Interesting reading:

http://www.go-lpg.co.uk/VSR.html Stolen / Gone: 2006MY Supercharged LPG Autobiography - Zambezi Silver with Sand/Jet/Jet Oxford Leather.....

Yes... But just one installers view! Speak to the boss at JE Engineering and he will tell you that VSR will occur in a Jag V8!!! Each one of these people have there own opinion/beliefs...

The thing is Craig lots of anecdotal stuff re VSR but not one concrete case of

"aye thats what happened to me" on this forum yet. or anywhere else tbh.

lets hope it aint me in a few years time

btw my installer reckons that the s/c engine is not on the list of engines that suffer from VSR

he would say that though eh

That's a rather well written article. Most of the facts are there as well which is refreshing. But it is only one person's view.

My only addition would be the octane issue which is missing from the article. If you're an old fart (like me) and remember the days when petrol came in 2*, 3*, 4* and 5* you will recall that 2* was 92 Octane, 3* was 95 Octane, 4* was 97 Octane and the premium 5* was 100 Octane.

There was a very real issue with using too good a fuel. Too much octane would slow the burn process down so that it hadn't actually finished when the exhaust valve started opening. This lead to burning of the exhaust valve seat; remember the seats weren't hardened then either. Unleaded petrol wasn't available back then.

Conversely, using too low a grade of fuel would lead to pinking (Pre-Ignition) and in extreme cases damaged pistons.

Anyway, LPG is roughly 101 Octane and the point (as it was explained to me) is that 101 octane fuel in an engine designed and mapped for 95 octane has also been seen as a contributing factor to exhaust valve seat recession through burning.

As for having it happen to me, well I've run many a motor on LPG, from a 3.0 Vauxhall Carlton, a 4.0 V8 Jaguar XJ, 2 Isuzu Trooper 3.5 V6's, a Disco 2 V8 etc. Quite a few anyway. So, the only 2 negative experiences I had were with the Jag and one of the Troopers.

The Jag burnt out 2 exhaust valves but was well over 100k when it happened. It was also one of the notorious V8's with teflon cylinder liners so was the damage caused by the LPG? You decide. I'm not convinced it was.

The Trooper was the wrong system really, a vapour induction Tartarini thing on an engine with lambda control. Anyway, the lambda sensors were burnt out twice (not cheap) and finally the right hand head gasket. Again, I'm fairly sure the lambdas were down to the LPG but the head gasket could have been anything.

Valve seat recession though? Only the Jag and very questionable that it had anything to do with the LPG. Incidentally, the Carlton did over 400K miles on LPG with nowt but regular servicing.

Cam-Tech-Craig wrote:

Yes... But just one installers view! Speak to the boss at JE Engineering and he will tell you that VSR will occur in a Jag V8!!! Each one of these people have there own opinion/beliefs...

Yeah, but the boss at JE Engineering probably makes money from selling his 'special heads'

I researched it well before I did it, sure there are horror stories but I also know of a few SC's that have done well over 100k on LPG without any flashlube system.

If I remember correctly CTC, your SC had the original LPG system removed and another one fitted as it was a bad install (previous owners own words) and he had lots of problems with EML light on and it not being able to cope with the power of the SC, so it probably had damage done to the heads on the first conversion.......

Everyone is going to have and is entitled to have their own opinion - I'm only expressing my own experience to date with mine.

Granted, if I'm going to be giving the SC a good hard thrashing, or some overtaking with the caravan hitched up then I'll knock it back to petrol for a short time but for normal cruising / driving then it's LPG. The LPG system is rated for the BHP but at WOT the lambda goes open loop and is then relying on replication of the ECU map whereas at all other load sites my LPG ECU is constantly adjusting according to the OBD2 connection from the lambda sensors. Stolen / Gone: 2006MY Supercharged LPG Autobiography - Zambezi Silver with Sand/Jet/Jet Oxford Leather.....

Really interesting reading and I agree with mzplcg. I would add the following, we all know the LPG burns hotter through the system including exhaust gases. You can improve the burn by upgrading the spark plugs, this in turn reduces the risk of damage to the exhaust valve seats and incidentally improves the efficiency of the burn ie when the valves are closed. Fitting brisk silver spark plugs. The plugs are actually race car rated to be more efficient when using high octane fuels. The only issue is they are only good for about 18 K miles. All things considered It,s a lot cheaper to fit a set of plugs than refurb your cylinder head.