don't get what I'm about to post wrong
I love Mopar & the Hemi's
BUT;
I think both engines were underrated to be lower
{partially for insurance reasons}
426ci street hemi 425hp at like 5500-5600 max rpm too
the LS7 454 was rated at 465hp at like 5200-5300 max rpm
{remember 454 has a 4" stroke vs 426 Hemi's 3.75" stroke, both started with a 4.25" bore}
either engine with the proper valve-springs
can/will rev far past them #'s
makes far more hp than advertised,
a stock 426ci Hemi in street trim, has a hydraulic camshaft,
the hemi heads/ports designs are much better suited
for a much higher rpm range, but it's not the race hemi,
it a race hemi, could make more closer to 500hp
but it had a solid lifter camshaft & much better valve springs
& a cross-ram race Holley carb induction,
not the inline 426ci 2x4bbls Carters like the street hemi versions had
SH maxed out at about "real hp" rating of 450-475hp depending on altitude,
before they fell off drastically or valve floated more likely,
not far/before or after 6000 rpm
the LS7 Rectangular port heads will easily take that engine
well over 7000rpm, even with or if it had a hydraulic valve-train
BUT;
LS7 was a solid lifter engine, it was intended for off road use,
a crate engine & not a street engine
they never were in street cars,
they made somewhere in the 500-510hp range @ near 7000rpm
in stock out of the crate form,
the lower #'s were rating for NHRA, they are always low,
{even for race or street hemi's too}
the LS6 450hp street version was much like the street hemi rating
but with a hydraulic camshaft & lesser valve springs
so it didn't/couldn't rev as high to make the big #'s
like the solid lifter 454 LS7 race engines, they were torque monsters
{the BBC 454 has a 4" stroke vs the Mopar Hemi 3.75", which makes for huge torque #'s}
just the fact mam, just the facts
I've had a bunch of both engines, I can attest to it, for both of them...
Don't believe the hype on either side...
