Cavitation

[Dr Goggles]

 Hi all
I'm in the process of making a new fuel tank for the lakester , from aluminium( sp).......what I was interested in was whether anyone had any particular ideas about how to guarantee that the outlet doesn't cause cavitation because we'll be using an external fuel pump and it seems that's what it may have been doing on the current fuel tank.Is it just a fine screen that I need or a sintered filter , or what? ideas on the best way to sump the bottom of the tank would also be gladly accepted.The tank is 14 inches wide , 6&1/2 deep and about 10 high with mitered top corners.

Thanks

[1212FBGS]

hey doc
funnel the bottom and run more fuel than needed, using fuel weight as pressure always helps the pickup feed. is it a bypass fuel return system? if yes use some reticulated fuel tank baffling to eliminate aeration caused by the returning fuel, and have the returning fuel at opposite sides of the feed pickup tube
kent

[Rex Schimmer]

Doc,
With an external pump you should put the pump as close to the tank as possible, I would highly recommend that you don't use any type of screen or filter on the inlet to the pump just make sure that your tank is real clean before you put fuel in. Also if the pump inlet is say 3/8 inch use a step up adapter and run a 1/2 inch line. Pumps like to make pressure not suck so you don't want to restrict the inlet. If you run a filter put it on the pump outlet side and make is around 10 micron, and make it about twice as big as you think it should be. Be sure to vent the tank and if you can make it deeper than 6 1/2 inches your pump will like it better. Adding a sump that will make the amount of fuel above the inlet is a great idea, also if you do put a vertical plate across the sump, above the pump inlet it will prevent the fuel from votexing which causes cavitation.

Rex

[Stainless1]

DrG
Are you feeding a low pressure or high pressure pump?  We have a #10 line from the tank to a Holly red, about 10 inches and pump is mounted even with the bottom of the tank, then 5 feet of #8 AND a large filter feeding the high pressure fuel pump.  High pressure is a #6, return is a #6, vent is a #8, Fuel tank is filled with Fuel Safe foam.
Of course we were feeding 1 liter when we designed it, now we feeding 1.5, but it seems to be doing OK, never had a starvation or cavitation issue... 
Hope this info helps, try to deliver way more than you need 

[Dr Goggles]

...Thanks gents , I just had an idea .I had wondered about putting a vertical plate above the outlet  and whether it would stop vortexing (I thought it might just cause multiple smaller ones) .....I'll put a horizontal baffle above that vertical piece ( like a t shape ) so even if it does want to vortex it won't pull air .yes it is a bypass return system and for the record we have 1/2 inch line from the tank to the pump which is a big bosch jobbie out of a 560 I think and a 1/2 inch steel bodied filter before it ...yes I will be putting an angled baffle for the return to run down so it doesn't aerate the remainder in the tank ...On a lighter note my neighbour went nuts last night when I was cutting the Al plate for the tank , yeah OK it was 8pm and he's a trucker who starts early ...I think I'll be buying him a six-pack.....I've got a lot of noisy stuff I do 

once again thanks for the ideas....

[Xea]

To avoid issues, run the pickup at the rear of the tank.

[ddahlgren]

an LSR car or bike at least on the salt can only make about .6 g accell.. don't get your shorts too bunched up over exotic pickup stuff. Keep the pump low and close to the tank with a suction line about twice the area of the pressure and life will treat you kindly.. Avoid a fine filter in the suction side at all costs though any filter there is a problem waiting to happen. Most pumps can pass some pretty grim looking stuff with no ill effects put the micron type filter on the prtessure side and consider the pump disposible if there is a massive hunk of FOD.. You are sort of filtering the fuel from the clean can to the clean cell right??
Dave

[JackD]

Remember, your VORTEX goes the wrong way so he swirlier stopper has to work on the other side.

[Dr Goggles]

don't get your shorts too bunched up over exotic pickup stuff.

Last year when the Amo brothers were here I was talking to Jon at one point and he seemed distracted , it was one of those moments when you slow down and think " what's he lookin' at?".....he was looking at my shorts ....stretchy, tight football shorts the like of which I don't think Jon had seen or would be seen dead in

Keep the pump low and close to the tank with a suction line about twice the area of the pressure and life will treat you kindly..
Dave

that's pretty much how it is ....and it all seems to be working A OK.

JackD wrote:Remember, your VORTEX goes the wrong way

uh, uh , our vortex goes the RIGHT way
thanks Gentlemen