series vs. parallel fuel pump set-up questions

[Reaper1]

I tired to get some opinions/experienced suggestions and comments on another forum with no luck as of yet.

Basically I'm looking for pros and cons of setting up a twin fuel pump system in series or parallel. I've got a car that's going to suck a LOT of gas in the blink of an eye when the "Go Baby Go" button is pushed and I want to make sure there is no drop in fuel supply when that happens.

So, let me hear what some of you have to say about this. Thanks!

[8valves]

Twin 255's are great in parallel for a large amount of airflow, something in the neighborhood of 700 WHP depending on your engine's BSFC.

In series I would THINK it would be less overall flow, BUT, it would fix any problems or thoughts that the 255 would run out of volume at a high pressure setting. This is why I think it's absurd people trying to make so much power on smaller injectors and cranking the pressure... your pump will run out of volume above 70 psi of rail pressure.

If you think it needs more than that, try an Aeromotive A1000. I've used them on some cars and had good results, although they're pretty loud.

[glhs875]

I'm running a stock in tank feeding a 255 in line on my GLHS. Seems to work fine.

[Reaper1]

OK, this is kinda what I'm looking for. I'm glad to see that somebody has actual experience running a high-po twin pump system.

I'd like to hear the theory in operation...which will flwo more fuel, be abel to keep up pressure, flow more at higher pressures, ect.

The application I'm investigating this for is a multiport N2O system on a 3.0....so fuel pressure really doesn't go above base setting at 0" vacume(probably around 45psi, but I have to see).

Keep the info coming...this is interesting to me!

[8valves]

If you don't have positive manifold pressure raising rail pressure then a single 255 might have enough flow to hold on for 500 WHP there as well.

However, with nitrous when you get on the jug it'll drop that fuel pressure off if you don't have enough pump to keep up for the initial hit. I would run the two in series for simplicity, and only to make sure that the pressure doesn't drop off when you get on the button then slowly come back as the pump catches back up. Hello ashtrays!

[Reaper1]

What you describe is exactly what I'm trying to avoid. So, 2 255lph type pumps in series you think would be the way to go? OK. Now I just have to find a pump I'm happy with! for the external application. It HAS to flow at least 255lph @45psi, and I HAVE to be able to connect -6AN or 3/8" line to it.

Let the seach begin....:)

[8valves]

Your search is over...

http://turbosunleashed.com/shop/product_info.php?cPath=25_29&products_id=141

[contraption22]

I'm running a stock in tank feeding a 255 in line on my GLHS. Seems to work fine.


I think Cliff Sebring toasted a motor with that setup. He had a stock in-tank feeding a S60 pump.

[glhs875]

I think Cliff Sebring toasted a motor with that setup. He had a stock in-tank feeding a S60 pump.

I have no problems at all, works great! Been running it that way for about a year now. Along with the alky, it supplies plenty of fuel for 28psi+ of boost. I run 48 to 50psi base fuel pressure. That's why I run 2 pumps. Because at 80+psi of fuel pressure when under boost, the flow rate is on the downward slope with one pump. Fuel pumps are pushers, they don't like to pull. Cliff probably had something else causing a problem.

[8valves]

I have no problems at all, works great! Been running it that way for about a year now. Along with the alky, it supplies plenty of fuel for 28psi+ of boost. I run 48 to 50psi base fuel pressure. That's why I run 2 pumps. Because at 80+psi of fuel pressure when under boost, the flow rate is on the downward slope with one pump. Fuel pumps are pushers, they don't like to pull. Cliff probably had something else causing a problem.

That, or your large does of methanol is masking possible fueling issues :confused:

[contraption22]

Can somebody explain the function of this little doodad?
http://turboxs.com/shop_prod.php?what_category=58

[8valves]

Yes, a small, reliable or even stock pump can fill the surge tank with very little effort. You then plumb a large pump capable of feeding your engine off of thse bottom ports. For short sprints it works wonders in keeping fuel supply up without having to sump your tank or run a cell.

I have my doubts about for running for longer that 15 or so seconds at WOT and if the small pump can keep up, but lots of people have no issues with it.

It's also a cheap way for road course guys because the pickup will never be dry using that setup.

[Frank]

Agreed on all of that.

Another thought is why dont you run one 255 for the injectors and the other 255 for just the N2O wet setup... assuming that is what you are doing. ;)

[glhs875]

That, or your large does of methanol is masking possible fueling issues :confused:

The alky helps, but before the alky I was running 2 aux. injectors that the regular fuel sytem had to supply fuel to as well. I basically just traded some gas for alky on my setup.

[contraption22]

I've been thinking of sumping the tank on the Horizon. If I run less than 3/4 of a tank of fuel, it will stutter before the 60ft mark. I'm currently still running the stock carbed fuel tank and an external Super60 pump. But I'm worried that it would be too low, as far as ground clearance, to have a sump on the bottom of the stock tank. Do you think the EFI tank is baffled well enough to prevent that from happening? Could I use a TBI tank and simply replace the pump with a 255l?

[glhs875]

I've been thinking of sumping the tank on the Horizon. If I run less than 3/4 of a tank of fuel, it will stutter before the 60ft mark. I'm currently still running the stock carbed fuel tank and an external Super60 pump. But I'm worried that it would be too low, as far as ground clearance, to have a sump on the bottom of the stock tank. Do you think the EFI tank is baffled well enough to prevent that from happening? Could I use a TBI tank and simply replace the pump with a 255l?


Sounds like a Turbo tank is baffled better than a carb tank. The EFI turbo tanks had to be designed to maintain proper fuel pressure at all times. Not so much of a problem with a carb. Although I don't like to run my car hard below 1/4 tank of fuel. I usually try to start out racing at the track with a 1/3 of a tank full. Still a sump of some sort is a good idea. A customer of mine just recently converted a Horizon to turbo. I made him use a fuel tank from a turboed Charger. I was testing it with only a 1/4 tank of fuel in it with without any problems.

[Aries_Turbo]

you should be able to use a TBI tank... I have a 255lph in the TBI k car tank.

Brian

[Reaper1]

I thought about running the secondary pump for just the N2O, but then there comes running another fuel line, check valves, ect.ect. ...it sounds good until you try to d it. Then you have to worry about that split second it takes for the pump to build pressure(hence check valves....but still). Nah...I like the way it is set up...t-d tright off the fuel supply line under the hood.

[8valves]

I thought about running the secondary pump for just the N2O, but then there comes running another fuel line, check valves, ect.ect. ...it sounds good until you try to d it. Then you have to worry about that split second it takes for the pump to build pressure(hence check valves....but still). Nah...I like the way it is set up...t-d tright off the fuel supply line under the hood.

Or you could do it the hardcore way and use a nitrous enrichment cell mounted up front. It would even put some weight over the front end for you.

Mike- my car will act like it's out of gas if it's under a 1/4 tank... even from a 50 roll on. That's using a stock turbo tank.

[Aries_Turbo]

you could do a "Russ Jerome" small fuel cell up front in addition to the stock tank to prevent fuel starvation.

Brian

[Reaper1]

I would, but it's getting crouded up there, and I don't think weight over the front wheels is an issue at this point. I want to get it running! I don't really even plan on hitting the "happy button" for a while after I get it running because it is going to need a LOT of tuning....time will tell....