What Size Fuel Line,...how Big Of A Pump?

CarMichael Angelo

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Remember when I ask this,..I have two less cylinders than you.

I have the book that creators of the mega squirt F/I system published on fuel injection. Inside that book are recommendations for fuel line size based on target HP.

My estimated/targeted WHP is gonna be something in the 350-400 range at 15 -18 P.S.I..
According to "the book",...it says that I need a 43lb injector (at minimum), with the fuel coming to them in a 3/8 line. According to the book, a 3/8 line is capable of fueling 500 HP.

A 3/8" line........... ( Thats -6 for the AN challenged) for up to 500 HP:shrug:

Now I was planning on 60 pounders for the injectors anyway,..so it looks like I'll be good there,..and I had a external, inline Mallory pump all picked out that has a -6 out,...but it's marginal.

View attachment 124313
Free Flow Rate:110 gph

Maximum Pressure (psi):65 psi

Inlet Size:-8 AN O-ring

Inlet Quantity:One

Inlet Attachment:Female threads

Outlet Size:-6 AN O-ring

Outlet Quantity:One

Outlet Attachment:Female threads

Quantity:Sold individually.

Notes pumps flows 110 gal/hr free flow @ 14V, 83 gal/hr @ 40 psi @ 14V, 63 gal/hr @ 65 psi @ 14V. Pump pulls 11.6 amps under full load. Includes 15 amp fuse. Pump is submersible.

If I set base fuel pressure at 42.5,..and the regulator increases fuel pressure as boost rises,..and I'm planning on capping boost at 18 p.s.i., then according to everything I'm reading here,..this pump will suffice. I'll only be asking it to go to 60.5 lbs of pressure,..it's rated to 65.

Our buddies at Summit have their own,...uhh,....."version" of the same pump,...and it's rating shows it's flow capacity in pounds per hour at 450.
sum-g3137_ml.jpg



Free Flow Rate:450 lbs./hr.

Maximum Pressure (psi):65 psi

Inlet Size:-8 AN O-ring

Inlet Quantity:One

Inlet Attachment:Female threads

Outlet Size:-6 AN O-ring

Outlet Quantity:One

Outlet Attachment:Female threads

Quantity:Sold individually.

In-Store Pickup:Choose In-store pick-up (OH, GA, NV) on our web site

So,..given that,..my ((6) 60 lb hr injectors should only demand 360 lbs hr of fuel cumulatively.

I should be OK then?. :shrug:

Why,..does it matter at this juncture? Why do I need to know today?

It's actually more about the fuel line, than it is the pump,..because after today,..I'll have my version of a Extreme matrix SF connector made,...and once installed,..trying to snake a 3/8 aluminum hard line under that will be almost impossible,..so,...it'll be better if the lines ( supply,...and return) are mounted before I weld those sonsabi tches in there.
 
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NIKwoaC

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Correct me if I'm missing something, but if gasoline has a density of 6.073 lb/gallon, then the second pump is only ~74.1 GPH. Also consider the fuel demand of your injectors "could" be 360 lb/hr, but the pump flows 450 lb/hr @ 0 psi, NOT 42.5 psi.

On a side note, even though it's industry standard, I always thought it was strange that fuel flow stuff is often rated in weight per unit time. The fuel pump has no idea how dense the fuel is you're pushing through it, so how is it accurate to define it by those terms? Volume per unit time makes much more sense to me.
 

85_SS_302_Coupe

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As I said in a previous thread, I'm still running my factory '85 fuel lines and I'm in the neighborhood of 400rwhp.
 

NIKwoaC

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As I said in a previous thread, I'm still running my factory '85 fuel lines and I'm in the neighborhood of 400rwhp.
I believe the factory V8 fuel lines are good for 500ish, or at least some people have managed that. I don't know what the stock fuel line situation is for the beast Mike is building.
 

David Pepiton

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Dec 17, 2011
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I'm not a fan of many of the products summit offers under its summit racing brand simply because most of it is low quality.
so I would go for the mallory just for that reason the Mallory also has more then sufficient flow numbers for your application but what will you be using for pressure regulation? also why are you going with a hardline over a nylon fuel injection hose? As Nik stated the summit is only putting out 74.1 GPH which is about the same as a walbro 255 if i remember maybe a little more.

lets see:
walbro----------190lph=50.198 GPH=304.85lbs./hr
walbro----------255lph=67.371 GPH=409.14lbs./hr
aero stealth-----340lph=89.828 GPH=545.43lbs./hr
summit racing. 288lph= 74.1 GPH= 450lbs./hr
mallory --------416.35lph=110 GPH= 667.92lbs./hr
 
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CarMichael Angelo

Nobody appreciates me..I'm gonna cut my ear off
SN Certified Technician
Nov 29, 1999
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Birmingham, al
m.imdb.com
I'm not a fan of many of the products summit offers under its summit racing brand simply because most of it is low quality.
so I would go for the mallory just for that reason the Mallory also has more then sufficient flow numbers for your application but what will you be using for pressure regulation? also why are you going with a hardline over a nylon fuel injection hose? As Nik stated the summit is only putting out 74.1 GPH which is about the same as a walbro 255 if i remember maybe a little more.

lets see:
walbro----------190lph=50.198 GPH=304.85lbs./hr
walbro----------255lph=67.371 GPH=409.14lbs./hr
aero stealth-----340lph=89.828 GPH=545.43lbs./hr
summit racing. 288lph= 74.1 GPH= 450lbs./hr
mallory --------416.35lph=110 GPH= 667.92lbs./hr
Actually Pep,..the aluminum line is dirt cheap,..and the ends are available in every configuration, and color,...so that is the reason for the aluminum. I always thought that when Summit brands something,..it is the same as the branded part that they sourced the part from....i.e. the Summit carb is actually a Holley,... and that pump looks exactly like the Mallory. I can't believe that they downgraded something in the pump internals to make it perform considerably poorer than the branded product. I know that the Summit carb I had worked perfectly,..as have several other parts I've bought over the years.

I'm using a Mallory return boost compensating regulator,..It's something I had sitting around,...its the only reason for using it.
 

David Pepiton

Active Member
Dec 17, 2011
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Actually Pep,..the aluminum line is dirt cheap,..and the ends are available in every configuration, and color,...so that is the reason for the aluminum. I always thought that when Summit brands something,..it is the same as the branded part that they sourced the part from....i.e. the Summit carb is actually a Holley,... and that pump looks exactly like the Mallory. I can't believe that they downgraded something in the pump internals to make it perform considerably poorer than the branded product. I know that the Summit carb I had worked perfectly,..as have several other parts I've bought over the years.

I'm using a Mallory return boost compensating regulator,..It's something I had sitting around,...its the only reason for using it.
yeah cost is a major consideration mike the nylon hose ain't cheap. I guess I've just had bad luck with summit brand equipment that has any moving parts so I'm holding it against them.
 

CarMichael Angelo

Nobody appreciates me..I'm gonna cut my ear off
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yeah cost is a major consideration mike the nylon hose ain't cheap. I guess I've just had bad luck with summit brand equipment that has any moving parts so I'm holding it against them.
I just bought the 3/8" stuff. I also spoke w/ a "tech" guy at Mallory prior to the decision to purchase it. I say "tech" tentatively,...he had to put me on hold after I asked about the pump. Maybe he was a tech-in-training,...... or a tit for short.