19 replies to this topic

[John Boy]

Looking for examples of where people have mounted their swirl pot/tank and secondary pump.

 

Experienced fuel starvation at a recent track day at Silverstone on the exit of Aintree at under 1/3 tank full. Understand from searches its not an uncommon feature, fixed by baffled tank or swirl pot. Swirl pot looks easier and cheaper.

 

Also, what size connections will I need to connect to? From searching it looks like a Bosch 044 is the way to go, along with a 1L pot/tank.

 

Hoping to have a tinker over Christmas, so want to get all the bits needed lined up.

 

Thanks

[CHILL Gone DUTCH]

Lee has one

[Nev]

If you install a swirl pot, with the extra hoses + pump, you need to consider the safety implications in an accident, as 8 Bar of fuel being squirted around won't be nice.

 

With this in mind, my swirl pot is inside the cabin, behind the passenger seat, which is the safest place for any sort of accident (in terms of stopping it being hit/dislodged). It is inside a further solid plastic housing to isolate it a bit. The pressure pump however is in the engine bay. All hoses are carefully routed to be on the inside of the chassis in case of an accident.

 

Some people have put swirl pots in the boot in the past (which is what I initially did until I changed things), but a rear end impact would be worrying I think...

 

The safest solution is to buy + install a baffled tank though, but I don't think they existed (off the shelf) when I did my conversion though.

 

 

 

Edited by Nev, 21 November 2017 - 05:41 PM.

[Spitfire Engineering]

Looking for examples of where people have mounted their swirl pot/tank and secondary pump.

 

Experienced fuel starvation at a recent track day at Silverstone on the exit of Aintree at under 1/3 tank full. Understand from searches its not an uncommon feature, fixed by baffled tank or swirl pot. Swirl pot looks easier and cheaper.

 

Also, what size connections will I need to connect to? From searching it looks like a Bosch 044 is the way to go, along with a 1L pot/tank.

 

Hoping to have a tinker over Christmas, so want to get all the bits needed lined up.

 

Thanks

 

 

What are you making in terms of BHP?

 

By the time you add up the swirl pot, brackets, Bosch pump, pump wiring, fuel lines, a box of fuel line connectors etc I'm not too sure how much cheaper it will actually be.

When you  consider the advantages of a new, corrosion resistant, large capacity tank with a built in trap (swirl pot) with nothing else to buy. Add all the advantages of a simple, clean layout with minimal risk of leaks and fuel heating issues caused by storing fuel in the engine bay and heating it further with two pumps, total about 20A

 

Worth a thought ......

Could be you need a new tank anyway, when was the last time you checked for internal and external corrosion?

 

[Doctor Ed]

my swirl pot is inside the cabin, behind the passenger seat, which is the safest place  

jackie_chan_wtf.jpg

[Nev]

 

my swirl pot is inside the cabin, behind the passenger seat, which is the safest place  

jackie_chan_wtf.jpg

 

 

It's a big thing, finding a suitable spot for it in the engine bay within the safety of the inside of the chassis is not easy, even then the engine bay is nowhere near as safe as in the cabin. The safest place (in a collision) is in the cabin (as it's designed to keep squishy passengers alive), basically if the swirl pot is smashed behind the passenger seat I'd reckon both driver and passenger are likely dead anyway.

Edited by Nev, 21 November 2017 - 09:02 PM.

[Spitfire Engineering]

 

my swirl pot is inside the cabin, behind the passenger seat, which is the safest place  

jackie_chan_wtf.jpg

 

 

Maybe this is true about safety, if I were driving around with a high pressure fuel supply in the same space as me I'd be pretty Fu_king careful how I drove!       

[Zoobeef]

You can have them internally for racing, but the lines need to be braided and screw type fittings. It would also all need protecting. I'd probably build something to box it in.

[Spitfire Engineering]

You can have them internally for racing, but the lines need to be braided and screw type fittings. It would also all need protecting. I'd probably build something to box it in.

 

 

Or you could just place it in the fuel tank with the rest of the fuel??

Then it refills itself with G rather than another pump.

 

[Zoobeef]

 

You can have them internally for racing, but the lines need to be braided and screw type fittings. It would also all need protecting. I'd probably build something to box it in.

 

 

Or you could just place it in the fuel tank with the rest of the fuel??

Then it refills itself with G rather than another pump.

 

 

 

Indeed, I'm meaning Nev as his is already done! Safety isn't a dirty word haha

[Nev]

Having the whole shenanigans integral in the main fuel tank is clearly preferable, however as I said, this option didn't exist when I overhauled my car.

 

My setup uses fully braided lines + aeroquip fittings everywhere. Also, as importantly it has been routed with careful thought to impact and shortness of hose and without strain on the joints and fittings (which could cause long term failure). Bear in mind, with the swirl pot directly over the existing fuel pump, the draw + return line to the existing fuel tank is totally minimal (is a few CM), so risk is minimal here. The pressure pump is in the engine bay, so the high pressure delivery line (which is the highest risk) is in the engine bay.

 

If the swirl pot were to be smashed by entry into the cabin safe zone, then passenger (and likely the driver (ie me!)) would be dead anyway. The swirl pot is fully shrouded in a hard plastic as an extra precaution.

 

The only genuine risk that I see is a leak, which I've never ever had. On the 1 or perhaps 2 occasions that I've disconnected any fuel pipes in the last 7 years I have meticulously tightened the joints, and done incremental duration engine switch on and checks for leaks (several times) before driving it.

 

All in all it's as safe as I could get it and it's stood the test of time. However, it's not as good as an integral (in tank) system, which is why I suggested the OP had a good think about it... Mind you even an integral tank would need an external pump(s) if you want to deliver fuel for 500+ HP, as the OEM canister is way too small for a meaty pump. This would of course mean high pressure lines + pump would still have non OEM fittings routed around the cabin + engine bay, so there would still be risk.

 

Perhaps Pro-Alloy or some other company would make a bespoke VX220 fuel tank with a catch baffle and internal fitting for 1 or 2 Bosch 044 pumps?

 

Edited by Nev, 22 November 2017 - 08:06 AM.

[Spitfire Engineering]

..... Mind you even an integral tank would need an external pump(s) if you want to deliver fuel for 500+ HP, as the OEM canister is way too small for a meaty pump. This would of course mean high pressure lines + pump would still have non OEM fittings routed around the cabin + engine bay, so there would still be risk.

 

Perhaps Pro-Alloy or some other company would make a bespoke VX220 fuel tank with a catch baffle and internal fitting for 1 or 2 Bosch 044 pumps?

 

 

Things have moved on Nev  

No need for any external pumps nor any other paraphanalia, we can supply pump units for in-tank use (trapped) which are easy to install right up to about 1100bhp, they are safer, much quieter and more efficient, probably a lot cheaper as well considering you need nothing else. The units are fully E85 compatible.

http://www.spitfiree...mp-conversions/

 

As OE, one pipe from to tank to filter and then to the rail/PRV

One return pipe to the tank.

Fuel supply system complete!

 

 

If you have a chat with Dan at HPE he may be working on something for the VX with a low inertia trap and correct fuel level monitoring.

 

[John Boy]

Its not a monster power car, and never will be, so no problems with general fuel delivery, just left handers.

 

Ive read about the uprated fuel tanks, and most seem to talk about what a ball ache the tanks are to change, cut access holes in bulkheads and with the long range tanks brimming can be problematic.

 

Had though about heat soak into the small tank if engine mounted, however when on track the draw through may be sufficient that heat build up would be minimal. What temp does fuel need to get to to cause issues?

 

Had planned on high spec hoses, connections etc (aeroquip) as didn't want the stuff spraying round the engine bay. However, is this any more risky than standard fuel lines if they leak? As the requirement is to counter he surge in the tank, rather than up the pressure, perhaps a standard pressure pump would be a better idea.

 

Splitfire, does your re-furbed pump eliminate the surge, or just produce a higher pressure?

 

Thanks all for comments. Plenty to think about. Particularly the safety of a rear mounted tank.

 

[Nev]

 

..... Mind you even an integral tank would need an external pump(s) if you want to deliver fuel for 500+ HP, as the OEM canister is way too small for a meaty pump. This would of course mean high pressure lines + pump would still have non OEM fittings routed around the cabin + engine bay, so there would still be risk.

 

Perhaps Pro-Alloy or some other company would make a bespoke VX220 fuel tank with a catch baffle and internal fitting for 1 or 2 Bosch 044 pumps?

 

 

Things have moved on Nev  

No need for any external pumps nor any other paraphanalia, we can supply pump units for in-tank use (trapped) which are easy to install right up to about 1100bhp, they are safer, much quieter and more efficient, probably a lot cheaper as well considering you need nothing else. The units are fully E85 compatible.

http://www.spitfiree...mp-conversions/

 

As OE, one pipe from to tank to filter and then to the rail/PRV

One return pipe to the tank.

Fuel supply system complete!

 

 

If you have a chat with Dan at HPE he may be working on something for the VX with a low inertia trap and correct fuel level monitoring.

 

 

 

Sounds good, 8 years too late for me though.

[Spitfire Engineering]

Its not a monster power car, and never will be, so no problems with general fuel delivery, just left handers.

 

Ive read about the uprated fuel tanks, and most seem to talk about what a ball ache the tanks are to change, cut access holes in bulkheads and with the long range tanks brimming can be problematic.

 

Had though about heat soak into the small tank if engine mounted, however when on track the draw through may be sufficient that heat build up would be minimal. What temp does fuel need to get to to cause issues?

 

Had planned on high spec hoses, connections etc (aeroquip) as didn't want the stuff spraying round the engine bay. However, is this any more risky than standard fuel lines if they leak? As the requirement is to counter he surge in the tank, rather than up the pressure, perhaps a standard pressure pump would be a better idea.

 

Splitfire, does your re-furbed pump eliminate the surge, or just produce a higher pressure?

 

Thanks all for comments. Plenty to think about. Particularly the safety of a rear mounted tank.

 

 

Hi

Tank

Starting with the tank, there is no reason why it should be any more difficult to fit an aftermarket tank than an OE one, it just needs to be designed correctly, we have spent some time with Dan working through the current issues with aftermarket tanks and looking to make a new design with a larger capacity but not so large it causes other problems. You certainly will not have to butcher the car.

The trap works much better and the fuel sender is in the tank not the trap (yes it is accessible should it fail)  

 

Leaks

Any joint is a potential leak, assuming any pipework is of the correct specification this part of the install should not be a problem however there are plenty of threads on SELOC about split pipes including sheathed ones. The biggest problem is lack of knowledge, with owners being ill advised that they need to use large bore pipes "because of the extra power the OE pipes cannot get enough fuel through" this is complete rubbish and the OE pipes can supply any engine you can fit in the Elise/VX series cars with little drag, a 500 bhp engine losses in fuel pipe drag is only about 2%, this doesn't mean you are down 2% on power it just means 2% of the pumps output is lost in efficiency, the pump should easily supply more than is required. As an example we always lower our output figures by 10% minimum to allow for such losses and long term wear and tear.

Once you start using large bore pipes you are creating your own problem as the force on the pipe wall is directly related to the internal surface area, worse, as the fuel is always moving due to the return there is some reduction in pressure due to the higher flow of the smaller bore pipe but I can't be arsed to calculate this at the moment  

 

To date I have never seen a split OE pipe, and as this specification pipe is used just about on every vehicle made clearly it is more than capable and doesn't seen to deteriorate either. This is helped by the small bore which reduces wall pressure which in turn restricts expansion and fatigue on the material.

 

Fuel heating

Problems are most common on swirl pot installations, this is not surprising as you have two pumps heating the fuel (pumps use fuel to both cool and lubricate) and the return fuel is stored in the engine bay initially, it works better on cars with a cool airflow over the swirl pot.

Vaporisation is directly linked to pressure and temperature.

 

Pumps

When you say surge you mean starvation of course, the situation is quite simple really, you either have enough fuel stored to keep the engine running or you don't!  

Storage is primarily the tank itself, secondary storage is the canister which is part of and one of the functions of the pump unit.

Left hand corners with the G and fuel level considered means you can quickly reach a situation where the fuel in the tank is not available to the pump so you are relying on the pump canister.

This works fine when standard engines are considered as consumption is such that the 200cc or so stored in the canister is enough for 15 seconds or so without access to the tank fuel, clearly as you start to increase consumption this time will fall, eventually to the extent the engine will stall because of starvation.

 

You now have only one option but several methods, you need to store more fuel so the options are an external surge tank, a trapped tank (internal surge tank) a better refill system for the canister if this is the problem i.e canister is not full before starting the left turn or a new tank design. Clearly the last is a function of the vehicle design so that is not really an option though it you stood the OE tank on one end it would work perfectly down to the last few drips! But it may look a bit odd sticking up through the engine cover.

 

The new pump units have a larger capacity and also a very quick refill system even a full power they still supply enough excess fuel to recharge the canister in about 4-5 seconds, quicker with higher pressure rail pressures, note this does not include return fuel.

 

If your consumption is still too high for the fuel available then this leaves you with the two captive fuel options, internal or external.

Clearly the internal is a far superior option as the main pump remains in the coolant hence it is protected and also MUCH quieter.

The trap is recharged almost instantaneously by surge in a right hander so much quicker than an external surge tank and you do not need any pumps or pipework to carry this operation out. The fuel also remains in a cool part of the vehicle and is fully mixed with tank fuel so you see no local heating as with an external option.

It has to be safer as there are no pipes/pumps/unions/power cables at all to service the stored fuel.

They are also much larger, it is easy to trap 6-10 litres internally and still keep the horizontal surface area of the trap to a minimum, i.e fuel is stored in height not width. Most external surge pots are small by comparison, this becomes more of a heating issue as the volume to surface area is smaller also.

 

In answer to your question power wise the HP pumps we do are for cars up to about 400bhp NA and 360 SC both at OE pressures, these will fall if you increase rail and/or boost. The VHP conversions we do can support anything in a VX.

Canister storage wise it depends on several factors including the time spent with the canister fuel alone and the specific consumption of the engine being the main ones, if you have a 500bhp car and want to track seriously you will need additional storage for sure.

For a road car you can use the pumps without any additional storage.

For anything in between ............

 

So the answer is both pump unit options supply a much higher output and the new units both store more fuel and refill quicker.

The OE units also fill quicker as we adjust the eductor pump to match the pump selected but you are still stuck with 200cc capacity.

 

What power are you hoping to make??

 

Gaz

[The Batman]

You dont have to cut an access hole to change the tank You have to cut an access hole to fit a fuel pump if you dont want to drop the tank

[siztenboots]

just also to point out the plastic fittings for the hard pipe to the fuel rail , are now getting old and brittle , the retaining spring on on the plastic clip has lost its clamping.

 

these ones with the xmas tree fitting to secure to the expansion bottle bracket

 

[John Boy]

so general consensus is little tank in boot/bay is bad as you don't want to catch fire when getting rear ended. Which leaves new baffled tank (belt and braces) or modified pump which has 5 seconds approx. reserve. Or, simply don't run tank much below 1/2 full when on a track with this issue. Very much cheaper.

 

Will have a think, and thanks all for the advice.

[Doctor Ed]

ach... look, theres 10000's of cars running around with secondary fuel systems in the boot/engine bay, and to call it a fundamental 'no-no' is drawing a long bow. theres definitely retarded ways to go about it (i used to have a fuel cooler mounted behind my rear bumper, that was dumb!) but smart and sensible isnt that difficult either. i personally think running any fuel inside the cabin, on the other hand, is suicide (same goes for oil lines big and small eg mechanical gauge capillarly lines etc) but each to their own. for moderate output, a drop in pot and pump combo is the simplest, easiest, and ultimately safest idea. if youre wondering what to do, and are lacking the experience to make such a decision yourself, id say thats probably the best solution for you.

[Spitfire Engineering]

so general consensus is little tank in boot/bay is bad as you don't want to catch fire when getting rear ended. Which leaves new baffled tank (belt and braces) or modified pump which has 5 seconds approx. reserve. Or, simply don't run tank much below 1/2 full when on a track with this issue. Very much cheaper.

 

Will have a think, and thanks all for the advice.

 

It's not bad but not the best solution, damage wise a bigger problem historically has been caused by engine ancillaries i.e flaying belts, failed joints either through poor quality, poor fitting (too stiff considering the engine movement) and vibration. The fuel heating is another issue but dependant upon other factors as well. If you are going to fit an external swirl pot you also need an external pump as well so it may not be such a cheap option compared to a tank.

 

The five seconds you mention equates to a 500bhp engine at max power in a left hand corner, this is not very likely in a VX and at least some of the time you will be trailing into the corner and accelerating in a lower gear so a climbing power requirement. Realistically if you at 330bhp you should get 10 seconds at max power without a canister refill, this is probably closer to 15-20 seconds for the entire manoeuvre, if at any time the G is reversed the canister will refill to full in about 4-5 seconds.