MX5Ireland

I need to get a new fuel pump as mine is getting tired, looking for a walbro 190hp, thought I'd post before buying just incase anyone has one lying around.

IS THE STANDARD PUMP NOT GOOD ENOUGH GER?

my fueling relies on pressure to flow enough fuel through 265cc injectors, I need around 110psi at the rail for 175rwhp. My fuel reg is asking for 64psi of fuel at 8psi of boost on top of the 48psi stock fuel pressure. My pump seemed to be doing the business but I think I was just maxing it out and its getting weak and running lean at the top end. If you are using a link you are going to be using flow through bigger injectors rather than pressure through smaller ones so your stock pump should be fine.

Read somewhere that you can add an additional pump in parallel or is that shite?

Running 2 pumps in parallel will make more flow, but wont help much sustaining high fuel pressure. For this you want to run the 2 pumps ins serie.
64psi is already quite a lot to ask to a fuel pump and raising the pressure doesn't improve flow by that much in the end (hence your requirement for 110psi which is beyond any fuel pump datasheet), so why not simply run bigger injectors with less pressure?
Nico

Raising the pressure greatly improves the flow of fuel
here is what happens to a 265cc injector running 96psi of fuel, it flows 393 cc.

96 / 43.5 = 2.206
sqrt of 2.206 = 1.485
1.485 x 265cc = 393cc

I have a stock ecu so cannot really run bigger injectors as it wont idle. I slightly overestimated how much pressure I need 100-105psi should support my boost/power at less than 80% duty cycle. Fuel pressure is stock when out of boost and only rises in line with boost at an adjustable rate.

Why would you run two pumps when a walbro is a straight fit and cheap?

not really looking for a discussion in the wanted section on the pros and cons of fuel pressure and pumps, just wondered if someone had one knocking about.