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Guys,

I'm looking for an adjustable fuel pressure regulator that fits onto the stock fuel rail.

I thought of raising the pressure by about 1 Bar to increase atomisation of the fuel especailly as I'm going to run a water injection as well.

Anyone any experience with raising the pressure ? Any pitfalls apart from the obvious. I checked my fuel pump and it seems pretty strong / high delivery rate, which means it should be up for the job.

If not I've seen ppl talking about walbro pump. Fill me in ? Where can I get them ? Which one ? What mods need to be done ?

Cheers,
Dave

If you don't get any response on here. Try talking to the various tuners - AMD, QST, Dynalinx etc.

You can get a 5bar FPR (I must admit, I'm not too sure what pressure the std RS4 runs at). Try on www.audiworld.com - they seem to have an attraction to fitting these, even to mildly modified S4's.

Nige.

Strictly speaking you should need a re map if you raise the fuel pressure. Raising the fuel pressure and leave the map the same will make the car run rich...
With aquamist you do not need more fuel in, its not like NOS.... Running rich is normally a safety net for forced induction cars to keep the pistons cool, which Aquamist does a better job of. So if you are running Rich Aquamist will allow you to run less rich. Even aquamist recommend cuation when running a bang on stoich map cos itf that means Aquamist fails youve lost your safety net.... If you follow me.

Aquamist also raises you octane level if you use a methanol mix..... It works well in my opinion.
The S4 System is smart enough to keep the fuel just right for the conditions of the vehicle and if you raise the fuel pressure without having a map tweak your just going to make the thing run richer everywhere..... SO basically IMO.... dont bother with a pressure hike unless you are having other significant mods and a remap as you wont see any gains... just less MPG!... My 2p...

confusionhunter wrote:Strictly speaking you should need a re map if you raise the fuel pressure. Raising the fuel pressure and leave the map the same will make the car run rich...
With aquamist you do not need more fuel in, its not like NOS.... Running rich is normally a safety net for forced induction cars to keep the pistons cool, which Aquamist does a better job of. So if you are running Rich Aquamist will allow you to run less rich. Even aquamist recommend cuation when running a bang on stoich map cos itf that means Aquamist fails youve lost your safety net.... If you follow me.

Aquamist also raises you octane level if you use a methanol mix..... It works well in my opinion.
The S4 System is smart enough to keep the fuel just right for the conditions of the vehicle and if you raise the fuel pressure without having a map tweak your just going to make the thing run richer everywhere..... SO basically IMO.... dont bother with a pressure hike unless you are having other significant mods and a remap as you wont see any gains... just less MPG!... My 2p...

Okay,

I don't want to raise the pressure to richen the mixture. Only to increase fuel atomization.
I'm going to custom remap the car but before that I need all the mods done.

Still on my list:

Aquamist
NOS (wet system)
Fuel pressure
Fuel Pump/Injectors ( If the stock stuff isn't up for the job)

I just thought that some ppl might advice me on certain FPRs as there are many manufacturers as for instance with DVs

FYI: Water injection doesn't increase your fuel's octane rating it just cools down the intake, combustion and exhaust temperatures and therefor decreases the chance of detonation. Also it keeps your turbos cooler, which mean they should live longer.
Also, I wouldn't use more alcohol than necessary to stop the water from freezing as it doesn't do you engine any good. Methanol tents to leave white residues on all aluminum parts and increases corrosion of you piston rings and bore walls as it washes away vital lubricant!! Also the small amount of methanol you're injecting compared to your fuel/air mixture is insignificant and wouldn't affect you performance in the slightest.


Cheers,
Dave

Cool, If you have a remap everything is a OK .... raising the fuel pressure without shortening the injector duty cycle will give you a richer mixture... That was my point thats all...

"Water injection doesn't increase your fuel's octane rating it just cools down the intake, combustion and exhaust temperatures and therefor decreases the chance of detonation. Also it keeps your turbos cooler, which mean they should live longer. "
All True, However the octane rating of methanol is higher than pump fuel thus the overall effect is that running a 30% methanol mix raises octane of the overall mixture by about 4 points... ish this can also allow you to run a tad more ignition advance...

"Also, I wouldn't use more alcohol than necessary to stop the water from freezing as it doesn't do you engine any good."
Hmm, I'll agree to differ. The limiting factor of how much methanol you can use comes from what it does to the resulting fuel mixture.... If you run too much methanol (over say over 40% mixture) the extra fuel burns hotter and it reduces the aquamists effect by reducing the injected mixtures latent heat capacity and there fore totally defeating the purpose of aquamist... (which is cooling!!! not fuel enrichment!)

"Methanol tents to leave white residues on all aluminum parts and increases corrosion of you piston rings and bore walls as it washes away vital lubricant!! " May be true for methanol mega rich environments. Ive not seen any evidence of this on my application and if Im honest Im not bothered about incresed wear! I think you'll find this is a minus point for water injection not for running methanol in water injection!!
"Also the small amount of methanol you're injecting compared to your fuel/air mixture is insignificant and wouldn't affect you performance in the slightest. "
It does beleive it or not. Car feels smoother and help top end and when you following a car using it it even smells cleaner! It all depend on the set up.... In my application (highly tuned VW Polo G40) which is a single jet after the intercooler on a small 4 cylinder effort, it works very well and would deffo reccomend it.
Its all trail and error and everyone will tell you differnet things...
For more info have a squiz here: http://waterinjection.info/phpBB2/
But I get your point in that the purpose of aquamist is cooling and Not methanol injection! In the S4 I would run 2 pumps and 2 jets after each intercooler... but IO havent looked into that.....

Anyway.... (can you tell Im not busy today).....FPR's Cant help you on direct application but the GTi-R guys seem to like Nismo FPR's and the
Walbro Fuel pumps....let me see.....
I couldnt see any Audi application kits from rally nuts but heres their details..
http://performance.rallynuts.com/render ... -pumps.htm
Hope that helps....
Cheers.
Mark.
PS sorry for the novel....

FWIW I have had a lot of issues in the past with ERL ( Aquamist) pump failures. Also if you are going to run a meth mix I would strongly suggest using a lubricant such as Uplon from Klotz.

There are pleanty of other WI kits out there too, many cheaper, and some have some pretty sophisticated controllers now.

On the fuel pump, do any of you guys use Walbro's. We use them on the Supras and have found that a single pump ( GSS341/342) will support 600bhp. They are cheap ( circa £100) and have a low current draw.

Lastly on FPR's in my honest opinion you would be better off getting a rail adaptor made and using a good quality Adjustable FPR. The Aeromotives, we have seen are good to 800bhp and cost about £120-150 whilst the Weldon like I have on my car is bullet proof and costs in the region of £250-300. The weldon has been seen to support 1000bhp+. Dont be tempted by the likes of the FSE ones as we have seen them lose pressure when hot.

Hope that helps