Big engine, meet little car

The LS3 is a perfect swap for the ND, because it hasn't been done enough times to be played out We're just starting on a build for a customer, so I figured GRM might be interested in coming along for the ride. This is basically the same build diary that's published on the Flyin' Miata website, but we should get some interesting conversation here. Don't mind the slightly breathless prose, that's the difference between writing for the website and chatting with my GRM buddies. I am assuming that a lot of people are familiar with the guts of an NA/NB but not an ND.

If I were in marketing mode, I'd insert some links here on reviews of the finished product, but I won't unless requested because we're all friends here

So, let's follow along. Ask questions!

Planned specification includes a 6.2l, 430 hp E-ROD LS3 V8 engine, a T56 Magnum transmission, Camaro differential, a completely new cooling system, a Flyin' Miata brake package and Flyin' Miata Fox Racing coilovers.
Yes, all that stuff in the foreground is going into the car - and that doesn't even include the engine!
This car is going to Hawaii when we're done, so we've decided to call it Humuhumunukunukuapua'a after the state fish of Hawaii. No, don't ask us to pronounce it.

After a surprisingly short time, the "rollerskate" is separated from the unibody.
This is how Mazda builds the cars so they're designed to come apart pretty easily.
All Miatas have been designed this way from the start, but there's been evolution. If you're familiar with the NA/NB, you'll notice the fact that the radiator is mounted to the subframe. The rear end is also a multi-link design instead of double wishbone.

Time to tear down the rollerskate.
This is the naked front subframe. We modify the factory subframe to take the V8 and the new steering rack.
Again, if you're familiar with the NA/NB it's quite a bit different up front, with an integrated crash structure and the sway bar mounts.

The original engine and power plant frame are put on a pallet and set aside.
These engines are either used for R&D or sold. Since almost all NDs are still under warranty right now, there's not much of a demand for them...yet.
They're not great swap candidates into other cars due to the complexity of the required engine management.

You can't see it very well in this picture, but this is one seriously weight-optimized engine. It's pretty clear that the block is aluminum that's been shrink-wrapped around internal passages, it's very complex with a lot of attention paid to grams here and there. The entire intake manifold is plastic, of course.

With the engine bay stripped free, it's time to start the minor modifications to the shell.
We've managed to place the big V8 and transmission in such a way that it fits with very little modification. It's tight, but it fits.

Here's the clutch master cylinder in an ND.
Yes, it's plastic. All of it, even the piston. You can take it apart really easily with just a plastic clip. It even attaches to the pedal assembly with a bayonet mount. Mazda's done a lot to make the ND inexpensive to produce, which is part of what makes it so affordable to buy!
Unfortunately, we need a bigger master to operate the V8 clutch so this little piece of engineering gets removed. We had to design an adapter to use a Wilwood master - you'll see it in a bit.

Even the clutch pedal is plastic!
Disassembling everything is a matter of popping out little plastic tabs. You have to watch out here, it's fun to play with the pedal assembly by pushing on the pedal - but once you get past a certain point, it goes over center and SNAP! will try to cut your fingers off. Very exciting.

Time to move on to the steering.
The ND Miata comes with electric power steering, which we remove. Why? Partly because we love the feel of a good hydraulic rack. But even if we preferred the electric rack, we couldn't keep it.
In order to give the best feel possible, Mazda mounted the electric assist motor right on the rack instead of on the steering column as in lesser cars. That gets in the way of our engine, so it had to go.
The ND rack has a surprisingly large distance between the pivots, so we had to look for quite a while to get the right unit. After all our searching, we ended up back in the GM parts bin with a Camaro unit. We'll change out the tie rods and the tie rod ends, use a custom U joint and voila.

Time to modify the stock subframe.We remove the stock steering rack mounts and weld in new ones, which are tacked into place here. In order to give the best isolation from the big engine, we decided to use factory Corvette motor mounts.
This requires some new mounting plates on the subframe as well. These mounting plates are designed to not only support the engine, but to give good access to mounting bolts so it's easy to service the engine in the future. They're a lot more complex than they look! These and the steering rack mounts are located with a custom jig to ensure perfect alignment.
We also welded on some new sway bar brackets, which are located with some factory mounting spots.

And zap, it's welded.
Ready for paint.

Time to work on the rear subframe.
We have several goals here: provide enough room for the beefy rear differential, reinforce the subframe and make room for a full dual exhaust. We've started here by cutting out some metal for differential clearance, and we're getting ready to weld in some strong plating to reinforce the subframe. The lower bracket will support the differential. Once again, there's a strong and accurate jig to make sure everything's in the right place.
All of these weld-in parts are laser cut from our 3D models so we know they fit every time.

The subframe is sitting upright so you can get an idea of the modifications.
That cross bar at the front gives a huge increase in strength where the acceleration loads are fed into the subframe. That "doghouse" structure is designed to trap the front of the diff and allows the differential to be removed without pulling the whole subframe. It also allows the condition of the bushings to be inspected via small windows and is positioned at a very precise angle for ideal drivetrain alignment. You can see by looking at the side cutouts how it sits slightly off vertical.

...and we're caught up to right now. This is what I call a "productionized" swap - as little as possible is fabricated on the spot, with as many parts as possible produced on CNC machinery and sitting on the shelf ready for use. This particular car is the first of the "production" builds, the previous ones have been used to fine-tune the bits and now we're seeing just what elapsed time is on the build. If you're wondering about timeframe, the car basically went on the lift on Friday.

Oh, and of course this happened. I couldn't resist.

I'm following along, those are some nicely made parts.

Thanks for posting this Keith it is really informative

Keith Tanner said: This car is going Hawaii when we're done, so we've decided to call it Humuhumunukunukuapua'a after the state fish of Hawaii. No, don't ask us to pronounce it.

...one more of life's mysteries solved on GRM

How much?

yupididit said:

How much?

 

If you have to ask... 

That clutch MC reminds me of the one that was in my '95 Cummins. Held in place on the firewall via a 45 deg turn-slot and secured in place with a plastic pin. That popped out and left me on the side of the road one day... 

Hoo-moo-hoo-moo-new-coo-new-coo-ah-poo-AH-ah.

What does a dressed ND motor weigh? I admit I find them interesting from an engineering standpoint and I'd love to take one apart.

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Following with interest... 

Very cool. Thanks for sharing.

I find the thought of the ND drivetrain in something old and light to be interesting. If you could pick whatever chassis, what would you put it in, Keith?

this is amazing. Can't wait to see finished project!!!