daijones

AFAIK, Powerstation will suggest you fit an uprated pump if it appears, during a remap, that it's needed. When I got my WRX done, up to 270 bhp, it didn't need the new pump so I didn't get one. However, tuning by definition involves putting more fuel into the engine: bhp is produced by releasing energy from fuel; more bhp means more fuel. Doing a remap to increase power means telling the ecu to put more fuel into the engine; ergo, there's a chance that once you get past certain levels of tune then the standard fuel pump can't keep up with the new demands of the tuned engine. There are actually two concerns: the quantity of fuel demanded, and the quality of the flow. An upgraded pump will ensure a more consistent flow at high levels of demand and low levels of supply. A standard pump is more likely to struggle to provide the required flow when, for example, the fuel level is low. A pump has to work harder when there's less fuel in the tank, because there's less weight of fuel pressing down on the pump intake.

Upgraded fuel injectors, naturally, increase the scope of the tuner to demand that the ecu puts more fuel into the engine. The injectors set an upper limit on the possible fuel supply - 550cc injectors can potentially deliver 25% more fuel than 440cc injectors.

A standard car will have plenty of margin of safety at standard tune, so the fuel pump in a WRX will quite happily supply the fuel required for 225bhp. However, that margin gets eaten up with retuning, and you will get to a point where the margin disappears and you need a new pump. The better question therefore may be, at what point of tune is a new pump required?

D

pslewis

OK, lets get the output of the standard pump and compare that to what is required by a certain mod. ...... I'm not talking what Big Billy said down at the Rolling Road Meet either - I'm talking real, hard evidence - Engineered solutions.

The fact is much more simple that that, as we all know. There are people who make a nice living out of selling stuff thats not needed - and uprated fuel pumps are one such item IMO.

What you are buying is simply 'Bragging Rights' at the next Geeks get-together ..... you know how it goes:-

"I've got a widget 60Bar high pressure uprated 12 volt hydro-dynamic specialist maximum flow rally proven McRae Solberg fuel pump"

"Why is that then?"

"Well, it's needed cos I'm running 750BHP and 900lbft of Torque!!"

"WOW, are you really?"

"YUP!! AND I've got some likkle lights that tell me something like my engine has blown up - called a random light generator, the Rally Proven RB McRae Model!!"

"Good God, can I have your children?"

"Sorry, I spend all my time talking bollox to geeks like you ... all I will say is that I use Oil that costs £45 for 4 Litres, aren't I the smart one?"

"£45!!! WOWIE, that must be REALLY good!"

"OH, yes ... it's used in the Harrier Jump Jet to lubricate the Rotor Blades - thats what the Oilman said anyway"

"The Harrier Jump Jet isn't a Helicopter I don't fink"

"What do I know?? I'm just a numptie who believes everything I'm fed and gets ripped off regularly ................. have you seen my Change Gear Light?"

daijones

I agree with you on both points, that it's one of those things that people just buy whether they need it or not; and that the way to decide whether you DO need it is to compare the output of the std pump with the output required by your mods. It's probably a good idea to allow for a safety margin, so e.g. you might upgrade if the standard pump can only supply 110% of the required output: any more keep the std pump, any less then upgrade.

Glad to see that you accept the point that uprated pumps are sometimes need

D

pslewis

Now, you have just made yourself look really stupid

That is NOT a PPP - it's NOT a Prodrive Pack as you claim ... is it now?

Prodrive do NOT supply an uprated Fuel Pump with their PPP - end of, your apology to me is eagerly awaited ..... if you are up to that?

Go away, get your facts right and then return ...

pslewis

As everyone knows, I am very open to being convinced one way or another.

I accept that a higher flow fuel pump would be required in a Hot Rod Impreza doing 0-60MPH in 2 seconds.

BUT, as an Engineer, I also know that so much stuff is bought when it's not needed ......... just because someone with a vested interest says so!

I have taken on the responsibilty for being the voice of reason on here, I have accepted the fact that many look to me to ask questions which others fear to.

Why accept the words of an Oil Salesman (for example) over someone with a solid Engineering background spanning many decades (who also has nothing to sell you!)?

Listen to me and we will sort out the crap and bollox from the well thought out Engineered solutions.

IMHO of course

J_sca001

Hello Pete, God don´t you cop some stick!!

According to powerstation, and i watched it performed. The Walbra uprated pump is not just to keep the pressure up. The standard one would do that. It increases flow to avoid leaning out when further mods and things are changed on the engine.
Thats what i was told anyhow!!

pslewis

My hide is as thick as a Rhino .... I'm pretty immune to the stick

The stick is used by those who couldn't string a coherent logical argument together if their lives depended upon it. They are not worthy of comment.

Of course, an uprated pump avoids leaning out of the fuel - but, and this is the crux of the matter - it only avoids it if the standard pump would fail to deliver.

Which is where I come in - I truly believe that many Impreza's are running around with uprated pumps when they are not needed and will never be needed, whilst a perfectly good pump was removed and waste created for the planet for no reason whatsoever, except to put some money into someones pocket.

MikeyTang

iTrader: (4)

I would imagine you've got a steel plate welded around your backside with all the stick you get. But you have to admit you give as good as you take.

Brilliant to read though ... keep it up

J_sca001

Yep you did put a smile on my face, which is a good thing!!

I was told by powerstation that the bugeye is very common for leaning out due to that batch of models having an ok fuel pump until it´s modded in the slightest way, which i found out to my peril!!

Alan MaC

Crikey, what have I started?

AS I said, the Guy who serviced my Scoob said it would help the Turbo, it's a VF28, had a remap &, a Decatted H&S Exhaust ( since the remap) it's runing at around 282 BHP, I've just had a bigger Intercooler fitted since then also.

I guess he is thinking of my next remap.

Powerstation who did the remap did say if I was adding any other mods, an uprated fuel pump should be looked at.

Both Powerstation & the Scooby Mechanic, to me, know what they are talking about, I don't, that's why I was asking for advice on here.

So, what are we saying then, will I need one for the next remap and, what will i do??

Regards.

Alan MaC

pslewis

Find out what the output of the standard pump is.

Ask when the re-map is done what the fuel requirements are.

And you will have your answer

If the mapper doesn't know the details I wouldn't pay them - they charge an arm and a leg they should know basic stuff like that ... of course, we know what will happen - the mapper will say "Up-Rate your pump!" not for any reason other than they do not know the answer so are playing safe (even better for them if they can amazingly supply the required pump!! )

It's all smoke and mirrors mate .........

Mikkel

If it is not the PPP why do Subaru sell it as the Prodrive Performance Pack on their website? Where the PDF came from.

Perhaps by PPP you meant Pslewis Palking Phit?

Official Accessories, Merchandise & Parts - Accessories | Subaru (UK) Ltd.

Now you go away and get your facts right... or just go away...

pslewis

http://195.212.11.58/imggb/www/subaru_accessories.nsf/NULL/9A189478360FA98C8025728F004DF270/$FILE/SACC2632%202007%20STi%20PPP.pdf

Where's the Prodrive Part Number then??

There isn't one!!

You really are a wally

STOP DIGGING and visit the Prodrive site and see what's included - NO PUMP!

Come back when you can shoot straight You are tooooooo easy

Sonic'

Pete

I would just like to butt into your delightful standpoint on the scooby modding world buying parts that they dont really need

Have you ordered your dealer badged way over prices rear brake pads yet ?

Or have you opted for the sensible 30 quid less ones without the Subaru Badge

Feel free to carry on your discussions

pslewis

I haven't bought them yet - but, I think I will stick with the Subaru Boxed ones - at £51 it's cheap to put a Subaru Invoice for pads into my car history folder .............. probably make the car worth £50 more come re-sale time, just for that one little thing!

Shows that the Owner isn't a skinflint and spends money when needed to maintain the vehicle in top condition

Sonic'

I take your point

I dont mind as i'm not selling mine, they arent worth much these days anyway anymore, a shame but true

Steve Whitehorn

iTrader: (13)

Both PSL and Dai are making decent sense to me.
I recon PSL has a valid point.

It would be really good if someone could post up the actual output of the standard pump verses the walbro.

Obviously there is the case for the Walbro at some point.
But when is that point.
What will the actual standard pump support in terms of mods plus some margin built in?

Anyone?

Steve

Bedders

Pete,

Check out this link: http://www.prodrive.com/up/03MY%20STi%20PPP.pdf

Clearly states 'high capacity fuel pump'

suffolkdar

Not even on the sti? are you sure?

nraponi

MY06 STI PPP gets a new fuel pump too. Assume '07 too.

pslewis

I am not disputing that it states it THERE ... what I am disputing is that the PRODIVE PACK does not come with an Uprated Fuel Pump, see here:-

Prodrive Performance Pack WRX (PPP)

Anyway, thats just a side issue ......

Steve Whitehorn has a valid question - anyone care to show what the output of the Standard Pump is and the uprated pumps on the market?

It's about time some of you started acting like real men and not wooly sheep swallowing everything you are fed!!

340BHP-WRX

iTrader: (6)

Alan MaC

Good point, can anyone do a comparison of standard V's uprated's ability??

Regards.

Alan MaC

StiX

iTrader: (4)

On Andy Fs website, he states that above 320bhp an uprated fuel pump is recommended?

AndyForrestPerformance


"Fuel Pump
The original fuel pump effectiveness varies both throughout model years and with mileage. For any horsepower goals above 320 bhp an uprated (255litres per hour rated up to 550 bhp) Walbro type pump is recommended."

Just thought I would throw that into the 'discussion'

pslewis

Means absolutely nothing really ..... not without hard numbers.

It is simply an opinion, based on good solid experience - granted - but, an opinion all the same.

Trout

iTrader: (1)

Pete,

I thought you were an engineer?

Of course the injector opens for a set period of time set by the ECU. However the amount of fuel that passes through the injector, which has a set apeture, is subject to the fuel pressure.

A pump needs to have an adequate flow rating to maintain fuel pressure to all injectors equally, something no helped by the design of the standard fuel rails.

So above around 320/330bhp remapping will start to push the limits of the injector duty cycle as the standard fuel pump struggles to maintain fuel pressure as it reaches it's flow limits and so opening the injectors for longer is a compensation for poor pump performance. (Of course this is to ignore other issues such as fuel heating and cavitation issues as the pump reaches or goes beyond its design parameters).

Poor fuel pressure and increased injector duty cycle will lead to poor spray patterns and less effiecient combustion.

One of the most cost effective solutions to this is a larger capacity pump. This maintains good fuel pressure throughout the system and typically the fitting of such a pump will see injector duty cycle much improved. This was certainly my experience in mapping my own STi V and performance over 5,500rpm was significantly improved.

Of course - it is highly unlikely that adding an uprated pump will 'help' the turbo and you are right to suggest that many pumps are fitted for the sake of fitting them rather than for an appropriate application.

Finally, AFAIK the STi PPP has always come with an updated fuel pump and Prodrive have sold uprated pumps for the Subaru for years. They originally came with the foam sleeve bonded on so you could not find out the part number of the original pump. And these were designed for rally cars running a mere 300bhp! I reckon they are selling them just to make a couple of notes on the side

Mikkel

You are a dick mate. You're whole unsubstantiated point is based on the fact you are an engineer, which unless you work for Subaru Prodrive or in the motor sport industry, means **** all to anyone or anything.

Mark'sWRX

It seems that most tuners (including Prodrive) feel that an uprated fuel pump is recommended if going for over 300ish bhp. As Mr Lewis has pointed out, the standard pump is adequate in a WRX PPP (265bhp), but if you go to his link and click on STi PPP, it shows an uprated pump is part of the STi PPP (305bhp).

I can't remember exact figures, but I vaguely remember figures of 130-160lph from a standard pump, 190lph from a Prodrive pump and 255lph from a Walbro.

Don't ask me what flow you need, but if Andy F, Prodrive and Tracktive all say the same thing, then I'd spend £100 to prevent my engine melting even if they might all be wrong.

Prasius

iTrader: (1)

The PPP argument - I think Subaru/Prodrive only started including the uprated fuel pump in 2003/2004 for the STI; I'm pretty sure the PPP on my 2002 STI hasn't got it.

Presumably they must have decided it was a safety margin worth adding in for an extra £90 (which lets be honest, is bugger all in real terms).

pslewis

We are now in the realms of where the suppliers and retailers LOVE you to be.

That 'never-never land' where things are bought 'just-in-case'

I have never seen so much of this go on as it does on ScoobyNet - it would make an interesting study. Is it that the owners of Imprezas don't have an Engineering background? Is it because they 'think' the Impreza is 'special' and needs supercar pampering? Is it because they are simply gullible? I don't know the answers ....... but I DO know that a LOT of money is wasted 'just-in-case'

While your at it, you could put an extra letterbox on your front door .... in case one is hit by a flying brick and it gets sealed up