Has anyone put a Twin Spark into a GTV

[Sam]

Hi, can anyone help?

I'm putting a TS into an Alfetta GTV and I need some help / advice

I'd like to know how people have approached the Fuel tank issue.

For a variety of reasons, I want to use the standard Alfetta 79 Fuel Tank
This has one opening to take the fuel gauge senderand tube.

I believe the Injected cars have 2 pumps. A small 'initial take up pump' in the tank , and a larger one outside.

To make the Fuel Injection system work, I guess I also need to the  initial 'take up pump' in the tank.
This means I have to modify the crap out of the existing Alfetta GTV tank to take the extra pump. i.e. I need two holes, one for the sender and one for the pumpand fuel tube.
This represents significant mods to the tank.

Another option is to use a GTV6 Tank. sits in the boot area, is bigger and comes complete.
Problem is that my Battery sits in the boot also.  I think it wouldn't be safe to keep the fuel tank and battery so close together

I there anything else can do? Is the initial pump really required?

Suggestions, ideas, thoughts welcome

Thanks
Sam

[Colin Byrne]

what is your concern about putting the fuel tank near the battary? as long as the terminals are insulated i don't see why this would be any more dangerous than the 12v fuel pump inside the tank!
i rekon your better off just modifiying the exisitng tank, if you can find an old 75 tank you could just cut the fittings out and weld them into the alfetta tank, its not a massive job, just make sure you have all the petroll vapour out of the tanks before you do any cutting or welding!

[Scott Farquharson]

Not sure if you have welded a fuel tank before - to get rid of the fuel vapour run your exhaust through a tube into the tank for about half an hour.

[Jekyll and Hyde]

Why not use a surge tank? 

I currently run efi with Quad throttles on a single external pump (VL commodore/GTV6 type (Bosch 070, essentially the same as a VL pump, but $50 cheaper  )) sucking out of the carby tank with nil mods, and it works fine so far, but I'm planning to fit a surge tank anyway as its heading for the track.  Then feed the surge tank with a low pressure pump (which supposedly don't really mind sucking air for short periods of time).

I do however have a Range Rover thats been running the same type of pump (secondhand, mind you!) sucking out of a carby tank for 2 years as a daily driver and weekend 4wding toy, and haven't had a drama so far - no tank mods or lift pump.

[Sam]

Hi everyone and thanks for your responses

Maybe I'm putting too much thought  into  this and I'm making a mountain out of  a mole hill.

Your  opinions  are much appreciated.

I'm  worried about putting the fuel tank near the battery from a safety perspective -  in  the case of an accident.
If the battery and  tank are  damaged in an accident, say the tanks leaks ...  Due to their close proximity I'm worried about arcing from the battery terminals
It feel a little unsafe about putting them both in there – but maybe I'm just being paranoid ?

As far as modifying the GTV tank – I originally had that intention.
I have already cut the fuel  sender mounting plate from the TS tank. I wanted to weld it into the GTVtank.

On the 75 the Sender is mounted from the top of the tank. Its is a plastic tube which travels the whole height of the tank i.e. from top to just below the bottom.

The 75 tanks is shallower but wider and longer than the GTV one.   So in the GTV tank I wont reach enough to the bottom. The result would be that the fuel gauge on the GTV would show empty when there is still a lot of fuel in the tank.

I though about using the original GTV sender, for this I would still need to weld the 75 mounting hole into the GTV tank. It would probably work, except that I can't see anywhere decent to put this in the tank.

The exhaust runs along one side – can't fit it there as the wires would probably melt.
The left rear wheel sits close to the other side. I guess this is an option, but stones, mud etc may be a problem (?)
The shape of the tank at the rear doesn't allow it at all.
And the front already has the fuel take-up hole which occupies most of the space. 
I think maybe the top of the tank may be a goer, but I need to lower the whole tank a little for ensure I have clearance from the boot floor.

Does anyone know if there is a fuel take up unit with a fuel gauge sender built in ? i.e.  an all in one unit?
I know these cars have Fuel Injection in the USA, anyone know what their fuel tanks looked like?

TurboGTV,
The 75TS tank also has baffle plates inside to act as a kind of surge tank.
I thought I needed to do this mod for my Standard GTV tank too, but If I understand correctly, you haven't done any mods at all?? And you have no problems .... hmmmm maybe I'm being a little over the top then.
Do you have any issues if the tank runs low? Does it still work ok? Do you throw the car around corners much?
I was told, just the slightest air in the line and the EFI shuts the system down.
Do the Commodors have an initial take up pump in the tank?

Once again thank for everyones help

Sam

[AR116]

To sam,
I have currently built an 1984 giulietta 2.0l that runs quad throttlies bodies and a wasted spark system. My fuel system comparise of a bosch 070 external pump, a lift pump and a custom made 2litre surge tank and return fuel lines. I only had to tap into the original fuel tank once as that was only for the surge tank overflow. My sender unit is of course the original giulietta one that still works fine.

If you run a surge tank you will only need one outlet from the tank to fill the surge tank via the low pressure pump and another inlet back into the fuel tank for the surge tank overflow.
Then one or two outlets from the surge to supply fuel to injectors via the high pressure pump. The outlet also depend on how much power your after as sometime you need to run 2 pumps when making 500hp. In your case 1 outlet would be enough.
Also surge tanks prevents any starvation especially when thrown around corners at high speed. Overall it keeps the injectors at a constant fuel pressure. The amount of fuel should never be keep extremely low as it will more than likely damage your fuel pump and maybe block your injectors. Keep it at a constant lever and you should be fine.

As for modifying the original tank, just buy the fittings required (brass) from pirtek and weld them in by means of braze welding (using specially rods). To get remove the petrol vapour rinse the fuel tank in water and then go ahead with the welding. then rerinse the tank in methylated spirits.

[Jekyll and Hyde]

The 75TS tank also has baffle plates inside to act as a kind of surge tank.
I thought I needed to do this mod for my Standard GTV tank too, but If I understand correctly, you haven't done any mods at all?? And you have no problems .... hmmmm maybe I'm being a little over the top then.
Do you have any issues if the tank runs low? Does it still work ok? Do you throw the car around corners much?
I was told, just the slightest air in the line and the EFI shuts the system down.
Do the Commodors have an initial take up pump in the tank?

Once the tank gets below half in my '81 I take it a bit easy (by my standards!) just due to paranoia, but it hasn't given me any troubles yet.  Like I say, I intend to fit a surge tank for track duties, but for road use it should be fine - I tend to reckon running the tank too far below half is a bit dodgy anyway, as you start to pick up more nastys floating around in there.  My range rover suffers from extreme bodyroll however, as well as pretty serious angles when offroad, and hasn't missed a beat in the 2 years I've been running the secondhand Bosch 070 with an unbaffled tank and no surge tanks or lift pumps.  If it dies, I'll probably fit a surge tank to that too, but not until then.

I wouldn't screw around too much with welding the tank, when you can pick up a surge tank for around $100, and then grab a low pressure electric pump to feed it (any carby cars electric pump should be sufficient, really).  One thing to note though - I've used the standard carby pickup and sender in mine, feeding the Bosch 070 directly, which gives you your outlet - the problem is the return.  Not sure if your GTV has the charcoal canister behind the rear seat on the parcel shelf, but mine does, and originally I just T-ed my return line into the vent line off the filler neck.  This worked fine, except for the fact that it filled up the whole vapour system, and I had fuel pouring out at the engine bay!  The solution was to plumb the return into the existing fitting on the filler neck, and then drill + tap a new hole about 3-4 inches further up the filler neck to plumb the vapour line to (you can actually see the fitting when you take the filler cap off!)

Incidentally, given your concern about putting a fuel tank in the boot:
a) GTV6s still have a boot mount battery with their boot mount fuel tanks, not only that but the battery is mounted at a lower level than the tank, so if it leaked the battery would float!
b) If your GTV does have the vapour canister on the parcel shelf, you already have a fairly crappy looking 25 year old bit of fuel hose running within a foot of your battery, and even if you don't, the filler neck runs a couple of inches away from it....

Personally I don't get why so many people are really scared of having their battery and fuel tank in the same place - to be as simple about it as I can, read the top of your battery.  If its a standard lead acid battery, it will have a warning to the effect that charging batteries emit hydrogen gas, and to keep them away from sparks and naked flames.  This should quell any concerns about putting a fuel tank in the same place - after all, if the battery itself releases flammable gases and vapours, then it would be a little ridiculous to fit them in close proximity to people if they are going to arc out and blow themselves up, wouldn't it?

Obviously if the battery comes out of its clamp, and the positive terminal strikes unpainted bodywork or metal that is connected in some way to the negative terminal, then yes you will get spark.  Note that your battery label will also warn against short circuiting - spark may    equal exploding hydrogen.  In my opinion, if it worries you, install a STRONG battery clamp, fit insulated terminals to your leads onto the battery, and forget about it.  If really worried, get a fully sealed AGM (absorbed glass mat) battery or similar, one of the ones you can mount upside down, as well as doing previous things (I did this because mine was sloshing acid out the vents everywhere).

As far as air getting in your fuel line - it won't shut your EFI down.  What will happen is your fuel pump will suck air, thus the fuel supply will drop until the pump picks up fuel again.  This then means your injectors aren't injecting as much as they are supposed to (the ecu is calibrated to open injectors for X milliseconds at conditions Y (rpm etc), which at a given pressure will let a certain amount of fuel through.  Lower pressure means less fuel comes through).  So if you were to have the pickup feeding air for one second, then you would get about 1 seconds worth of lower fuel supply (a lean condition).  This can cause detonation, which can be a problem under load.  Of more concern however is that the fuel pump may die when asked to pump air (possibly due to overspeeding?).  Also of concern, is now that the pump is filled with fuel vapour rather than liquid (the liquid part of petrol is not flammable, and actually cools the pump down), sparking from the armatures inside it may conceivably cause an explosion, turning your fuel pump into a grenade.  Very rare, but it can happen.  Only with roller cell type pumps, I'm fairly sure, and even then I believe they may have designed a safety feature into the newer ones anyway.  The facet style pumps generally used as a lift pump don't have this issue to the best of my knowledge, and will simply die if pumping air for long periods of time.

VL commodores do have a lift pump, GTV6s don't as far as I know, the pump simply takes fuel from the lowest point on the tank, via a large banjo fitting.

[Sam]

Hi everyone

Thanks for your help with this. It's much appreciated.

I'll mull over your advice , take it all in  and make sure I understand it before continuing.
I'll let you know how I go

P.S.
Angelo
You mentioned that you have a wasted spark system. Is that a Multi Spark Distributor or something similar?  Are there any threads in this forum talking about these?
Sam

[AR116]

hey sam,
wasted spark system basically means that each cylinder has its own coil. There are a couple of ways to do this setup with the old alfa twin cam engine. Since you have a twinspark engine you can eliminate both distributors and retain the chopper disc at the front with the factory crank angle sensor. You then have to purchase 8 individual coils or you may run a factory coil pack from another vehicle, for example ford v8 or something similiar.
Overall this will only work if you run an aftermarket engine management unit, ( Microtech being my personal choice).

[Colin Byrne]

Wasted spark is the term for an ignition system that doesn't know which cycle the engine is on, so it sparks both on the compression stroke and the exhaust stroke.  Running a wasted spark system means you only need a trigger wheel on the crank but then that trigger wheel needs to have some kind of missing tooth to provide the system with a position.  To run a non wasted spark system there needs to be a trigger on something that is running at half crank shaft speed, eg distributor or cam.

[Jekyll and Hyde]

wasted spark system basically means that each cylinder has its own coil. There are a couple of ways to do this setup with the old alfa twin cam engine. Since you have a twinspark engine you can eliminate both distributors and retain the chopper disc at the front with the factory crank angle sensor. You then have to purchase 8 individual coils or you may run a factory coil pack from another vehicle, for example ford v8 or something similiar.

Actually, in strict definition that would be Coil-on-plug, if you require a coil pack for each spark plug.  Wasted spark, as Colin said, fires two cylinders at once, which are as distant from each as can be in the firing order.  This reduces the number of coilpacks to half your spark plug count, using twin post coilpacks. 

To give an example, a Rover V8s firing order is 1-8-4-3-6-5-7-2, and the wasted spark pairs are 1+6, 8+5, 4+7, 3+2 (note that each of those pairs are as far apart in the order as is possible).  This means that each cylinder now fires a spark once EVERY engine revolution, instead of every second.  First it fires on the compression stroke, just before the piston reaches top dead centre, which ignites the mixture and helps the piston down on its power stroke.  However, because the two posts on the coil pack are linked, it also fires on the other cylinder it is connected to - which will be just reaching TDC on the exhaust stroke.  Obviously this spark doesn't do much, other than possibly burn off any remaining unburnt particles left from the combustion process (or make flames in your exhaust if you are way too rich!), hence the 'wasted' part.

The advantage to coilpacks in general is much more precise timing than from a distributor, along with the ability to dynamically modify timing according to other engine data (O2 readings, temperatures etc).  The extra advantages gained from wasted spark setup are that you have half as many coils, therefore a reduced cost (bonus to both the manufacturer and the keen modifier, especially since V6 VN commodores use wasted spark, providing a good source of cheap coilpacks).  I'd also speculate that it could possibly reduce emissions of hydrocarbons from unburnt fuels etc, but that is simply my musings and not fact (that I know of!).