Have you ever seen someone rip apart a 2-bolt BBC block in the 600-700 HP area?

Thanks. :flag

 

HP and Torque is not what kills parts. RPM is what kills parts faster than anything. If the RPM is limited to around 6000-6500 I see no real danger (although a 4 bolt main is nice for piece of mind).

I'm running a 2 bolt block and putting down about 500 horsepower at the flywheel. I have taken my motor up to 7000RPMs before.

*EDIT* I should point out though that I am running ARP main studs.


[Modified by bence13_33, 3:19 PM 3/24/2003]

 

You might be suprised to see how many 9.90 racers run 2 bolt BBC's. I see no problem with a well setup BBC 2 bolt going into the 700 hp range. Unlike a SBC, a BBC has much beefier main caps and larger main cap bolts - its all good.

Thomas

 

Not sure how much horsepower the motor was making, but I spun the 2 bolt block to 8000. With my foot on the gas while shifting, it would spin to 8500. It was a .060 over 327 with 12.5:1 TRW's, dual quad tunnel ram with 2 600s , and the Camaro 140 off road cam. The block was a '63 870 casting. That was a great motor. This was back in '75 and I had no rev limiter. And I did miss a shift once in a while. Don't even want to think how high the motor actually went. Anyway, the 2 bolt block and small journal crank NEVER let me down!!!
Won many a race including many big blocks!
Lou

 

:iagree:

We ran a S/G car with all the "wrong" parts------ Two bolt block, 3/8" rods, oval port heads.

 

Like bence 13_33 said, rpms are a major factor. It all boils down to the forces the block is subjected to. The forces are comprised of speed and mass (weight). E(energy) = M(mass) X V(velocity) squared. The weight (M) has a direct effect on the forces, but the forces go up with the square of the speed (V). As the stroke increases, the speed of the big end of the rod increases at any given rpm. At XXX rpms the time remains the same, but the distance is greater with a longer stroke. That beefy, indestructable rod may never break, but because of the weight, it increases the load on the crank and bearings, and consequently, the block. Possibly one of the reasons that Dan Plett's engine, "with all the wrong parts" lives, is because everything is carefully coordinated. I hate to get "technical, but maybe that helps explain why rpms are a greater "killer" than HP. Good luck, and...

RACE ON!!!


[Modified by CFI-EFI, 7:30 PM 4/3/2003]

 

650+ :D

 

I built a 468 with 2 bolt mains and a cast crank that dyno'd 636.4 hp@6800rpm 588.0tq@5400rpm. It has over 10,000 miles and 100+ 1/4 mile passes and it still runs strong! They are amaizingly strong! :cheers:

 

:iagree:

My friend has a 468 cubic inch (0.060" over 454) in his 1969 GTO that is apparently good for 745 hp naturally aspirated and spins to 7500 rpm. This is the part that blows me away. The only thing that's forged are his pistons. The rods are stock cast units, shot peened and polished, and it's a cast iron crank in a 2-bolt main block. The metallurgy of this combination should have given up long ago, but he's had this engine previously in a 10.01 second 1969 Firebird, and has run it for the past decade in his GTO. Although a heavier car, he once tried to G-tech it. He lifted before the end of his run because of a pedestrian that suddenly appeared, and still scored a low 11 quarter, at 6000 feet altitude, uncorrected and with no nitrous. He does spray a 200 hp shot of nitrous occaisionally, but it makes his goat uncontrollable. I'm talking spinning tires still at 120 mph!

I'm very impressed with the strength of the Chevy engines. Go for the 2-bolt without worry. If you want some extra insurance, stud the mains with ARP and get the Milodon main caps. But if you do, CAUTION: Make sure to check the seating of the oil pump in the rear. Oil pump will need grinding to seat. If you don't, it will look seated in the front, but the nut on the rear main stud will hold the oil pump off of its seat and you will experience low oil pressure.
Happened to me. I caught it before any engine damage took place. :eek:


[Modified by Bearcat, 8:16 AM 4/5/2003]