My friend's $15k Bennett motor made over 900hp and was based off a late-80s production 351W block. I have numerous friends making 700+hp on late model blocks.

The older motors are stronger because Ford lowered the nickel content every year from 72-78 until it leveled off. All the 78-newer blocks are approximately the same strength and they get stronger as they get older back until 72. Before that they are all about equal also. It would be near impossible to put an actual set figure on how much stronger the older blocks are.

 

i have seen a lot of 80's 351 blocks bust out the mains and not making big hp at all usualy only running around 500 hp.

 

Installing a main girdle will buy you some strength. I wind over 500HP on a '69 block with no issues thus far. Make sure the rotating assembly is balanced too.

 

yeah but thats a 69 block not a 86 block a 69 block would usualy hold 500 with no girdle at all.

 

Right. I'm not running a girdle ( yet ), but the original author would to achieve improved strength on the weaker block.

 

ok thanks for the input, also how much more would it cost to have a machine shop machine for a 4-bolt main rather then getting the dart block, im not really a lotto winner so i wont be buying a dart block anytime soon

 

Moocow... I would not recommend converting to 4 bolt mains. There really isn't that much "meat" in the lower webbing of the block. Drilling and taping for the
outer bolts may actually make the webbing weaker. For money spent on this, I would upgrade and go to an internal balance on the rotating assy. Going internal
on the balance is great when it comes to bolting on a blower.....the less weight on the crank snout the better. Use a quality girdle with a forged crank and you can push some big HP out of the Windsor.

 

honesly this is where i would put my money on the block.
http://www.fordracingparts.com/parts...tKeyField=6880

 

True True....if you have the $$$

 

buy the time he buys a set of splade main caps and has all the machinging done to his block it wouldn't be much more to just buy that block.