lesd Posted November 26, 2006 Share Posted November 26, 2006 Not sure if this has been done here, but here is my idea : Mount a coffee can sized surge tank inside the normal 240z gas tank. Have a low pressure fuel pump feeding it with that pump fed from the low point of the 240z tank, but outside the surge tank. It fills the top of the surge tank. The EFI pump feeds from the bottom of the surge tank, which is always overflowing with fuel inside the 240Z tank. So even if the gas sloshes around a lot, there is still a quart or so of surge tank reserve to keep the air out of the EFI system. No space taken up by external surge tank. The "cup always run-eth over" safely inside the main fuel tank. The low pressure carb type pump should flow at least 4 times the flow needed for the engine, so it can refill the surge tank ASAP when it gets starved on it's intake. Keeping air out of the EFI system is very important, as even a momentary lean out due to air can cause detonation on a turboed engine. Thoughts ? -Les Quote Link to comment Share on other sites More sharing options...
johnc Posted November 26, 2006 Share Posted November 26, 2006 That would work. The stock 240Z tank is pretty good and I've autocrossed it as low as 1/8 of a tank without fuel issues. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 26, 2006 Share Posted November 26, 2006 You can also do an external surge tank. Several people have gone that route. Tim240z had a pretty good post on his a couple years back if you search you'll find it. Basically works just like you said, doesn't need to be big, and just uses a carb type fuel pump to fill the surge tank with a fill and return nozzle at the top and the fuel feed to the engine at the bottom. Oops, I see now that you had already considered an external tank... Why do you think it's going to take up a lot of space??? 12 oz of fuel in the surge tank should be MORE than enough. The surge tank on carburetors is the float bowl, so it really doesn't have to be a large container at all. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted November 27, 2006 Share Posted November 27, 2006 Couple of other people have posted picks of sumps you weld onto the bottom of the stock tank. Seems like the easiest, cheapest and one of the most effective ways to do it. According to the post the key is to drill no more than 3 holes 1/2 inch in diameter to let the fuel in. Quote Link to comment Share on other sites More sharing options...
lesd Posted November 27, 2006 Author Share Posted November 27, 2006 I'm not 100% convinced that a shallow sump welded to the tank would be enough, without some flaps or other tricks to keep the fuel in there. On a car with a carb, the carb bowl takes care of fuel bubbles. I'm scared of bubbles in a fuel injection system, as I think it could lead to some dangerous detonation when the cylinders get only 1/2 a fuel shot. Turbo makes it even more sensitive. Maybe I'm being overly cautious, I don't know. -Les Couple of other people have posted picks of sumps you weld onto the bottom of the stock tank. Seems like the easiest, cheapest and one of the most effective ways to do it. According to the post the key is to drill no more than 3 holes 1/2 inch in diameter to let the fuel in. Quote Link to comment Share on other sites More sharing options...
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