Size Comparison: BMW S52 I6 vs. Ford 302 V8 -or- “I can’t believe you crammed a V8 in there!”

We’re taking a short break from your regularly-scheduled build thread to address the concerns brought up by people that can’t be bothered to do 38 seconds of Google searching.

When I tell someone that I’m installing a Ford 5.0 V8 into my ’97 BMW M3, the most common reactions are:

  • “How are you cramming that huge engine into a little BMW???”
  • “You’ll completely destroy the balance of the car!!!”
  • “SHOULDDA LS-SWAPPED IT, BRO!!”
  • “That’s very nice, sir, but did you want the combo meal or just the sandwich?”

HAHAHA just kidding. As an introvert, I’d never willingly initiate a conversation with someone and admit that I own a BMW.

Like The Hulk, but less green

But for real, people seem to correlate “V8” with “hulking, giant…uh…hulk…of iron”. As you’ll see below, the simple, compact pushrod V8 is dimensionally smaller than the DOHC inline-6.

“But what about the car’s balance,” you’ll ask me. “Have you forgotten to address the second of only three potentially legitimate points you brought up way back at the beginning of this post?”

No, astute reader, I have not forgotten. Here the deal – believe it or not, the installed weight of a Ford pushrod small block V8 is less than that of the original engine. This internet denizen slash hero weighed an M52/ZF combo at 548lbs. Compare that to 475lbs. for the aluminum headed 302/T5 combo he weighed, or about 525lbs. for an iron-head 302/T5 combo.

Worst case scenario says that adding the V8 is pretty much break-even on weight, and if I ever swap to aluminum heads, I’ll lose 50lbs. The funny thing is that turbocharging a car by adding charge piping, intercooler, turbo, and more will routinely add 120-150lbs to the car (much of it at the very front), but no one heckles turbo swaps for ruining their car’s perfect, German-engineered balance. What now, turbo-bros?

LS LS LS LS LS LS LS

And the LS? The small block Ford 302 is dimensionally smaller than a GM LSx engine by an inch or two in width and height, and the T5 transmission I’m using is at least 50lbs lighter than the T56 that an LS needs behind it. The complete aluminum LS1/T56 combo comes out to 609lbs. fully dressed (for the math challenged among you, that’s 84lbs more than a 5.0/T5), and an iron block LS/T56 combo adds at least 80lbs more to the Al block. So the 5.0 setup is significantly lighter.

What about cost? Get. Out. You can probably find a decent iron block 5.3 from a truck for a few hundred bucks, and you can even find the LM4 aluminum 5.3 in the $500 range, but good luck finding a T56 for less than $2000, versus the $300 and $150 I paid for my 5.0 and T5, respectively. So AT A MINIMUM, expect to spend $2500 for the LS drivetrain, or more than 5 times what I paid for the 5.0 setup.

Where does the LS win? Stock power and max power. Your basic 5.3 LS will usually pump out at least 300hp right out of the box, and the stock blocks are good for ungodly amounts; more than enough for me to break the record for “World’s Quickest Death During the Initial Test Drive.”

The best factory 5.0 only ever put out 240hp. Obviously modifications help, and the right combination of heads, pistons, and cam (or maybe a stroker kit) can see the 5.0 heaving out an honest 400-450hp. But now you’re at least $3000 into the engine and you’re definitely pushing the limits of what a stock T5 will take without stripping itself faster than a pre-med co-ed with overdue student loan payments.

Also, the stock 5.0 blocks will BREAK IN HALF at 450-500 horsepower. So that’s your ceiling.

So when should you go LS? I say only if you want to make 500+ horsepower. You can pump a 5.0 up to stock LS power levels, but you can’t strip an LS down to 5.0 weight. Something something Colin Chapman.

Look at my junk

So not only does swapping to the Ford V8 not add a ton of weight versus the stock BMW 6 cylinder, but if you look at the top-down pictures, it’s obvious how much shorter the engine is. That means more of the engine sits behind the front tires, which means more favorable weight distribution and handling characteristics. Win-win. Have a look below. And apologies in advance for the obnoxious watermarks. These kind of photos often end up spreading to the far reaches of the internet, and I just want to make sure they can find their way home.

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2 thoughts to “Size Comparison: BMW S52 I6 vs. Ford 302 V8 -or- “I can’t believe you crammed a V8 in there!””

  1. First, much respect to all your hard work. It definitely shows with this great build. What 5.0 would you suggest as being the best for this type of build? I am a big bmw lover and I cant tell you how many times I went back and forth with swapping out my e36 motor with 313,000 miles on it with the 5.0 or going the s54 route. I think with cost and all this is most likely the route I will go too. Also what rear end are you using. Did you have to beef up the diff? I gotta run but again awesome build and thanks for sharing this with us.

    1. I like the Explorer 5.0 for its compact accessories and easy use with Megasquirt. But on the other hand, I think the simplest way to go is to get a full engine/transmission/ECU from an ’87-’95 Mustang and drop it straight in. Way less work, saving you hours of setup time and probably quite a bit of money in buying all of the separate bits to put together what’s needed for the swap.

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