Fuel Lines? CAUTION LONG POST!!HELP PLEASE

[phantomjock]

FUEL SYSTEM THOUGHTS PLEASE!

This was orginally posted in another thread - but no activity - or interest? So, I make this as a repost and a new request. Then again, maybe I was too cryptic - asking yet again an OBTUSE question or who knows???

SO, here's a restart:

In my typical "Parallel-Activities", I am now starting on the Fuel system. Body is (still) off the chassis, currently building new brake lines and suspension -- so, I thought while waiting for some parts to arrive -- I'd ask about the Fuel System.

I found a pretty cool illustration -- and added a few questions to it so if you can help, here is the picture:



This was described as a "Best Street/Strip Configuration." Is it Redundant - a Good Idea - or just more money?

http://www.centuryperformance.com/ was the source for the image...


Starting at the Fuel tank.

FUEL FILTER:

I see 100 Microns used as a suggestion at the tank - and finer at the engine. I note the diagram has only a single filter - but seems logical to put a finer close the the carb. The diagram doesn't show that -- but if it makes sense - I'll add one to each line.

FUEL PUMP(s):

My 350/383 won't get to 700 HP - so, since I'm shooting for around 400-450 (with the NOS) I should be ok with maybe 100 - 150 GPH pumps with plenty to spare?
But if running 2 pumps - should the BOTH be that size? Or, maybe primary (daily) smaller {OR the NOS/RACE Larger?} - knowing the extra horsepower will be with the NOS only?
This all Stands to reason -- BUT -- I am looking for advice from experienced members here on the forum!

Seems like the second pump would be engaged only prior to the NOS?
So, that seems kinda like a good idea - and then use the second pump only when using the NOS?
Or should I dump the idea of dual set up?

FUEL LINES:

OK. I have seen and heard the discussion between HARD LINES and BRAIDED LINES along the frame. I'll most likely go with the hard - and I'll use steel, not aluminum along the frame.

So what about using steel braided from the tank to the filter and filter to the pump? Note the image has 2 pumps and dual lines from the tank.

So, if there are dual sets per the Illustration - what size fuel line? Here again seems like 3/8 ought to do it (6 AN).

This is what they recommended on the site -- but no discussion when using dual setups:

Use these figures as a fuel line sizing
Up to 250 HP = 5/16" or -04 AN
Up to 375 HP = 3/8" or -06 AN
Up to 700 HP = 1/2" or -08 AN
Up to 1000 HP = 5/8" or -10 AN

And for return (from the regulator)lines they recommended basing these on fuel pump sizing:
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

Here it would look like dual 1/2 inch lines. Or would 3/8 inch be adequate? Again hard lines along the frame and into the tank?

I've done some more thinking and the 3/8 inch line ought to be enough. Use both for feed and return. Sound about right? added edit...

REGULATOR:

Here is a diagram from HOLLEY:



I would REALLY REALLY like your thoughts and recommendations here too. Somewhere around 9 psi for each electric fuel pump seems OK - or something else for the NOS Side? I am considering a Wet System, that will be another set of questions downstream -- But I'd like to do the set up now and add the remaining NOS bits later -- if that makes sense.


Or should I dump the idea of dual set up?
I gotta say it seems kinda like a good idea - just let the use the second pump be ïn reserve and use only when using the NOS.

Currently, the engine has a mechanical pump mounted and steel braided line to the Edelbrok carb on the Torquer intake. Steel return line from the carb - but no regulator. Hense, I am open to a TOTALLY new set up, and gettin ready to order some parts -- 'Start the New Year off Going for Broke!'

I am in the middle of the body-off -- so now is the best time to do all this -- before some other wild idea pops into my head!

ANY RECOMMENDATIONS? HELP! Please.


Cheers, Jim

 

[Fuelie74]

I am no expert here but for the little bit for price and physical size difference why not just run 1/2" if you are unsure? That way you will also have room for future growth.

 

[enkeivette]

I am no expert here but for the little bit for price and physical size difference why not just run 1/2" if you are unsure? That way you will also have room for future growth.

I wonder if you can just use the return line in addition to the main line for extra flow. Lots of pumps don't need return lines now.

 

[big2bird]

I am no expert here but for the little bit for price and physical size difference why not just run 1/2" if you are unsure? That way you will also have room for future growth.

I have to agree here. I like the KISS principal, and that looks like something ready to go wrong.

 

[TimAT]

Figure out what kind of volume you can get thru a given diameter line at a given pressure. If you can get 200 GPH thru a 3/8 line at 200 PSI (just throwing numbers here, no real idea) and then drop it to the 5 PSI the carb can use and return the rest to the tank, I see no real good point to a dual system. But if you're concerned about cooking a pump and having a standby system, then----

GM used a 3/8 line on the L-88 and ZL-1 Vettes- never had any fuel delivery problems I've heard of. I'm still running the original lines and a stock pump on Red with no problems- but I'm not running all day at 6500 RPM either.

 

[mrvette]

Tim, the way I look at it is that the diameter of the line don't matter, it's how much fuel you need at the end, and at what pressure you need to ensure the engine don't run out....IMO, i'ts in the PUMP, not the line diameter....except maybe a bit of back pressure....but still a 3/8 OD line will suffice for most any streetable engine....

this is NOT John Force we talking about either....

:rofl: the way I read it, the same sorta thing you are saying...

semantics...:clobbered:

 

[Grampy]

Some is good, more is better & too much is just enough

The short answer is it's just more money. I'm sure it will do the job but so will a very simple stock fuel system. Gene has the central point covered, you just need the fuel. You are aiming for 400-450 with the nitrous. Assuming a 100 shot your base is a 350HP carb SBC requirement. There are a zillion 350 HP small blocks running arround with stock fuel systems. A carb needs x quantity of fuel to support Y horsepower. The pump delivers the fuel to the float bowl and the needle valve determines how much. The float bowl is vented so the fuel in the carb is not pressurized. Normal fuel pressure for carbs is about 7 psi and regulators are not needed to extend pump life. When the engine is making 350 HP you will use about 28 GPH. At 450 HP on squeeze this will go up to about 40 GPH. Add 10% or so to be sure you don't run lean and a pump of about 45 GPH should cover you needs. 45 GPH will flow thru a 3/8 line at less that 3 ft/sec which is well within normal velocity limits. Filtration as shown is good protection. Check with your NOS supplier to see what fuel pressure their system expects and be sure your pump will supply it.

Grampy