Swirlpot and Fuel pressure regulator plumbing on Cosworth N/A.

[fingersnfumbs]

Sorry guys a bit more advice needed.
In the process of plumbing in the fuel system for converting my N/A YB to Throttle bodies in my Mk2 Escort.

A few issues Im confused about.

So... im fitting a swirl pot complete with in tank HP fuel pump. Planning on putting it in the boot up against the rear seat back.

Firstly, The fuel pressure regulator I was planning to fit in the boot of the car next to the swirl pot. Will that work bearing in mind the long run to the fuel rail up front? I have heard it can cause issues with maintaining constant pressure.

Secondly, Was planning on keeping the original Escort Mk2 fuel tank as its almost new. I plan on removing the sender unit in the main tank to gain access for fitting a connector for the fuel return from the swirl tank. Should I put an extended piece of pipe in the tank to the bottom? Thinking if I dont I will hear the petrol running into it when not fully topped-up.

Lastly, what pump for the low pressure side, I see two types of Facet pump. A square type and a bigger cylindrical one. Also I see they are rated at different pressures, So. What pump is best and what pressure pump should I get?
Any info or advice most welcome.

[katana]

That's a mixed up system IMO. Normally you pump low pressure from fuel tank to swirl pot - mount a Facet oe pump below the boot for gavity flow from tank to pump. Then from that pump, up to swirl pot upper side connection. Lower swirl pot connection through good filter to HP pump. From pump to fuel rail inlet with FRP on exit of rail then back to top of swirl pot with the very top connection of swirl pot back to main tank. You can have FPR close to the tank but then pipe friction does drop pressure a bit - my described way ensures correct / required pressure is always over the injectors.
If you can find an RS tank sender they have the return built into the sender top as a return was standard on Pinto engined cars. Either of the Facets will work - you don't need big pressure as the swirl pot is the reservoir for the HP pump BUT the incessant 'ticking' of these may get on yer tits - I use a motorcycle pump - its an interupter type so when it senses a head of fuel, it stops until the level drops and it starts again.

[fingersnfumbs]

I like the idea of the motorbike pump.

Sorry, I know im a bit dumb...whats a 'FRP'?

Thanks again.

[rallyrob]

you don't need big pressure as the swirl pot is the reservoir for the HP pump BUT the incessant 'ticking' of these may get on yer tits -.

I love the ticking, it can get on my tits any day

[fingersnfumbs]

And a link for a sutable LP motorbike pump would be good as I really havent got a clue what one.

[Graham]

I like the idea of the motorbike pump.

Sorry, I know im a bit dumb...whats a 'FRP'?

Thanks again.

Fuel Pressure Regulator

[katana]

This is the pump I used for mine, its a pattern part - https://www.wemoto.com/bikes/honda/n...ture/fuel_pump - but the price of a genuine Honda one will make your eyes water ! ! ! Also, just noticed that Facet do an interupter style pump - https://www.lasaero.com/products/article/G01J6S5HF - never used one of these and a bit more spendy, so pays yer money, takes yer choice!

[rallyrob]

Lol. The cheap ones of those pumps are crap.

You have to make sure they're primed otherwise they kill themselves pretty much instantly.
My son-in-law keeps using them on his bike carbed st170 engined Sierra, they don't last 5 mins. If you're going to use one of them I would at least use a good one.

[stevieturbo]

Sorry guys a bit more advice needed.
In the process of plumbing in the fuel system for converting my N/A YB to Throttle bodies in my Mk2 Escort.

A few issues Im confused about.

So... im fitting a swirl pot complete with in tank HP fuel pump. Planning on putting it in the boot up against the rear seat back.

Firstly, The fuel pressure regulator I was planning to fit in the boot of the car next to the swirl pot. Will that work bearing in mind the long run to the fuel rail up front? I have heard it can cause issues with maintaining constant pressure.

Secondly, Was planning on keeping the original Escort Mk2 fuel tank as its almost new. I plan on removing the sender unit in the main tank to gain access for fitting a connector for the fuel return from the swirl tank. Should I put an extended piece of pipe in the tank to the bottom? Thinking if I dont I will hear the petrol running into it when not fully topped-up.

Lastly, what pump for the low pressure side, I see two types of Facet pump. A square type and a bigger cylindrical one. Also I see they are rated at different pressures, So. What pump is best and what pressure pump should I get?
Any info or advice most welcome.

Dead head systems are common these days on OEM, no big deal. But it is preferred to operate a full flow system with FPR close to the fuel rails. Unless you're running the system at or near it's limits, its not really a concern. And you'd never really want to do that anyway, always have spare capacity.
Just monitor/log fuel pressure at the rails to ensure things don't get silly.

Put the return anywhere, chances of you hearing it with the engine running are slim. Well, anywhere but too close to the fuel pickup.

Low pressure pump will depend on overall plumbing and fuel demands of the engine itself. Ensure it always has enough capacity to keep the engine happy, and then some.
Pressure is largely irrelevant here, as there should be no real restrictions in that system, so it will never really be making any pressure. Just lots of flow.

[fingersnfumbs]

Thanks,
That makes sense.
What I cant understand is why an FPR would go after the fuel rail (outlet side) as I have seen in many diagrams. Surely a regulator regulated flow after itself not before.
Im a Plumber and thats how they work in plumbing anyway.
Hence why the 'dead head' thing sound more the way to me.

[stevieturbo]

Thanks,
That makes sense.
What I cant understand is why an FPR would go after the fuel rail (outlet side) as I have seen in many diagrams. Surely a regulator regulated flow after itself not before.
Im a Plumber and thats how they work in plumbing anyway.
Hence why the 'dead head' thing sound more the way to me.

There are many ways to configure it.

But I think you're trying to compare different things.

A pressure reg say in your house....you're sort of limiting pressure, rather than regulating it. ie at source you might limit it to 2 bar, but if I went round and opened all the taps in the house, it is going to drop due to various losses in the system, and lack of supply. Will your upstairs sink have the same pressure/flow as the kitchen sink right beside the mains/reg ? No. There are losses throughout.

The same can happen with a dead end FPR some distance from the rails.

But despite the above, your real source, the mains water, will still be at 6 bar for example. Your FPR first, then having to travel a long way with multiple outlets is less efficient getting the water where you need, with the flow/pressure you need.

The closer the regulator is to any actual outlet ( injectors ), the more easy it will be to maintain that constant pressure.
And I have not said after the rails, I've said close to the rails. Really it can go anywhere, just after is generally easier and more common. But distance from the rails is generally key, you want it close.

So see your mains water as your fuel supply, and then the tap outlets your injectors. You want the mains to have as easy access to the injectors as possible, but still at a chosen pressure. You don't put a regulator out in the street, you have it in the house, close to the outlets. Although you're regulating for a slightly different reason too...to ensure you don't blow the crap out of pipes and fittings lol.

If a household tap loses 5, 10, 15psi pressure is it a big deal ? not really. If your fuel system loses this much and there are not systems in place to ensure safety, it can be a big deal.

Hence, especially if you run a dead head setup, monitor/log fuel pressure at the rails. This is where it matters. Nowhere else. It will be less consistent with a dead head, than a full flow/return system with the reg close to the rail or rails.
Some modern OEM setups are dumb, fixed rail pressure and not monitored, but obviously well designed and tested.
Some systems can be fully closed loop with variable pump supply adjusted to maintain constant pressure at the rails.

Some don't even use a mechanical regulator at all, it's all done electronically controlling pump speed.

[stevieturbo]

Should also be noted.

"close" FPR systems will generally also be intake manifold referenced in terms of pressure.

Far type setups with a reg near the pump are often a fixed rail pressure regardless, often 60psi or thereabouts.

Generally for tuning it's easier to have a fixed pressure delta across the injectors....ie with that intake manifold referenced FPR. That's not as easy with a far mounted, dead end setup, unless you ran a pipe all the way to the back to give it a reference.

Not a big deal for a n/a setup, but another thing to be aware of.

Strangely, this is one the slightly better videos I can find lol

https://www.youtube.com/watch?v=XJ9BsLmnRbY

https://www.youtube.com/watch?v=aWuFFhKuQZs

https://www.youtube.com/watch?v=iGVZMzm0GNI

[Miniliteman]

When "mapping" you determine the time the injectors are open for every rpm/load combination.
You want a consistent amount of fuel injected every cycle and because the amount of fuel injected is determined by the time the injector is open AND the differential pressure across the injector (fuel pressure - inlet pressure) that differential pressure needs to be exactly constant all the time.
So for best results the fuel pressure regulator needs to be close to the injector rail. When the FRP is on the other side of the injector rail it allows excess fuel inside the rail to go back to the tank and thereby the temperature increase of the fuel inside the rail is minimal.

As rallyrob states don't use cheap/copy/Chinese pumps, I've seen lots of copy Bosch 044 and also copy Facet pumps go tits up within no time at all.