454 to 496?

[Mike29]

I just talked to a guy at the marina that bought the 496 c.i. 450 horsepower 515 ft lb. version from these guys http://www.1800runsnew.com/ Any body ever bought an engine from them? There is a shop here locally that I talked to stroking and boring the old 454 to 496 but they still use the small oval heads for marine applications. Theory is higher intake charge velocity gives better torque and economy at a lower rpm. It's not time for a repower for me but a few Blackfin 29 owners are going with the Yanmar diesel option which is extremely pricey. Was wondering if this wouldn't be a nice alternative. I guess more Hp/Torque you can go more pitch on prop? Looking for you experts opinions on this.

 

[Viking76]

Have a friend who did this. Very happy with the results.

 

[crankbait]

i had a similiar experience involving drag racing a 351 cleveland. the heads had the monster ports on them. we put intake runner restrictor kit on....which basically converted the heads into two barrel carb heads. the results were outstanding ! the torque went through the roof......horsepower stayed the same.

 

[makomark]

When it comes to moving a boat, there is no substitute for torque...if cost is not an issue, the diesel wins purely on the spec sheet....factor in cost and, assuming a rebuilt is due, keeping the gasoline engine is the normal winner. To maximize the torque, there is nothing like displacement so adding the longer stroke from the 496 will yield more torque at the prop.

Yes, keep the "peanut port" heads...the engine and your wallet will know the difference. And whenever your repower, it is always prudent to match the prop size to the engine...