ls1, truck mp112 maggie kit, lingenfelter blower cam, 2.9 pulley, 60# injectors, factory fuel pump, comes with a pump that goes on the frame.

just wondering if I need to upgrade or not, this stuff has been waiting to go in for awhile and and getting sick of looking at it on the floor.

 

Save some headache and buy a new pump. two walbros would do it. The stock is a 190lph i think and the inline is a 255. So that will cause one pump to suck on another and the smaller to overheat.

 

hmm, so why do they even put an inline pump in there if its just going to cause the other to overheat?

1 walbro wouldnt be enough?

 

I have no ideal, But think of it like connecting a fire hose to a straw and trying to flow as much water as possible. For one walbro in the tank I think u can go up to 550 to the wheels with a fuel pressure regulator_ boost referance. Im not sure of the specs on the inline it may be a 190lph pump I dunno but the if the inline is bigger it has to draw fuel through the other pump thus rasing the demand on the stock pump.

 

LPE reccomends another 255lph pump past 400 RWHP. I DEFINATLY would NOT rely on only 1 255lph pump at 500+RWHP.

Two good working 255 lph pumps have been proven to support more than 1,000 RWHP.

Just make sure the pumps are not the chinese knockoffs "claiming" to be a Walbro pump (there are a ton out there, I went through 3 of them before I said "screw it" and bought a Racetronix 255 lph pump). The chinese knock offs are notorious for failing in relatively short periods of time.

 

damn, 2 pumps, i wouldnt even know how to install them. im looking at about 500rwhp with my setup when im done with it.

 

Is the pump that came with the kit designed to be used inline with the current pump or sumped in the tank? There are a million different ways to attack your need for fuel. I would think a single pump in the tank with good voltage will be just fine.

If the inline pump had a larger flow rating it would not be any restriction and would actually take load(pressure head) off of the pump in the tank.

Saying two pumps will make 1000 rwhp but one isnt safe for 500 rwhp is kind of silly.

 

The intank pumps have a check valve wich is smaller than a walbro. The in line wont be the restriction but it wont flow anymore than 190lph will allow it. The intank picks up from the bucket, and sends it to the rails, But u have a 255lph pump inline demanding more fuel because it has a higher flow rate. Thus it wont flow anymore fuel then the intank can provide. The intank has a motor aswell and its desighn to spin at a certain rpm, same thing with the walbro. Its common sense why try to pull 255lph through a 190lph pump?

Now to the op, Buy a new 255lph walbro intank pump, Install it, then install your inline maker sure both have the proper voltage, and add a rail mounted fpr. With that and some good injectors on stock fuel rails u can grow to 600+ to the wheels. Its similar to how the vettes are set up. They have one intank main pump and one inline of equal flow.

 

I'll agree it is not the best way to go about things but yes it is very common. Like I said it takes some of the pressure head away from the first pump and allows it to flow more. I was mainly responding to the overheating comment.

 

the kit was designed for the 5.3-6.0 truck engines, the reason it wasnt meant to work on the fbodies is because the motor sits halfway in the firewall, in my case, since its an 88 trans am, I dont have that issue.

 

oh ok cool

 

There are several write ups on this. Here are a couple of good ones;

https://ls1tech.com/forums/fueling-i...ick-cheap.html

http://www.camaroz28.com/forums/show...dual+fuel+pump


If you were using only one 255 lph fuel pump, I would really reccomend doing some more research (if you don't believe me) on the limits of using just one 255 lph fuel pump and that power level, but with your other pump assisting, you may be okay?


Given LPE's stance as one of (if not the most) reputable performance shop ever, I would have to argue that it is "silly". Especially given the amount of people doing the dual in tank 255lph fuel pump setups. It isn't black magic or some random fact I pulled out of the air. I would bet if you did a poll, you would find most guys running more than 450 at the wheels FI, are running more than one 255 lph fuel pump.

 

one 255lph pump should take you up to 600rwhp if you have it hotwired, several people have done it before, if you go over that get two.

 

[QUOTE=OUTLAWZ RACING;13627181]The intank pumps have a check valve wich is smaller than a walbro. The in line wont be the restriction but it wont flow anymore than 190lph will allow it. The intank picks up from the bucket, and sends it to the rails, But u have a 255lph pump inline demanding more fuel because it has a higher flow rate. Thus it wont flow anymore fuel then the intank can provide. The intank has a motor aswell and its desighn to spin at a certain rpm, same thing with the walbro. Its common sense why try to pull 255lph through a 190lph pump?
[QUOTE]

Because together they will flow more than either one can provide alone.

The "190 LPH" designation in this case means absolutely nothing, except to give the pump a name. Why? Because when two pumps are configured in series, the upstream pump is delivering fuel into almost zero pressure (head). This is beacuse the downstream pump is sucking fuel away. In fact it sucks fuel away so much that there is no restriction to the fuel coming out of the upstream pump. Why is that significant? Well, the "190 LPH" rating occurs at only one operating point, namely 43.5 psi. Look at any flow graph. It flows less above 43.5 psi, and more below 43.5. And at zero pressure (or "free flow") it delivers alot more than 190. In fact, a W242 (190 LPH) in free flow will deliver as much or more than a W34x (255 LPH) at it's rated pressure. Check any flow graph.

In series, the downstream pump is now having fuel delivered to it. So it has to work less hard. It is doing all the heavy lifting, providing fuel against the load (head, in the ls1 case 58 psi). In fact, both pumps will draw less current while delivering more fuel. Check any flow rate (and amps) versus pressure chart to verify for yourself.

 

[QUOTE=70GS455;13629700][QUOTE=OUTLAWZ RACING;13627181]The intank pumps have a check valve wich is smaller than a walbro. The in line wont be the restriction but it wont flow anymore than 190lph will allow it. The intank picks up from the bucket, and sends it to the rails, But u have a 255lph pump inline demanding more fuel because it has a higher flow rate. Thus it wont flow anymore fuel then the intank can provide. The intank has a motor aswell and its desighn to spin at a certain rpm, same thing with the walbro. Its common sense why try to pull 255lph through a 190lph pump?
in english sorry for my lack of understanding fuel systems, but thats why im asking, to learn will the stock one work for me?

 

[QUOTE=firechicken76;13631436][QUOTE=70GS455;13629700]The stock pump by itself won't provide enough fuel to run 60# inj at high duty cycle % levels.

A single in-tank 255 lph or external 255 lph pump will not supply enough fuel either. There is too much demand from the injectors, especially if you're running enough hp to push them hard (in other words, lots of duty cycle) and this is what you want because you want more hp.

The stock pump together with the external pump in-line will deliver more fuel than either one can by itself. As long as the external is a bigger pump, like a 255 lph for example.

 

I have the single pump kits in stock, plus a custom dual intank setup if you plan to push much beyond 550rwhp.

Feel free to call me for more info.

 

so all i need to do is figure out what kind of pump (external) I have, and if its not bigger than my intank stock pump then I should upgrade my external?


OK, so i ran out to my garage and found the external fuel pump. here is what it says.

WALBRO
Made in USA
CSL394

is that a 255?

[QUOTE=70GS455;13633271][QUOTE=firechicken76;13631436]

 

so all i need to do is figure out what kind of pump (external) I have, and if its not bigger than my intank stock pump then I should upgrade my external?


OK, so i ran out to my garage and found the external fuel pump. here is what it says.

WALBRO
Made in USA
GSL394

looks to be a 190, and the website i was looking at said it was rated 400hp for boosted cars or 500 n/a

 

I would save the headache and talk to Lonnie about what you need. Or you could just send the whole thing over to me since you are tired of looking at it and I'll put it on my truck