Help with my LPG project

Hello there

I have a 90 with a 2.5td 19j. I was wondering If any body have done a LPG conversion (not 100% but assisting the engine with LPG). I am doing the conversion all by my self and building the kit my self. I’m a refrigeration technician and I know how to handle gases very well. In the end all you need is a small amount of LPG flow while the engine is running. My problem that I found till now is how much flow of LPG. From info that I searched I found that the maximum of LPG-diesel mix must not be more than 30%, but how much is 30%? I mean liquefied LPG expanded in a ratio of 1:250 to convert to gas but I don’t know diesel expansion ratio from liquid to vapor. I don’t know how much liter per min of gas I have to mix. Other wise the rest I pretty easy just a solenoid controlled with a switch with the throttle so LPG is only used when power is needed and another switch with the alternator so LPG won’t flow while the engine is off.

Thanks in advance for your help

dont do it

Sounds 'kin dangerous to me. Your MOT man will sh*t himself.
Why not use Nitrous Oxide and go the whole hog?

Because it is cheaper. And btw LPG is stored @ a max of 10 bars nitrous is stored @ over 40 bars

very little monetary saving over a big load of grief and hassle, let alone the safety issue your thinking of doing this yourself and ask on a general forum how to do it?

and Why dangerous? All cars that work with fuel are all dangerous. If you crash and the car is hit on the fuel tank the LPG tank is safer than a diesel tank because it is build thicker.

I’m asking information regarding the fuel as I could not find enough information. This so the engine won’t stay knocking due to the lack on oxygen.

Why bother?



To mix LPG with the existing Diesel fuel before induction (Fumigation, not Conversion)


Various attempts have been made to achieve this with varying amounts of success. Go LPG! have examined many systems and installations and after much consideration have come to this conclusion;

Overall, the Savings are Not Huge...

None of the LPG / Diesel mix systems examined have resulted in Diesel consumption being reduced by more than 25%. Those savings made must also have LPG costs (for the LPG that replaces some of the Diesel fuel consumed) subtracted from that 25% saving. This results in final savings of only the low teens of %, or thereabouts.

There are other problems to consider as well - The unmodified Diesel engine was relatively slow-revving, producing its maximum torque at lower RPM than a similar Petrol version. This is not the case when it is converted to run on Diesel and LPG mix. The revised engine has to'rev' more when running on Diesel / LPG mix because its maximum torque will have been moved higher up the rev. band. This can bring new problems of reliability and longevity. The crankshaft, bearings and connecting rods (to mention but a few components) were all designed to rev. at a lower rate. These components will suffer much higher stresses (stress increases at the square of RPM) at the increased RPM necessary to get sufficient torque when running on LPG. Mechanical breakdown may result in far less time, whilst increased wear and reduced component life are certain. Given the low overall savings achieved (to date) and the cost of the adaption ( often equal to that of an injected Petrol engine conversion) many miles would have to be covered before any real savings are realised whilst reliability has been reduced. This does not seem to be an economically viable alternative.*

* Summer 2008 - We keep an open mind.

As world Diesel prices continue to rise sharply, there may be more economic benefit in mixing LPG with Diesel. We are still waiting to see a system that works well and comes with audited figures for reliability and the cost savings achieved. If such a system comes along, with UK LPG accreditation, we'll do some long-term evaluation before a decision is made to offer it to our customers.



Benefit becomes Burden

There are some other benefits apart from saving fuel cost.

The Diesel engine becomes quieter and more responsive when using the LPG / Diesel mix. The classic Diesel 'Knock' can be greatly reduced. The main reason for increased smoothness and reduced noise (vibration) is that the LPG element begins its combustion before the Diesel fuel does, a result of 'detonation' due to the compression ratio being so high. The engine may also get up to its optimium temperature more quickly, whilst harmful emissions like Particulates and Carbon Monoxide can be reduced. These all appear to be benefits.

Sadly, a new set of problems arise when the Driver begins to use the increased performance of an engine that wasn't designed to rev to the new, higher levels. As a result of this apparent improvement in performance, one of the best attributes of the Diesel engine (relative longevity and reliability) is dramatically reduced by the Diesel / LPG adaption.

Conclusion

On a purely fuel cost-reducing basis this adaption or fumigation system does not appear to be an attractive or useful alternative for the average Diesel motorist. That doesn't mean that the people working on these projects should stop, we hope they succeed. Perhaps their research will continue and go on to give us all a better solution.

Overall Conclusion

Above it has been shown that niether true conversion of a Diesel engine nor the mixing (Dual fuelling, Fumigation) of LPG with Diesel give economic benefits large enough to make either choice worthwhile for the average motorist. With current LPG and Diesel technology as it stands, it would be more economical to simply remove the Diesel engine and fit a Petrol equivalent

Im not only seeing this from the financial side but also form the environment side
LPG Diesel Conversions
Diesel/LPG BiFuel

Fair enough, good luck with a diy job

see below

Economy of Gas Injection

and the enviroment savings?

ive been looking into this myself.Seems a gain in power and economy are there for grabs.

nathan5346 said:

and the enviroment savings?

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**** em it goes faster for less

jsprinter said:

and Why dangerous? All cars that work with fuel are all dangerous. If you crash and the car is hit on the fuel tank the LPG tank is safer than a diesel tank because it is build thicker.

Click to expand...

Was not thinking about if you crash as I'm sure you will keep the LPG in a purpose designed tank but more along the lines of a high compression diesel engine being fed highly explosive gas from a DIY system all of which your engine was not designed for. Petrol engines are much lower compression so LPG is very much like the fuel vapour they were designed to run on but I still would not want a DIY set up. If it works then good luck to you.

I'll stick to pouring filtered reclaimed oil into my diesel engine as it costs about 10p per litre which no LPG set up will better for pence per mile. It also means I dont have to mess about with my engine or fuel mixtures etc.

A 19J diesel engine is short lived and fragile enough without exposing it to more stress.

hughesy said:

A 19J diesel engine is short lived and fragile enough without exposing it to more stress.

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Ed Zackery !

i rekon he sud go forrit,ya dont need a gud reason t want t mek summat ya sen.if he's jus doin it fa ****s n giggles,well fair play to im.best of luk t ya sprinty.