Horsepower limit for out of the box Edelbrock RPM heads
Do these heads that flow 300+ work worth a crap in the lower rpm ranges, say in a street or road course car? For my use cases, a nice flat torque curve from 2500 rpm on up is more desirable than a few more HP all on the top end. Obviously cam selection plays here but does a 370 cfm Victor or Indy 360-1 have good port velocity for responsiveness?
FWIW..... My experience is a qualified 'yes', based on my long-ago builds of a 351C and a 1.6L Mitsubishi, where that wide range flat performance was desired. Both had what would usually be classified as 'too big' on most or all of the flow parts (heads, intakes, headers) for low RPM use, but the cam selection in each case was small-medium and the static CR kept up. The cam and SCR/DCR made the low end 'fully awake' to or below 2500 RPM and the large flow parts allowed them to still wind out with good torque to 6000 RPM or so, with optimum shift points on both engines right at 6500 RPM.
Sure, neither had the peak HP that COULD have been accomplished, but both did what was desired. The 351C was an all around cruiser/street racer/tow vehicle/daily driver that would beat factory 4 BBL 440's with a 3.08 rear gear every time, yet cruise at 18.5-19 mpg on the interstate, with a standard C4 trannie & stock TC. The 1.6L was a rally engine, and was one of my favorites; you had the torque you needed all over the RPM range, and in a light Arrow body, was the equal of much larger engined rally cars.
Now for this type of use, in the 300-360 ci engine range, I've never done one with the 300+ cfm sizing of ports in a small block V8 to see if that would push it 'over the edge' at the low RPM's: IO doubt I wil ever get the chance. But that 1.6L had cut-down 327 valves and had been ported out the wazoo, and flowed in the 'near-stock-hemi' range, per the porters (who did Bob Glidden's Ford heads LOL), so for a 1.6L, it's flow was in 'Victor-equivalent' land. Yet, it was fully up on the torque curve at 2500 RPM, with twin 40 Weber side-drafts and medium sized headers. The cam really set the performance and was one from the Direct Connection C2 package line specifically for rally use.
Something in the 250 flow range for this type of engine in a 300-360 ci engine is pretty adequate, IMHO, and I would not go smaller if I wanted a responsive range up to 6000 RPM's or more. Cam
and carb selection become more critical IMHO with large flow parts to keep low end torque. And EFI becomes a big plus.
