13:5 compression with lots of spark advance.
My up! runs 11,5:1 , compared to the regular petrol-up!'s 10.5:1

Also means FE isn't too great on petrol

E85 runs 95-102 octane, so it would be OK warm-up and purge fuel for a CNG car.
Mine ran rough on hydrous hE15
Not going to try E85 - which it isn't rated for - unless I know it'd work.

Converting FFV to CNG was quite popular - with FFVs already having the more heat-resistant valves/seats required by CNG.
GasDwarf's fuel consumption :
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