6an feed line too small?

[Bbuchanan11]

Not sure where to put this but it’s for a drag truck. I’m trying to clean everything up I want to make the feed lines for the cp3s an line. I got 8an going in to 2 6an lines for the feed lines. Looking inside the 6an fittings they look pretty small will they work or no? Thanks in advance

 

[PureHybrid]

Being a drag truck, no. A -6 line would be the same ID as a stock fuel line feeding the cp3. A -8 matches the inlet size of the cp3 case pretty well, assuming you've got different inlet fittings installed already.

 

[Ne-max]

I suggest doing 1/2 fittings and 8an hoses. You need volume. Otherwise you have to make up for it with pressure. Witch most stroker cp3s dont like.

 

[2004LB7]

Is this a stock CP3 or ported?

 

[OregonDMAX]

I wouldn't even bother with anything less than -8 for feed side. I have 1/2 hose with -8 fittings running from sump through airdog straight to cp3 and all 3/8 hose with -6 fittings on the entire return side.

 

[2004LB7]

If its a stock pump, isn't the input fitting something like 1/8" inside?

 

[LBZ]

Just keep in mind the smallest orfice no matter where it is in that line is your highest restriction. You could put 3” line on but that restriction will only allow so much flow through at X pressure. Hence the reason some people port the orfice in the fuel rails or the fpr.

The only thing larger hose does for you is reduce friction and slow the speed of the fluid while raising the volume up to that point. Especially if it’s going around bends.

Running larger fuel hose will benefit you if you have increased the inlet size at the pump or are splitting the flow to two or three pumps. Running -8 or -10/-12 would benefit you in this instance.

 

[PureHybrid]

If its a stock pump, isn't the input fitting something like 1/8" inside?

5/16". The port in the case itself is 3/8" IIRC, so going bigger than that is pointless. BUT I did put a 1/2" fitting on mine (which steps down at the threads) just because I wanted to run one solid hose from the filter.

 

[JoshH]

Exergy stroker pumps come with stock barbs installed. If they required a bigger fuel line, I would think they would supply a larger fitting. A 1/2" hose may make you feel all warm and fuzzy inside, but I don't believe it really does anything for performance. You are splitting a single 1/2" line into 2 3/8" lines; I don't see how you will gain anything by splitting one 1/2" line into 2 1/2" lines.

 

[OregonDMAX]

I replaced the stock cp3 inlet fitting with a -8an fitting, weather it helps or not wasn't my concern just assembling everything was easier knowing it was all the same size

 

[Nickracer9]

I think you’ll be fine, I’m running a -8 all the way up and dropping down to a -6(12mm pump)cause space is limited. Just make sure you have a good volume fuel pump.

 

[2004LB7]

As mentioned above, the gear pump on the back has a 0.108" opening for fuel. That is less then 1/8"

Also the feed fitting for the pump is also quite small, maybe smaller, as shown in this photo. Stock on left, ported on right

 

[Bbuchanan11]

They are both stock pumps and as of right now have the stock 5/16 fittings on The back of them

 

[Ne-max]

Exergy stroker pumps come with stock barbs installed. If they required a bigger fuel line, I would think they would supply a larger fitting. A 1/2" hose may make you feel all warm and fuzzy inside, but I don't believe it really does anything for performance. You are splitting a single 1/2" line into 2 3/8" lines; I don't see how you will gain anything by splitting one 1/2" line into 2 1/2" lines.

Going from 5/8 and splitting into (2) 1/2 " lines helped by 3psi wot. Before was 1/2 split into (2) 3/8.

 

[LBZ]

Going from 5/8 and splitting into (2) 1/2 " lines helped by 3psi wot. Before was 1/2 split into (2) 3/8.

3psi on the lift pump?

 

[OregonDMAX]

As mentioned above, the gear pump on the back has a 0.108" opening for fuel. That is less then 1/8"

Also the feed fitting for the pump is also quite small, maybe smaller, as shown in this photo. Stock on left, ported on right

That's if you use that fitting, I just put a AN fitting on the back. Even ported that fitting is the big restriction

 

[Lonnie]

Just keep in mind the smallest orfice no matter where it is in that line is your highest restriction. You could put 3” line on but that restriction will only allow so much flow through at X pressure. Hence the reason some people port the orfice in the fuel rails or the fpr.

This is incorrect. You care about the sum total of all restrictions.
An 1/8" orifice that is 1/4" long is way different than 10 feet of 1/8" line as an example.

Any small opening (such as a fitting) that is a restriction causes the fluid to speed up to pass through at a given flow, this causes higher frictional losses due to velocity. It takes pressure to overcome the restriction. Line loss is a function of distance. If 1 foot of line loses 1 psi at a given flow, then 5 feet would result in approximately a 5 psi loss.

 

[PureHybrid]

As mentioned above, the gear pump on the back has a 0.108" opening for fuel. That is less then 1/8"

Also the feed fitting for the pump is also quite small, maybe smaller, as shown in this photo. Stock on left, ported on right

That fitting is for the high pressure side

 

[2004LB7]

This is incorrect. You care about the sum total of all restrictions.
An 1/8" orifice that is 1/4" long is way different than 10 feet of 1/8" line as an example.

Any small opening (such as a fitting) that is a restriction causes the fluid to speed up to pass through at a given flow, this causes higher frictional losses due to velocity. It takes pressure to overcome the restriction. Line loss is a function of distance. If 1 foot of line loses 1 psi at a given flow, then 5 feet would result in approximately a 5 psi loss.

I think both of you are correct. If you look at what he wrote he stated the smallest opening would be the highest restriction. He wasn't stating that the remaining line had no contribution to the overall pressure drop, just the highest restriction was the smallest opening.

Ultimately it is the smallest/highest restriction that will determine your max flow vs pressure. As an example, if a 1/2" line provides say 3 gallons per minute at X pressure and a 1/8" port restricts it to 0.5 gallons then upgrading to 5/8" line would not gain you anything

Of course a 1/8" line the whole way woud net you less the just a port at 1/8" but there is a steep diminishing returns on larger feed lines

 

[2004LB7]

That fitting is for the high pressure side

My bad if it is. There doesn't seem to be many images of the feed side showing the inside. I've seen them in person and it is considerably smaller than the feed hose