mazmike

iTrader: (5)

please can someone help me and send me some pics on how to fit them .i have seen loads for sale, some with 3/4 and 5 out lets. all so how to wire the pump please

budd

iTrader: (5)

I'm in the process of fitting one at the moment, basically you need to get the hardware (swirl pot, external pump) plumbed in between the OE in tank pump and the fuel rail, how you do this can vary, and there are pros and cons between various methods.
Firstly how much power are you running (or intending to run)? this matters because it effects A. the size of the actual swirl pot and B whether 2 external pumps are necessary. If you require 2 pumps then the swirl pot needs 2x pump outputs.
Secondly normal rubber fuel hose is porous and bleeds vapour into the cabin causing at best a fuel smell and headaches and at worst well make sure you've got 999 on speed dial. The way round this is to use PTFE /Teflon fuel hose (braided TTFE is mandatory for MSA sanctioned Motorsport if the hose runs through the drivers compartment)
The problem with PTFE / Teflon pipes is they need AN fittings, using AN fittings also means problems integrating the new pipe work with the old, the OE system uses rubber hose held with hose clamps, AN fittings are an assembled joint that isn’t readily compatible with push fit hoses, you can use AN > push fit adopters, but the best solution is replacing the whole fuel system, this gets very expensive when start adding the cost of the hose and all the individual AN fittings. And this is before you buy the swirl pot and new pump.

But before this puts you off it is possible to do it on the cheap, OK you don’t get all the nice braided hose and sexy blue and red alloy fittings but you will save an awful lot of money.
Here’s what I did, used 1.5 litre swirl pot with push fitting 1x 12mm output (to external pump), 2x 10mm inputs ( 1x feed from OE pump, 1x return feed from fuel rail) and 1x 8mm output (overflow return to tank), used Bosch Motorsport fuel pump (a 013 rather than a 044), this lot is piped up using marine grade fuel hose and clamped push fixings. All this as cost me around £150 all in and although is been done on the cheap it will be perfectly functional.
I’m not sure how porous the marine hose is compared to normal hose but I can’t imagine fuel vapour trapped in a boat is a good thing so I’m assuming it’s a lot better, but vapour still may be an issue in a road car, it’s not a problem for me because mine as a MSA spec sealed firewall that isolates the drivers compartment from the boot where the hardware and internal hoses are, by retaining the OE internal metal fuel lines I don’t need to use PTFE hose as the metal OE pipe is non porous so no vapour in the cabin.
At the moment mine is all plumbed in ( I’ll post a pic later) it just needs the Bosch pump wiring in, I’m currently looking into the best method of doing before I see if it all works.(fingers crossed)
Another thing to consider is the fact fitting a external pump can change the furl pressure at the rail (even with the stock regulator) if this is the case you will need a remap to correct the fuelling or an adjustable reg to lower the rail pressure.
I know this a large post but this isn’t as simple as it appears (few this are with car tuning) and I’ve probably missed out some things but I hope it helps.

MartynJ

Very well put together informative post, the only thing I will add to it is. To save the hassle of firewalling, we have been known to fit small 1 litre swirl pots under the bonnet, passenger side mounted on part of the chassis rail.
From memory Mikes car already has a catch tank mounted there, so unfortunately unless that is relocated, it's going in the boot on this one.

budd

iTrader: (5)

Yes I've seen them under the bonnet, and if you can make it fit it solves some of the problems but as you say space can be abit tight and if fitting under the bonnet it needs to be as close to the n/s baulkhead as possible away from crush zones and heat sources (turbo), I saw one fitted in the battery space (battery relocated) really nice tidy instal but IMHO way to close to the front crush zone, in an impact the last thing you need is 1 litre fuel in an area likely to be deformed in a front end crash..

Same applies to a rear install, make sure the hardware is well away from possible impact zones, between the rear wheel arches is most popular and I'd say the best and safest position, but it's not uncommon to see them right behind the o/s or n/s rear light unit or in the spare wheel well or strapped to the underside the o/s rear corner all these positions could cause problems in a rear end shunt.

no_more_oil

just to confirm chaps :-)
is this diagram right for an Imprezza fitment?



My catch tank is mounted on the passenger side chassis rail but I like the
sound of going under bonnet if I can squeeze it all in. :-)

what BHP is the limit of a 1L pot?

PS: I already have a high pressure pump so I guess that is replaces the low pressure pump in this diagram?
Or do I need to stick 2 high pressures after the swirl pot? Ah **** I've not got the hang of this yet have I! ;-)
M

mazmike

iTrader: (5)

that looks good

budd

iTrader: (5)

That diagram looks the exact same as every other swirl pot diagram I've seen. Some pots very with where they put the fittings but they all run in the same configuration.

When you say you already have a high pressure pump do you mean in tank?

Re 1 or 2 pumps; usually one external pump is enough to supply the rail, I'm using a single Bosch Motorsport item that will be more than enough (over kill in fact) for circuit racing, I'm limited to 286bhp by Subaru Cup production class regs, at this low HP the engine won't be demanding massive amounts of fuel.
My reason for fitting a swirl pot is to combat fuel starvation, due to the design of the Impreza tank once the fuel level starts to drop fuel starvation is a very real problem on long / high G corners, the swirl pots solves this issue.
However if real big HP is planned or drifting /drag racing then a simple system my not be up to it, a larger capacity pot, multiple pumps, revised fuel line bore size etc etc may be required, if this the case then best approach would be to re-design the whole fuel system from tank to rail, build a no compromise system with enough 'headroom' to cope.

re swirl pot size; I found this on NASIOC it uses Nissans as examples but the principles are the same for any car and the math can be used to work out Impreza fuel usage.

There seems to be a lot of debate regarding how big you should make a fuel surge tank. Everybody will give you a diffrent answer from no surge tank at all to 3L. Some people even claim you need a 5L one for drifting

So I'll try and clear it up for you (the way I see it, if you think I'm wrong please abuse me!)

The size of your fuel surge tank really depends on your engines fuel system. You can use maths to work out how big it needs to be:

Take for example a RB30/25. It runs 6 fuel injectors that flow 270cc (270ml) of fuel per minute at 43psi (2.96 bar) at 100% duty cycle

Therefore your total maximum fuel flow is 1.620L per minute. This figure is calcuted by multiplying your number of fuel injectors by the size of your injectors.

So in a surge condition in your fuel tank when your lift pump is sucking nothing but air a 1.620L fuel tank will give me a whole minute of surge "protection"

But really the sort of turn that would create a condition like that would have to be a big one. I mean how many places are there where you can pull a high G turn like that for over a minute (beside the donut pad!) I doubt that drifters can hold a high G drift without changeing direction for over a minute. So what I do is half that figure.

So now I'm down to a 810cc (.81L) surge tank. Its small and compact and gives me a whole 30 seconds.

Now before somebody shoots me down this only applies to a N/A EFI engine. To apply it to a boost engine (be it turbo or supercharger) you'll need to factor in how your fuel pressure regulator works.

To clear a few things up, the fuel pressure regulator changes the fuel pressure depending on the pressure conditions in the inlet manifold. For example on a N/A engine at full throttle you will get zero manifold vacume. For every PSI of inletmanifold air pressure you put into that the Regulator will add a extra PSI of fuel pressure to your injectors. This will increase your injector flow by a few CC a min.

Say if I was going to throw 10psi of boost into my N/A RB30/25. The fuel pressure regulator would "see" 10psi of manifold pressure and increase the fuel pressure by the same amount. My 270cc injectors are now 332.79cc injectors.

To get this figure you divide your injector size by its base fuel pressure (43psi for most Nissans) So my 270cc injector will flow a extra 6.279cc of fuel for every extra PSI of fuel rail pressure. So 10psi of boost will cause the regulator to add 10psi of rail pressure which adds a extra 62.79cc of injector flow.

Now we times this figure by the number of fuel injectors I have and then divide it by 2. We get a result of 188.37

Simply add 188.37 to our prevously calculated surge tank volume (810ml in this case) and we have our surge tank volume -- 998.37cc -- 998.37ml -- Almost a Litre in english!

See so simple As a example I'll work it out for a SR20DET that runs 7psi of boost pressure stock

370cc (injector size) x 4 (number of injectors/cylinders) = 1480cc <-- Fuel used at 100% cycle

1480cc / 2 = 740cc <-- divide by 2 to give you 30 seconds of "protection"

370cc (injector size) / 43psi (base fuel pressure) = 8.6 <-- Extra cc of fuel flowed from injector when another psi of fuel pressure is added to the rail

8.6cc (extra fue when adding 1psil) x 7psi (boost pressure) = 60.23cc <-- extra fuel flowed through 1 injector at 7psi of boost

60.23 (extra fuel when adding 7psi) x 4 (number of injectors/cylinders) = 240.93cc <-- Extra fuel flowed at 7psi of boost

240.93cc (extra fuel) / 2 = 120.465cc <-- 30 seconds of "protection"

120.465mm (extra fuel from 7psi of boost) + 740cc (calculated surge tank size) = 860ml

Now as you can see depending on how much boost you run, and how big your inectors are (not to mention fuel pressure) all play a part in saying how big your tank will need to be. I have not taken into account riseing rate fuel pressure regulators. They alter the rail pressure at a diffrent rate to your boost pressure eg 1:1.5 make sure you include this in your calculations.

You also have to realise that not many EFI tuners like to run injectors at 100% duty cycle. And its very rare to run a motors injectors at 100% duty cycle. The fuel surge tank takes care of a "worst case" scenario.

Some people also like to over size their tanks to accomadate more boost etc. Thats fine the problem is you can go tooooo big and have the same problems with your fuel pickup like in your stock tanks. The tank should be tall and narrow, to get as little fuel "slosh" as possible. It *must* be mounted vertically.

Hope this helps.

budd

iTrader: (5)

a few pcs of my ongoing install;
this shows the stock pipe layout, you need to connect to these n3 is the in tank (low pressure) feed to the swirl pot, no 2 is the retuen from the rail, this needs to be re-routed to feed the swirl pot rather than straight rather then feed straight back into the tank, the overflow from the swirl pot returns excess fuel here. pipe no 1 is the feed to the 'jet' pump within the tank and should be left untouched, (this basically draws fuel from the N/S half of the tank to supply the O/S half )


pic below; final position of swirl pot in boot, note alloy firewall to isolate hardware from driver.


below all laid out in final positions, to route hoses I welded some short lengths of tube into the floor I'll seal with Sikafex on final assembly, the 2 hoses on the N/S are main feed from external pump and return feed from rail as you can see this now goes to the swirl pot rather than back to the tank, the other 2 hoses are feed to pot from in tank lift pump and finally the hose out of the top of the pot is the overflow back to the tank, the only hose missing is the swirl pot out let to the main pump but it's easy to see where it goes, I'll also include a fuel filter between the pot and the pump, I think once it's all finished and painted it will look OK, then the firewall will cover it all up see final pic.


firewall

no_more_oil

very interesting budd, thanks for the post and the maths to back it all up.... I'm slowly starting to make sense of it all. :-)

mazmike

iTrader: (5)

hi i am going to use goodridge 811 hose how can i join the hose to the subaru in tank pipe which is solid pipe (pipe 3 in above post please) cheers

no_more_oil

@mazmike - I'm guessing you are aiming at 500+ ? I'd be interested to see what swirl pot and pump set up you actually go for if you are aiming at those figures.

Are you running 800cc injectors?

mazmike

iTrader: (5)

looking at 460bhp as turbo is sc46.spec r are getting back to me with a swril pot .going to use a bosch 044 pump sytec filler been .been to merlin motor sport (castle coomb race way) to day going to use goodridge 811 hose as no fuel smell pumbing it in is ok but not to shore on how to fit hose to in tank pump as the pump has i push on end and the goodridge hose is not .been told to do a proper job (race regs) no jubile clips

mazmike

iTrader: (5)

yes using lateral 800cc injectors

no_more_oil

sounds good... keep us informed as to how you get on. I'm def looking at doing the same but would like to go under bonnet.

@budd - I have a Walboro 255 in tank.

Looking to go 500+ on 20% meth so presume I'll be ok on the current fuel lines (standard I think?)? Not sure of their flow capacity?

Anything else I should consider due to the Meths whilst I'm speccing this up???

Interesting the boost factor in the maths in budds post.... I run close to 2bar and had never factored this in before.

mazmike

iTrader: (5)

here is a pic of my swirl pot just fitted what do you think

jason_2801

iTrader: (2)

On these setups can a walbro pump be used as the low pressure pump

mazmike

iTrader: (5)

fitted mine today with 255 in tank drove it around the block ,worked ok having it maped at enginetuner in morning

jason_2801

iTrader: (2)

Spot on although mine is a long way off needing this yet need to sort out why the previous owner decided not to put much antifreeze in thus resulting in the car overheating and the heaters being stone cold. I am planning on doing a big bhp engine build though as money allows maybe sooner than later if my engine is damaged

budd

iTrader: (5)

That looks a real nice install

you can use a Walbro but in most cases it's not necessary as the pot is been back filled with the return fuel flow so the OE pump is adequate, assuming it's in good order, so the extra £70-80 for a Walbro isn't a bad investment, belt and braces etc

no_more_oil

@mazmike

looking good fella!

let us know how the mapping went and also what feedback you got from Martin on your swirl pot install. :-)

mazmike

iTrader: (5)

hi mate @ no more oil


martyn said it looked fine and pumbed in and wired up right

had it mapped to day map 1/ 410 bhp 370lb
map 2/ 420 bhp 440lb have left my car there had a change of mind and going to have a sc50 fitted and going to run 10 % meth.picking it up next week

no_more_oil

440lb is pretty good on the 2nd map. was that maxing out the sc46 then?

any ideas what you can achieve on the 10% meth and sc50 or is it just what ever Martin can squeeze out of it?

mazmike

iTrader: (5)

not to shore if it was maxed out but he said it should have more bhp so sc said they would just replace it

no_more_oil

really! is that free of charge £££ then?

mazmike

iTrader: (5)

yes mate but my turbo is new sc are very good about it so is mj.it all baffles me .boost /spool/lag.just looking 4ward to getting it back .sould be good the sc 46 was wicked so the sc50 mite be better

Dazza9t9

iTrader: (2)

At what point do you need to consider a swirl pot?
My wrx classic is pretty much standard at the moment but it is off the road while i do some work on it.

One thing i was looking at was a swirl pot prior to getting it remapped. Would i need one at this point or would a walbro intank do?

Or would it be ideal time to do it while it is off the road to future proof it as it were?

mazmike

iTrader: (5)

hi mate a swirl pot doz to things keeps engine supplyed with fuel at high speed cornnering . walbro can max out at about 450bhp .i am looking at a bit more than that + using meth .but i am not the best person to ask as its all new to me

dazdavies

iTrader: (22)

I have a similar set up on mine.
Walbro 255 intank lift pump.
SM Engineering 1.5 litre swirl pot
Single Bosch 044 fuel pump
and Injector Dynamics 1100cc Injectors

This setup proved good enough for 601 bhp on Friday when it got mapped.

Dazza9t9

iTrader: (2)

By the sounds of it for me and the for the time being a in-tank walbro will be in order. Then in the furture up-grade to a swirl pot!

Great thread tho, keep it going

mazmike

iTrader: (5)

your 255 will not be any good @500bhp .this is that i done . if you have spent the money getting a 500bhp engine ,thats a few quid more mine this £125 new