diesel LPG conversion - how clean is exhaust?

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retspeej
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diesel LPG conversion - how clean is exhaust?

#1 Post by retspeej » Sat Jun 23, 2018 1:08 am

The conversion is acutally twin-fuel: the engine burns mostly diesel with 20-25% LPG. So it doesn't save you much money. But the proponents claim that it eliminates soot from the exhaust, which would be a bonus when coked-up diesel particulate filters cost a motser. When diesels are now a pollution problem, seems worth considering.
I have found a few scientific papers on blending diesel with short alkanes (methane propane pentane) and I doubt it would reduce soot to zero.
Who has an LPG diesel? What is your opinion?

Gilbertd
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Re: diesel LPG conversion - how clean is exhaust?

#2 Post by Gilbertd » Sat Jun 23, 2018 4:18 pm

You'll never eliminate the soot from the exhaust other than by not starting it but adding LPG might reduce it a bit (but never down as low as a petrol engine). As I understand it, not having a diesel (and would never consider one either), the LPG addition will give extra power or better economy depending on how you drive it. An improvement in emissions is regarded as an added bonus not the reason for the conversion.
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LPGC
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Re: diesel LPG conversion - how clean is exhaust?

#3 Post by LPGC » Wed Aug 01, 2018 11:29 pm

Has more effect on older diesels with the dirtiest exhausts, the addition of a bit of LPG in the mix helps the diesel engine fully burn a greater proportion of the diesel it uses rather than just spitting unburned / partly burned diesel / particulates out of the exhaust. Can get more power and economy by putting in more LPG but put in too much LPG and the diesel engine suffers from starfire which is like pinking but for diesels and is worse than pinking on petrol engines, starfire can knock holes in pistons... matter of getting the balance right. Claims are up to around 30% LPG but that sort of ratio is likely to be on an old dirty diesel but the same old diesel probably couldn't handle the increased power of adding 30% LPG at high load. Besides starfire increased exhaust gas temps can be a problem for diesel LPG blend systems but most purpose designed systems allow connecting to an EGT sensor and will shut-off LPG if EGT gets too high.
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hitman
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Re: diesel LPG conversion - how clean is exhaust?

#4 Post by hitman » Thu Aug 02, 2018 2:51 pm

We have v32 diesels at work running on compressed natural gas at 340bar and using between 5-10% diesel for ignition purposes

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Re: diesel LPG conversion - how clean is exhaust?

#5 Post by LPGC » Thu Aug 02, 2018 6:33 pm

You can do that with CNG / LNG, can't get as much LPG in the diesel/gas mix as you can with methane.
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