Are factory BiFuels less grunty on Gas? Mine is by a lot...

CNGBiFuel · Jul 11th, 2013, 01:03

OK, I'll level, as my moniker I run CNG. Great as it is and me being long past the boy-racer stage it doesn't worry me too much, but my factory Bifuel has less grunt on gas as compared with petrol.

Yes I know, I've read the spec sheets and this is to be expected. A stock V70 runs to 140bhp (on petrol) and about 135bhp on CNG or LPG, but I'm running CNG, and I'm sure I'd not notice if I took a hit of 5bhp, but I see a marked difference. I'm sure it is more.

Forget the spec, in practice, do your LPG factory cars suffer the same hit? I understand an LPG or CNG powered car is theoretically more grunty, but needs 13:1 or 14:1 compression ratios and valve/ignition timings no petrol engine could ever run on. So any gas powered engine is hobbled by the compromise if it is also required to run petrol, which is why we see a hit. LPG is higher in octane and CNG higher still. Agreed the ECU shunts forward rteh ignition timing but can't do anything about the 14:1 CNG likes.

So, do your LPG factory cars suffer the same hit?

reggit · Jul 11th, 2013, 12:04

I can't tell the difference - performance wise - between running on petrol and LPG.

Pete_c20 · Jul 13th, 2013, 00:38

I have an S40 1.8 2002 Factory BiFuel. The car always has had a little more power on petrol than gas. Although 99.9% of my mileage is on LPG I see this on the odd occasion when I run out of petrol and don't notice, until I pull away from somewhere and its slightly smoother power delivery and a little extra power on petrol is noticeable.

On some of the conversion accounts I've read, especially if it was a conversion of something more unusual where they're working from scratch, they've mentioned that the power delivery was virtually the same and that they'd worked it to be so. So I'm not sure what the difference is down to without going into it.

However it has more torque at very low revs on LPG than it does petrol. But the 'I'm happy up to this point' red line comes earlier on LPG than it does petrol.

NI_Volvo_Nut · Jul 13th, 2013, 13:47

Mine has a slight misfire idling on gas, but doesn't drive any different to gas or petrol

CNGBiFuel · Jul 13th, 2013, 19:43

Mine runs slightly smoother on gas at all revs. It must purely be the extra hobbling CNG has to suffer when running Bifuel. LPG is nearer to the running characteritics of petrol than CNG (... I'm told).

I'll live. Thanks all.

Pete_c20 · Jul 14th, 2013, 12:37

In Vadis (mine's 2004 edition, and I can't view it properly as it doesn't install properly) there's a power/torque graph for the B5244SG2 engine which I believe is the V70 2.4 20v bifuel. It has a side by side comparison of Petrol & LPG. Search for n2000340.gif on the CD. There's not much between the two from that.

Some of the differences we see here could be down to individual setups and/or problems with the cars.

CNGBiFuel · Jul 19th, 2013, 08:57

Yes mine is the B5244SG 2.5, same engine as you fellas with LPG. I think the difference is more pronounced running CNG rather than LPG, but I'll not cry too much.

I've just answered my own question, see attached. The CNG takes a hit not in total grunt but in 'talks' see attached.
It needs higher compression than LPG so is furhter hobbled over LPG by the Bifuel requirement

The Thong · Jul 25th, 2013, 08:10

My S60 has more grunt on petrol than LPG. The engine does run smoother too. I have a BRC system on mine.

TT

CNGBiFuel · Aug 3rd, 2013, 11:37

Yes to be clear, if you look as I did just at peak power, there's littel or no real hit. It is lower down in torqs (sic) that we see the hit.

Jul 11th, 2013, 01:03	#1
CNGBiFuel Classic P80 1999 BiFuel Last Online: Mar 6th, 2024 00:34 Join Date: Aug 2012 Location: 48mph Middle Lane M4	Are factory BiFuels less grunty on Gas? Mine is by a lot... OK, I'll level, as my moniker I run CNG. Great as it is and me being long past the boy-racer stage it doesn't worry me too much, but my factory Bifuel has less grunt on gas as compared with petrol. Yes I know, I've read the spec sheets and this is to be expected. A stock V70 runs to 140bhp (on petrol) and about 135bhp on CNG or LPG, but I'm running CNG, and I'm sure I'd not notice if I took a hit of 5bhp, but I see a marked difference. I'm sure it is more. Forget the spec, in practice, do your LPG factory cars suffer the same hit? I understand an LPG or CNG powered car is theoretically more grunty, but needs 13:1 or 14:1 compression ratios and valve/ignition timings no petrol engine could ever run on. So any gas powered engine is hobbled by the compromise if it is also required to run petrol, which is why we see a hit. LPG is higher in octane and CNG higher still. Agreed the ECU shunts forward rteh ignition timing but can't do anything about the 14:1 CNG likes. So, do your LPG factory cars suffer the same hit? __________________ Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl*dy blah."] Last edited by CNGBiFuel; Jul 11th, 2013 at 01:14.*

Jul 11th, 2013, 12:04	#2
reggit Premier Member Last Online: Today 07:14 Join Date: Feb 2012 Location: Preston	I can't tell the difference - performance wise - between running on petrol and LPG. __________________ 2009 Volvo V70 D5 (Polestar 225bhp) r-design 180,000 miles

Jul 13th, 2013, 13:47	#4
NI_Volvo_Nut Volvologist Last Online: Dec 6th, 2023 11:13 Join Date: Aug 2008 Location: Bangor - Norn Iron View Photos By: NI_Volvo_Nut	Mine has a slight misfire idling on gas, but doesn't drive any different to gas or petrol __________________ What's the matter with the car I'm driving? Can't you tell that it's out of style? Should I get a set of white wall tires? Are you gonna cruise the miracle mile?

Jul 13th, 2013, 19:43	#5
CNGBiFuel Classic P80 1999 BiFuel Last Online: Mar 6th, 2024 00:34 Join Date: Aug 2012 Location: 48mph Middle Lane M4	Mine runs slightly smoother on gas at all revs. It must purely be the extra hobbling CNG has to suffer when running Bifuel. LPG is nearer to the running characteritics of petrol than CNG (... I'm told). I'll live. Thanks all. __________________ Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Jul 14th, 2013, 12:37	#6
Pete_c20 Junior Member Last Online: Oct 25th, 2014 17:39 Join Date: Jul 2010 Location: Manchester	Vadis BS5244SG2 Engine power / torque graphs for LPG In Vadis (mine's 2004 edition, and I can't view it properly as it doesn't install properly) there's a power/torque graph for the B5244SG2 engine which I believe is the V70 2.4 20v bifuel. It has a side by side comparison of Petrol & LPG. Search for n2000340.gif on the CD. There's not much between the two from that. Some of the differences we see here could be down to individual setups and/or problems with the cars.

Jul 13th, 2013, 00:38	#3
Pete_c20 Junior Member Last Online: Oct 25th, 2014 17:39 Join Date: Jul 2010 Location: Manchester	I have an S40 1.8 2002 Factory BiFuel. The car always has had a little more power on petrol than gas. Although 99.9% of my mileage is on LPG I see this on the odd occasion when I run out of petrol and don't notice, until I pull away from somewhere and its slightly smoother power delivery and a little extra power on petrol is noticeable. On some of the conversion accounts I've read, especially if it was a conversion of something more unusual where they're working from scratch, they've mentioned that the power delivery was virtually the same and that they'd worked it to be so. So I'm not sure what the difference is down to without going into it. However it has more torque at very low revs on LPG than it does petrol. But the 'I'm happy up to this point' red line comes earlier on LPG than it does petrol.

Jul 25th, 2013, 08:10	#8
The Thong VOC Member Last Online: Today 16:27 Join Date: Jun 2012 Location: The Independent Republic of Leamington Spa	My S60 has more grunt on petrol than LPG. The engine does run smoother too. I have a BRC system on mine. TT __________________ Never underestimate the power of stupid. It’ can’t be reasoned or negotiated with and you’ll never never beat it…. Cut your losses, smile and walk away Currently Volvoless but Thong will be back

Aug 3rd, 2013, 11:37	#9
CNGBiFuel Classic P80 1999 BiFuel Last Online: Mar 6th, 2024 00:34 Join Date: Aug 2012 Location: 48mph Middle Lane M4	Yes to be clear, if you look as I did just at peak power, there's littel or no real hit. It is lower down in torqs (sic) that we see the hit. __________________ Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

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