Fuel pump
11-04-2014 | 12:10 AM
#62
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From: wisconsin
MT Problem with the suction side of the fuel pump is, there are so many variables, ie; length of draw, material & resistance being drawn threw, size, length & material of pick up. micron & filter size inline , number, type & size of fittings, G forces.............. you get the Idea here.. If you have all the above, there is a formula. But off the top of my head .... sorry its not in there, LOL. We all know that in most cases you can get away with # 10 line. Lets face it most tank pick ups are between 3/8 to 5/8"... so on the suction side its not going to do much, going way bigger then your pick up size... That being said, if you have too much restriction on the suction side of things ( not to forget vent sizing) you will see it in you WOT fuel pressure, and lose thereof.
11-04-2014 | 12:36 AM
#63
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From: wisconsin
Randy you pretty much answered your own question. You are pushing the fuel through the seat not pulling. The smaller the hose/ fittings and whatever b4 the bump create restrictions and reduce the efficiency of the pump. If you feed the pump with a small hose then have a larger hose on the outlet side of the pump you also reduce the efficiency of the pump because you have to fill the larger hose before the pump can make pressure to go through the seat. It's the same thing if you do a regulator b4 the carb you are pushing through a small oriface then filling a larger hose b4 you can make pressure to go through the seat. If you use a regulator b4 the carb (I use it after) all you need is -4 after the regulator. I've seen a 3000hp motor run with -6 after the regulator and -4 on the dyno. Believe it or not it made a hair more power with the -4. I think the largest regulator out there has a .125 hole in it.
Last edited by Bawana; 11-04-2014 at 12:39 AM.
11-04-2014 | 04:13 AM
#64
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From: bel air, md
Maybe I was thinking of the size of the hole in the little holley regulator everyone uses and wonders why the have fuel pressure problems. I used to know all that stuff but its been years since I was playing around with it. I know what works and doesn't work so the rest of it is elementary.
11-05-2014 | 06:36 PM
#65
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The information on this site is unbelievable, ok so I am going to run -10 line from tank ( making sure pick up is big enough ) to filter inlet -10 from filter outlet to pump inlet then -6 to carb. That should be more then enough to feed 800 hp 598 ci motor. The problem I still have is how do I mount the mech. fuel pump to the block with the sea water pump in the way. Is there a different type of sea pump that I can use. Also I have never seen the type of sea pump that is on this boat, ( just bought it about 3 weeks ago ) It has water inlet and outlets that face the block instead of going straight back. I would really like to run a mech. pump but its looking like I my have to run a elec. just because I cant mount the mech one. Any ideas....
11-05-2014 | 06:44 PM
#66
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From: chicago
The information on this site is unbelievable, ok so I am going to run -10 line from tank ( making sure pick up is big enough ) to filter inlet -10 from filter outlet to pump inlet then -6 to carb. That should be more then enough to feed 800 hp 598 ci motor. The problem I still have is how do I mount the mech. fuel pump to the block with the sea water pump in the way. Is there a different type of sea pump that I can use. Also I have never seen the type of sea pump that is on this boat, ( just bought it about 3 weeks ago ) It has water inlet and outlets that face the block instead of going straight back. I would really like to run a mech. pump but its looking like I my have to run a elec. just because I cant mount the mech one. Any ideas....
Also, for what its worth, I personally would run a -8AN line up to the carb. I mean, what ya saving by going with a #6, 12 bucks? Heck alot of the nice dual feed premade carb fuel logs are -8 anyhow. Just my opinion on that anyway. I am no engineer.
I've used these on some single carb setups. They have a 1/8 NPT gauge port too
http://www.summitracing.com/search/p...4%2B4294949389
Last edited by MILD THUNDER; 11-05-2014 at 06:47 PM.
11-05-2014 | 07:13 PM
#67
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From: cleveland ohio
I'm using a fuel log exactly like the summit piece MT posted the link to. I'm planning a -8 for all my fuel lines. I wonder if I should upsize the tank to water separator line to -10. I was thinking -8 as the pickup is 3/8 NPT on a 1/2 tube in the tank. I plan on a straight 3/8 NPT to -8 to a long radius 90 degree fitting on the supply host out of the tank.
I bought a 0 to 15 psi fuel pressure transducer for a dash mounted fuel pressure gauge. The transducer was twice the price of the gauge. Go figure. That said, I'm going to feel good being able to watch fuel pressure at the helm and at full load and when running hard.
I should add that the engine will be a 517" NA piece. Relatively mild at around 650 to 675 HP.
I bought a 0 to 15 psi fuel pressure transducer for a dash mounted fuel pressure gauge. The transducer was twice the price of the gauge. Go figure. That said, I'm going to feel good being able to watch fuel pressure at the helm and at full load and when running hard.
I should add that the engine will be a 517" NA piece. Relatively mild at around 650 to 675 HP.
Last edited by vintage chromoly; 11-05-2014 at 07:20 PM.
11-05-2014 | 08:31 PM
#68
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From: yorkville,il
in my 1200 hp supercharged engines i run a -10 from tank pickup to filter head,then-10 to my a1000 aeromotive pump then-10 to my fuel log,then-6 to each fuel bowl.my regulator is behind the fuel log with-8 line back to tank.at WOT my fuel pressure never goes below 6.5 lbs.i am at 8 lbs everywhere except WOT.
11-06-2014 | 05:59 AM
#69
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From: bel air, md
A bought a fuel log off ebay for $50 it looks identical to the $400 Aeromotive log and functions just the same. I can tell you how many time I had the bowls off my carb and never had to take the log off. I have -10 to the log fuel regulator hangs off the back and then the return. Nice thing about the log with the swivels is if the starboard valve cover needs to come off I can swivel the log up and get the valve cover off. Couldn't do that with my old setup had to disconnect the fuel line. My buddy has a holley log that does the same thing that mine does but he has never taken his bowls off because he thinks his Nickerson carb is perfect (you should see the plugs).
11-06-2014 | 11:19 AM
#70
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From: chicago
