DrMayf is quit correct in his statements but there is one more
qualifier. According to a tubing catalog I have 5/16 tubing comes in 5
different ID's from .182" to .248" and 3/8 tubing ID = .245" to .311".
Therefore a thin wall 5/16 tube would flow slightly more than a thick wall
3/8 tube. You need to know exactly what you're buying for tubing.
The stock Tiger 5/16 tubing has .214" ID, my guess is that 3/8
tubing would be .277" ID. If you really need all the extra flow possible
get the thin wall 3/8 tubing with .311" ID.
Ron Fraser
-----Original Message-----
From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net] On
Behalf Of DrMayf
Sent: Saturday, May 24, 2003 5:53 PM
To: tigers@autox.team.net
Subject: More Fuel Lines and Pumps...
Was watching the thread on changing out the fuel lines for larger ones and
noticed that some said not much gain going to a larger line... Well, here
are some numbers and things to think about. If the Tiger's fuel line is
5/16" and you go up to a 3/8" line, a gsain in diameter of only 1/16", you
gain 44% in flow. I'd say that is pretty significant. Does it need it,
probably not, but if you are running any kind of performance motor then you
most likely do need it. Why? well, a gasoline engine, normally aspirated
uses about 0.5 lbs fuel per hp per hour. So if you are running a 300 hp
motor then you need 150 pounds of fuel per hour. Dividing that by the weight
of a gallon of gasoline (about 6.4 pounds depending on the temperature) then
you need about 24 gallons per hour. Now the old pumps put out just abouth
this much fuel (as I remember, could be more, could be less). But this is if
the entire amount of fuel was used and the system flowed continously into
the float bowl. No pressure. ANd no margin of safety for the motor. What's
that, you say? Well consider that you have your jewel wound tighter than
Dick's hat band making lots of power and you get a lean stumble. Oops, lean?
Ahhh detonation and most of our cars have some reasonable compression so the
beginnings of damage or blown headgaskets happen. So, IMHO I would go to a
larger line for the added flow margin and to a higher performance fuel pump,
with a regulator, for anything other than bone stock. Just adds margin...
mayf, out in PAH rump...
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