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Old 08-28-2019, 06:07 PM   #41 (permalink)
cRiPpLe_rOoStEr
It's all about Diesel
 
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Quote:
Originally Posted by teoman View Post
Also, could you inject the lpg with a gasoline injector? That would make it much easier to control for us computer oriented guys. I suppose one could have to read the pressure and the temperature of the lpg before injection.
It's working with direct-injection engines, enabling them to run solely on LPG instead of resorting to both port-injection for LPG and direct injection for a small amount of gasoline. With CNG on the other hand, there is always the need for a small amount of gasoline through the stock injectors, so CNG must go through port-injection. Volkswagen has that TGI engine which operates on CNG as the primary fuel through direct injection, but I don't know how the gasoline limp-home mode is enabled through the same injectors...


Quote:
Originally Posted by skyking View Post
When it works out, it is usually on pickups that have spare bed space and room for the plumbing
Or even some underbody setups, not taking space from the bed. I see a lot of those on trucks converted to CNG in my country (retaining their stock gasoline tank).


Quote:
Originally Posted by teoman View Post
Although i have most of the equipment, i do not want to mess around with CNG.

I am thinking low pressure natural gas, pumped with a small diaphram air pump.

Methane stored in an air mattress with roughly 200*100*20 cm dimensions. That would be 0.4 m^3 of volume or 0.4 liter diesel equivalent of volume. 40 cents worth of fuel.
Seems like you want to try something similar to those "gas bags" widely used with coal gas in Europe during WWII, and until the '90s on buses in China with methane in some provinces.


Quote:
Originally Posted by Isaac Zackary View Post
Ok. So I'm seriously contemplating this for my 1.6L non-turbo 23:1 CR 1985 VW Golf diesel.

I consistently get about 55mpg gallon already on the highway. But perhaps what I'm more interested in is reducing emissions, black smoke, etc.

Any thoughts? How would this best be hooked up?

One problem I foresee is that on the Golf the air cleaner is in the top of the plenum. So if I add propane it would either have to be before the air cleaner or into each intake runner or I'd have to relocate the air cleaner.

Also this is mechanical injection. So I can't meter propane electronically by taking data off of an EFI system.
If you could work around some sort of a phase sensor, that would enable the sequential injection through each intake runner, which would be much more desirable as it would avoid wasting fuel during each valve overlap. But not every multi-port injection is sequential anyway...

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