sdh2903
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| posted on 3/9/16 at 08:25 PM |
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Fuel pressure regulation
I'm building a westie with a 2.0 ecoboost. I'm just shopping for the fuel system bits and bobs but am confused with the fuel pressure
regulator. The manual for the ecu kit requires fuel pressure at 55 psi (3.8 bar) feed to the high pressure pump. As it's a return less direct
injection system I also need a return to the tank from the regulator.
So I was looking at the weber alpha ones like this
http://www.webcon.co.uk/shopexd.asp?id=12882
This has 3 fittings. Feed from tank. Output to hp pump and return. Ideal. However they only list at 3.5 or 4.3 bar. Am I going to do damage at an
extra 6 psi if I run a 4.3?
Alternative is the adjustable version (not a fan if I'm honest) but that only seems to have the 2 fittings. Where do I get my return from?
Lastly the small fitting on the top of the regulator. This usually gets plumbed to the manifold for vacuum? In a turbo application where do you plumb
to as the inlet is pressurised so does it affect it? If so where does it go?
Cheers
Steve
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madteg
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| posted on 3/9/16 at 08:52 PM |
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Do not buy a cheep pressure regulator as its the most important part. You will also need a gauge in line to check pressure. A drop in pressure can do
all sorts of weird things
[Edited on 3/9/16 by madteg]
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CaptainJosh
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| posted on 3/9/16 at 08:58 PM |
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The vacuum line is to make sure the pressures across the INJECTORS remains constant, so its technically the gauge reference pressure. Puting it into a
turbo manifold is completely reasonable. It should always be after the throttle body.
If the regulator is two fittings you can just use a t-piece.
[Edited on 3/9/16 by CaptainJosh]
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obfripper
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| posted on 3/9/16 at 11:17 PM |
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The pressure regulator is for the low pressure feed system, and is a constant pressure to supply the high pressure fuel pump.
Only port injection uses a manifold reference to vary the feed pressure and keep the effective pressure constant, direct injection needs a constant lp
feed pressure to keep the hp fuel pump at the ecu requested pressure.
The regulators you are looking at are setup for port injection, not a problem in it's self, as you can just blank off the vac connection, and
you will get a constant pressure (there may be some issue with this if you're going to operate the engine at high altitude depending on the
internal design of the regulator)
The oem ford pump has a pressure regulator in the swirl pot and does not need an external pressure regulator.
You would need to check (i'm assuming you may have an aftermarket ecu), but afaik a couple of psi above at the lp feed should be within the
operating range of the hp pressure regulator/ecu, vw did this to superceeded fsi fuel filters (+0.3bar) for the purpose of preventing fault codes
relating to insufficent hp pressure, but there was no software update required to account for the higher feed pressure.
I would go with something you could buy off the shelf, a vw oem filter like GENUINE VW VOLKSWAGEN PETROL FUEL FILTER
6Q0201051J would provide a constant 4.0bar supply and filter in one unit.
Dave
[Edited on 3/9/16 by obfripper]
[Edited on 3/9/16 by obfripper]
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sdh2903
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| posted on 4/9/16 at 07:21 AM |
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Thanks gents
Yes I'm using the Ford racing ecu kit. Having read again it doesn't give a tolerance on the LP fuel feed psi. Just states should be a
constant 55 psi although it's been suggested elsewhere a higher pressure would help prevent Hp pump cavitation but am sure ford know what their
doing.
Re the reference manifold line. I was going to say the westfield demo car and one in build both had this line open to atmosphere, would it be better
to blank off or leave open?
That filter in your link. Do you have any further info as the Vw blurb on the FSI states it's LP pressure can vary up to 6 bar
[Edited on 4/9/16 by sdh2903]
[Edited on 4/9/16 by sdh2903]
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obfripper
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| posted on 4/9/16 at 12:23 PM |
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The filter in the link is for non fsi constant pressure returnless port injection at 4 bar, they use a calculated factor to alter the fuel injected
amount in reference to manifold pressure instead of a vac presssure regulator.
The fsi uses an ecu controllable feed lift pump, but the filter regulator caps the pressure at 6.6 bar.
All the vw fuel filters use a common casing design with different pressure internals, the part number is the key for the output pressure, there may be
a 3.8 bar version but i can't think what it would go on to give you a part number.
If the weber regulator is left to open air for every 1000m it will produce ~0.11 bar less pressure, if capped off may add ~0.11bar pressure or do
nothing depending on design, unlikely to affect uk use, but places in europe like stelvio pass are ~3000m and it might cause an issue.
A non vacuum regulator like the vw reg/filter would not be affected by the air pressure change at altitude.
I've just had a quick look at this, i assume
this is the ecu setup you have, it does look to be very insistant on 110l/min & 55psi for the feed and it does stiplulate a non vacuum pressure
regulator and an in-tank lift pump is strongly recommended.
It may be an idea to directly contact ford racing to see if they can provide tech help.
I do notice they don't give a system schematic drawing for the fuel system, but they suggest to have the regulator as close to the engine as
possible which is completly different to the oe setup which has a regulator in the same housing as the in tank pump.
Looking closer at the oe setup, ford do have a controllable lift pump like the vw setup, the regulator caps max pressure at 6.8 bar.
Afaik the controllable lift pump setup is aimed at saving power and reducing pump noise at idle and low throttle.
Dave
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sdh2903
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| posted on 4/9/16 at 01:46 PM |
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Thanks dave.
Yes that's the ecu I'm using. I've been chatting to a very helpful chap over on the wscc forum who's been involved in the
development of the ecoboost engines and he reckons a slightly higher LP pressure will be fine and encouraged if anything. I have already dropped ford
racing an email anyway so will be interesting to see what they say. I'm surprised as they are so specific on pressure and flow rate and location
that they don't offer one for sale with the kit.
Steve
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