setting up your fuel system

[grumpyvette]

Ive always been rather amazed at the number of guys that want to build a 600hp-800hp big block or turbo small block engine, who tend to think the stock fuel lines, fuel pump and fuel tank can keep up with the new higher flow rate demands required.
OR guys that see the need for larger fuel lines and fuel pump but connect those components to the stock un,modified fuel tank and internal fuel pick-up.
the result I usually see, with guys who do that is a car that runs fairly decent until about the top end of second gear and then leans out, because the fuel system can,t come close to filling the new higher flow requirements.
Most electric fuel pumps PUSH fuel fairly well, but will stall or not feed fuel easily if even slightly restricted on the intake port side, at some point (usually at or near 500- 550 hp) the stock fuel lines , even with a new high pressure fuel pump and larger fuel lines just won,t work if you retain the stock tank and fuel tank pick-up. at some point your forced to upgrade from the stock fuel lines that rarely exceed 3/8" to performance application 1/2" or AN#8 fuel lines OR larger and compatible tank fuel pump and fuel lines, that should support up to about 800 plus hp, over that you might need AN#10 lines and components.

in tank electric fuel pumps REQUIRE fuel sloshing over the pump to keep it cool, obviously the ideal pump installed location will require a lower sump, to keep the pump submerged in a partly filled tank, EXTERNAL electric fuel pumps will occasionally fail to prime if the pump is not mounted lower than the tank floor pick-up height.

RELATED INFO
viewtopic.php?f=32&t=33&p=41#p41

http://www.carterfueldelivery.com/fuelp ... P_Inst.pdf

external electric fuel pumps should generally be located as close to the fuel tank as practical to minimize restriction
,and inside the frame rails, to provide some extra protection in an accident,away from exhaust pipe heat,or moving components,
and as low as possible , to ease the pump maintaining its priming
http://www.kartek.com/Product/FuelSyste ... ickup.html

http://www.racerpartswholesale.com/prod ... ick_Up_Kit

http://www.racerpartswholesale.com/cate ... Safe_Cells

http://www.racerpartswholesale.com/prod ... And_Wiring

http://www.summitracing.com/parts/sum-290108/overview/

http://www.summitracing.com/parts/rci-2 ... dia/images

http://www.summitracing.com/parts/rci-2171a/overview/

http://www.summitracing.com/parts/rci-1160ds/overview/

http://www.summitracing.com/parts/sum-2 ... /overview/

READ THIS
http://autolabscopediagnostics.com/fuelpump.htm

 

[grumpyvette]

http://www.quickfueltechnology.com/tech ... -fuel-flow
"Carb Class: Fuel Requirements / Fuel Flow

Admittedly a scary title, something every racer should ensure is an adequate fuel system. Sometimes simple things stand in the way of glory and fuel delivery can be the gremlin before the finish line. Here at our tech support office we receive a number of calls each day varying in complexity and nature. One repeating call seems to revolve around a car that seems to "nose over" before the stripe every pass. After running through fuel pressure and ignition parameters it is often determined that the customer might not have a fuel pump that is up to the task and fuel bowls become empty when it counts. Though this problem can mask itself in several variations, having the right pump and regulator will eliminate a lot of potential issues.

Fuel delivery has several key factors affecting it. One factor that determines total fuel flow is lateral acceleration. Most racers mount fuel cells and pumps in the back of their car; this configuration requires the pump to "overcome" the force of acceleration that the car is producing in its pursuit of E.T. One "g" (32 feet / Sec2) will require roughly 10 P.S.I. of pressure to push fuel forward in the line. A larger fuel line means more there will be more fuel in line which is more weight and in turn requires more pressure to move forward - you can see where this is going by now. Modern race engines making the horsepower numbers we see in drag racing today have the potential to be severely underfed by the fuel system.

So if more is better then why not get the biggest pump and turn it all the way up? Have you ever heard the phrase "Too much of a good thing can be a bad thing"? What's true in most cases proves true in the world of fuel pumps. Increased fuel pressure is generally misconceived as increased volume, in fact it is the exact opposite. Excess fuel pressure means there is more amperage draw on the pump. Higher amperage draws will heat a pump up and lead to cavitation which shortens the life of a pump. Cavitation usually goes undetected and can leave you stranded between rounds with failed fuel pump. The lesson here is that a modern fuel pump does not have to operate at maximum output to meet the demands of most racing engines except in extreme cases. Our advice to the customer is to use the recommended pressure provided by the manufacturer of your particular fuel pump.



Here is an example: A standard 220 GPH = 1,364 lbs. per hour = 2728 HP

In perfect conditions this pump can support more horsepower than the track would see in both lanes!



All of our carburetors at Quick Fuel Technology utilize a float system to regulate incoming fuel. The float moves according to volume in the fuel bowl and as the bowl fills up it has to shut off the inlet to prevent flooding (think of the tank on a toilet). If you have your fuel pressure set at 9 p.s.i. then it will require 9 p.s.i. from the float to shut off the inlet (needle & seat). Floats in a carburetor, no matter what brand, are simply not designed or capable of operating at this pressure. Ideally fuel pressure needs to be between 5-7 p.s.i. Setting your float at a pressure of 6.5 p.s.i. is usually a good start and will give you plenty of float travel.

Put simply, more float control leads to a more stable fuel system. A carburetor that can sense and react to variations in fuel level will always be first to the finish line; combine this with a pump and regulator setup that can get the fuel forward and you have a winning fuel system. "

 

[matchframe]

Lots of GREAT info here !! Exactly what I was looking for.

My Vette build is a '78 which was originally an L-48 small block. Since my particular model Vette was not one of the collectables I decided I wanted a street rod instead of originality . I am about ready to drop the body back on the frame and am at the point where I need to install the fuel lines. My plan is a big block for my build so I want to plan for high horsepower and if I end up with medium high HP, I will have plenty of fuel feed. After asking around with friends who build track cars, I came to the conclusion that 1/2 inch lines is what I want to go with. My Vette is not really going to be a track car, just a street bruiser.

Here is what I want to go with; 1/2 inch stainless steel lines. I have located an industrial supply that has many versions of SS tubes. The one question I have right now is what wall thickness should I use? Keep in mind, the thicker the wall, the more difficult it will be to bend and fit.

Thanks!

 

[grumpyvette]

don,t ignore reading the sub links because 90% of the infos in those sub links, (no sense copy and pasting in some cases)
but Id suggest a .028-.030 minimum wall thickness, and if you don,t plan on exceeding 500hp the 3/8" line will work ok.
the stainless braid coated flex lines one easier to work with option

http://store.fedhillusa.com/cnf6.aspx

viewtopic.php?f=55&t=7787&p=34866&hilit=stainless+fuel+lines#p34866

viewtopic.php?f=55&t=8356&hilit=stainless+fuel+lines

viewtopic.php?f=55&t=9305&p=33631&hilit=+bend+fuel#p33631

viewtopic.php?f=55&t=1860&p=4870&hilit=blue+pump#p4870

viewtopic.php?f=38&t=1113&p=2217&hilit=blue+pump#p2217

viewtopic.php?f=32&t=67&p=37351&hilit=fuel+corvette#p37351

viewtopic.php?f=55&t=9305&p=33636&hilit=fuel+corvette#p33636

viewtopic.php?f=80&t=8505&p=32247&hilit=fuel+corvette#p32247

 

[matchframe]

Thanks Grumpy !!

Lots of really good info!!

I need to take the time tonight to go through it all so I can digest it.

Main reason I want to go 1/2 is to leave my HP options open for later on. I will seriously consider the 3/8 however.

Thanks!!

 

[grumpyvette]

If your looking for an effective inline carb filter for most performance cars , theses have been popular for decades
https://www.summitracing.com/search/brand/ict-billet/department/fittings-hoses
viewtopic.php?f=55&t=6105

http://www.summitracing.com/parts/sum-g1512/overview/

these glass filters are in my opinion a HUGE POTENTIAL fire hazard and are known to be restrictive to fuel flow rates required once you exceed about 400hp
http://www.jegs.com/i/Russell/799/650130/10002/-1
read the details carefully when you buy a fuel filter, rated pressure, fuel flow rates, and fuel line sizes are all important in making your selection.
from an engineering stand point a AN#6 fuel filter rated at 130 gph at 75 psi ( linked above ) is likely to flow CONSIDERABLY less than the rated 130 gph fed by a 9-11 psi feed from a manual fuel pump,how much less obviously will be dependent on the filter medium and its surface area, and how long its been in use.
sintered bronze inserts used as filters are noted for clogging up fairly quickly, as the total surface area is not that great.

http://www.summitracing.com/parts/wix-24003/overview/
a filter like this is larger longer and far less restrictive to flow, but takes up more room , but with a replaceable paper filter rated at 12 GPM (thats 720 gallons per hour GPH) its also a better deal on a performance car if you have room and use an #8 fuel lines, yes its large, it requires more room and adapter fittings to reduce the thread sections on the ends to fit AN #8 lines, and obviously you have several other good options

 

[legerwn]

working through the links included in this wealth of information on the century performance wed site linked here they recommend two regulators for what they call the best fuel system setup for drag racing. The first regulator is a bypass regulator followed by a dead head regulator to the carb.

This is the first time I've seen this (not sure how I missed it as I have been reading through this thread a bunch) and was wondering your thoughts on this one.

I would think that you would want the fuel flowing through the fuel line as close to the carb as you can,

I figured this is the reason for mounting the regulator as close to the carb as possible and have the regulator after the fuel log.

What would be the purpose of the second regulator?

Neal

 

[grumpyvette]

working through the links included in this wealth of information on the century performance wed site linked here they recommend two regulators for what they call the best fuel system setup for drag racing. The first regulator is a bypass regulator followed by a dead head regulator to the carb.

This is the first time I've seen this (not sure how I missed it as I have been reading through this thread a bunch) and was wondering your thoughts on this one.

I would think that you would want the fuel flowing through the fuel line as close to the carb as you can,

I figured this is the reason for mounting the regulator as close to the carb as possible and have the regulator after the fuel log.

What would be the purpose of the second regulator?

Neal

it theory it would tend to stabilize the fuel pressure at the carb inlet port, in practice Ive NEVER seen it do more than make a bit more restricted and expensive, a good high quality return style fuel pressure regulator ,matched to the correct line size for the application is fully capable of consistently delivering fuel at a relatively constant pressure.
when I see problems its almost always related to guys wanting to reuse the existing fuel lines or return line sizes that are too small for the application , or guys doing stupid stuff like connecting a AN#8 or 1/2" line they ran,to the original 3/8" or 5/16" tank fuel line connections

http://fuelab.com/understanding-fuel-line-fittings-straight-thread-and-an-vs-tapered-thread/

https://www.asap-supplies.com/us/fittings-valves-strainers/fittings/hose-tail-fittings

Use these ratings to decide your return line sizing based upon fuel pump output:

*
Up to 45 GPH = 5/16" or -04 AN
*
Up to 90 GPH = 3/8" or -06 AN
*
Up to 250 GPH = 1/2" or -08 AN
*
Up to 450 GPH = 5/8" or -10 AN
*
Up to 900 GPH = 3/4"or -12 AN

Use these figures as a fuel line sizing standard: if your feeding a carburetor with the typical 8-10 psi fuel pump feeding to the fuel pressure regulator

* Up to 250 HP = 5/16" or -04 AN
* Up to 500 HP = 3/8" or -06 AN
* Up to 700 HP = 1/2" or -08 AN
* Up to 1000 HP = 5/8" or -10 AN
* Up to 1500 HP = 3/4" or -12 AN

https://www.amazon.com/10AN-AN10-Stainless-Steel-Braided/dp/B01MT5C6HO/ref=sr_1_15?ie=UTF8&qid=1528719700&sr=8-15&keywords=5/8+fuel+hose

http://garage.grumpysperformance.co...ing-up-your-fuel-system.211/page-2#post-39677

https://www.discounthydraulichose.c...MI8JPO183L2wIV0oV-Ch2E-w80EAQYAyABEgKUU_D_BwE

http://garage.grumpysperformance.co...c-fuel-pump-selection.10664/page-2#post-46237

http://garage.grumpysperformance.co...-sizing-return-vs-feed.3067/page-2#post-44823

http://garage.grumpysperformance.com/index.php?threads/fuel-line-problem.9305/#post-33631

 

[Strictly Attitude]

Grumpy what is your opinion on the Gm style short return rear regulator fuel system. Where the regulator is rear and it has a short return line to the tank. I for get the book it was mentioned in but it raised my eyebrow a little bit.

 

[87vette81big]

Great info Grumpy.