lpg performance
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From: Jason James on 29 Aug 2007 21:09 "Paul Saccani" <saccani(a)omen.net.au> wrote in message news:lvpad39vevt1g2gcf6tgcgfn8k56vu9f6l(a)4ax.com... > On 29 Aug 2007 09:34:24 GMT, Ron <dodo(a)hotmail> wrote: > > >motoxxx43(a)hotmail.com wrote in news:1188375500.446790.194600 > >@q3g2000prf.googlegroups.com: > > > >> hi i have recently have had my toyota 4runner converted to lpg and > >> have loss significant amount of power and was wondering if this is > >> just normal for gas and if so what sort of engine mods work good with > >> lpg? any info on this wold be greatly appreciated thnks > >> > >> > > > >Tuning, you may have to retard the ignition > > It's the other way around - you advance the spark curve at low RPM, > and retard the high end *compared* with a petrol curve at high RPM by > as much advance as you added at low RPM. > > This used to be done by distributor modifications, but it hard to get > these done nowadays, so you could use something like an AEB > "Electronic Spark Advance Variator", which comes in a range of models > to suit different kinds of ignition systems. Besides being easier to > set up, it runs dual curves, one for Petrol and one for LPG. > > >and increase the gas flow. > >It will use more gas, but it is cheaper :-) The theory is, as far as I can dtermine, that LPG/air burns slower than petrol-mist/air, and hence this imparts a higher octane rating. The Cleveland 5.8L I have on gas will not ping with quite high advances up to 50 degrees BTDC. Hasten to add I didnt leave it like that, the "HEI" dizzy I bought new was set-up that way initially. This engine also has a significant power drop on gas, and after much investigation including a wide range of inneffective mixture and ignition timing settings, Athol who is an engineer here, passed the opinion that its likely the "mixer" is too small and is limiting intake. The carter carby has quite high CFM figures, but opening the secondaries doesnt alter engine output, or more significantly, doesnt cause a mixture change, hence the open secs are only acting as a larger intake manifold 'mouth' size without any chnage in flow thru the mixer on top, as its already maxed-out. Not saying this is the OP problem, but thought it worth mentioning. Jason
From: Ron on 29 Aug 2007 16:21 "Jason James" <at(a)peace.com> wrote in news:46d56fee$0$15512$c30e37c6(a)pit-reader.telstra.net: > > "Paul Saccani" <saccani(a)omen.net.au> wrote in message > news:lvpad39vevt1g2gcf6tgcgfn8k56vu9f6l(a)4ax.com... >> On 29 Aug 2007 09:34:24 GMT, Ron <dodo(a)hotmail> wrote: >> >> >motoxxx43(a)hotmail.com wrote in news:1188375500.446790.194600 >> >@q3g2000prf.googlegroups.com: >> > >> >> hi i have recently have had my toyota 4runner converted to lpg and >> >> have loss significant amount of power and was wondering if this is >> >> just normal for gas and if so what sort of engine mods work good >> >> with lpg? any info on this wold be greatly appreciated thnks >> >> >> >> >> > >> >Tuning, you may have to retard the ignition >> >> It's the other way around - you advance the spark curve at low RPM, >> and retard the high end *compared* with a petrol curve at high RPM by >> as much advance as you added at low RPM. >> >> This used to be done by distributor modifications, but it hard to get >> these done nowadays, so you could use something like an AEB >> "Electronic Spark Advance Variator", which comes in a range of models >> to suit different kinds of ignition systems. Besides being easier >> to set up, it runs dual curves, one for Petrol and one for LPG. >> >> >and increase the gas flow. >> >It will use more gas, but it is cheaper :-) > > The theory is, as far as I can dtermine, that LPG/air burns slower > than petrol-mist/air, and hence this imparts a higher octane rating. > The Cleveland 5.8L I have on gas will not ping with quite high > advances up to 50 degrees BTDC. Hasten to add I didnt leave it like > that, the "HEI" dizzy I bought new was set-up that way initially. This > engine also has a significant power drop on gas, and after much > investigation including a wide range of inneffective mixture and > ignition timing settings, Athol who is an engineer here, passed the > opinion that its likely the "mixer" is too small and is limiting > intake. The carter carby has quite high CFM figures, but opening the > secondaries doesnt alter engine output, or more significantly, doesnt > cause a mixture change, hence the open secs are only acting as a > larger intake manifold 'mouth' size without any chnage in flow thru > the mixer on top, as its already maxed-out. Not saying this is the OP > problem, but thought it worth mentioning. > > Jason With the XJ6, the timing has to be changed from 6 BTDC to 12, otherwise it gets very hot :-)
From: Ron on 29 Aug 2007 16:31 "Noddy" <dg4163@(nospam)dodo.com.au> wrote in news:46d54e7d$0$90162$c30e37c6(a)lon-reader.news.telstra.net: > > "Ron" <dodo(a)hotmail> wrote in message > news:Xns999BC82D95BE4GPS(a)64.209.0.82... > >> Tuning, you may have to retard the ignition and increase the gas >> flow. It will use more gas, but it is cheaper :-) > > Don't do that :) > > Retarding the timing will only make it worse unless it's got way too > much advance now, and you'd notice that on petrol if it did. > > Tuning gas systems is like tuning anything else in that there's > different types of systems than each have their own peculiarities and > need special attention to suit. There shouldn't be anything other than > a mildy noticable power difference between gas & petrol on a dual fuel > system, but if there is then you need to get it back to the gas fitter > and have them tune it *properly*. > > That's what you paid them for. Noddy, The XJ6 has a OMVL R90e. The ignition timing for LPG has to be altered or the car overheats. I assumed most vehicles would be the same :-) Ron
From: Jason James on 30 Aug 2007 06:51 "Ron" <dodo(a)hotmail> wrote in message news:Xns999C41A6E3DA1GPS(a)64.209.0.92... > "Jason James" <at(a)peace.com> wrote in > news:46d56fee$0$15512$c30e37c6(a)pit-reader.telstra.net: > > > > > "Paul Saccani" <saccani(a)omen.net.au> wrote in message > > news:lvpad39vevt1g2gcf6tgcgfn8k56vu9f6l(a)4ax.com... > >> On 29 Aug 2007 09:34:24 GMT, Ron <dodo(a)hotmail> wrote: > >> > >> >motoxxx43(a)hotmail.com wrote in news:1188375500.446790.194600 > >> >@q3g2000prf.googlegroups.com: > >> > > >> >> hi i have recently have had my toyota 4runner converted to lpg and > >> >> have loss significant amount of power and was wondering if this is > >> >> just normal for gas and if so what sort of engine mods work good > >> >> with lpg? any info on this wold be greatly appreciated thnks > >> >> > >> >> > >> > > >> >Tuning, you may have to retard the ignition > >> > >> It's the other way around - you advance the spark curve at low RPM, > >> and retard the high end *compared* with a petrol curve at high RPM by > >> as much advance as you added at low RPM. > >> > >> This used to be done by distributor modifications, but it hard to get > >> these done nowadays, so you could use something like an AEB > >> "Electronic Spark Advance Variator", which comes in a range of models > >> to suit different kinds of ignition systems. Besides being easier > >> to set up, it runs dual curves, one for Petrol and one for LPG. > >> > >> >and increase the gas flow. > >> >It will use more gas, but it is cheaper :-) > > > > The theory is, as far as I can dtermine, that LPG/air burns slower > > than petrol-mist/air, and hence this imparts a higher octane rating. > > The Cleveland 5.8L I have on gas will not ping with quite high > > advances up to 50 degrees BTDC. Hasten to add I didnt leave it like > > that, the "HEI" dizzy I bought new was set-up that way initially. This > > engine also has a significant power drop on gas, and after much > > investigation including a wide range of inneffective mixture and > > ignition timing settings, Athol who is an engineer here, passed the > > opinion that its likely the "mixer" is too small and is limiting > > intake. The carter carby has quite high CFM figures, but opening the > > secondaries doesnt alter engine output, or more significantly, doesnt > > cause a mixture change, hence the open secs are only acting as a > > larger intake manifold 'mouth' size without any chnage in flow thru > > the mixer on top, as its already maxed-out. Not saying this is the OP > > problem, but thought it worth mentioning. > > > > Jason > > With the XJ6, the timing has to be changed from 6 BTDC to 12, otherwise > it gets very hot :-) Yeah, I'm starting to think, earlier conversions (mine was in '99) were less than optimum in many cases. Sensitivity to ignition advance seems to vary radically from engine to engine on gas. The Clevo needs very fast ignition advance to quite high figures to put out any sort of power. Jason
From: the_dawggie on 29 Aug 2007 18:57
On Aug 29, 6:18 pm, motoxx...(a)hotmail.com wrote: > hi i have recently have had my toyota 4runner converted to lpg and > have loss significant amount of power and was wondering if this is > just normal for gas and if so what sort of engine mods work good with > lpg? any info on this wold be greatly appreciated thnks Get it set up for LPG only, not dual fuel. Better yet, install a diesel 3L or 5L engine and turbo it. |