Discussion
I thought I was sure ! Just used the model number from my pumps (factory supplied) GP4601HP and plugged it into summit. It was a good number of year ago when I wrote them down so I guess I could have made a mistake or the spec has changed since then. I'd go check but I'm half way around the world from my car at the moment.
Russ.
Russ.
RussF said:
I thought I was sure ! Just used the model number from my pumps (factory supplied) GP4601HP and plugged it into summit. It was a good number of year ago when I wrote them down so I guess I could have made a mistake or the spec has changed since then. I'd go check but I'm half way around the world from my car at the moment.
Russ.
They have probably changed the spec in that case.Russ.
I am amazed that no one knows the answer to this or has a pump in hand to check?
We need to know the flow rate, as we are going to return the rail to the tank rather than back to the swirl pot, so we want to ensure that the pump is capable of supplying enough fuel to the swirl pot under race conditions/constant fuel throttle without relying on the bleed back from the fuel rails.
We need to know the flow rate, as we are going to return the rail to the tank rather than back to the swirl pot, so we want to ensure that the pump is capable of supplying enough fuel to the swirl pot under race conditions/constant fuel throttle without relying on the bleed back from the fuel rails.
Forgive me if I am wrong but I don't think that the flow requirements from the LP pump will change.
It wil be spec'd to supply more than enough fuel than the engine uses at full throttle. The engine is not going to use any more fuel with a different plumbing arrangement.
What did flow back to the tank still will only via a different route. Now you will have the same amount in total from 2 sources.
The return from the reg and the return from the swirl pot.
You must have a return from the swirl pot to clear any air/vapour.
If it was ok up to now then it will be OK with the new plumbing solution.
It wil be spec'd to supply more than enough fuel than the engine uses at full throttle. The engine is not going to use any more fuel with a different plumbing arrangement.
What did flow back to the tank still will only via a different route. Now you will have the same amount in total from 2 sources.
The return from the reg and the return from the swirl pot.
You must have a return from the swirl pot to clear any air/vapour.
If it was ok up to now then it will be OK with the new plumbing solution.
Back in the UK now so just checked....I had made a mistake, doh! they are GP4600HP --> http://www.summitracing.com/parts/CRT-P4600HP/
Same flow rate (100gph) but lower pressure 5psi, which correlates with Steve_D's comments.
Same flow rate (100gph) but lower pressure 5psi, which correlates with Steve_D's comments.
Can someone tell me why we get air in the swirl pot.
I know you can get air sucked in by the LP pump if the tank is empty but you should avoid this.
Vapour should not be a problem if the fuel is not being boiled by the engine (which is never good).
So if you avoid pumping air and boiling fuel why do you need a return from the swirl pot? The LP pump would then be able to be an "on demand" pump which when it reached pressure it would stop. With a 2 to 3 litre swirl pot you should never run short of fuel.
The LP pumps mentioned have capacities well above what the engine can consume (at least 400%) so why do they have to run continuously?
I know of no production car or vehicle that have LP pumps that pump fuel continuously but instead they pump "on demand up-to pressure" and this includes engines that consume way more fuel than we could have nightmares about.
HP pumps often do have over-supply returns but it is usually a low volume that is returned to the tank.
I know I have said most of this before but I still haven't been convinced by the replies I've received.
Paul
I know you can get air sucked in by the LP pump if the tank is empty but you should avoid this.
Vapour should not be a problem if the fuel is not being boiled by the engine (which is never good).
So if you avoid pumping air and boiling fuel why do you need a return from the swirl pot? The LP pump would then be able to be an "on demand" pump which when it reached pressure it would stop. With a 2 to 3 litre swirl pot you should never run short of fuel.
The LP pumps mentioned have capacities well above what the engine can consume (at least 400%) so why do they have to run continuously?
I know of no production car or vehicle that have LP pumps that pump fuel continuously but instead they pump "on demand up-to pressure" and this includes engines that consume way more fuel than we could have nightmares about.
HP pumps often do have over-supply returns but it is usually a low volume that is returned to the tank.
I know I have said most of this before but I still haven't been convinced by the replies I've received.
Paul
Storer said:
Can someone tell me why we get air in the swirl pot.
The air or more likely some other gas (i'm not a chemist) is caused by cavitation at the entry to the HP pump. The pressure is reduced as the pump sucks and the gas forms. This is why people are talking about putting a restriction in the swirl pot return so that the LP pump creates a small pressure in the pot to reduce the cavitation.Steve
Can someone tell me why we get air in the swirl pot.
Unless your swirl pots/headers were pre-filled, remained at constant coolish temps and never changed pressure you will always get 'gasses' (fuel vapour) but not neccessarily air.. Its merely the fuel changing state... remember the old days of physics... water doesnt have to boil to evaporate ... neither does fuel. In fact petrol evaporates like the clappers even at low temps.. and in doing so expands (as it changes state to gas).. SO gases are formed wherever a fuel volume exists and temp/pressure change can occur.. (latent heat of evaporation)
Fuel is so good at absorbing heat energy it was frequently used by the military to cool bottled beers in hot locations..
Give a liquid pump a few gas bubbles to play with and it will frequently mis-behave...particularly if it relies on the liquid to cool itself...then the problem just multiplies.. more heat, more evaporation, more gas bubbles.. etc etc.. The key is to always have fluid present in the pump and encourage any supply vessel to breath away gases (bubbles or airborne)
All good fun.
Unless your swirl pots/headers were pre-filled, remained at constant coolish temps and never changed pressure you will always get 'gasses' (fuel vapour) but not neccessarily air.. Its merely the fuel changing state... remember the old days of physics... water doesnt have to boil to evaporate ... neither does fuel. In fact petrol evaporates like the clappers even at low temps.. and in doing so expands (as it changes state to gas).. SO gases are formed wherever a fuel volume exists and temp/pressure change can occur.. (latent heat of evaporation)
Fuel is so good at absorbing heat energy it was frequently used by the military to cool bottled beers in hot locations..
Give a liquid pump a few gas bubbles to play with and it will frequently mis-behave...particularly if it relies on the liquid to cool itself...then the problem just multiplies.. more heat, more evaporation, more gas bubbles.. etc etc.. The key is to always have fluid present in the pump and encourage any supply vessel to breath away gases (bubbles or airborne)
All good fun.
Edited by 738 driver on Friday 9th December 09:13
Edited by 738 driver on Friday 9th December 09:35
Storer said:
Steve
OK I can understand that thinking, but surely a LP pump that pumps up to a pressure (6 to 15psi) before shutting down would give that pressure bearing in mind that it will pump far more than the HP pump will?
Paul
The sort of LP pumps we use are pressure regulated internally but do not shut down when they reach pressure.OK I can understand that thinking, but surely a LP pump that pumps up to a pressure (6 to 15psi) before shutting down would give that pressure bearing in mind that it will pump far more than the HP pump will?
Paul
Steve
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