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MG MGF Technical - Re-rated fuel pressure regulator

Hi guys

from the other thread "Rolling Road Results", the subject of fuel pressure regulators came up once again.

Been chatting with Roger Parker as a result of this thread, in the light of Carl's fascinating lambda sensor recordings and observations with his FSE.

The standard regulator maintains fuel pressure at a nominal 3.0bar - but has a tolerance of 0.2bar. From Carl's observations (and backed up by Roger's work with Mat on his Rover BRM), it appears that even 2.8bar can result in blunting of performance and loss of top end urge: throttle response improves when fuel pressure is set at the top end of the tolerance range. Unfortunately Rog has failed to see a gain in power on the Rolling road, but perhaps this is not the best environment to judge this modification.

Apparently an engineering company based in Coventry is able to "sort" the standard fuel pressure regulator to put out a pressure at the top end of its tolerance range (3.2-3.3bar) - but in order to do this, they need an order for a minimum of 10 units.

The advantage over the FSE is that the regulator is STILL a standard part - which is great news for us sprinters, and for anyone else whose car is under warranty. And since once the regulator is set up (3.2/3.3 bar is what everyone seems to end up using anyway) it never needs to be touched again, there is no need for the expense of the adjustable FSE.

I'm certainly interested - and judging from the other thread, so is Paul (?), so I need about 8 other "orders" to get the parts made up.

Let me know chap and chapeses! :o) - and I'll keep you all appraised of costs/times etc as and when I find this out.
Rob Bell

anyone knows what the cost is of the FSE from i.e. B& G

David. (interested)
david

The B&G item is 99.99..... if less than that I could be persuaded.

Tim
tim woolcott

I get the impression that if we order 10, then the cost should be comfortably less than that - but as yet, I have no hard figures to give you.

FWIW if these re-rated items cost 100 quid each, then I'm not THAT interested either! LOL
Rob Bell

So T, Lux.s RR testing costs more than the PBV he has installed. *LOL*
david

Well I would be interested, there are still disadvantages over the FSE which builds pressure up very smooth and faster then the standart valve (advertising claims..)

Rob, is 3.0 bar the standart value for all F's like : MPI,VVC,Trophy ?
T

Thats correct, but I wont do them at that dealer. Ill try to find another RR dealer here, which is difficult.
T

>> Rob, is 3.0 bar the standart value for all F's like : MPI,VVC,Trophy ? <<

Yup, that's correct to the best of my knowledge Thierry. Certainly correct for the MPi and VVC, and I suspect correct for the 160Ps VVC variant too :o)
Rob Bell

Let me know the price, and I am in....
Erik

We're working on a price Erik - but from what Roger is saying, it is going to be significantly less than the FSE.
Rob Bell

Rob, would it be an idea to cross post on the Elsie forums too!?
tim woolcott

Hmm, yes, good idea.

Might need to enlist Victoria's help too - but will chat to you tomorrow about that...
Rob Bell

I'm interested at the right price.

Bruce
Bruce Caldwell

Me too at the right price :)
Overseas could be done as bulk.
Dieter K.

Shall keep you posted chaps - but no news yet :o(

On the rolling road yesterday at G-Force. A bit of a story there, but bad news was their Lambda sensors were all up the creek, so I wasn't able to confirm or refute the possibility that the FR on my car was running weak. Pitty. :o(
Rob Bell

I had to replace my regulator as it was dying the mems can cope with it failing to a certain extent, but the emerald could not, for>170 bhp on a mpi this could be usefull for me as the power flattens over 68000rpm.
so count me in for the right price.
Kingsley

<the power flattens over 68000rpm> Jeez scary, stand clear of the flywheel;-)
mike
mike

Count me in too.

SF
Scarlet Fever

Okay guys - will keep you all posted. No news yet (this will take time to sort out), but as soon as I have an idea as to the likely costs, I'll sound you all out again and get a 'definite list' sorted. :o)
Rob Bell

I know the regulator is at the end of the fuel rail, how does it come out?

Also, this sounds like something Mike sould supply exchange so you don't need to have the car off the road for a week.

Alastair
Alastair McLeod

The regulator is retained by a circular spring clip, this is flipped and turned and the regulator pops out, after market regulators have an adaptor which sits where the stock regulator does and diverts the fuel to a remote regulator. QED do a cheaper after market FPR (45) than Demon Thieves, maybe you should be looking at one of those. An after market FPR will only really help if you are running lean, otherwise you will just be jettisoning fuel and losing power....

The stock FPR is to an extent rising rate since it is referenced against manifold pressure rather than atmospheric.

Dave
Dave Andrews

Rob

A bit late finding this thread but count me in.

Neil
Neil Stothert

Question, is this easy to fit?

If So and you get a good price you can count me in.

Greets Maurice, Holland
mpmgf

An after market FPR will only really help if you are running lean, otherwise you will just be jettisoning fuel and losing power....
------------------------------------------------------

Not quite sure about that rob, don't forget you can adjust the pressure on an PBV, so why would you loose power ? If the standart runs on 3.1 and you set the PBV at 3.1 you doen't loose power. You may loose money but not power.

The aftermarket FPRs' offer more advantages over the standart valve than simply the pressure regulation.
T

Maximum power is made over quite a narrow band of Air/fuel ratio , around 12.5:1->13.5:1, if you are running at the correct AF ratio and you add more fuel you will make less power, simple physics, the extra fuel will displace some of the air, hence there will be less oxygen to combine with the hydrocarbons.

If your A/F ratio is correct then you can't make more power by simply adding fuel, you need extra air as well. Let's be clear...

An after market FPR will only really help if you are running lean, otherwise you will just be jettisoning fuel and losing power....

Dave
Dave Andrews

> if you are running at the correct AF ratio and you add more fuel you will make less power,

Won't them MEMS adjust the injector timing down using the LAMDA sensor? (i realise it can only do this closed loop, but the settings must propergate?)
So if this is the case then the net result will be a short term loss in power until the MEMS adjusts, and then back to 'normal'
Will Munns

The only time an ECU can accurately monitor and adjust fuelling is when in steady state (closed loop) and that is only to keep the catalytic convertor happy. In this mode it will cycle the fuelling either side of stoichiometric. These setting do not propagate. When accelerating the ECU will enter an open-loop state and will revert to the original mapping. The MEMs will only learn the idle personality not the overall fuelling.

Dave
Dave Andrews

Interesting stuff, if i'm reading this correctly Dave, you are saying that to achieve maximim efficiency the fuel pressure needs to be matched to the air flow and that therefore adjusting the FPR to provide more fuel will do so at the expense of air and this will cause the car to run rich, loosing power.

So, back to the original proposition. Rob says that

>> The standard regulator maintains fuel pressure at a nominal 3.0bar - but has a tolerance of 0.2bar. From Carl's observations (and backed up by Roger's work with Mat on his Rover BRM), it appears that even 2.8bar can result in blunting of performance <<

and

>> Apparently an engineering company based in Coventry is able to "sort" the standard fuel pressure regulator to put out a pressure at the top end of its tolerance range (3.2-3.3bar) <<

So, my questions are (assuming a standard induction set up, there are too many variables otherwise), by setting the stock FPR at the top end of it's range (3.2bar) is this too much fuel for the amount of air that can be delivered?

and

Assuming that by fitting an aftermarket air filter / induction system you improve the efficiency of the air flow into the engine, would setting the FPR to 3.2bar be more beneficial to cars thus equipped? (basically what i am asking is does an air filter gain power by supplying more air (as surely this is limited by the flow characteristics of other parts of the engine, TB, plenum, head, etc) or is is simply an efficiency gain in so far as the engine has to do less work to draw the air in)?

Intrigued...

SF
Scarlet Fever

As I understand it (and you know, if I'm going to be wrong I might as well do it all in one thread!) the MAP sensor will work out there is more air flowing and adjust fuel accordingly, it has to do this to cope with atmospheric changes as well as airfilters.
Will Munns

So the fuel and air ratio is adjusted automatically by the MAP sensor?

Does this mean that, given that the FPR can only supply fuel up to is maximum setting, that you may not see all the potential gains from an air filter as the MAP sensor can only supply fuel up to the pressure limit on the FPR?

SF
Scarlet Fever

Errm yes, If what Dave is saying is correct (and I have no reason to doubt it) then the ECU assumes 3 bar pressure and knows how much fuel is passed at that pressure, having low pressure will cause you to run lean (a bit more powerful and hotter?) and high pressure will make you run rich (less power, greater fuel bills, cooler) BUT at the very top end of the fueling map, when the injectors are continiously open then the only way to get more fuel into the air is to add extra pressure to the fuel line.
I do not know where the upper end of the fueling map is, but the Lotus boys seem to think that 160BHP is about the limit for the standard MEMS (I assume this info is also from Dave) But if you incresse the pressure across the range then you will sacrifice the lower torque of your engine for high RPM BHP.
Will Munns


God ! I wish i had a brain too!!

Can't add any comments really other than if the mems is only good for 160bhp, where does this leave the guys with the head porting producing 170+..

Stu
Stu

With an emerald ECU ;-)
Will Munns

Will

I dont think Dave Livingston is running a Emerald ?

Can't recall his RR print out of hand, but don't think he had problems at the top end?

Stu
Stu

interesting read here
http://members.aol.com/emeraldm3d/ems.htm
Kingsley

Kingsley !

Hows yours running now? Did you get it remapped ok ?...

No probs with reliability?

Stu
Stu

Kingsley,

I wrote that EMS article that is on Emeralds website..

Dave Livingstone started with a VVC ECU who's baseline is 143BHP and therefore the map is very different to the stock Mems.

The MAP sensor is able to sense airflow and will modulate what it thinks is the correct fuel according to its assumptions about fuel pressure, if the fuel pressure is higher than assumed then more fuel will be injected than the Mems thought...

Dave

Dave Andrews

>>So, my questions are (assuming a standard induction set up, there are too many variables otherwise), by setting the stock FPR at the top end of it's range (3.2bar) is this too much fuel for the amount of air that can be delivered?

and

Assuming that by fitting an aftermarket air filter / induction system you improve the efficiency of the air flow into the engine, would setting the FPR to 3.2bar be more beneficial to cars thus equipped? (basically what i am asking is does an air filter gain power by supplying more air (as surely this is limited by the flow characteristics of other parts of the engine, TB, plenum, head, etc) or is is simply an efficiency gain in so far as the engine has to do less work to draw the air in)?<<

Andy, 3.2 - 3.3 bar would seem to be the maximum, maybe even optimum fuel pressure for a lightly modified car (filter/exhaust - maybe even for a car running MEMS and a DVA head...)

At 3.2 bar, I doubt that you'd be at the point at which fuel starts displacing air and reducing power in the way that Dave describes. Think more in the order of 5bar...
Rob Bell

@Dave :

-----Quote----------
If you are running at the correct AF ratio and you add more fuel you will make less power
If your A/F ratio is correct then you can't make more power by simply adding fuel, you need extra air as well.
-----Quote----------

I am far from being an expert and far from understanding completely what's all about, however your AF ratio reminded me of this statement (Quote:http://freespace.virgin.net/steven.crook-dawkins/tuning%20guide/FSE.htm):

With a standard control valve the pressure in the fuel rail increases by 1 part of fuel for every 1 part of air in the inlet manifold (a ratio of 1 to 1). With a FSE Power Boost Valve the pressure is increased by 1.7 parts of fuel for every 1 part of air (a ratio of 1.7 to 1); thus the maximum flow of fuel is achieved earlier in the rev band.

Is this the "extra" air you refer to ?
T

Forget my last post, sometimes I wonder if I actually comprehend what I wrote.
T

Yes
;)
Dieter K.

"click here to get a copy of the page without all of the superfluous information"

One question remains: How does that script identify Dieter ?
T

This thread was discussed between 16/07/2003 and 30/07/2003

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