Lotus Elan

Plus 2 fuel tank baffles.

PostPost by: dougal9887 » Sun Dec 18, 2016 1:50 pm

All my research on this site seemed to suggest that the standard tank did not contain baffles.
I therefore decided that I would need to use a swirl pot and all the associated paraphanalia to feed a fuel injection pump.
I have just removed the sender unit to install a return pipe and I can see that the tank does indeed contain baffles.
20161218_123738.jpg and
Plus 2 fuel tank baffles.

This is a road car so sustained high speed cornering isn't the issue, more of a short duration thing on say twisty roads or at a roundabout when the fuel will certainly slosh about and it looks like the tank would need to be really empty for surge to uncover the outlet (but I have no experimental data to justify that thought!). I can also see an advantage, in terms of better cooling, if the return fuel goes straight back into the main tank.
So now I'm thinking of gravity feeding the injection pump, with a pre and post pump filter, piped to the injector rail, regulator, then back to the tank via a fitting in the sender unit with a pipe terminating near the bottom of the tank.
However maybe this is insufficient baffling when using a high pressure pump?
And maybe a swirl pot has some other advantage, maybe fuel sloshing about in an emptyish tank gets air mixed in which a swirl pot should resolve?
What do you guys think?
Dougal.
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PostPost by: elanman999 » Sun Dec 18, 2016 5:18 pm

Whether those baffles in the pics are sufficient I cannot say but I know from the experiance of myself and others that insufficient baffling will cause misfiring. So IMHO you must either fit some more baffles in the tank or an external swirl pot.
When I fitted EFI to my +2 I just went straight to a swirl pot. At first I had gravity feed to the pot but I found that air got trapped in the pot and would not get up the vent pipe. Long story but basically when the tank is full the vent fills with petrol to the same level, any air that then gets into the pot is then trapped by the head of petrol on top. It did not cause misfires but every so often there was the great girggling sounds from the tank as things sorted them selves out.
I had to go the normal route and use a lift pump to feed the pot. This works fine.
It's not easy which ever way you go but only you can dicide. Or you could just buy an Axminster panels tank. :D
Cheers
John
Last edited by elanman999 on Sun Dec 18, 2016 5:53 pm, edited 1 time in total.
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PostPost by: dougal9887 » Sun Dec 18, 2016 5:39 pm

Thanks for the reply John.
Since I've got the swirl pot, lift pump etc I might as well fit it. Just thinking I might have gotten away without all that!
Dougal.
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