Cigs w/ superchargers
 

I have a '90 Cafe with 3/8" factory fuel lines. I'm moving up to twin-carb blowers. I hate to tear out the 3/8" lines since Cig does such a nice job with them. Is anyone else running twin 750s on factory lines, or did everyone migrate to 1/2"?

Broom the 3/8 lines- not enough fuel for a blower motor. GO TO AT LEAST 1/2 " LINES or you will burn pistons. Good Luck, Steve

the 3/8 line will be enough if you run an eletric boost pump close to the fuel tank outlets, along with a high volumn mech. pump.
you're probably not going to require more than 60 gph at wide open thottle with 750 hp
dave

Doctor Dave:
I believe Cignificant is talking about twin 750cfm carbs on top of the superchargers. My Cafe has twin 800cfm Holleys per motor(650hp) and I believe the lines are 1/2". Not enough fuel spells big trouble. Also, are you talking 60gph per engine at WOT?

Cignificant:
Check with Bruce. He should give you the info you need.

Bill

Thanks for the responses. Yes, these are twin 750s.

I've decided to go 1/2". I now have to figure out a way to convert the 3/8" "L" at the tank - along with the fuel pickup tube - to 1/2". I'm working with Bud at Cigarette to get some ideas. Looks like it will have to be fabricated.

Hey Cig: i had the same problem w/ my 31 Bullet. On mine, you actually have a 1/2" pipe thread w/ a reducer that comes out. we pulled the tube and it is beefy enough to use a 1/2" drill bit and open up. i thought i was going to have problems too but after i had it all apart, it was a simple fix. i would also consider using elect pumps i use holleys 160gph w/ 1/2 lines to feed and a 3/8 return. i was using mr gasket 130gph manuals but had a problem keeping pressure up over 5lbs. the elect work very nice.

Thanks Russ. My tube is plenty thick to drill out, but it's 14" long. It will be hard to find a drill bit half that long. And I still need to get a 1/2" "L". You're right about the tank connection - it's 1/2" reduced to 3/8".

I'm going to be using the 130gph Holley Marine mechanical pumps.

I cahnged my lines to 1/2 inch and drilled the shutoffs as well with no troubles. 60 hrs and counting, i have B&m 250`s with single 800 cfm 600+ hp moves my boat to over 80 mph
TOM

Cig, Drill bits do come that long. Check Pleasants Hardware.

Dupont Marine is making the parts I need. :cool: :cool:

If Dupont Marine would go full time there would be a lot happier boaters in our area!

1/2" is the best bet. Also you can run the electric pump into the manual as a boost pump, just regulate it down to 8-10 p.s.i. and you will have no problems. :D

my merc 600 sc's run 3/8 fuel line with merc manual pumps of of the sea pump and they hold 5 lbs at wot (4-5 lbs of boost) for as long as you want to hold it stock carbs(700 holleys)
on my 540 i ran 1/2" line with a big mechanical pump (130gph) it held 7.5 lbs at wot more than enough for 6-7 lbs of boost and 900 hp
it really depends on how much hp you are going to make?
good luck

fuel pressure is one thing but does it have enough volumn??? im not so sure about that


***COME GET SOME*** :D

hmmm - is there ever too much volume? Give the pumps what they need...

Anyway, I found a local fabricator that will make what I need. Good prices, and fantastic turnaround. In case anyone ever needs him, he's listed as "Dave Howard" on the following web page..
http://www.geocities.com/richmondpba...?1010510815387

if it doesn't have enough volume it won't maintain the pressure i would go with half inch but they didn't on the 600 sc's?