what fuel pump do you guys recomend for a s/c setup? I only plan on 400-450 max hp.

the t-rex pump looks like it will be more than enough but, looks like a rig job to me so I was thinking of just dropping the tank and putting in a better than stock pump in it. will 255 lph pump work ? or any better ideas?

 

I have the walbro gs340 with hot wire kit from www.racetronix.com

 

A walbro 255lph pump should be fine for your setup.

 

I have a Vortec T-Rex in my TT Iroc. Does good delivering the fuel, but it is too noisey for my tastes (annoying). I will be swapping in a Holley 255lph in- tank pump in the near future. Its been awhile, but I did the math and figured 255lph should be adequate for me (I'm also in the 400-450hp range). The Holley pumps are very competetively priced as well- cheaper than the in-line T-Rex Pump.

 

you are running a T-rex, an FMU, and the stock in-tank right now right? When you switch to this new 255 in tank you are getting the ECM and running bigger injectors, and ditching the FMU?

There seems to be a problem with FMU's without an inline. It has to do with volume at pressure not just volume alone. If you intend to get rid of the FMU then disregard this. Here is a repetitive post I have made in referrence to people that install blower kits and figure since they have a walbro 340 pump (255 lph) that they don't need to run the inline:

 

Thanks for the info. I may be keeping the T-Rex longer than I had planned. Maybe I will try to do the 255lph pump, ECM programming, and larger injectors all at once, like you suggested.

I can easily see your point here. The T-Rex is not only rated at high flow volume (50gph), but achieves this high volume at 70psi (hence the name T-Rex 50/70). The 255lph pumps may put out the required flow, but at lower pressure (say 40psi). Physics dictates that as a pump is required to increase pressure, the volume will go down. And inversely, as the pressure goes down volume will go up. I just was assuming that a 255lph pump would do the trick. Good to hear you have hands-on experience in this area.

 

How much pressure are you going to need?

I think its funny that people think because I have a TBI pump in my tank that it will magically feed SOO much HP because it pumps 15psi. That doesn't mean its a high volume pump.

I have a holley blue ready to go in. That should do the trick nicely.

 

yeah anyways....

Yes don't get me wrong, I definitely like the idea of going with the 255 lph, but don't ditch the T-rex til you ditch the FMU (if ever). Those 85 - 100+ psi runs under full boost will need all the help it can give.

 

ok, if I go with the high psi GSS340 pump will it still be ok, if I run stock psi ?

 

The reason is because of volume loss at high fuel pressure. Thats why walbro has a High pressure version for supercharged applications with a 1:1 or FMU, and a normal 255 for stock fuel pressure (50psi or less) applications.

Heres a table to help you understand:

http://www.autoperformanceengineerin...l/fpspecs.html

-- Joe

 

yeah except in actual use the "boosted" 255 lph in tank pumps with FMU behave the same as the normally aspirated 255 lph pumps

 

If you look at the table, the max recommended pressure with the walbro 255 is around 60lbs.

In reality, no fmu, large injectors, and 60psi is the way to go.

-- Joe

 

I had a 255 in tank and a Trex outa tank. Your right that T rex is loud.

Im gona go with the GS340 and hotwire kit this time arouns

 

I am doing some digging on fuel setups for boosted apps....came across this thread .... You are saying you are ditching the two pump setup for the single boosted 255 version ??? I am getting the BBS 650 hp . I am haveing a hard time getting what I need. My dilema is .... my kit says this 650 hp can be had on a stock setup . All things I am reading is contradictory to that . SO now I am slowely gongi through reading old threads. Doing some of the calcs leaves me a little confused. Like apperantly I can get 650 hp from the stock setup ..... but injector calcs say I need like a 60 lb injector to accomidate 650 hp



...see why I am so darn confused . I have just completed Maximum boost ....now I am into the "turbochageing book " just to educate mysefl a bit on it all .

thanx for any feedback

 

yes you can go with one pump UNLESS you are staying witth the FMU.

FMU = 2 pumps (one decent "in-tank", and one very good "in-line")

2 bar or 3 bar map ECM and large injectors = 1 pump (very good pump)

 

This will be the way Im goin.

as for why Im getting rid of the rex. its loud.

 

Weird. I've read many posts about how loud the T-Rex AND the ATI in-line pumps are. I have run both (at different times) and neither were any louder than the noise my stock in-tank pump makes. Today, I have the ATI in-line pump and a GM GN in-tank. This combo is just as quiet as the stock in-tank. Simply strange......

Back to the topic. I've had good success with the current setup. Pushing a D1SC to 15-psig boost at ~63-psig fuel pressure with no problems. I have my baseline fuel pressure (vacuum reference disconnected) set at 53-psig. I installed a BAP after my last pass at the track with this setup years ago but never experimented with it with my F1 blower. I've since gone to a completely different setup so I have no data on this.

With my new twin-turbo setup, I will have to modify the TPI fuel rails to run the feed and return lines from the back of the engine. Not knowing how much boost I'll be making nor knowing if my current fuel pump setup with a BAP is sufficient, I decided to modify my fuel rails for two inlets, one per side. For the time being, I will tee both inlets together to tap into the single feed line. If this setup proves inadequate, I will make the following changes:

1) Discard both the in-tank GN and ATI in-line pumps.
2) Install a pair of either 190 or 255-lph in-tank pumps.
3) Run another feed line for the second pump and tap into the second rail inlet.

Everyone I've read about who runs two in-tank pumps use one feed line and leaves only one pump running constantly. The second pump is turned on via a Hobbs switch. I'm not going to do this. Instead, I've learned a little about how Ford runs twin in-tank pumps and I like it much better. I had this stock twin setup on my Lightning before I sold it and a similar twin setup in my '03 Cobra. More on this later but only if my needs dictate a change.

 

“how ford runs them?”

Ford uses a PWM power signal from the ECM which changes the speed of the pump to maintain a steady pressure, as reported back by a pressure transducer usually mounted on the driver’s side fuel rail.

I’ve been playing with/testing a PWM box a friend built that changes the PW with a few different schemes (either a high/low setting that can be triggered by a hobbs or WOT switch or a proportionate setting that will ramp from minimum to maximum setting proportionate to a 5V signal, like a TPS, MAF, MAP output)

 

Which will immediately void your warranty with walbro too, according to their website.

-- Joe

 

Ford uses a PWM power signal from the ECM which changes the speed of the pump....

True but not for every dual in-tank application. The Lightning is one exception I know of (used to own one and had schematics).


Which will immediately void your warranty with walbro too....

If Walbro doesn't want voltage variance to their pumps for whatever reason, don't use them. The twin Cobra pumps are good to 500-525 hp. With a BAP, they are good to 700hp or so. And if this isn't sufficient, use a pair of Focus pumps which are good to 800hp or so. And if that's not enough, use a BAP with the Focus pumps to push the upper limit to the 1000 hp range. These pumps have been proven to work under high voltage with no issues.

Controlling these pumps can be accomplished with the same method the Lightning uses. It's simple and easily duplicated onto our third gens without getting into electronics.

I should also make another point that I feel needs clarification. The Cobra system varies voltage to the fuel pumps. The maximum voltage is system voltage. The majority of the time the engine is running, the voltage is reduced. This design does NOT increase voltage above system. I don't know anything about Walbro's warranty issue. Is it RAISING voltage to the pump that voids it? How about running it at a LOWER voltage? Using the BAP increases the system voltage up to ~17-18 volts. The Lightning system is similar to the Cobra's except that it cannot vary voltage. Basically the PCM toggles between reduced and system voltage. Again, it does not raise voltage beyond system voltage.

Willie

 

PWM doesn’t vary voltage to the pump, it varies the amount of time the voltage is applied to the pump.

What, does the lightning use a resistor and relay like a 3000gt/stealth? Supposedly that can cause premature pump failure.

FWIW, KB use to package a little pamphlet with their BAP’s that pretty much said that a lot of the “twin focus pump” stuff is mostly rumors and they aren’t as good as most say they are… I might be able to find one and post exact text.

 

PWM doesn’t vary voltage to the pump, it varies the amount of time the voltage is applied to the pump.

PWM = Pulse Width Modulator?

You are correct about the voltage. My mistake. I was actually thinking of something else which has been on my mind recently -- varying voltage to the IC pump on water-to-air systems to increase efficiency.

I posted a question about how the Cobra fuel pump system works and here's the thread which includes the answer from Mike:

http://www.svtperformance.com/forums...d.php?t=202282


What, does the lightning use a resistor and relay like a 3000gt/stealth?

It sounds similar. The L system uses two parallel grounds. One provides a continual ground through a resistor. The remaining ground is either on/off, commanded by the PCM.


Supposedly that can cause premature pump failure.

On an L, I don't believe this is the case. I've never heard of premature pump failure and Ford used this design for all six years, 1999 - 2004. I had 56,000 miles on my L when I sold it and never had to replace either pump. Maybe it was a problem on the imports only???


FWIW, KB use to package a little pamphlet with their BAP’s that pretty much said that a lot of the “twin focus pump” stuff is mostly rumors and they aren’t as good as most say they are… I might be able to find one and post exact text.

That would be nice if you could locate this. I did not receive this "addendum" with my BAP I purchased over two years ago.

Willie

 

Who’s Mike?

Basically that’s what I’m talking about… Pulse Width Modulation. Basically it uses an amplifier circuit/mosfet that can switch the power on and of fairly quickly. It’s easier on electronics then trying to sink the power with a resistor or something similar.

What does this resistor look like/what type of resistor do they actually use? What value? One of these pumps can draw something in the range of 250watts, so something big enough to 2 pumps would be fairly large and get damned hot, I’m guessing some sort of nicrom wire wrapped job…

Last one I installed in a car was about 6 months ago… I’ll see if I can find it, but I’m not seeing it around the shop…

 

Who’s Mike?

Sorry. Mike = evil04cobra @ SVTP.


What does this resistor look like/what type of resistor do they actually use? What value?

It's in the engine compartment, housed in a mysterious black box. I never took the time to measure the resistance.


One of these pumps can draw something in the range of 250watts, so something big enough to 2 pumps would be fairly large and get damned hot, I’m guessing some sort of nicrom wire wrapped job…

Your guess is better than most.....


Last one I installed in a car was about 6 months ago… I’ll see if I can find it, but I’m not seeing it around the shop…

Just another bonus if you can find it.

Willie