LPG Dual Fuel Leaded Query?

[Hilux Max]

Guys,

Need to pick your brains abit.....

the 84 lux Im getting runs dual fuel ....twin LPG tanks fitted.

A couple questions that I need assistance with.....

What fuel can I use when the 84 lux 2 litre petrol engine is running on petrol since they dont make Super/Leaded fuel anymore? Whats the substitute for that now?

Is it worth converting the engine to straight gas?
Will it go better on straight gas and/or cause engine any harm?

Am I better off removing the lpg system and running straight petrol and maybe just fit a weber carb for better performance?

Appreciate your replies....I dont have a clue in regards to LPG or leaded vehicles...this will be the first second hand vehicle I have ever owned....

thanks...

[Gulfstream8]

Hello mmaaxx

Now I have to remember!! The 2.0lt Hilux engine has a compression ratio of 9.3:1 and is carburetted so I would recommend staying away from ethanol fuel, Plus you will need a fuel with an octane number higher than 95. BP Ultimate is 98 octane and unlike Shell V-power does not contain ethanol.

As far as I can remember the 84 2lt does not have stellite valve seats or bronze valve guides so if the previous owner has used GAS there is a good chance the head is worn anyway.

Most good engine shops can install Bronze valve guides and stellite valve seats with harden valves to overcome this problem but you may as well just keep using the vehicle until compression drops and get the work done then.

The Hilux will not go harder on gas as gas does not have the energy or the same BTUs as Petrol but you can increase the compression ratio and purchase a GAS dedicated cam shaft that can take advantage of LP`s higher octane and different burn characteristics.

[Hilux Max]

Thanks mate, so your basically recommending I either drive it on gas till she stuffs up or I get rid of the gas and run BP Ultimate.

[Gulfstream8]

Hello mmaxx

Sorry mate I forgot to add that there is no “Upper Cylinder” lubricant in any petrol fuel that you can buy today. The higher octane will protect your engine from detonation only.

So I’m suggesting that you may as well use it on GAS but when driving on petrol use the higher octane. That way you will not damage the engine through detonation.

Yes you will have to do the valves when your compression becomes too low.

Outright horsepower you will make more power with petrol.

[Hilux Max]

sounds to me like your saying Im buggered if I do and buggered if I dont and at some stage Ill be up for a new engine anyways.....

better start looking for cheap 3RZ's....

[tasibrett]

As far as I can remember the 84 2lt does not have stellite valve seats or bronze valve guides so if the previous owner has used GAS there is a good chance the head is worn anyway.

I thought it would have a 3Y which has the alloy head which has the hard valves and seats and is ok on unleaded and gas.Should do over 400k if its had good water in it.

[Hilux Max]

Tasibrett,

It has the 3Y and I think you may be onto something.....I found a bloke on 4x4 action that rebuilt his 4Y engine and put it on straight gas and comps it....I asked for more info and he came back to me with the following....

fistly most jap vehicles from this era had ok valve seats for LPG. i am rebuilding my 4y now and have just put it on straight lpg

i can tune it up to run better on lpg than with the asain carby but it wont match the webber though..but for what i need it will be more reliable due to angles ect ( racing)


the 4y block and heads are same just different stroke 3y is 86x86mm and 4y is 86 x 91mm from memory

straight gas can be tuned up to give excellent reliability and performance, much better that the performance on lpg when set for dual fuel...(all due to octane ratings, i can explain more if needed)


now with myset up....i had a 32/36 webber rebuilt and jetted to the max...it was again doe to race not for the street and therefore the fuel eccomony was horrible

all that i did was fit the jetted webber, extractors with a fairly open 2 1/4" pipe and tuned it all up

the webber is a fickle SOB... it breathes through the shaft so tries to suck crap in through the butterfly seals, linkages always jam ( i fixed it by greasing all the links heavily) and they are tempremental they floody and starve at times...

whilst it gives a heap of performance the reliability and ability to say climb vertically are reduced....

in my opinion,
if the vehicle will tour around straight LPG may not be ideal
straight LPG will be the most reliable fuel off road
fit the hei ( built in coil) distributor from the 3y in tarago
dont do the webber!!

and with straight gas it al;l depends on how the system is designed for fitment and how its tuned

which has given me more confidence....I think Im gonna look into getting it setup for straight gas, its got twin tanks and it will be primarily used around town so should be fine...and looks like the valves will take it....if need be cant you fit a drip system lube into the intake manifolds?

Its got a sport exhaust so Ill get it tuned up properly for straight lpg and see what happens.

always open to other opinions and suggestions.

[Hilux Max]

got another reply to add to the previous one -

any elec dissy gives a stronger ( high energy) spark to the plug and more is better especially with lpg
..and no points to wear out
id say it will have an asain carb on it ( with vac secondary) and yes its way more reliable..best solution is to hut for an asain with mech secondary's ..more fuel delivery and more power

as for lpg.. you can leave all the fuel stuff in if you want and not use it, just leave all as is and just get the timing advanced for lpg ( it wont run on petrol then it will just ping) the best option for straight gas is to change the system for an impco negative pressure system, it is a different convertor and mixer..bit of goofying around but better performance..

not sure how worth it it is, as it can be costly to get those bits set up... stick with the origional set up for now, throw it on a dyno for 1/2hr and get the timing set correctly fot lpg only..whilst im using impco in mine for racing, i have all the bits laying around

also as soon as thats done stick a timing light on the car and see what its set at..then if you need petrol, swing the timing down a tad and use it and then youy know where to set tit back to with out a dyno

I think Im gonna go that route...get an electric dizzy, wack it on and get the thing tuned for straight gas....

[tasibrett]

If its a good cov.( when I've been asked to put on two tanks they have always wanted the best) it will have a little black box fitted into the ign wires that changes the timing when you switch fuels.
I would check were its timed before I did anything.
We also fitted a ignition amplifier that stops the points burning out, but you still got to put a bit of grease on the lobe, it may have one fitted as well so have a good look . They are easy and cheap to make from a kit

Hope your new toy arrives tomorrow

[D4D Hilux]

if its running gas it would have to have either the hardened valve seats or the drip lube system you are talking about, other wise your head would be cactus in no time, id definitely tune for straight gas, but id retain the option of running petrol to some degree.... even if it runs like shit on petrol and goes great on gas it is a good back-up plan if ever you run out of gas in the bush or even on the side of the road...... bit hard to go get a "jerry" of gas (read: not possible).

Hope this helps a bit mate

[Twiddles0]

mmaaxx

I'll keep it short and sweet, havng owned a dual fuel 4x4.
Regardless of running it on gas or fuel, get yourself a flash lube kit. It'll cost you less that $50.00 and the lubricant drip feeds into the inlet manifold. A bottle lubricant will cost about $20.00 and will last about 10,000kms. The kit will keep and valves and valve seats lubricated and largely avoid wear from lack of lubrication.
With the fuel, if you use a high octane fuel i.e. 95 or greater, the fuel won't gel over time and stuff your fuel pump. Ideally you would want the engine to start on fuel everytime and then change over to gas at say 1800revs, this will keep the fuel fresh in the fuel pump.

Hope this helps

[hodgo81]

Maxxx, I had duel fuel on my old 89 nav. and it ran a lot better on LPG than fuel. It had the duel fuel dealer fitted in 1989, with no flashlube kit until I bought it and added it. So that was 15years of duel fuel use with no upper lube kit.

Unfortunately it had a run of dodgy owners before me and the engine was in pretty ordinary condition It had a blown head gasket for a few years I think, when I finally did the head gasket I found the nuber 4 piston and valves pitted and corroded...so I bolted it back together with a new head gasket and left it as is hahaha.

One other thing is I can REALLY REALLY REALLY Strongly reccomend an electronic Dizzy. I douldn't find a bolt on one for my navara, I was replacing points every 6mths on it.

But on a hot mini clubman I used to have I put an elec dizzy on it and I recon that added more power than the cam and exhaust. A really worth while mod.

[Hilux Max]

Thanks for your advice guys....still not 100% sure whether Im gonna keep the lpg on it or not.....not in a rush either way.

Yes, Im lucky the previous owner had fitted an electronic dizzy......

If its gonna end up as my daily, then Im probably better off keeping the dual fuel.

[hodgo81]

I reckon you are better off doing dedicated LPG. It will run better and be more reliable.

The only reason to keep petrol system is if you are worried about range or LPG availability

[Hilux Max]

Just read the pdf download for the LPG grant and it says that when you submit the form you have to provide proof of purchase of the vehicle, menaing you have to submit rego papers in your name.

I cant do that since the vehicle wasnt purchased, it was a "gift" , and is currently unregistered.

meaning it would be a big hassle trying to get the grant if tyou cant supply the relevant documentation.

ripping the system out is looking alot more attractive again

[jap]

Keep in mind that 95+ fuels lose their juju after about 2 weeks of storage.
Might as well run base unleaded as the aromatics in the fuels boil off.

Use the busiest service stations you can find.

[hodgo81]

Maxx, isnt the LPG already installed? why do you need to get the grant if its already in? provided the plate in the engine bay is stamped less than 10 years ago you dont need to spend anything

[Hilux Max]

The lpg kit installed is complianced of another vehicle of the same spec.....its a dodgy backyard swap over. Done bout 15 years ago or so. Thats why I can still get the grant but I dont plan on registering the hilux until Ive serviced and fixed everything 100% which might not be anytime soon and you need to prove ownership to get the grant which I cant.....

I have an old registration certificate from my uncle (same surname) but thats it.

[2010Blulux]

Hi MMaaxx
I spent plenty of years working for a carby specialist and a leading LPG converter and have a few cents to lob in on this one.
On the carbies firstly the webber is a bloody good unit and suits the hilux really well as old mate had mentioned in the post you copied in here. I have used these in duel fuel applications many times before and fairly successful in even the crudest applications. One important thing to consider if using any carby in this situation is the type of float that is fitted. When a carbied engine on petrol backfires its generally happy days, you get a little bang maybe do a little damage to the air cleaner but nothing too major, however when running on LPG they can be a little more of an issue. The most painful of the more minor, problems caused by this is damage to your float (which are usually hollow copper/brass jobs) they'll squash up like a xxxx can, get a few holes in em and then tend to not want to float anymore. A manual choke version is also a better option in the duel fuel situation so you have the option of the butterfly staying fully open if a cold startup on LPG is required

The solution to this is either a hollow plastic float or the ones made from solid black stuff (had a few of those cans cant think of the name). This of course wont prevent backfiring obviously but will reduce the risk of one leaving you stranded.I think from memory most of the factory carbs are fitted with these solid black style floats.

Going straight gas will eliminate the need for this alltogether, however there are some downsides to this to consider aswell.
I notice your one of our southern cousins and mornings can be a little fresh don your way. Older style setups especially will sometimes struggle to start up easily on a cold morning as there is no heat in the converter to convert the LPG from a liquid into a nice atomized gas that engines like to burn. The easiest way to get a nice startup is to fire her up on petrol then switch over to LPG (leaving a few seconds for the bowl of your carby to drain in the middle) Also as someone mentioned earlier I think LPG burns best at a richer air fuel ratio so you do chew up a little more than you would with petrol. Having the reserve tank of Unleaded, or at least the option to take some on board can be a massive help when you cant get to a LPG pump for a little while
So theres my 29.5 cents worth.

Mick
Mick
p.s sorry about the super long post got a little carried away