Power limitations of stock hpfp

[AWSAWS]

If the lpfp is upgraded to a point where it isn't a limiting factor. Let's say dual walbro 450s/stage 3, then how much power can be run with a stock hpfp before port injection etc is needed? I suppose on e85 or a lower mix of ethanol.

Let's say no water meth injection.

Thanks

[Chris@VargasTurboTech]

I've seen ~520 on ~e55 mix personally. I've heard of bigger numbers, but not personally observed them.

[AWSAWS]

As power increases will the hpfp pressure drop and drop? Even though the lpfp can stay at around 65 to 70 psi?

[Chris@VargasTurboTech]

As power increases will the hpfp pressure drop and drop? Even though the lpfp can stay at around 65 to 70 psi?

Yes, it'll mechanically run out of flow capacity. Pressure drops once it can no longer keep up. That's why the shotgun flows so much more; we're spinning the pump faster. Similar sort of idea as using a different cam shape on the cam-driven hpfp's out there on other models.