Peter Hill wrote:

More to the point is that most vapourisers run out at 150-200Kw
(200-266bhp) and the V12 HE runs around 300bhp so he needs one per
bank or as you say an oversize one. Either way not cheap.

Having used OHG mixers and convertor/vapourisers for many years,
I'm surprised that the physically larger but smaller capacity
Italian units seem more popular...

I'd seriously suggest an OHG X450 mixer and X1 convertor
(vapouriser) for a V12 Jag. The X1 is far more compact than an
OMVL, and can be mounted in just about any orientation possible.

The only drawback is that you're not likely to find them cheap.

--
Athol
http://cust.idl.com.au/athol
Linux Registered User # 254000
I'm a Libran Engineer. I don't argue, I discuss.

On or around Wed, 7 Apr 2004 23:42:35 +0100, "Steve Shuttleworth"
enlightened us thusly:

I thought I might have problems with space, there really isn't much room
under there. The conclusion I came to was that I would re-site the washer
bottle in the boot if necessary.

How big is a vapouriser? The car kicks out over 300hp at the moment, so I
understand I will need something sizeable. Am I looking at something the
size of a brake servo, or bigger?

The OMVL 90 is about the size of a small brake servo. I guess it's about 9"
diameter by about 6" deep overall. You need room for pipes to get to the
front of it (2 water, one gas inlet, one gas outlet) The water ones have
connections which can swivel slightly to align 'em, there are 2 gas oulets,
top and bottom, of which you can use either. The gas inlet is a small
copper pipe.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Beyond the horizon of the place we lived when we were young / In a world
of magnets and miracles / Our thoughts strayed constantly and without
boundary / The ringing of the Division bell had begun. Pink Floyd (1994)

In message , athol
writes
Peter Hill wrote:

More to the point is that most vapourisers run out at 150-200Kw
(200-266bhp) and the V12 HE runs around 300bhp so he needs one per
bank or as you say an oversize one. Either way not cheap.

Having used OHG mixers and convertor/vapourisers for many years,
I'm surprised that the physically larger but smaller capacity
Italian units seem more popular...

I'd seriously suggest an OHG X450 mixer and X1 convertor
(vapouriser) for a V12 Jag. The X1 is far more compact than an
OMVL, and can be mounted in just about any orientation possible.

The only drawback is that you're not likely to find them cheap.

Are OHG still in business?? If so who's the UK supplier as I might need
a refurb kit soon? I have an X1 on my V8 LR (4.0L)
--
hugh
Reply to address is valid at the time of posting

First of all, please accept my sincere thanks for all your helpful comments
so far, the clouds are beginning to clear for me now an I have a few ideas
on how to proceed.

The picture forming in my head is of a vertical donut tank located where the
spare wheel should be (which is pretty much directly below the existing fuel
filler flap). However, there's also plenty of rom to fit a cylindrical tank
in the bottom of the boot.

Question - roughly how much extra is a donut tank to buy, and are there any
drawbacks with this type of tank?

The car doesn't have exhaust sensors so I'm looking at an open loop system
with either an OMVL 90 or a OHG X450 mixer and X1 convertor
(vapouriser)

Question - Where can I find prices and specifications for these

I have never really seen an LPG setup, but I assume that the vapouriser
senses either manifold pressure or throttle position to increase or reduce
the flow of vapour to the manifolds.

Question - How do you set this up for the right mixture

I have seen some pictures of gas mixer rings, which look like they fit
somewhere near the throttle butterflies.

Qustion - do they go on the manifold side of the butterfly or the air filter
side, and how thick are they likely to be for a 2 1/2" diameter butterfly ?


I know some of my questions may make me look a bit of a nugget, I probably
am, but I would appreciate any help you can offer

Most Grateful

Steve

Because there's more to the internet than hits alone, Steve
Shuttleworth wrote:

The picture forming in my head is of a vertical donut tank located where the
spare wheel should be (which is pretty much directly below the existing fuel
filler flap). However, there's also plenty of rom to fit a cylindrical tank
in the bottom of the boot.

Question - roughly how much extra is a donut tank to buy, and are there any
drawbacks with this type of tank?

A doughnut tank is a more expensive option (don't know any specific
prices), and you are limited in how big it can be. However, last I
heard, a vertical doughnut is the most expensive option of the lot.
Ludicrously so.

You have to get used to having the spare wheel as luggage, or leaving
it at home, which concerns some people.

The car doesn't have exhaust sensors so I'm looking at an open loop system
with either an OMVL 90 or a OHG X450 mixer and X1 convertor
(vapouriser)

Question - Where can I find prices and specifications for these

Yellow Pages; Exchange & Mart; Auto Trader; Google; people here. Phone
around. Traders wander in and out of this group, so you may get some
contacts from here.

I have never really seen an LPG setup,

I just found this page for you:

http://www.lpg-autoconversions.co.uk/gallery.htm

Also, hunt around for some articles from Jaguar enthusiasts. It's a
commercial site, but it may give you some ideas.

People keep wandering up to me as I'm leaning on the pump button at
filling stations and asking me about LPG. If two LPG cars are filling
up at the same time there is often a decent conversation about
conversions going on; sometimes bonnets get lifted as vaporisers are
compared. May be a good idea to hang around your local LPG filling
station for a while.

but I assume that the vapouriser
senses either manifold pressure or throttle position to increase or reduce
the flow of vapour to the manifolds.

Question - How do you set this up for the right mixture

The vaporiser is a demand valve that responds to inlet vacuum from the
mixer.

On an open loop system, things are pretty simple, and it is akin to
old fashioned carburettor tuning. On my setup there are two new things
to adjust. There is a screw that alters the pressure applied to the
diaphram in the vap; this effectively gives you a mixture control.
Simply adjust this to get the best idle; it is very sensitive; take
your time with it. If you have a CO meter, stick this up the exhaust
and adjust accordingly. You may need to fiddle with the car's existing
idle speed control, too, to get the final idle speed right.

The other adjustment is a flow control, and simply adds restriction to
the vapour pipe going to the mixer. The instructions with mine we
rev engine to half its maximum; turn down screw until it just starts
to affect idle speed; back off two turns. From there you can adjust
for economy by screwing it back in a little.

Your supplier should be able to give you the low-down on the specifics
of the kit you end up with.

I have seen some pictures of gas mixer rings, which look like they fit
somewhere near the throttle butterflies.

Qustion - do they go on the manifold side of the butterfly or the air filter
side, and how thick are they likely to be for a 2 1/2" diameter butterfly ?

They go air filter side. They need to go upstream of the throttle
valve so that the throttle controls the mixture flow just like in a
carburettor. It's a good idea to keep your mixer(s) as near to the
throttle valve as possible, so that you are filling as little of the
inlet tract as possible with mixture - backfires can and do happen -
it is reasonable to expect this particularly during the setting up
stage. The more explosive mixture, the bigger the bang. Make sure your
mixer has a blowback arrestor in it to help minimise possible damage.

Having said this, I have seen a conversion where the mixer was
attached to the airfilter outlet several feet away from the throttle
valve. The owner reported never having had a backfire. I think he was
lucky (backfiring on mine was eliminated completely when I renewed all
the HT components).

My mixer is of such a size that it fits directly onto the spiggot of
the throttle body. Dunno about 'thickness', but the venturi diameter
needed will be governed by the output of the engine.

--

Stewart Hargrave

Never wear a hat that has more character than you - Utah Philips


For email, replace 'SpamOnlyToHere' with my name

hugh ] wrote:

Are OHG still in business?? If so who's the UK supplier as I might need
a refurb kit soon? I have an X1 on my V8 LR (4.0L)

I don't know exactly what happened to OHG, but the last X-450 I saw
was actually branded M&M. I do know, however, that the X-1 has been
copied, and there are 3 other brands around. Nolffs Model H-420
and Elko in the US, and another brand I don't know the name of make
the "B-1" in Australia. The B-1 is distinctly different, having a
black plastic front cover without the mountings for the Gann prime
solenoid. There's a B-1 on ebay.com.au ATM if you want to look at
the photos...

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=2471821529&category=50 138

They are _so_ accurately copied that when I discovered that the
Nolffs H-420 front cover button was 1mm bigger in diameter than
the Impco and OHG ones and hence the Gann prime solenoid pushed
the button part way open when screwed onto the cover, I swapped
the front cover. I still have an OHG X-1 cover on a Nolffs H-420.

I believe that the reason why the convertor was widely copied is
because it is rated 325HP (with blue spring) / 350HP (with orange
spring), making it higher rated than the Impco E and L, which are
both bulkier and harder to install. It will happily replace any
of the Impcos by using a blue spring, or run the less restrictive
OHG mixer with an orange spring in the convertor. The OHG isn't
much harder to fit into tight spaces than the tiny Impco Model J!

AFAIK, the X-450 patent should either have run out or will soon
run out. I'm hoping that it will also be replicated, as the OHG
units are hard to get. I only have 2 myself, and I'm trying to
buy back a 3rd one (brand new, unused) from a friend. I also
want to buy a pair of brand new Corvette alloy heads, from him,
but that's another story. :-)

Given that I'm in Australia, I don't know about UK suppliers...

--
Athol
http://cust.idl.com.au/athol
Linux Registered User # 254000
I'm a Libran Engineer. I don't argue, I discuss.

"Steve Shuttleworth" wrote in
message news:RPkdc.13384$4N3.6219@newsfe1-win...
First of all, please accept my sincere thanks for all your helpful
comments
so far, the clouds are beginning to clear for me now an I have a few ideas
on how to proceed.

The picture forming in my head is of a vertical donut tank located where
the
spare wheel should be (which is pretty much directly below the existing
fuel
filler flap). However, there's also plenty of rom to fit a cylindrical
tank
in the bottom of the boot.

Question - roughly how much extra is a donut tank to buy, and are there
any
drawbacks with this type of tank?

The car doesn't have exhaust sensors so I'm looking at an open loop system
with either an OMVL 90 or a OHG X450 mixer and X1 convertor
(vapouriser)

Question - Where can I find prices and specifications for these

I have never really seen an LPG setup, but I assume that the vapouriser
senses either manifold pressure or throttle position to increase or reduce
the flow of vapour to the manifolds.

Question - How do you set this up for the right mixture

I have seen some pictures of gas mixer rings, which look like they fit
somewhere near the throttle butterflies.

Qustion - do they go on the manifold side of the butterfly or the air
filter
side, and how thick are they likely to be for a 2 1/2" diameter butterfly
?


I know some of my questions may make me look a bit of a nugget, I probably
am, but I would appreciate any help you can offer

Most Grateful

Steve

The vapouriser works in exactly the same sort of way as a demand valve on
SCUBA gear. If you suck it opens and lets gas flow.

If I were you I would fit a lambda sensor in the exhaust manifold and run it
closed loop. This is fairly simple. The lambda output feeds some electronics
that control the position of a stepper motor that is fixed in the pipe from
teh vapouriser to the mixer and if the exhaust says "weak" it opens more and
vice versa. The thing that makes it easy is that there is generally no
interaction between teh two parts. ie an open loop system can be made a
closed loop just by fitting extra parts and they don't affect the system
that is already installed.

On or around Fri, 9 Apr 2004 00:01:29 +0100, "Steve Shuttleworth"
enlightened us thusly:

Question - Where can I find prices and specifications for these

I have never really seen an LPG setup, but I assume that the vapouriser
senses either manifold pressure or throttle position to increase or reduce
the flow of vapour to the manifolds.

have a look at http://www.chrisperfect.com for some pictures of kits. He's
aiming at land rovers, but the big end of the land rover kits is much the
same as you'll want for an XJS. He supplies the OMVL vapourisers, and
various shapes and sizes of tank.

the latest one i saw up at his place is the squat cylinder thing, which is
like 2 ends of a very big cylinder tank welded together without the actual
cylinder. 's got it's own mountings built-in, and for Range Rovers etc.
it'll bolt in straight under the rear floor, 's also 10 litres bigger than
the twin tank I've got on my 110.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Plus ça change, plus c'est la même chose"
Alphonse Karr (1808 - 1890) Les Guêpes, Jan 1849

People keep wandering up to me as I'm leaning on the pump button at
filling stations and asking me about LPG. If two LPG cars are filling
up at the same time there is often a decent conversation about
conversions going on; sometimes bonnets get lifted as vaporisers are

I concur with that, usually chats about range of vehicle and where the
other pumps are in the area and of course, where the cheapest fuel is!



David.