3.8/4.0 bar FPR

ash_pearce

ash_pearce

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Right then people, in the past I've had lots of vauxhall's, lastly a 3.0 v6 calibra. The trend is to fit a bigger pressure FRP as lots of VAG owners do so when having a remap/big turbo etc...

The vauxhall parts shed offers a 3.8 bar bosche fpr for around £20 +vat.

A few vauxhall tuners (not naming any) offer a 4.0 bar bosche FPR for around £45 + vat.
There were rumours of the said vaux tuners removing the 3.8 part number and re stamping it with 4 bar although I cant confirm this.

I've checked around on here and found some p/n's on the net revealing that the VAG part number is 0280160575 exactly the same as Vauxhall 4.0 bar.

I would like to confirm this find, so can some one dig out there receipt or go outside and get there part number of their 4 bar reg please?

The 3.8 is also the same fitment and is a cheaper option.

This might be a great loophole in the over priced VAG parts bin.
 
Ash, just get your self to a scrappy and buy one from a scrap A4 1.8 / 1.8t or whatever as they are all 4BAR std. Surely wouldn't cost you more than a few quid
 
Byzan A4 said:
Ash, just get your self to a scrappy and buy one from a scrap A4 1.8 / 1.8t or whatever as they are all 4BAR std. Surely wouldn't cost you more than a few quid
Click to expand...

I agree but the i was just trying to save members on here a few quid when they are going down the bt route etc... saying that the big spenders that can afford bt conversions might not appreciate a 'few quid'.
 
Biggest prob with fuelling a BT etc is not pressure so much its flow... 3bar is plenty of pressure if you have the right injectors etc... Increasing the pressure may potentially increase flow through the std injectors but will make the pump (which lets face it, is prob a bit tired anyway) work harder.... It may be ok until you hit higher revs and it just runs out of flow which would not end nice...

On a BT, you want to get bigger injectors and even then prob look at an inline fuel pump too... This is what I am doing on my car but still running 3bar...

<tuffty/>
 
bit late for me to save on this as i used an audi 4bar fpr when AMD wanted to use 4bar on my stage2
 
no worries guys, spend your big bucks, hehe. I'll come back when i find some big turbo's for £20 instead.
 
indeed we need a 4.0 bar FPR
thats the miss conception to stick with your factory FPR since it is easier
for the "tuner" to use original tables, however its a very bad idea.
we have Atomization form of injector Vs Pressure gradient.
lets say you have 2 bar boost in intake and 3 bar fuel press in rail, the gradient hopefully will
stay at 3 bar, I mean the tuner pray and cry for it to stay BUT in reality as the factory FPR is 1 to 1 ratio it is hard+ it dosent rated above factory boost design = > lower pressure gradient
also the pressure curve will change way off the chart in 3.0 bar FPR......
 
I am not sure what Dr Mechanic is trying to say above. I can see that atomisation may be a little better at higher pressures which can only be a good thing. AFAIK the fuel pressure change in relation to the vacuum change is the same with a 3 bar and 4 bar regulator. With a 3 bar FPR there will always be 2 bar of difference between the pressure seen in the manifold and the fuel pressure and a 4 bar will have 3 bar of difference in pressure.
I fitted a fuel pressure sensor to my boost gauge on the TT so can see fuel pressure as boost varies and I know this is how it works on both a 3 and 4 bar FPR as I changed the original 3 bar FPR to a 4 bar to get some more fuelling instead of upgrading the injectors.
It's only running a standard turbo with the original pump and it keeps the pressure up exactly as it should.The standard pump delivers 5.3bar of fuel pressure when boost is at 1.3 bar I wouldn't use a second hand 15 year old part for the sake of saving £20 assuming they charge you £10 it's not worth it. You can buy a genuine Bosch 4 Bar FPR's delivered for just over £30. There are some slightly cheaper sellers on Fleabay.
I got mine from here
http://www.ebay.co.uk/itm/028016057...RE-PARTS-BRAND-NEW-GENUINE-PART/152273709326?
 
Dr. mechanic said:
indeed we need a 4.0 bar FPR
thats the miss conception to stick with your factory FPR since it is easier
for the "tuner" to use original tables, however its a very bad idea.
we have Atomization form of injector Vs Pressure gradient.
lets say you have 2 bar boost in intake and 3 bar fuel press in rail, the gradient hopefully will
stay at 3 bar, I mean the tuner pray and cry for it to stay BUT in reality as the factory FPR is 1 to 1 ratio it is hard+ it dosent rated above factory boost design = > lower pressure gradient
also the pressure curve will change way off the chart in 3.0 bar FPR......
Click to expand...

what exactly are you trying to say here?
 
For about £25 you can get a set of EV1 440cc injectors from China, I know plenty of people who use them with no issue.

Now if my maths is correct, which it usually isnt:

386cc @ 4bar = 0.07341 KRKTE
440cc @ 3bar = 0.07436 KRKTE

So basically the same increase in fueling ability without stressing the pump.
 
There are plenty of 1.8T cars that use 4 bar FPR from new and the same pump in the tank and they manage fine. The pumps are designed to support a 4 bar FPR. I am sure there are people using cheap Chinese injectors but at £6 a pop I can't imagine the quality is great. You can also buy nice shiney big turbos from China for not much more than £130 to bolt onto the engine but I don't see many people using them.
 
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audi upgrades
K04 turbo'd cars got a 4bar pump... k03 turbo'd cars a 3bar (transverse engined 1.8t's)

Most intank pumps are pretty much end of life these days and struggle with a 3bar let alone a 4bar

<tuffty/>
 
I never said to going 4.0 bar on stock pump, since they passed their efficient life and they are
brush type and so....
I say the 4.0 is a must for upgrade, injectors + FPR 4.0 bar + aftermarket pump is one package.
flow is influenced by pressure but it is not in linear equation, the line will diverted on higher
pressure, cant find real sample to show.
this estimation when they saying " +15% more by 1.0 bar increase" it more on higher duty cycles.
and this graph shows why not with stock pump :
Vag65vchart



apart of way better fuel atomization on 4.0 bar,
you hook wideband and lets say see 14.5 BUT that only shows the amount of unburnt fuel in exhaust,
less atomization of the fuel = more unburnt fuel
=>>> false positive reading


Injector Duty Cycle with 3 or 4 bar Fuel Pressure Regulator

http://forums.vwvortex.com/showthre...Cycle-with-3-or-4-bar-Fuel-Pressure-Regulator
 
There's something wrong with the graph above. My car is a 225 TT with a standard pump and a 4 bar FPR. It makes 1.3 bar of boost and when it does the fuel pressure is at 5.3 bar , the car makes 275 bhp .
5.3 bar is near as dam it 80 psi, and according to the graph above at 80 PSI the pump has no flow . Can anybody explain that ?.
 
audi upgrades
Dr. mechanic said:
I didnt try to saying, I just said it mate.
if you cant understand it, educate yourself ;d
Click to expand...

ooooo... you really said that to Bill?....


Anyhoo... yes... you will get arguably better atomisation with a 4bar FPR but you need to watch out you don't lock the injectors out especially if running a lot of boost...

On larger injectors you can also lose a bit of control at the lower pulse widths on idle as the ecu can't open the injector for a short enough time without falling into its non linear range and then you have to play with the mapping to allow for minimum injector time...

There is still the issue with fuel pumps of course as you will be taxing it with a 4bar no matter what

If a tuner tells you you need a 4bar FPR then its more likely that its because that the only way they know how to tune... depending on the power levels you are looking to run the best aftermarket injector I have ever used myself and the easiest to tune is a genuine Bosch 550cc

<tuffty/>
 
desertstorm said:
There's something wrong with the graph above. My car is a 225 TT with a standard pump and a 4 bar FPR. It makes 1.3 bar of boost and when it does the fuel pressure is at 5.3 bar , the car makes 275 bhp .
5.3 bar is near as dam it 80 psi, and according to the graph above at 80 PSI the pump has no flow . Can anybody explain that ?.
Click to expand...
you will also get pintle lockout at high pressures to throw into the mix
bottom line is "if" you have a pump which is up to it, and dont want to spend on new injectors, "and" your scope for needing more fuel is less than 15%, then a 4bar fpr "will" delivery 15% more fueling, presuming pumps keeping up with the rising rate regulator + boost... BUT if the pumps tired it wont delivery more and actually deliver less as the tired pump will drop pressure and flow. Larger injectors advised on 3bar is the norm... the 4bar thing dates back years when these cars were much newer and less worn out..
 
Thanks for the explanation Bill @badger5 . Looks like I am living on borrowed time with my pump then. At some point in the future I may upgrade the turbo etc and of course the pump will need doing. What would be your recommendation for an in tank pump good for 400 bhp. I would rather just one in tank pump than a second in line pump as probably going to be running a smaller battery so be good not to be running 2 pumps.
 
desertstorm said:
Thanks for the explanation Bill @badger5 . Looks like I am living on borrowed time with my pump then. At some point in the future I may upgrade the turbo etc and of course the pump will need doing. What would be your recommendation for an in tank pump good for 400 bhp. I would rather just one in tank pump than a second in line pump as probably going to be running a smaller battery so be good not to be running 2 pumps.
Click to expand...
We fit and sell the DW65 pumps for these. In tank and adequate for most peoples power.... 450-500bhp level
 
desertstorm said:
There's something wrong with the graph above. My car is a 225 TT with a standard pump and a 4 bar FPR. It makes 1.3 bar of boost and when it does the fuel pressure is at 5.3 bar , the car makes 275 bhp .
5.3 bar is near as dam it 80 psi, and according to the graph above at 80 PSI the pump has no flow . Can anybody explain that ?.
Click to expand...

5.3*14.5 = 76.8 psi
the fuel regulator orifice is the main restrictor in each system regardless of
what is your written pressure, you have to dig it deeper it is dynamic not static.

ideal is what you dream to have but actual is what you get,
by increasing demand/flow you have unilinear dropped in pressure
and this the design of FRP.

" The amount of increased pressure above setpoint needed to achieve shutoff is called lock-up.
Lock-up is an important regulator characteristic because it affects how well the pressure regulator
fulfills its reason for existence: maintaining a constant outlet pressure. "

Screen Shot 2017 11 15 at 181734


I marked ~ 75 psi keep in mind even with best fuel pump you will have problem unless
using good after market FPR + TWO thought parallel pumps ,
no need to say the series pump w/o surge tank is carpe.

Vag65vchart
 
<tuffty/> said:
ooooo... you really said that to Bill?....


Anyhoo... yes... you will get arguably better atomisation with a 4bar FPR but you need to watch out you don't lock the injectors out especially if running a lot of boost...

On larger injectors you can also lose a bit of control at the lower pulse widths on idle as the ecu can't open the injector for a short enough time without falling into its non linear range and then you have to play with the mapping to allow for minimum injector time...

There is still the issue with fuel pumps of course as you will be taxing it with a 4bar no matter what

If a tuner tells you you need a 4bar FPR then its more likely that its because that the only way they know how to tune... depending on the power levels you are looking to run the best aftermarket injector I have ever used myself and the easiest to tune is a genuine Bosch 550cc

<tuffty/>
Click to expand...


I cut my writing since I got waring to keep it "civil " :p
just say that the injector CC is marketing crap,
you should look after dynamic of injectors not on bench by 1 min,
pluses per duty cycle.

for future reference the "Bosch" is very commercial brand, tuner cant rely on them.
last thing injectors also need brake time, so you cant instal them and tuning right away.
 
bottom line :

- is the 4.0 bar is better ?
for owner and performance yes,
for grauge bro tuners no, harder to dail
I can assume any one who paying lots of money on maintenance of car can afford extra 100 euro

- who much better is 4.0 vs 3.0 bar, dose it worth ?
totally depend on your setup

- can a wide band show normal A/F stoichiometric but engine running low or hight on fuel ?
yes


- what is acceptable fuel injector brand ?

 
Dr. mechanic said:
I cut my writing since I got waring to keep it "civil " :p
just say that the injector CC is marketing ****,
you should look after dynamic of injectors not on bench by 1 min,
pluses per duty cycle.

for future reference the "Bosch" is very commercial brand, tuner cant rely on them.
last thing injectors also need brake time, so you cant instal them and tuning right away.
Click to expand...

Reality is I have seen and used many different types of injectors in real world situations including iterations on my own car that I have tuned myself...

If you believe that a 4bar fpr is the future of tuning then fill your boots... for what its worth I still run a 4bar fpr but thats because I chose 750cc Bosch injectors (modified from 550's)... this is primarily due to personal choice and lack of faith in some of the large injectors I have seen...

So far this setup works for me... gives me over 850cc of flow potential on full boost (30psi)

And... 'for future reference' the Bosch 550's have been the most consistent injector I have ever used personally or on any of the potentially 100's of cars I have seen go through Bills that use them...

There are of course copies out there that are sh*te but... you can indeed drop a set of injectors and use them straight away... having done so many times...

Use of higher pressure regulators on modern fuel injectors is not the massive advantage you seem to think it is... its also not without its problems...

<tuffty/>
 
guys i asked my girlfriend and she says 3bar is better "because 4bar is too big a pressure"
 
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Dr. mechanic said:
bottom line :

- is the 4.0 bar is better ?
for owner and performance yes,
for grauge bro tuners no, harder to dail
I can assume any one who paying lots of money on maintenance of car can afford extra 100 euro

- who much better is 4.0 vs 3.0 bar, dose it worth ?
totally depend on your setup

- can a wide band show normal A/F stoichiometric but engine running low or hight on fuel ?
yes


- what is acceptable fuel injector brand ?

Click to expand...


4bar is "better" - by your own definition...
LOL, ok then.. If that makes you happy..
Way more to it than just stick a 4bar fpr on for ALL occasions and specs of builds and requirements..

Its a "band aid" for those with insufficient fuel delivery for their existing injectors, and so long as their "pump system" is up to it, its a valid thing to do.. But nothing more than that. Regardless of the stuff you're posting up.
 
For what its worth I have now reverted back to a 3bar FPR on my 750cc injectors and idle/part throttle/transient response is so much better than it was before on the 4bar...

I guess it doesn't suite every application... who knew!!! ;)

...does mean that once I have tweaked the map to dial them in I will need to go through the process again with a set of larger injectors if I want my power levels back where they were of course as 750cc isn't really enough...

<tuffty/>
 
I wanna go back to a 3bar FPR, my fuel pumps have nearly 6bar peak demand to cope with. Can I just swap back to 3bar with my existing 1000cc injectors even though it was mapped with a 4bar FPR? Or will the injector map need re scaling


Sent from my iPhone using Tapatalk
 
Last edited:
S3 Hilife said:
I wanna go back to a 3bar FPR, my fuel pumps have nearly 6bar peak demand to cope with. Can I just swap back to 3bar with my existing 1000cc injectors even though it was mapped with a 4bar FPR? Or will the injector map need re scaling


Sent from my iPhone using Tapatalk
Click to expand...
Will need rescaling

<tuffty/>
 
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