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How durable is the 5 main engine compared to the 9? I know the Hudson hornet engine made good power with only 4 mains and there have been V8 fords making huge power for over 50 years on only 3, has anyone on here heard of any inherent weaknesses with the 5 main design?

The 5-main Packard L8 engines were more than sufficiently durable for their intended use and lifespan and I don't think there is any credible information that suggests that the 9-main versions were more durable. What Packard tried to promote on the 9-main engines was a refined "smoothness", not reliability or tolerance for abuse.

i heard that. physics might suggest that nine bearing would be better , but that crank is the weak link. long and heavy .

thats good information thank you, i think the bigges problem with the long crank would be extreme rpm or oil starvation if memory serves the lifters are oiled first on these engines

I you look at the oiling diagram in the Data Book, you will see the the mains get oiled first. I believe they refer to it as "full pressure lubrication".

ill take a look at it again your very likely right and thankfully they are full pressure

In the Packard 8 the difference is not so noticeable, but go back to the 3 vs 5 main bearing four cylinder motors and the difference is clearly audible. Noise generally indicates distress which is why virtually all fours today have five mains. However, that long crankshaft in the Packard is a delicate issue that takes a lot of energy to spin.

We sometimes get overly focused on main bearing count and need to keep in mind it's just one part of the total engineering package that results in a good or not so good design. For example, the Packard Twelve, smooth as they come, had 4 mains. Chrysler's Slant Six, as durable an engine as anyone could want, wasn't a 7-main design.

Quote:One thing to keep in mind is all the modern V8s, including multi-thousand horsepower top fuel dragsters, are five main bearing designs. The ubiquitous SBC is readily modified to produce 500hp with five main bearings smaller than the Packard I8.

Quote:A full-race Ford flathead V8 making a real 150hp is rare and expensive. Much more than that and even more massive expenditure is required to keep them from flying to flinders. Bottom line - putting horsepower into a flathead Ford T, A, B and V8 with only three spindly little mains is among the most expensive dollar per horsepower per cubic inch developed one might try to build. BTDTNA.

jack vines