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The LS7 Probably is right at the top, along with the Viper V10, you could probably add a few more to list with not much arguement.

If you want to go back to the 60's and 70's, Id say the Mopar BigBlocks, especially the 440, had fairly stout bottom ends for production motors. The had deep side skirt blocks and came with forged steel cranks right up to 1972.
 

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a lot of turbocharged 4 cylinders have near indestructable bottom ends. You can run 25psi at 7000 RPM on a stock Thunderbird TC and not have a thing to worry about as long as you have enough fuel.
 

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streetpirate said:
what commonly available production gas engine has the strongest stock bottom end?
Most everybody's modern designs have gone to the girdled main cap design where all the caps are part of a larger casting that ties them together and cages the entire bottom end. This is a far superior design to engines that end the crankcase at the mid diameter of the main bearings whether equipped with 2 or 4 bolt main caps or use a deep skirt without crossbolting the mains. The girdled design supports the caps in all directions and reduces the labors of the bolts to simply clamping the major parts together. No longer do the bolts see bending moments as they struggle to keep free caps aligned with the crankcase against the forces of the flailing crankshaft and twisting block.

Going back to the muscle car era, the two blocks most likely to survive were the cross bolted Chrysler RBs and Ford FEs. Of those two, first prize at least in calendar sequence is the Chrysler as it had a wide rod bearing which was more able to hold the oil wedge inside the bearing against the forces trying to blow it out. Ford used a large diameter bearing with less width, while this lead to a shorter block without loosing support area, by the time they got to the 401 horse 390 the rods were beginning to protest. By the 405 hp, 406 they had to do things which led to side oiler, and cross bolted blocks. By the 425 horse, 427 the problem went critical and they had to add reservoirs in the rod throws and cross drilled mains which rather made a poor mans end-to-end lubricated crank. Finally they had to widen the rod journals and reduce their diameter which made the LeMans crank and rod assembly. All this because as the power levels of the FE went up, the narrow bearing couldn't keep the oil wedge from being blown out the clearance. Widening the bearing and flooding it with oil finally overcame the problem. The issue of keeping the oil wedge insde the bearing to journal clearance is a reason why engineers went to cross drilled mains instead of grooved cranks or bearings. It turned out that grooved mains or bearings with grooves in the bottom insert couldn't keep the forces from blowing the oil wedge out and this technique of insuring full time rod journal lubrication fell out of favor and was replaced with cross drilling the mains so there would always be an oil passage connecting the groove in the upper insert to the rod journal.

The history of crankshaft support is well seen in the hyper V-12 aircraft engines of WW II. The Daimler Benz 600 series and the Rolls Royce/Packard Merlins used a deep skirted block with cross bolted, independent main caps. The GM Allison 1710 used a one piece machined skirt with integral mains that bolted as an assembly to the crankcase that was split along the mid diameter of the crankshaft. Quite frankly, when pushed to the limit, the Allison was less likely to chuck the bottom end than either the Daimler or the Merlin, which is why it became so popular with the unlimited hydro-plane racing crowd for the couple decades after the war in spite of the much greater quantity of the more powerful V-1650 Merlins laying around than V-1710 Allisons.


Bogie
 

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Discussion Starter · #9 ·
I love discussions like this

so right now its looking like the best compromise between strength and availability would be the big block mopar? Is there a specific element that makes the RB's better than the B's?
 

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Strange has had a hybrid "S-60" rear end out for quite a while now. It has the 9.75" ring gear.

They say: "...the Strange S-60 is equal in strength to a 9" Ford." They also say "...is significantly stronger than a 12-bolt w/only 20-25 lbs. of added weight.

From that, one can infer that the 9" is stronger than the 12-bolt.

For years (pre 9" Ford), the early Olds and Pontiac diffs were used in dragsters, etc.
 

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Discussion Starter · #13 ·
cobalt327 said:
Strange has had a hybrid "S-60" rear end out for quite a while now. It has the 9.75" ring gear.

They say: "...the Strange S-60 is equal in strength to a 9" Ford." They also say "...is significantly stronger than a 12-bolt w/only 20-25 lbs. of added weight.

From that, one can infer that the 9" is stronger than the 12-bolt.

For years (pre 9" Ford), the early Olds and Pontiac diffs were used in dragsters, etc.

9">dana 60>12 bolt without upgrades?
 

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Dana 60 and the Strange S-60 are the same thing, the Strange version is just a new cast center section that is available with GM style upper control arm mounting points cast in.

As far as the 9" goes I see it as this: an aftermarket 9", with a back braced housing, nodular iron centersection, and Daytona(large bearing) pinion support is roughly equal (almost but not quite, the 60 has a bigger gear) to a Dana 60 but has an advantage of a million more gear ratio's. The average junkyard 9" however, is a POS- flimsy housing that needs a brace, weak cast iron center with small pinion bearings that becomes a problem over 400 hp with slicks, and as such will require twice as many $$$ as a comparable Dana 60 to get it beefed up for real power. Full tilt Dana 60 from a $100 yard core(3/4 ton) cost us $1200 total(housing ends, 35 spline axles, spool, gears, bearings). The same strength 9" was going to be $2300+.

The 12-bolt brings up the rear only due to axles being held in by c-clips, fix this with axle retainers and it is a better rear than a stock 9".

Just my opinion. ;)
 

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streetpirate said:
I love discussions like this

so right now its looking like the best compromise between strength and availability would be the big block mopar? Is there a specific element that makes the RB's better than the B's?
CUBIC INCHES

The "B" engine would be the , 361, 383, 400
"RB" would be the 413, 426, 440
 
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