k.russell Posted June 23, 2004 Share Posted June 23, 2004 going to fit injection to my 2L VX, considered making a swirl pot, have the equipment and know how but unsure of the size, looking at DT they have 1 and 1.5L tanks, I have some 100mm x 14swg(2mm) tube at work will this be ok, thought about 150mm tall, not done the maths but again if anyone can advise, the one I was shown at QED was much smaller in size, was going to weld on -6 jic fittings for feed from tank(via low pressure pump), -6 to fuel rail and -6 return, the have -4 from top to bleed into fuel filler where i can weld on a similar fitting, was going to stand the tank in the boot against the rear suspension turret. any info welcome , Kev. Link to comment Share on other sites More sharing options...
Wightwash Posted June 23, 2004 Share Posted June 23, 2004 Alright Kev, It seems to be accepted that a swirl pot should have a sufficent volume for the engine to run full throttle for typically 30 seconds or so (long bend!!!). Based upon formulae banded around quite commonly for a fuel injected 4 cylinder engine, your injectors require 4.8cc of fuel per minuite per Bhp. so for a vx putting out say 175bhp you will need 840cc/min of fuel supply. The swirl pot supplies the HP pump and should be overated, (people seem to go for 20-30%), so you get 1.3x840 = 1090cc/min. Therefore you require a minimum volume of 546cc, (basically a pint, think milk bottles), for 30 seconds. Based upon a 100mm dia 14swg tube you would only need it to be about 8cm tall ! At that height the swirl function maynot work all that well so you would end up using a taller tank, hence QED's (i havent seen it) is probably 65-75mm diameter and a bit taller. I am currently doing a carb to injection conversion using a 75mm outside diameter pot in 16swg stainless, 200mm high with 8mm inlet from tank, outlet to pump, return to pot from fuel rail and 6mm return to tank. this gives a volume of around 800cc. Its a good idea to mount the HP pump right underneath the pot so it is gravity fed. Hope this makes some sense and helps in some way. Happy swirling mate Cheers Chris Link to comment Share on other sites More sharing options...
k.russell Posted June 23, 2004 Author Share Posted June 23, 2004 Thanks Chris, the QED tank was about 75mm and about 175mm long, but i have seen stubbier ones, I can understand what you are saying regarding the tall thin cylinder though,will have a think before i go any further with the fabrication. where have you positioned your tank. Link to comment Share on other sites More sharing options...
k.russell Posted June 23, 2004 Author Share Posted June 23, 2004 Just had a look at SBD site, they kindly give a dimensioned photo of there tank designed originally for a caterham and the sizes are the same as you quote Chris, will try and scrounge some 75mm tube and start again, their tank i presume, sits upright on the rear bulkhead. Link to comment Share on other sites More sharing options...
Wightwash Posted June 23, 2004 Share Posted June 23, 2004 Glad to be of help. My tank will be mounted just behind the drivers side engine mount directly above the pump. Link to comment Share on other sites More sharing options...
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