Stuttering at Spa?

[DuncanR]

I love all our technical discussions ESP when NZ_M3 and The Gorilla are involved.

Trouble is I am not clever enough to understand who is right everytime :bigcry:

+46 of us !!! :hahaha:

[cslnutta]

BMW seems to think otherwise.
Check pipe number 3 in the diagram.

http://www.realoem.com/bmw/showparts.do?model=BL92&mospid=47621&btnr=16_0484&hg=16&fg=15

Please keep this going guys, this is getting very interesting:thumbs:

You guys are obviously very knowledgeable, please continue to bless us mere simpletons with your plethora of info!

Fascinating stuff

[cantfind1]

yes true, didn t read that bit but the point is it flows back to the tank to the siphon system and if you haven t got much flow back then the siphon system will be less efficient.

[_Nathan_]

That doesn't come back from the rail though which was the point being made - go and look at the rail on your car, it just stops at the front of the engine.

http://www.realoem.com/bmw/showparts.do?model=BL96&mospid=50641&btnr=13_0909&hg=13&fg=15

[cantfind1]

Hi,

Cantfind1 - your correct that it is tiresome.

There is no flow back from the rail on a s54.

Regards,

The Gorilla.

BMW seems to think otherwise.
Check pipe number 3 in the diagram.

http://www.realoem.com/bmw/showparts.do?model=BL92&mospid=47621&btnr=16_0484&hg=16&fg=15

[shimmy]

I love all our technical discussions ESP when NZ_M3 and The Gorilla are involved.

Trouble is I am not clever enough to understand who is right everytime :bigcry:

[glendog74]

Tiresome

:hahaha:

[azrael]

I am not going to argue the point anymore with you as it is tiresome Gorilla.

I thought it was a discussion, no need to argue here :thumbs:

[The Gorilla]

Hi,

Cantfind1 - your correct that it is tiresome.

There is no flow back from the rail on a s54.

Regards,

The Gorilla.

[cantfind1]

Hi,

If an engine requires 5 Bar fuel pressure at 200 GPH
then revs do not enter into it.

Going faster or slower does not alter the
delivery of fuel made by the pump, whereas
the engine may burn more or less fuel, if
its delivered at 5 Bar, there will always be
enough fuel.

There are no problems on long straights at WOT
pulling 7500/8000 rpm.

The only issue is when the pump is starved of fuel
and can not make the 5 Bar required, due to the
factor of G forces on longer radius bends washing
fuel away for prolonged periods from the pick up.

This has nothing to do with the pump.

Regards,

Thje Gorilla.

Yes people do have problems on long straights pulling 7000-8000 rpm and no sometimes the oem fuel pumps are not producing enough flow to give the required 5 bar. But you do not need 5 bar of pressure at low rpm!! Have you ever driven your car with a pressure gauge attached to see what happens??

5 bar is not required by the engine at low rpm the requirement for fuel to the engine increases with rpm therefore you have less flow back to the tank, this in turn affects the siphon system and makes it less efficient in cornering.

I am not going to argue the point anymore with you as it is tiresome Gorilla.

[The Gorilla]

Hi,

If an engine requires 5 Bar fuel pressure at 200 GPH
then revs do not enter into it.

Going faster or slower does not alter the
delivery of fuel made by the pump, whereas
the engine may burn more or less fuel, if
its delivered at 5 Bar, there will always be
enough fuel.

There are no problems on long straights at WOT
pulling 7500/8000 rpm.

The only issue is when the pump is starved of fuel
and can not make the 5 Bar required, due to the
factor of G forces on longer radius bends washing
fuel away for prolonged periods from the pick up.

This has nothing to do with the pump.

Regards,

Thje Gorilla.

[cantfind1]

I agree!:thumbs:

[shane@mbtech]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:

I know ~I answered my own question,

I was discussing. I like discussions such as these, very good and informative.

[cantfind1]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:

[The Gorilla]

Hi,

Cantfind1- as Laswy says. the electric fuel pump
is constant, it has nothing to with engine rpm.

That is very reason there is a fuel regulatro.

You can only test a fuel pumps true pressure rating, when
its off the car, and there are no other factors like-

Faulty Fuel regulator-
Clogged fuel filtre-
Obstructed fuel lines-
Fuel line connectors seeping-
Fuel injector seals split or pershied-

So while your own experinces may have been
very costly, there are many items that
can impact fuel pressure.

Regards,

The Gorilla.