again,.. the rate is irrelivant(and we ant talking about air compressors!) HENCE why there are fule pressure regulators!

but again... please answer me this,.. you dont deny, that a "spi" pump will work with a GT,... why not a G40 again please look at the book information,.. the SPI will fule a "2.5" bar injection system but never will it fuel a 1.9bar G40!! system!,. and please dont go ona about a G40 needing twice the fuel as a spi, when its on boost,...what the hell! its a supercharger! there always on friggen boost!!!

a compressor is a pump and its all relevant, the difference between an spi and a G40 is the rate at which they empty the fuel tanks, a G40 fuel pump supplies more fuel because the engine drinks more fuel on boost.

its not exactly rocket science :lol:

again,.. the rate is irrelivant(and we ant talking about air compressors!) HENCE why there are fule pressure regulators!

but again... please answer me this,.. you dont deny, that a "spi" pump will work with a GT,... why not a G40 again please look at the book information,.. the SPI will fule a "2.5" bar injection system but never will it fuel a 1.9bar G40!! system!,. and please dont go ona about a G40 needing twice the fuel as a spi, when its on boost,...what the hell! its a supercharger! there always on friggen boost!!!

ok so the g40 might "might" empty the tank quicker but its still going to be regulated by the fule pressure regulator!!! so none of it makes a difference!

lol phill ...

the fuel pressure isnt the problem, its the quantity of fuel that the pumps deliver that matters.

if you're just driving like a granny and not going on boost you'll probably be fine with either of the inline fuel pumps.

First off mate, its a supercharger not a turbo!! superchargers are always ''ON boost'' stop watching so much fast and the furios!

Secondly, polo fuel pumps are all the same, yes the fuel pressures might be diffrent at the fuel rail, but thats because it has a ''FUEL PRESSURE REGULATOR'' hence the varying fuel pressure's as everybody else has said, If a G40 fuel pump is diffrent from every other pump, why does GSF sell them under the same part code as everyother pump !!!

a fuel pump is designed to pump fuel to the injector rail, the fuel goes into the injector rail and is then pressurisied to the required pressure by the fuel pressure regulator!

A FUEL PUMP IS NOT DESIGNED TO PRESSURISE THE WHOLE FUEL LINES, ITS A DELIVERY METHOD FOR THE FUEL!!!

ONLY TIME YOU HAVE TO UPGRADE A FUEL PUMP ON POLO ENGINE IS WHEN YOU GO TO SILLY POWER! the fuel pumps cant deliver the flow rate needed to get the fuel pressure that required for the power!

wants to argue this further, BRING IT ON

Edited 23 October, 200718 yr by GTmark3

Oh somebody answer me this?? why is a G40 so special it needs it own pump????

and what makes a g40 a quick car?

Now, there's answering someone's question, then taking the piss. You are trying to start and argument just for the sake of an argument...

What makes a G40 a quick car? I don't know. A standard G40 isn't a quick car. 150 + bhp G40s are quick cars because of their good power to weight ratio.

What makes a G40 a quick car? I don't know. A standard G40 isn't a quick car.

lol..... its not a quick car????? u HAVE BEEN ON HERE TOO MUCH!

look..

TO THE GUY WHO STARTED THIS.... u'll be fine mate!

I'm sorry if I don't think that over 20 seconds to a hundred is quick.

lol..... but u cant call that "not a quick car" LOL

kids these days!!

if gts and g40s are fine on an spi pump then why are they higher pressure? cos they need it - and i've heard of quite a few piston melts or dodgy running on gt/g40 cos of the wrong pump

yea people may have run ok too... but i can run my g40 on meths, spark plugs from the scrappy and no air filter doesn't mean its good for the car....

and for people - who say that the g40 is always on boost... its not. It produces boost but doesnt use it - it recirculates, so until you put your foot past about half way then its not on boost.

Personally i would swap the pump.

oh and they arent the same part at gsf - only the lift pump is... the main fuel pump isnt. It is a different vag part number

lol..... but u cant call that "not a quick car" LOL

kids these days!!

Anyway, surely if I believed everything I read on here, a G40 would be the fastest car in the world?

LOL... thats a fair point!

18377 FUEL INJECTION PUMP PO 1.3 55 BHP MPi 10/90 >12/92 94.50

18377 FUEL INJECTION PUMP PO G40 10/90 >7/94 94.50

18377 FUEL INJECTION PUMP PO 1.3 75 BHP 10/90 >7/94

there we go.... ok.. the SPI has a different code...... but does the SAME

Just because something has worked so far does not mean it always will, or will work without problem in an other car.

I personally would change it, better to spend £100 or so now, than having to find a replacement bottom end, or the cost of a 1341cc conversion in the future.

oh and they arent the same part at gsf - only the lift pump is... the main fuel pump isnt. It is a different vag part number

from vagcat!

24 867906091

fuel pump

/ NZ,3F,PY

(24) 867906091B

fuel pump / also use:

357 972 772 / AAU,AAV

if you read this all,.. we do not deny the spi and mpi have alternative numbers! just again how can a "spi" pump fuel a mpi gt system rated at .5bar higher than a G40 which also uses the same fule pump as the Gt it's self!

oh and they arent the same part at gsf - only the lift pump is... the main fuel pump isnt. It is a different vag part number

from vagcat!

24 867906091

fuel pump

/ NZ,3F,PY

(24) 867906091B

fuel pump / also use:

357 972 772 / AAU,AAV

if you read this all,.. we do not deny the spi and mpi have alternative numbers! just again how can a "spi" pump fuel a mpi gt system rated at .5bar higher than a G40 which also uses the same fule pump as the Gt it's self!

WOOP THERE IT IS!!!

here it goes... a lil summit like this..... WHHOOOPP THERE IT IS! nice one phill

gain tho, what supercharged cars doe you drive that can have variable boost with half throttle?!,.........o0o0o its re-circulating ITS still ON boost! does it not recieve a proportionl amount of boost,.. we are not describeing weather it has full boost! its still getting fucking boost LOL

unlike a turbo which will have negative/no boost untill u have enough speed to create positive boost!

BUT THE ORIGINAL QUESTION HAS BEEN ANSWERED!

gain tho, what supercharged cars doe you drive that can have variable boost with half throttle?!,.........o0o0o its re-circulating ITS still ON boost! does it not recieve a proportionl amount of boost,.. we are not describeing weather it has full boost! its still getting fucking boost LOL

unlike a turbo which will have negative/no boost untill u have enough speed to create positive boost!

BUT THE ORIGINAL QUESTION HAS BEEN ANSWERED!

LMFAO phill mate, you are on fire 2nite!

and producing boost means creating forced induction, hence a turbo has lag, because it relys on exhaust gasses to spool the compressor up! so when pootling before the turbo has time to spool is called OFF BOOST! a supercharger is belt driven, ALWAYS PRODUCING BOOST untill you turn the engine off ofcourse !!

Edited 23 October, 200718 yr by GTmark3

GOOD CALL!

ok ok - its produciing boost but not using it

and as for gsf - same part number. Same part number for radiators - even tho the g40 and gt one is different and has a more efficient core... it works but not as well. As for vagcat - well its not what etka says!

Yeah fuel pump will work but for how long - it will fuel a gt- yeah but properly, effectively? hmm

I'd buy a gt/g40 pump or get a second hand one.

I'm not quite sure where the info on PY lumps being 1.9 bar regulated pressure came from. They're 3 bar regulators, similar to the 3 bar regulators used on the 3F and NZ lumps. That is to say, all the MPI Polos use a nominal 3 bar fuel rail pressure relative to their vacuum signal.

A PY lump uses a different reg to the NZ/3F because it has to work with boost - so at 1 bar of boost you'll see a fuel rail pressure of 4 bar relative to atmosphere, but the pressure differential across the injectors is still 3 bar as you've got a bar above atmospheric within the inlet manifold.

So, hopefully everyone's happy that the MPI Polos are all 3 bar regulators?!

As Dominic correctly stated, regulated pressure and flow rate are two distinctly different things. The weaker SPI inline pump seems to manage okay on most GTs with 3 bar pressure. However, the fuel flow rate is not the same as a G40 - the injectors are 150cc per minute @ 80% duty for the GT vs 192cc per minute @ 80% duty for the G40. Both are at 3 bar pressure, but the G40 demands more fuel at that pressure - so an SPI pump struggles.

I've run both pumps on both 3F and PY engines. On a stockish 3F, the SPI pump was okay - as soon as I added a wet nitrous kit things went awry, swapping to an MPI pump sorted things out. Running a 130bhp PY lump on an SPI pump didn't work well at all - G40s demand much more rapid fuel enrichment on acceleration than a GT as their boost builds so quickly, so any deficiency in fuel pressure and/or fuel flow can be easily felt. The piston meltage that engine ultimately suffered didn't come long after I'd swapped to an MPI pump - but the damage had already been done.

It's a simple fact that the pumps are different - they're rated for different flow rates at different rail pressures. Practice may dictate that they're okay for use on a few GTs, but it'd be good practice to fit the fuel pump that VW intended.

OEMs do not like having multiple parts unless absolutely necessary, so on any MPI Polo I'd suggest you use an MPI inline fuel pump. You may get away with an SPI one on a 3F or NZ lump, but good luck to you if you're trying it on a PY.

I'm now locking this, before any more bollocks is 'contributed'.