First and foremost what year car are we talking?

Swapping to a v8, there's a lot to do before you build the engine. If it's a 67 and later the spindles will work, but the rest of the suspension has got to go including the rear axle.

Swapping to a 351w is gonna be more expense than a 302/289.

 

The project car is a 67 convertible…and the plan is to replace everything, suspension and drivetrain.

 

Can't go wrong with a 302/5.0. Put it together with a stage 1 style cam and some decent AL heads and you'll hit 300HP with no problems.

 

I'd go with the 351W. More cubes from the get go and 300hp isn't hard with just a cam and intake. It will be more fun to drive given it's less HP per cube.

 

Honestly, i have a 351w in my 68, and i'd probably go with a 5.0. It already has roller lifters, and the 351w would need a couple of brackets that a 5.0 wouldn't (assuming you go v belt). Also the 5.0 would leave a little more space between the shock towers. But in the end, it's up to you. Granted i wouldn't pass on a good deal if the 351w was good enough to outweigh the minuses.

 

Any other figment issues with the 351?

 

I’m a fan of 5.0l 89-93 Mustang, Thunderbird, et all engines available as a good short block to start with.

 

Another vote for 351W. I don't know why it be any more expensive than building a 302. 351W short blocks are cheap and plentiful. 351 parts are no more expensive than 302 parts. I suppose one could save a little by going with a small base circle roller cam in a 5.0 compared using a link bar lifter roller cam, but in the grand scheme of an engine build, a few hundred dollars is no big deal. And weren't the later model 351Ws roller cam engines?

For the same amount of money, the 351W will always put out more torque and horsepower compared to a 302. It's a very reliable engine that will last many years and many thousands of miles. For ealier cars you can easily source shorty headers that will fit any situation. Most people want to run headers anyway.

One will have to source appropriate brackets and pulleys for the 351W. But since the OP currently has no V8 engine, he would have to do that for a 302 as well.

Have fun!

 

289/302 any day of he week for a mild 300HP. Is it more effort to hit than the 351? Sure....but the only advantage the 351 offers over the 302 at that HP level is torque...and lets be honest here...v8s don't lack in the torque department to begin with.

302 Pros @ 300HP:
-less weight
-more aftermarket parts available
-smaller physical size
-better fuel mileage(which may or may not matter to you)
-far easier to find a roller block

302 Cons @ 300HP
-less torque than a 351w

Now...once you start aiming for higher HP numbers, I would then immediately favor the 351w...but not at 300HP.

 

Are there really more aftermarket parts available for a 302? If there are, there are still plenty of parts available for the 351W.

The weight difference between a 302 and 351W if both are fitted with aluminum heads, aluminum intake and headers is negligible.

To each their own, but in my book, torque is why you install a V8; so why would you want less torque?

But there is absolutely nothing wrong with building a 302.

 

Why not a 300 hp six cylinder, if a horsepower number is the target?

 

You could not go wrong with either. If it was me with the same car, I would go with a stroked 302 based block simply because it can be dressed to look like a factory 289 with all factory brackets/pulleys, and in reality would be a tire fryer.

 

....and it easily fits between the four walls.....

 

If I’m starting from scratch, I’m going 408W all day

If I’m on a budget, I’m starting with a JY explorer longblock. With an aftermarket intake, exhaust and mild cam, it’ll put down 280rwhp and be a riot in a 3000lb vintage mustang

 

To each their own, but why waste the money on a 408 to make 280RWHP? Seems like an expensive way to not do much.

 

I've run a 289,5.0L, and 351w. Never put any of them on a dyno. All had a good set of heads, decent cam, and headers. The 289 will absolutely scream and wind up quickly. The 351W is fun and the low end torque difference is noticeable, I could light up the tires at 45 mph. IMO-The 5.0L is a good quick combination that you'll enjoy for a daily driver and have some fun with your right foot when you want. There are plenty of dyno tested top end/cam combos that make it really easy to get the HP you want. You can pick up a complete 5.0L with a serpentine drive system fairly easily and it will bolt right in, and any engine builder knows how to work on them. If your car is a '65-68 , with the 351W you'll need to make sure you get the right motor mount and intake combination so it'll clear under the hood.

 

Depends on your budget, but for 300 hp, a roller 302 block with aluminum heads sounds like the way to go. Since you are coming from a 6 cylinder, your suspension plans will be just as important.

 

327.

 

Well, it's nothing more than a 331 kit in a standard bore engine...

 

5.0 roller motor out of a late 90,s -2001 Explorer, pretty easy to find in wrecking yards and good foundation for a build. I'm sure the OP's machine shop will agree. Nothing against the 351, just hard to find untouched and set up for roller lifters. A more expensive build for 300hp.

 

For your stated goals, 5.0/302 out of an Explorer, just like @Huskinhano did here Got my GT40P up and running in my 66

 

Horse Power means nothing for a street engine. You only make HP at high rpm.
You want lots of torque. Massive amounts of torque.
To get that you need a long arm crank.
Spend the money on the block and crank. The bigger the better.
Torque gets you going, horse power keeps you going.

 

Horse Power means nothing for a street engine. You only make HP at high rpm.
You want lots of torque. Massive amounts of torque.

Torque gets you going, horse power keeps you going.

🤦🏻‍♂️

 

To me, the best choice, if you have no idea of what you want, would be the path of least resistance. In my opinion that would be the 302 because of the variety of off-the-shelf build options.
If you're in the position of being able to build anything you want, the 351 is the best choice for performance. This is just one of many opinions and is not backed by factual information.

 

There's no wrong answer

 

I’m fond of the Explorer 5.0 motors. For one these were the last of the 5.0’s. Most of these are the GT40P variant which is the best version of theses. The GT40 isn’t that bad either. The down side of the P version is a revised plug angle which causes fitment issues with some headers. It’s really just a matter of being aware and buying ones that fit.

I don’t know how much HP mine makes personally. It does have a used stock factory Mustang cam that’s like a RV type, nothing crazy. It runs very well. I have talked with two different guys who have actually ran my exact combination on their engine dynos. Both said in the 270-280 range. With a light Mustang they run fine and it was super cheap to build.

Here’s a short clip of my 66. I had to lift after shifting into 3rd. I was way over the 45 mph speed limit and the state police barracks are just up ahead

Short run

m.youtube.com

 

If the OP does decide to go the Explorer 5.0 route, there are still some great camshaft options out there if you’re looking to make power. Ed Curtis at FTI makes some like this one FTI "GT40-KR-X" Hydraulic Roller Camshaft

 

I'd go with a 302 (preferably roller) because you could get 300 hp barely trying. It really depends on what you want.

 

I don't have any direct experience with the options, but I'll offer this ...
I've owned cars that had torque monster motors (like my current S-code; BMW 325e) but didn't go over 5,000 rpm; and cars that had motors that didn't want to go below 3,000 rpm (Lotus TC; Z3 1.9). The high rpm motors are really fun to drive, but can be tiring, while the torquers are more lackadaisical (think truck like) and relaxing. Pick from the column that meets your intended usage.

 

Some dont get my 327 comment. Stroke your 289-302 to 3.25" and with a 4" bore its a 327. If you need to bore it it becomes bigger.

 

Really mess with their heads and call it a "5.4 Liter".