Right chaps got a little question for those Impreza experts on here.

Basically my car is being mapped tomorrow to run on 20% methanol.
My question is to do with fuel tank size.
My mapper said that my tank (STIV3) is 50 litres so we will need to put in 10 litres of meth and the brim with VPower.
I asked Tony on here what he thought and he told me that my tank size was not 50 litres it is infact 60 litres as only very early WRX and N/A cars got a 50 litre one. Ok I thought, I'll take 12 litres of methanol, pour it in and top up with VPower.

Tonight I decided I'd fill my tank from empty to see infact how much fuel it actually held. So I arrived at my nearest shell with as nearer empty tank as I dare (car actually cut out as I gave it the beans between the roundabout and the garage so I knew it was bloody low). Pulled up to the pump and started filling expecting the board to read pretty much 60 litres. But no, got to just over 36 litres and the pump stopped. Managed to squeeze a couple more litres in until I could actually see the fuel in the filler neck. "this can't be correct" I thought so let the fuel settle and had another go. But no joy, maximum I could get in the car was a shade over 38 litres.....

What is going on there chaps ?
Have I got a 40 litre tank ?
Did they even do a 40 litre tank ?

Really confused here as I know both Tony and my mapper are super clued up on Imprezas but both were wrong.
Please any advice or similar experiences would be very much appreciated.

Thank you as always,
Matt..


PS.. Mods, I know this should probably be in the technical section but knew more people would see it here and it's quite important to me.
Apologies...

 

its 100% either 50 or 60 litres, my 95 wrx tank is 50 litres

 

You can't do what you did and get an ACCURATE result. Unless you ran it dry, WHICH IS NOT ADVISABLE, it will still have fuel in. Mine has about 2 gallons in when the reserve light comes on, low fuel warning, whatever. That's about 10l.

The fact that it MIGHT have cut out due to being low on fuel, well, it would still have some, and these cars suffer from fuel surge on 1/4 tank, which is 2.5 gallons.

It's NOT a good idea to make it run out, OK?

 

Both my V2 classics are 50 litres, one WRX and one an STi I'd say yours was a 50

 

Agreed 50 litres.

 

My old car (sti 3) was defo 50 litres

 

I thought the 60 litre tank launched with the bugeye......

Shaun

 

I never ever run my car below quarter of a tank, but just needed to this time to get as close to accurate reading as possible.
The gauge was reading empty, I mean showing nothing. Would you think there would still be around 10 litres in the tank even when the gauge is that low ??

 

Oh,
And all the research I did using my Impreza books and articles all said 60 litres..
But after reading all the above posts I would imagine it being 50...

 

Double post, sorry...

Bloody phones...

 

Yes mate.

Trust me, the tank holds 50 litres, that's why you are told to add the meth first, so that when the fuel is added, the TOTAL will be 50 litres.

OK?

 

Re. the Classic, I thought all JDMs were 50L and other markets, inc. UKDM, are 60L(?).

My previous 93 WRX was defo 50L; as is my STi 5. Ergo, I'd bet my ISA savings! lol that your STi 3 is 50L.

On the occasions when I forget to fill up from c.1/4 tank left and let it get to "E", it usually takes about 46.5-48L to brim. As said above, there's always some left in the small reserve tank - you can't run it completely dry, as such.

If you're adamant the petrol pump read 38L (and not 48L?!), then you must have had an issue -- what it was, not sure. Airlock, perhaps?

 

lol why do people think fuel gauges are accurate, they aren't! Its just to give you an indication.

 

I don't.

But in the case of the OP, if his gauge is on E and he has c.10-12L left to go!, then something's clearly not right. As said, when the needle reads E, you normally have around 2.5L left in the tank (in my experience from brimming an Impreza 50L tank from an indicated 'E').

Unless, for whatever reason, he DOES have a 40L tank fitted!!!

 

It obviously wasn't that empty! Simples.

You can get fuel surge at just below half a tank if you push hard enough!

 

I completely agree that fuel gauges are far from accurate. But I can't get my head around that even though the gauge was reading zero it still had 12 litres in the tank.
Would my car cut out at full chat with 12 litres still in the tank ??

 

Agree with ScoobyDoo69.

Airlocks can happen - although not common. This is the only thing I can reasonably think of....

 

lol you clearly do. How do you know its 2.5ltrs?? from the empty on the gauge, unless you empty the tank completely and measure it?

OP has a 50L tank that is fact ok

 

https://www.scoobynet.com/scoobynet-...-question.html

Fuel surge / cutting out threads have cropped up from time to time over the 10 years I've been on SN LOL

Shaun

 

Guys,
Thank you for all of your input.
I'm going to except what you all say and go with a 50 litre tank. I shall put 10 litres of methanol in topped up with VPower to give me my 20% mix.

Maybe my gauge is not quite as accurate as I hoped or maybe I do have an airlock etc. definitely only got 38 litres in so there MUST of been circa 12 in there already.

 

50ltr tank is incorrect, here is a brochure for a version 2 STI, note the opposite page, half way down where it says "60".
That is the fuel tank capacity.

http://www.subaru-impreza.org/downloads/1995-sti.pdf

Tony

 

Look. Talking of a "50L" tank, then if we assume MY own tank is 50L, then when the needle reads "Empty", the tank typically has around 2.5L left in it. It's the average of how much the pump reads - c.47.5L, give or take obviously - when it reaches it's 'stop'. This is based on many fill-ups I've done over the 5 years of Impreza ownership - not plucking figures out the sky. That's "how I know".

The same would prob be true of a 60L tank at an indicated "E" i.e. circa 57.5L to brim.

It doesn't matter about the absolutes, etc. - that's what physically happens in practice. It gives you a base-line to work from. That's what I was trying to convey in my earlier post - not that "it definitely has 2.5L left" or whatever. It was to give the OP an indication of what he can expect to have left.

 

There is no point basing the meth level on an estimated full tank, you will never get it to be consistant that way IMO.

 

We were just going to base the first use on a full tank. Seems an easy way to get a 20% mix.
For further meth use i will add say 6 litres of meth then 24 litres of fuel on top.
Can't see any other way to map it with exactly 20% meth without completely draining the tank...

I'm even more confused now, so is Tony correct ??

 

You also have to remember that this tank is not like other fuel tanks, the drivetrain goes through the middle which means you have 2 dips either side, even my 50ltr spec c showed "E" and the warning light came on, I still put 38ltrs in there and it was on "E" for quite some time (slow motorway driving).
These gauges are not the most accurate either so dont take them to heart

Tony

PS, its still a 60ltr fuel tank

 

Of course im correct or are you calling Subaru Japan liars?

Tony

 

That's interesting Tony. Is it a special case for the STi II only, then?

 

What affect does methanol have on your car?? my speedway bikes run on methanol and have loads of it around but never thought of putting it in the Subaru.

 

No, the version 3, 4, 5 and 6 all have 60ltr fuel tanks, afaik it was only the really early wrx's that had 50ltr tanks.

Tony

 

When mapped, it gains you a decent %age extra power, compared to just V-P only.

I believe 20% meth to 80% petrol is the max. ratio to use i.e. any more than that you don't gain anymore extra bhp. Plus I think it can attack seals if too much is used(?).