Swirl Pot

Rick S. · 08-22-07, 11:47 AM

What's the function of a Swirl Pot? Gas is pumped from the tank to the swirl pot, then from the swirl pot to the carb/injection system. Is it's function to supply a steady "bank" of fuel to the motor?

I'm visiting RCR next tuesday, be great to see Fran's new building. Will take pics and post them if they turn out. Sometimes my camera skills are shaky...

Dutton · 08-22-07, 12:23 PM

If you think your camera skills are a bit shaky now, Rick, just wait until you get a good look at the inside of Frans shop... shaking knees combined with some serious drooling won't help your photography skills one bit!

As the new RCR shop is just up the street from the old one, it's should still be a breeze to find. If I remember correctly, it's about 30 minutes from the airport. Have a good look at a map when you pick up your rental car, get yourself onto Groesbeck Hwy and your set.

If you have some extra time, HIGHLY recommend you take in the Henry Ford museum if you hadn't already seen it. Some pretty remarkable things in there. If you're fond of the color red on a GT40, you'll especially enjoy what you find inside the HF...

Best,

T.

jyrki · 08-22-07, 12:39 PM

Put me right if i`m wrong:
i have in rallycars swirlpots (original factory-team built), and they are for hot water which is coming out of engine and before it goes into radiator, air is separated from water in swirlpot.
If same name is for "gas/fuel container" (?), i think the idea is anyway secure that the engine is getting gas without any cut-off in delivery. In basic, getting air out of gas, too

Rick S. · 08-22-07, 04:11 PM

I like red...red hair, red lace, high heels (not on me), GT40's...

Really looking forward to meeting Fran as he has been a great resource to this forum, and getting a peak into his shop. Won't be able to buy anything right now as we have a bunch of home improvements going on ....but this will establish a serious quid-pro-quo situation with the other half that should allow business with Fran...

Mesa · 08-22-07, 04:21 PM

Yep, the Henry Ford Museum is a MUST see for gearheads.....for sure Ford flavor gearheads. I had a few hours to kill on a business trip once and I nearly broke my neck zipping through the place. Well, well worth a visit. Been out to see Fran a few times since but have never had time to get back to the museum, yet.

Mark Worthington · 08-22-07, 04:54 PM

Quote:

Originally Posted by jjs

Put me right if i`m wrong:
i have in rallycars swirlpots (original factory-team built), and they are for hot water which is coming out of engine and before it goes into radiator, air is separated from water in swirlpot.
If same name is for "gas/fuel container" (?), i think the idea is anyway secure that the engine is getting gas without any cut-off in delivery. In basic, getting air out of gas, too

You have the idea right, although the terminology I've heard is different. As far as I know, swirlpot = gasoline, while header tank = coolant.

Ian Anderson · 08-22-07, 05:18 PM

Rick

I'll try to answer your question

The swirl pot is used on the GT40 as a "holding tank" for a small quantity of fuel so the high pressure pump has a constant source of fuel to feed to the fuel rail.

The reason being in the 40 the tanks are long and thin and under braking the fuel will slosh away from the rear of the tank leaving the fuel outlet dry and the pumps will be pumping air.

Now on a carb fed variant it shoud not pose a problem having the pumps gulp some air as the carb bowls will hold enough until the fuel flows again but in EFi the fuel rail has no such carb bowl so it will run dry and the engine cut out.

So you ask why does my road car not need a swirl pot? Well in most modern cars the fuel tank has a small sump from which the fuel is drawn - this in effect is the swirl pot, but forms part of the main tank.

The others on this thread have mentioned swirl and header tanks on the cooling system - both can be used and some units are both a swirl and header in one. The header tank allows room for expansion of the fluid and the swirl is a collecting vessel from various points on the engine from where the liquid is drawn by the pump / flow system.

Ian

Gary Kadrmas · 08-22-07, 05:45 PM

Help me think through this........

My Cobra has a dual 4 Holley set up (factory), and the set up has a fuel log. ie: a large tube running besides the side of the carbs, and the tube is about 1" in diameter, to allow for some fuel storage. The fuel delivery is connected to this tube or fuel log. Did the GT40s not come with something similar?

Dean Lampe · 08-23-07, 01:06 AM

I am currently running a swirl pot on my RCR for exactly the reasons given. I am running webers and they have very small floats. I am also running a bypass regulator to help increase available fuel with low pressure. I believe it is cheap insurance against leaning out a very expensive engine. The RCR has a swirl pot built into the chassis.

Rick S. · 08-23-07, 12:28 PM

Thanks Ian and Dean for the education. Very helpful!

Chuck · 08-23-07, 10:43 PM

At the risk of showing my ignorance, if one always keeps a few gallons of fuel in the tank so that the fuel pickup sucks only fuel, not air, will a swirl pot be necessary? I suspect this is needed for serious racing, significant G's on the curves, and going as far a possible without refuelling. Am I missing something?

raca · 08-24-07, 04:42 AM

i believe the problem was the long shape of the tanks...

i suspect you don't need to try to hard to get the fuel sloshing about

Peter D · 08-24-07, 05:17 AM

A friend of mine has an RF with the so-called built-in swirl pot at the back of one tank, connected directly to the main tanks via a small low-level connection pipe/aperture. All was fine for normal up/down hill driving, but when parked facing downhill for some hours with low tank fuel levels, all the fuel drained forward into the main tanks & the car had no fuel delivery until he ran it down the hill onto level ground to back-fill the low level "swirl pot".

So I guess that the lesson was to have a separate swirl pot with the LP input & tank return towards the top of the tank, & with the final fuel delivery (LP for carbs, HP for EFI) out of the bottom of the swirl pot & return to the top.

Kind Regards,

Peter D.

Ian Anderson · 08-24-07, 08:43 AM

On the Dax with anything less than 1/2 tanks I can get the pumps to suck air when slowing for lights or similar. (So not even really trying)

As soon as stationary or back on power the air pumping stops.

This is another reason for the fuel swirl pot as it will allow some arated fuel into the pot and the bubbles escape back to the tank via the return. Whoever first made the idea was a clever bloke!

But I don't think the Dax has any internal baffles in their tanks. And likewise not foam filled - both things are used to stop the slosh!

Then again the secret is to keep on the loud pedal!

Ian

Dean Lampe · 08-24-07, 09:49 AM

To make it work properly, you will need to pump out of the main tank into the swirl, then out of the swirl through filter past carbs through bypass regulator back to swirl. Excess fuel should be able to flow back to main tank through an over flow line. With the RCR the tanks are baffled so I think you would be okay for most application without it. I think it is great for open track cars.