Everything you build is a gamble. Build it as tough as you can afford. But, these two have yet to fail...............
My 500"/440 using 440 Source crank and rods, Ross pistons and a Pro-Gram 4-bolt main conversion has progressively gone 750, 850 & 928 horsepower.
The 451 stroker with a factory 440 forged crank, Scat H-beam rods, Ross pistons, stock main caps and ARP main studs has hundreds of pulls from 621-787 horsepower. It is now at 580 HP and running in the shop truck.
I don't think there is an exact "number" anyone can definitively say X for example, above or below which a Block will break, vrs be fine ?
IMO, just far too many factors to longevity at any power level ?
* Bobweight of the rotating assembly itself
* Balancing factor for the rpm, 50% or slight overbalance
* The rpm itself
* How it's firing, ie: detonation, which even though nobody's hearing it with Dome Pistons and Heads that Flow off the backside of the cylinder(remix), it can still be there, and remember here... a "little bit" of detonation makes the best power, so in my experience best to back down slightly from that highest Track mph.
and of course,
* the differences in the Blocks themselves, thickness of the detroit wonder metal in places
on and on
We've seen them live just fine at 700+ with just Main Studs... on stock caps !
and then again,
we've seen them presenting during refreshening after a mere 100-200 runs at 750, with main webs cracks, #4 registers developing mountain ranges, pretty much getting ready to calve, and with Aluminuim Caps/Girdle/partial fills in place ?
I DUNNO !
I would trust & defer to what these 2 guys say...
pretty much anything Jim/IQ52 says I take as gospel...
----------------------------------------------------------------------------
I've had several 470-479ci B-Engines based on the weaker 383 blocks also
with aftermarket internals, that made north of 700hp & some with N20 too
upwards of 1000hp on the track, in street/strip 68 RR's...
1st one ran best of 9.77 @ 135 N/A & a best 8.58 & 156mph 3520#'s on N20
on drag radials, 6pt roll bar
{couldn't make too many passes, usually on test & tune days too}
but, I never dyno'd them, I went by on track performance...
I always used a girdle, it was/is cheap insurance, it doesn't hurt you...
The 1st one, my old silver 68 RR is still running around Sacramento today,
it had 12k miles when I sold it, he claims he's done a fe 9.90 passes
in it & still driving it too...
I've also ran 426ci max wedge filled to the freezeplugs with Portland cement
running early on a Hampton 8:71 & later a Littlefield 10:71 blown
Hi helix twisted rotors as much as 45#'s boost, Enderle Mech. FI on alcohol
that lived in an light-ish 23 T (T/A Funny Car chassis) Altered,
engine solidly mounted in the chassis, engine plate & ears off the front
for 2 seasons freshening regularly, doing a full block check it up yearly,
checking of cracks (especially in the center main webs) etc.
1800#'s plus (with 200#'s of ballast) me 250# running 6.90's @ 190+
Even with all that chassis flex, it didn't split or crack or grenade
{like everyone says they will}
That's a far sight more than 700hp, it lived, lived well
it didn't split the bock or break the crank,
it did have aftermarket lightweight parts everywhere,
Forged crank, Childs & Albert rods, Venolia pistons,
billet "one off" splayed 4 bolt caps, a hand built girdle
a fuunycar style 12 qt. pan & Milodon pump system {external}..
I also stayed on top of it, broke it down pretty much after every race-day...
You'd be surprised what some blocks can handle,
would I do the same thing today ?,
probably not !!
not with all the available {usually} aftermarket pieces we have today
20+ years ago we didn't have anywhere near what we have today
especially for Mopar's, let alone the wedge combos...
I'd say for the OP's combo the girdle is a great idea,
a 4 bolt or aftermarket/better block later isn't a bad idea either,
it's not if they will break ?, it's when !!, even on all that high dollar stuff...
