Get 255lph Fuel pump or keep 190 and get KB Boost a Pump??

255 definetly

I am subscribing because I have the same question. I think that I am at the limits of my 155lph pump with my 351. What is the difference in running this in tank and an in line (eg Edelbrock EFI) to supplement versus a larger in tank pump? Especially when in line pumps can be had for about the same price as an in tank one, and you don't have to drop the tank.

The primary difference (aside from the obvious L/hr difference), is that a vast majority of 190L in-tank fuel pumps, internally bypass at around 60 psi. If you're not running an FMU and don't expect to see pressure as high as this, then it won't be a problem for you.

With a KB-BAP, that 190L will provide you enough fuel volume to support that blower well beyond block splitting territory. Elevated fuel pressures will be the only factor to be mindful of.

With my old stock block, I was making 325 HP and 375 TQ with 19 lb injectors, an 88L fuel pump, and a KB-BAP. I hit the limit of the injector WELL before I hit the limit of the pump and BAP.

Hope that helps.

Here are some additional figures that might help you make your decision:

Stock Fuel Pump - 13V = 98L/hr @ 40 psi________ 17V = 137L/hr@40psi
190 L Fuel Pump - 13V = 176L/hr@40psi ________ 17V = 242L/hr@40psi
255 low pres. FP - 13V = 233L/hr@40psi ________ 17V = 312L/hr@40psi

A BAP and smaller pump will heat the fuel less than a larger pump (since the BAP is boost referenced and only comes on when it sees boost). You can see that a 190 is capable of delivering more fuel at 17V than a 255 is at normal system voltage. So it's more than adequate to deliver the fuel volume necessary.

sorta on topic, any recommendations for the best brand of intank 255lph?

walbro

here this is what i've got
http://cgi.ebay.com/ebaymotors/Walb...ItemQQcategoryZ33555QQitemZ160092409059QQrdZ1

Hey Dagger...do you happen to have the flow rate of the 255lph HIGH PRESSURE pumps? That's what I have in my stang and I'm trying to decide if I'm gonna need a second pump/bap for my nitrous.

BlooDReigN said:

Hey Dagger...do you happen to have the flow rate of the 255lph HIGH PRESSURE pumps? That's what I have in my stang and I'm trying to decide if I'm gonna need a second pump/bap for my nitrous.

Click to expand...

255L High Press = 13V - 244L/hr@40psi / 17V - 322L/hr@40psi


I'm not sure why they are referred to as "high pressure". They do flow more and fall off slightly less than the other units do as the pressure rises but I chock that up to just having more windings. All in all, I think it's just a larger (internally) pump than the low pressure version. I imagine they just called it "high pressure" for simplicity sake? It's actually just built to put out closer to 255L/hr than the other pump is.

On average, the high pressure pump puts roughly 10L/hr more (across the board) than the low pressure does. It doesn't appear to be much more resistant than the lower pressure pump at sustaining flow rates at elevated pressures. It's just consistently bigger in terms of flow rate.

For example:

The low pressure lost 34L/hr going to 60psi and 71L/hr at 80 psi @13V
The high pressure lost 27L/hr going to 60psi and 64L/hr at 80 psi @13V

17V:

LP lost 25L/hr at 60 psi and 64L/hr at 80psi
HP lost 32L/hr at 60 psi and 66L/hr at 80 psi



So even though the overall percentage lost is less (on the HP pump), the actual amounts in volume that each lost is pretty close. As a percentage of the total, the HP DOES lose less at elevated pressures but I would have thought that it would be more resistant to higher pressures given it's name.

Overall, the HP unit does consistenly outflow the LP unit. As I mentioned before though... I don't consider it a "high pressure" unit... I just consider it a slightly larger pump.

I know that's more than you asked, but I got on a roll. LOL

Cool, thanks.

I prefer when somebody over explains something instead of under explains

Definately Walbro. The most reliable fuel pumps around. They actually make a lot of OEM pumps. Most companies like Holley for example just boxes walbro pumps and charges more for their name. I heard from one of the local tuners that the boost a pumps have a fairly high failure rate too... not sure if it is true. Just thought I would pass it on.
Kevin

Does adding a T-Rex in-line pump defeat the purpose of having a 255 in-tank pump? I've heard it will just "dead-head" and stifle the 255 pump. Is this true or does it actually help?