pparaska Posted April 1, 2003 Share Posted April 1, 2003 Ugh, the search engine is NOT being helpful. Here's the story. I'm running a Holley 4D Pro-jection system (700 cfm). This may be replaced at some point with port injection. Anyway, I'm going to be running new lines, feed and return. The engine is in the 475-500 peak horsepower range. Obviously the 700cfm TB is a restriction, but the price was RIGHT! Someday I'll upgrade. I get conflicting advice on what fuel line sizes to run. Holley tech support says 3/8" feed and 5/16" return. Grape Ape Racing's tech page http://www.grapeaperacing.com/GrapeApeRacing/tech/fuelline.cfm says use 1/2" for anything over 350 hp, but that's for a carb. I have 25" rolls of 3/8" OD AL and steel line on hand. I notice that the Aluminum tubing wall thickness is about 1/32", so the ID of the 3/8" AL line is about 5/16". The steel 3/8" line is a good bit larger on the ID. I'm leaning towards 3/8" steel, but it's a pain to bend, etc. Will 3/8" AL be sufficient for 475-500 hp at ~15psi from the pump? Or will the ID increase of 3/8" steel over 3/8" AL be worth much? Or should I go with 1/2" AL or Steel? I'm not going with SS braided hose, too much money for fittings, etc. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 1, 2003 Share Posted April 1, 2003 I get conflicting advice on what fuel line sizes to run. Holley tech support says 3/8" feed and 5/16" return. Grape Ape Racing's tech page http://www.grapeaperacing.com/GrapeApeRacing/tech/fuelline.cfm says use 1/2" for anything over 350 hp, but that's for a carb. Keep in mind that carbs like volume, not pressure, thus the need for larger ID lines. IMHO the 3/8 ally lines will be adequate. Tim Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted April 1, 2003 Share Posted April 1, 2003 For my port injection system, I'm using Alm 3/8" feed and return at about 50 psi with no problems. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 1, 2003 Share Posted April 1, 2003 For my port injection system, I'm using Alm 3/8" feed and return at about 50 psi with no problems. That is fine for 50 psi, I'm sure. Pete, what fuel pressure are you running? If it is lower than 40 psi or so, maybe you should consider 7/16" or 1/2". Aside from having to buy the line, you won't have trouble going bigger... Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 1, 2003 Author Share Posted April 1, 2003 15psi - I know I'm probably on the edge of needing more line. I might go get some 1/2" AL line. Having trouble finding 1/2" steel. Quote Link to comment Share on other sites More sharing options...
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