E30 Zone

Hi all,
following my first dry track day in my little track toy (325) I experienced a problem that you may be able to advise me on? When I had warmed up mid way through the day I started experiencing problems coming out of right hand bends, the engine would cough & splutter. It didn't happen during left hand bends or if I took it a bit easier so I wondered if was due to the fuel in the tank slopping to one side.
Is this a common problem? Is there a standard track/race mod that needs to be done? Is the fuel pump/filter to blame? Oh, the car started life as a 316 so could that have an impact?
Any advice would be appreciated

If you're regularly using it on track and this is happening then you'll need to baffle the tank (Don't ask me how on the OEM tank) with some special foam blocks to prevent it from happening.

easiest way would be to fit a swirl pot between the tank and engine to prevent this.

We have had this a lot. I understand a swirl pot is the fix (although i have no idea what it is and where it goes). Potentially worth relocating the tank to the spare wheel well at the same time.

moggy wrote:We have had this a lot. I understand a swirl pot is the fix (although i have no idea what it is and where it goes). Potentially worth relocating the tank to the spare wheel well at the same time.

your tank can stay, a swirl pot is just a buffer of 1-2 liter of petrol to make sure the main pump is fed all the time.

When you corner hard round right hand turns the fuel in the tank is pushed over to the left hsnd side but the pump pick up is on the right hand side of the fuel tank. So no fuel for the pump!

A swirl pot can be fitted in the boot and is fed via the intank lifter pump. The fuel return (which currently feeds back in your main tank) is also feeding the swirlpot to make sure it satys full at all times. Once the swirlpot is full there is an overflow line feeding excess petrol back to the main fuel tank (instead of the old fuel return line).
To summarise it, the swirl pot is fed by TWO lines and this makes sure there will always be fuel for the main pump.

Only short term solution for you problem is to fill up above 1/4 tank (this is when my car starts bogging down)

If you have a two pump setup, make sure your lifter pump in the tank is working.

Thanks for your advice guys.
UweM3, it first happened when the tank fell just below half full so I topped it up to see if it would solve the problem. My friend then took it on track and it seemed to be fine.....until I took it out again (I think with it being my car I pushed it a bit harder?!) and it started happening again but this time with over 3/4 of a tank of fuel.
You say there could be 2 pumps & one faulty? Where are the pumps, I'm assuming the lifter pump is the thing in the top of the tank behind the driver? Where's the other?
Cheers

Tommoed wrote:Thanks for your advice guys.
UweM3, it first happened when the tank fell just below half full so I topped it up to see if it would solve the problem. My friend then took it on track and it seemed to be fine.....until I took it out again (I think with it being my car I pushed it a bit harder?!) and it started happening again but this time with over 3/4 of a tank of fuel.
You say there could be 2 pumps & one faulty? Where are the pumps, I'm assuming the lifter pump is the thing in the top of the tank behind the driver? Where's the other?
Cheers

I only know my way round the M3, but there are two setups of pumps on E30's as far as I know.
One with TWO pumps, one lifter in the tank and the other in front of passenger rear wheel and the other with only ONE pump in the tank. Don't knwo if this is down to face lift model or engine size but I am sure if there is a pump under the car you will find it. Also worth noting is that the fuel filter on the two pump cars is in the engine bay.

Have a look here fella.. (bottom of the page)

http://www.team156.co.uk/pbmw_build_photos_005.asp

We have recently got a swirl pot fitted in our production bmw race car, the reason for which was two-fold, firstly we experienced fuel starvation around long right handers, such as the last sequence at brands, meaning we had to run at least 5/8 to 3/4 of a tank there at all times, and we were also about 20kg over the base weight for the series.

We got the swirl-pot fitted by koba racing and tested it at a trackday on the 1st. Koba also supplied all of the braided fuel lines, the extra pump (our car is a 1 pump late 320i) and a new fuel filter, we got the actual swirl pot itself from someone on the www.pbmwc.co.uk site.

^^ How much did that all cost?

Tommoed speak to nigel at CDH. If you need a number to contact him PM me.


I've got a 20L baffled tank if anyone is interested. Good for half an hour around Brands on a fill.

PM for details.

I was chatting to a chap yesterday - apparently fitting a 318 pump is a cheap way of sorting out fuel starvation...

moggy wrote:I was chatting to a chap yesterday - apparently fitting a 318 pump is a cheap way of sorting out fuel starvation...

tell us more please......

Uwe - I don't know the technical details as I was talking to the chap about a lot of things we need done to the car (guy is a specialist e30 mechanic and was recommended to us). Possibly the 318 pump fits in a slghtly different way?

I can try and find out more details if you want.

My 318i suffered the same, mine now runs a swirl pot setup.

Black_Potato wrote:My 318i suffered the same, mine now runs a swirl pot setup.

that's why I am asking. The 318 is no different than other E30's.
The E30 tank is split into two halves by the prop. If all the petrol is in the left hand side of the tank, there is nothing for the fuel pump to suck. I am planning of making a swirl pot and fit it to the left hand side of the boot next to the suspension turret. right after I have finished the other 100 jobs I have to finish to get my car back on the road

Our swirl pot and the covering plate came from CDH (Nigel) since we needed an extra pump and a new fuel filter and were playing with fuel, we decided to let koba racing do the fitting etc, since they were quite local to us.

Suppose the total cost was about £350, but it's worth it to get down to the base-weight for the series and to stop our fuel starvation problem - we recently ran a simulated 15 min race session at a track-day with the fuel light on with no problems!