[Diy_efi] Re: LPG vapor injection with gasoline injectors: calculating fuel req.

[Ken Nelson]

There are a couple ways to deal here that I would try given you don't want
to get different injectors:
Increase injector pulse by 40-50%
double up the injectors and maintain pulse time, if low impedence: series
(total Ohms ~6) if high impedence then parallel.

You don't need to "fool" the MS, just tell it what to do.  The size of the
engine has little to do with fuel.  Desired power output and VE has
everything to do with choosing the appropriate size of injectors.

You may have freezing problems at 40psi.  Lower will get you less problems
with this, however you give up flow, not much but even still you would have
to increase PW of injectors indirectly proportional to fuel pressure if all
else stays the same.   Once you hit about 90% duty cycle you are at/beyond
staturation and you will not have any head room to work with if you need
more fuel


On 6/9/06, John Smith1882 <dirtrider218 at hotmail.com> wrote:
>
> Expected fuel(vapor)) pressure will be ~40psi.
>
> LPG comes out of portable cyclinder as vapor already unless you turn it
> upside down. No convertor necessary.
>
> I expect the gas will get cold from the expansion, so I guess roughly
> 30-40*F/0-10*C. Hopefully it won't go any lower than that.
>
> I have no idea what the propane/butane percentages are for the average LPG
> here in the U.S. It's not critical anyway; I just need to figure out the
> numbers to "fool" the MegaSquirt into making a working basemap. For
> example,
> if I need 50% more propane than gasoline, I can tell the MS it's a gas
> engine that is 50% larger than what I have. However, before I can do that
> I
> have to know the reduction in mass flow from liquid gasoline to vapor
> propane through the same fuel injector....or something like that. I'm
> still
> learning about liquid/vapor/caloric values/etc.
>
> In RE to the rest of your post that I excluded: I don't have a dyno and
> won't until I build one. I don't have an exhaust gas analyzer nor
> vepor-specific injectors and it is cost prohibitive for me to purchase
> either for this project.
>
>
>
> >Date: Fri, 09 Jun 2006 20:40:14 +1000
> >From: Phil Lamovie <phil at injec.com>
> >Subject: Re: [Diy_efi] LPG vapor injection with gasoline injectors:
> >       calculatingfuel requirements
> >To: diy_efi at diy-efi.org
> >Message-ID: <4489500E.7C70ED18 at injec.com>
> >Content-Type: text/plain; charset=us-ascii
> >
> >
> >Hi John,
> >
> >Without specifying the pressure and temperature of the activity
> >it is impossible to calculate the equivalence in litres of flow per
> >minute.
> >
> >You don't say how you intend to produce the vapour. If you are using
> >a converter with an internal regulator or some other form of pressure
> >control that will answer some of your question. The temperature of the
> >vapour will be more difficult to determine.
> >
> >That said you also need to determine the propane/butane mix so that
> >you can correct for energy per unit volume.
>
>
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