At what power level are parallel fuel rails needed?

I have a Racetronix in-tank pump (Walbro 255 lph) and SVO injectors.

Also, does to stock pressure regulator have enough flow capacity for the highr HP application?

Which press regulator is the best option for the injector/fuel pump combo I have?

 

At 500 flywheel HP the stock fuel rail configuration and the stock fuel pressure regulator work fine. I'll assume you're asking about a normally aspirated application. Forced induction and nitrous require substantially more fuel flow to achieve the same HP level. Also might want to mention the injector size

 

Yes, NA. The injectors are 30#/hr SVOs (red). The engine is a 383 with 11.8 CR, AI 200cc heads and matched cam. PCM tuned by PCMforLess.

 

You need more than a 30# injector for 500HP at the flywheel.

 

You might consider using an injector calculator such as:
http://www.rceng.com/technical.aspx
They should get you in the ballpark.

 

The online calculators are wayyyy too conservative. The one you linked is typical, and will tell you that you need a 39 #/HR injector for 500 N/A HP. My recommendation, specific to our engines, is to simply multiply flywheel HP x 0.07 to get the minimum injector size. That corresponds to an 0.476 #/HR/HP BSFC (vs. 0.500 in the typical calculator) and an 85% DC (vs. 80% in the typical calculator).

That said, he will be fine with either a 36#/HR or a 42 #/HR injector.

 

The 30#/hr rating for the SVO injectors is at the lower Ford fuel pressure of 38 psig. GM runs at 43.5 psig, so their capacity is actually higher at 32#/hr. Anyways I went through the calcs again and Fred you're right (as usual), at 0.45 BSFC and 80% DC, I calculate the flow needed per injector at 34.9 #/hr. At 0.475 BSFC is 36.8 #/hr. At 70% DC 42#/hr (best option).

Anybody wants to buy a set of SVO 30#/hr injectors?