Fuel Pumps: Best Internals or Complete Units.

[MPS2NV]

So once you hit the limit where inj DC is no longer effected by raising FRP and providing you dont hit the 2050psi max everything should be fine? Do you limit your inj DC to a few % less than 100% for safety margine?
Just getting around all the principles before I change anything! Still havent done MAF cal or sorted boost issues... so lazy HAHA!
Thanks!

[mituc]

Setting the injector duty cycle limit at 95 or 100% should be fine. 100% is still ok.
With upgraded fuel pump internals even when you command, say, 1750PSI, you will get 1850-1900 especially at WOT. So don't command more than like 1800 or so because you will get more anyway and will make the relief valve open like nuts, so you will not get more than 1850 PSI constantly to the injectors no matter what you do.

[MPS2NV]

I was told there was a 1950 relief valve availble? Is there no advantage of trying this or does FRP become uncontrollable above your suggested commanded FRP?

You know your way around VT well! love your work!

[mituc]

You can get relief valves that will open later (1950, 2050 or even 2150), but to make everything work you will need another FRP sensor which you will have to re-calibrate (just like we do with the aftermarket MAP sensors). The problem is that so far none of the tuning softwares available (Cobb, VT) offer control over that calibration, I assume it's not in the ECU. So probably to use that one will have to go with some stand-alone ECU solution which doesn't make much sense and doesn't worth the effort simply because higher FRP will not result into a proportional injector flow increase.
Some people considered that it's better to use additional fueling (WMI even additional multi port injection with a separate in-tank fuel pump and heavily modifier intake manifold).

However, you will need of significantly more fuel with a built engine. On a stock block/stock head/stock connecting rods engine, even with larger turbos, any significant fueling increase (past maybe a WMI kit) can lead to power levels which the stock engine will not handle, or not for long. So unless you want to rebuild your engine it's safe (and more efficient) to keep things simple and upgrade only the fuel pump (or FP internals).

[MPS2NV]

Anyone want to try an extra DI injector/s in the inlet mani ? lol
My block is built but also has alot of money invested in it so not keen on stuffing it up!

Thanks for your comments!

[Steve @ VersaTune]

Fuel flow is proportional to the square root of pressure. You have to square the pressure to double the flow. Going from 1800 PSI stock to 2100 PSI only gives a small increase in flow. The stock fuel pressure sensor only reads up to 15 MPa or ~2175 PSI. The solution that is needed is larger injectors.