LPG on a turbo engine..

[Lankytim]

I'm hoping to get one of my Volvo 940s converted to LPG to make running it a little less painful. Ive been offered a crashed 740 with an injected engine and a pretty new singlepoint LPG system on it and I'm looking into stripping the LPG system out and transferring it across.

I understand that ill need extra bits to get it to fit my turbo'd engine but I'm not sure what. Has anyone got any ideas on what ill need and how much its likely to cost? If its a fair wedge of cash I may just go out and buy a multipoint turbo system outright.

Any advice much appreciated!

[ben711200]

I don't really know, but I'd hazard a guess at a bigger mixer being the first port of call. I'll be watching this thread just incase I get carried away with the 240...

[lolface]

I've read that turbo engines need multipoint injection ie just before the valves like you mentioned, not sure why though

[arrocuda]

You can do a singlepoint turbo conversion but you need a special vapouriser. I have one here for my arrocuda project it is a Landi Renzo SE 81 SIC. You can google it.... I think there is a page in english for it that explains what it's all about and why it's different to standard models. IIRC it can provide enough LPG to produce 200 horses which should be adequate for your engine even at increased boost levels. As far as mixers are concerned the agents for BLOS claim that they are unable to advise as to whether it's suitable for turbo engines or not cos they've never done one. .... but you could always use the Landi recommended device which might be the best alternative if you can get hold of an SE 81.

With turbo installations a flame trap is essential..... especially if your engine has a plastic manifold as a lot of moderns seem to have these days. When the turbo is boosting there is always a lot of explosive fuel mixture in the manifold just waiting for a backfire to ignite it and blow yer hat off bigtime so extra safety precautions are needed that are not the case with multipoint.

[ben711200]

www.go-lpg.co.uk/Turbo.html

Go-LPG agrees. Multipoint is the only way. Something about it causing a right bloody mess if it backfires up through the inlet

[arrocuda]

Don't forget that all these specialist LPG companies are out to sell you a lot of expensive electronic gismology not just a relatively cheap vapouriser!!

[hotrodjon]

Plastic manifolds with LPG are prone to problems from backfires without a turbo. I think multipoint is the way to go, I have had several LPG converted cars and multipoint systems are far more efficient as on single point systems precision tuning can be a bit hit and miss !!!

[ben711200]

Dec 14, 2009 18:13:50 GMT arrocuda said:

Don't forget that all these specialist LPG companies are out to sell you a lot of expensive electronic gismology not just a relatively cheap vapouriser!!

absolutely, that's why a BLOS rather than a sequential injection system is at the top of my wish list

[Lankytim]

The Volvo has an ally manifold so no plastic to blow to bits. Can you just add an multipoint fuel thingy onto a single point or is the whole system different?

[arrocuda]

Dec 14, 2009 19:03:17 GMT Lankytim said:

The Volvo has an ally manifold so no plastic to blow to bits. Can you just add an multipoint fuel thingy onto a single point or is the whole system different?

Multipint is a sequential device that opens a valve and allows the gas to flow to each cylinder seperately so is only ever a small amount of gas in the manifold if a back fire occurs. Is very similar to petrol injection in how it works. With LPG though it's not directly injected into the cylinder.


Anyways... answer is... no you can't.

[Lankytim]

Ah, ok, so its different tank, pipework and everything?

[arrocuda]

Tank is same and also has a vapouriser....... it's just the way the gas is delivered to the engine that's different. Uses electronics to open and close the solenoid valves that allow the gas to enter the manifold.... and has one for each cylinder. Like I said .... is a very similar system to EFI.

[Lankytim]

Soooo, a single point system can be adapted to fit a multipoint application. Simply remove the single point stuff and add multipoint stuff...?

I don't want to take any chances with using a single point system. I really don't fancy a load of turbo trunking full of compressed air/lpg just waiting for the right time to go bang!

[arrocuda]

Dec 14, 2009 19:54:01 GMT Lankytim said:

Soooo, a single point system can be adapted to fit a multipoint application. Simply remove the single point stuff and add multipoint stuff...?

In theory yep! You might just need to check that the vapouriser is compatible cos I've never done a multipoint conversion so not sure on that.

[10mpg]

I used a single point system on my Saab 900 T16 aero worked fine but tended to lean out a bit on big boost worked fine on standard boost, though didn't really give the economy i wanted...

Worked great with an ignition advancer though defiantly a must have.....

[LowStandards]

I'd def get a computer controlled system so you can 'map' it slightly...


On another note, lpg for turbo'd engines should work great, even a poor quality lpg has at least 110 octane so you should (in theory) be able to bump up the boost

[Lankytim]

Ive just worried about backfired blowing pipework to bits and the mixture leaning out too much and melting pistons. Its a tinleytech kit anyway, they seem bob-on regarding advice and that.

[arrocuda]

Dec 15, 2009 10:48:55 GMT Lankytim said:

Ive just worried about backfired blowing pipework to bits and the mixture leaning out too much and melting pistons. Its a tinleytech kit anyway, they seem bob-on regarding advice and that.

Spend yer money on a multipoint then!!

[UtterPiffle]

Dec 14, 2009 19:54:01 GMT Lankytim said:

Soooo, a single point system can be adapted to fit a multipoint application. Simply remove the single point stuff and add multipoint stuff...?

I don't want to take any chances with using a single point system. I really don't fancy a load of turbo trunking full of compressed air/lpg just waiting for the right time to go bang!

If the car is single point, and the cars CPU is managing single point, then surely a multipoint system is a whole world of complication?

All the multipoint LPG systems I've seen use a piggyback CPU to emulate the multipoint petrol injectors. On a single point car, I don't see how you will get that emulation unless you go to the trouble of custom management such as megasquirt or suchlike.

This is where my interest takes off with LPG and forced induction as you could then have two different maps to run on petrol, then to utilize the extra octane of LPG with the FI. Calorific value is less with LPG (i.e. it doesn't pack as much punch as it combusts), but the higher octane (which seems to vary between 112 and 130 depending on what you read) means that you can squish more fuel into the cylinder on each cycle (i.e more boost). However, that is probably going off on a tangent...

But back on subject, single point LPG doesn't work too well - that's why for example, the 80's Mercs are never a good to LPG. It's k-jet mechanical injection, but same principle; large inlet chamber filled with lovely LPG backfired and blew the top off my fuel distributor. Expensive mistake. Always fitted a blowback valve/paddle after that, but it would still backfire occasionally.

[arrocuda]

Dec 15, 2009 12:48:31 GMT UtterPiffle said:

If the car is single point, and the cars CPU is managing single point, then surely a multipoint system is a whole world of complication?

All the multipoint LPG systems I've seen use a piggyback CPU to emulate the multipoint petrol injectors. On a single point car, I don't see how you will get that emulation unless you go to the trouble of custom management such as megasquirt or suchlike.

This is where my interest takes off with LPG and forced induction as you could then have two different maps to run on petrol, then to utilize the extra octane of LPG with the FI. Calorific value is less with LPG (i.e. it doesn't pack as much punch as it combusts), but the higher octane (which seems to vary between 112 and 130 depending on what you read) means that you can squish more fuel into the cylinder on each cycle (i.e more boost). However, that is probably going off on a tangent...

But back on subject, single point LPG doesn't work too well - that's why for example, the 80's Mercs are never a good to LPG. It's k-jet mechanical injection, but same principle; large inlet chamber filled with lovely LPG backfired and blew the top off my fuel distributor. Expensive mistake. Always fitted a blowback valve/paddle after that, but it would still backfire occasionally.

That's where the thread started from Utter!! ;D but agree with everything your saying about getting the most from LPG as a higher octane fuel and why turbo engines are better suited to burning LPG cos of the increased compression ratio as the boost level increases.