Adding fuel Filter to Sai Li and GT500 vs GT350 Pumps

Tommy V

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no, larger lines create less friction, less friction = less pressure drop acrcoss the an identical lenght of hose(6an vs 8an). The flow gains would be minimal, on a high pressure EFI system, pressure drop across hose is a lot smaller than it is on a low pressure carb set up. So IF you are only be seeing a 3psi drop on 6AN that is maybe 1.5-2psi on 8AN, you would then need to refer to the pumps flow chart and see how much more flow the 1-1.5psi you just saved will give you. Chances are it's a negligible amount.

best way to know is to measure fuel psi at the pump outlet and then at the rails
I'm not sure about fuel but I though whenever u increased the size of the feed or return line the cfm would increase but the pressure would drop,I know it's like that with hydraulics and other systems.Im just asking because this is something I want to know also before I do mine.

 

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I'm not sure about fuel but I though whenever u increased the size of the feed or return line the cfm would increase but the pressure would drop,I know it's like that with hydraulics and other systems.Im just asking because this is something I want to know also before I do mine.
That’s the same thought I had when reading his statement. I work on O&G equipment as a mechanic. The larger the lines the more pressure drop. We have made tons of internal modifications to lube systems and switched to smaller lines to boost the pressure. So that seemed a little backwards but I’m sure depends on the pumps and a ton of other variables. I’m not an engineer or well versed in flow dynamics or fuel demands. Just going off personal experiences and talks with our engineers.
 

dubster99

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I guess due to less restriction it causes less pressure drop across the line. I'm probably going to go 8an feed with rails to the stock hat and dual 350 pumps. Debating adding a filter under the car. Will it fit under the plastic cover that goes over the lines?
 

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I'm not sure about fuel but I though whenever u increased the size of the feed or return line the cfm would increase but the pressure would drop,I know it's like that with hydraulics and other systems.Im just asking because this is something I want to know also before I do mine.
larger lines to mean more LPH, how ever fuel pumps also have a "open" LPH rating. This is the maximum fuel the pump is able to move when the outlet is open with no hoses attached. You cannot exceed it no matter how large a line you get. A 8AN line will have less pressure drop across the same length of hose when compared to a 6AN how ever you need to refer to the pumps flow chart to see how much additional flow you are really going to receive.
 

Tommy V

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larger lines to mean more LPH, how ever fuel pumps also have a "open" LPH rating. This is the maximum fuel the pump is able to move when the outlet is open with no hoses attached. You cannot exceed it no matter how large a line you get. A 8AN line will have less pressure drop across the same length of hose when compared to a 6AN how ever you need to refer to the pumps flow chart to see how much additional flow you are really going to receive.
Gotcha that makes sense,I was also.talking to Kcc and we were thinking about using the stock feed line as the return line.Use a fitting off the regulator wheir u could still use the quick connect,u know anyone that has done the fuel system like this.This way u still only have to run one line for feed and add a filter.
 


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kcc0521

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I am going to let Tommy be the test dummy for the fuel system. If our setup works well on his car I will go with it as well.
 

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I've seen lots of people on previous generations use the stock feed as the return. Is there much advantage going from stock feed to 6an? Both should be 3/8 line I think. I'm probably going to go 8an feed I think.
 
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kcc0521

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I've seen lots of people on previous generations use the stock feed as the return. Is there much advantage going from stock feed to 6an? Both should be 3/8 line I think. I'm probably going to go 8an feed I think.
I would say 0 improvement going from stock to 6AN. I am going to try 10AN or 8AN.
 

Jn2

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Gotcha that makes sense,I was also.talking to Kcc and we were thinking about using the stock feed line as the return line.Use a fitting off the regulator wheir u could still use the quick connect,u know anyone that has done the fuel system like this.This way u still only have to run one line for feed and add a filter.
The stock line as a return is something that has been done got ages, a quick connect in engine bay will let you route the return fuel to it. The main issue is the return hose is push lock right up to the tan where it turns to hard plastic that then goes to the fitting on the hat. You will need to pull the whole line out of the car, strip off the PEM hard plastic line off the barbed end on fuel feed, then connect your own hose to go to your need return port on the hat. This set up prevents you from using PTFE hose since PTFE isn't meant for a PTFE connector not push lock.

Because of this I decided to just include enough hose/fittings to do the entire feed/return, it's not hard or any more time consuming than doing one hose. routing the hoses under the car is the easiest part, it's all one long straight section with like no bends. It's tricker in the engine bay where you need to make 4 varying lenght hoses for the fuel rail
 
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kcc0521

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The stock line as a return is something that has been done got ages, a quick connect in engine bay will let you route the return fuel to it. The main issue is the return hose is push lock right up to the tan where it turns to hard plastic that then goes to the fitting on the hat. You will need to pull the whole line out of the car, strip off the PEM hard plastic line off the barbed end on fuel feed, then connect your own hose to go to your need return port on the hat. This set up prevents you from using PTFE hose since PTFE isn't meant for a PTFE connector not push lock.

Because of this I decided to just include enough hose/fittings to do the entire feed/return, it's not hard or any more time consuming than doing one hose. routing the hoses under the car is the easiest part, it's all one long straight section with like no bends. It's tricker in the engine bay where you need to make 4 varying lenght hoses for the fuel rail

I would think you could just convert it right at the hat but I have not looked at the connections on this car.
 

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When running a return style fuel system what base fuel pressure are you guys running? The stock 58 psi?
 

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When running a return style fuel system what base fuel pressure are you guys running? The stock 58 psi?
Whatever your tuner tells you to set it at.

I would ask your tuner. I think most go with around 65.
65 is way high for base pressure. Lund/AED usually are in the 55-58 range. PBD does 50. This is with the vac line off the regulator.
 

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When running a return style fuel system what base fuel pressure are you guys running? The stock 58 psi?
It will be up to your tuner who will decide based on your set up. Normally 50psi with 1:1 reference will yield higher flow from your pumps and the boost reference will offset the pressure in the manifold.

Highest I would do is 55psi(stock) with boost reference, and this is only if you need al little more flow out of your injectors and arent running out of pump...but if you are running out of pump, more pressure will just make it worse. Remember that pump flows less volume at higher pressure how ever your injectors wil spray more at those higher pressure, so it's a balancing act. This is why it's best to ask your tuner what they want your base pressure to be set too
 

dubster99

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I'm still wondering if the gt350 pumps flow enough for an 8an feed line.
 

 
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