Alternative Auto is offering another replacement engine option
for the late model 4.6L Ford followers.

Using the new Ford racing BOSS-5.0 iron modular block.

For about a decade now we’ve been supplying very well done “forged” 4.6L Ford engines that are used in various passenger car, light truck, and above all our most popular customers…. the Mustangs. We offer our forged 4.6L for the 2-valve, 3-valve, and 4-valve combinations.

Before I get into the new BigBore FRP block known as the BOSS-5.0, and why we like it. I want to go into some of our configurations, and thoughts on our basic and stroked forged short blocks.

Besides the usual forged rebuilds that we do consisting of; steel cranks, or even stock “cast” crankshafts some times, combined with good steel rods, and above all; a forded piston. Starting a few years ago we also began stroking the popular 4.6’s too. This would bring a typical 4.6L (281cu in) to about 5.0L, or 300cu in. with a .020 overbore on the cylinders. Stock, production “iron” 4.6L blocks can safely handle .060 overbore bringing those to 307 cubic inches when stroked. We’ve had terrific success with our modular stroker combinations in every 4.6L application we can think of.

One of the key reasons we try to push most of our “forged” short block customers into stroking while their in there any way is; a lot of people need to under stand that some times when adding a steel crank in general (if not equipped with stock) along with a good heavy-duty steel connecting rod, and to top it all off -- a beefy forged piston too…. All of this starts to make the rotating assembly weight a lot more then the standard rotating components. Quite often when going to a forged short, if other steps, modifications or upgrades aren’t taking into consideration, you could potentially and realistically loose some power simply from getting into the heaver/beefier rotating assembly. This is one of the key reasons that we at Alternative Auto try now days to get our customers to seriously consider stroking they’re new short blocks when working with us on 4.6L replacement engine.

Because of the potential power loss from the heavier forged rotating assembly, there are a couple of other things we try to do also in an effort to make sure that the new forged short will right off the bat make equal to, or better then stock power. First off on almost all of our forged short blocks regardless of stroking or not, we shoot for no less then 10.25 to 1 compression. No matter what the combination is gonna end up with. This is a good all around compression ratio we found because it greatly enhances the performance of most of the 2-valves that are usually at 9.0 to 1, and most 4-valve and 3-valve applications that start out at about 9.8, and a couple of years worth of 4-valve motors were at 10.1 to 1 from 2003 to 2004 in several Ford products.

We’ve found with proper tuning, and 93 octane (or race fuel in more aggressive/higher boosted set-ups) that 10.25 to 1 compression is a good all around number even if the application is headed for some mild boost in its future, or is already seeing boost of some sort. Not every thing is done at 10.25 to 1 though, but most are on our watch with great results and tuning durability.