NeverEnough

I'm thinking of picking up another expensive toy like C7 Vette, ZL1, etc. But maybe I should V8 swap my 97 Miata instead.

I would not be doing the work, though. So let's say I bought the Monster Miata ot FM LS motor swap kit (I would be going with an LS3 or LS2)...what am I looking at realistically after paying a shop to to do all the work?

BGordon

For a person who is interested in owning a V8 Miata you would financially be much better off buying a car that has already been swapped.
The garage built cars I have seen for sale over the last couple of years appear to generally be sold for about the cost of the swap parts unless you have somebody like Flyin Miata or Monster Miata do a commercial swap.

My swap used the Flyin Miata kits and all the parts except the engine itself were brand new or professionally rebuilt/upgraded so I have a real good idea on cost of the parts.
If I had gone with a new crate engine it would have been in the $22-$25k range on just the parts (excluding the value of the Miata utilized) depending on exactly which crate engine is used.
Flyin Miata charges about 50k and up to do the swap so that says it is about a 50/50 split between parts and labor for an all new LS based V8 drivetrain swap.

You need to look real hard at the condition of your existing Miata.
If the car has sketchy wiring and rust and all the other problems that go along with a 20+ year old car having a V8 swap done on the car will simply transfer those issues over to a more expensive car.

The next thing to consider when comparing a C7 Vette to a V8 Miata is that the Vette is a nice new car that should be mostly trouble free with any issues being easily fixed at any Chevy dealership.
With a V8 Miata even finding a mechanic that would be willing to work on it could be a problem.
Since mechanics can't possibly know how to diagnose and fix every possible problem they rely heavily on service manuals and diagnostics to fix a vehicle.
By having a Miata with a Chevy drivetrain you have a Frankenstein car that a lot of mechanics will not want to touch.
Don't get me wrong, most of the potential issues with a V8 Miata are either a Miata issue or a Chevy drivetrain issue but a couple of common problems would be a real head scratcher for a mechanic not familiar with what components come from what source.
Think wiring for the prime example.
Cooling issues are another example.

Something else to consider is that a newer Corvette is a more refined vehicle than a 20 year old Miata.
I love driving my Miata around town with the top down listening to the V8 rumble and rowing thru the gears but will drive my 2015 Mustang every time for a road trip.

Doing the V8 swap into the Miata was a personally satisfying project that gave me many hours of planning and weighing options as well as many hours doing the actual work.
For me that was a very important aspect as I can say "This is what I have done and this is how I went about doing it and this is the finished car".
Not sure how much of the personal satisfaction a person would get out of buying a completed swap so with that context in mind my personal inclination would be to spend the money on a newer high performance car if I were not interested in doing the actual swap process.
Put another way, weighing $ for $ puts things in favor of a newer all done performance car over a V8 swapped Miata.

Just my personal opinion, your mileage may vary.

engineer

I totally concur BG, well written. I totally agree that the Miata is an ageing platform. Even the good cars have squeaks, rattles, some have fuel fume smells, water leaks etc etc.

For the most part these can be repaired and sorted but the economics are not always favourable.

I agree the wiring is a tough one. It is good wen working, but can get tough to find faults if things are not working properly.

Also having a pristine donor car makes the end result much better.

Recently I have been considering a better platform for a v8 roadster than the Miata and I came across Renegade Hybrids in Las Vegas. They have kits for LS conversions for the Porsche Boxster S.
Renegade Hybrids - Porsche V8 Conversions

This car is a significant uplift in engineering from the Miata and will likely make a great roadster once completed. The cost to build one will be very similar to a Miata. about $25K in parts (inc new LS3). The Boxster conversion retains the factory 6 speed gearbox and cv shafts thereby making it a bit lighter on the wallet from a drivetrain perspective.

There are some great videos on youtube of the conversion

Porsche Boxster S V8 Conversion Videos


I probably would have done this instead of the Miata if I had known. It would have cost a little more, but the end result would be a much better car.

I have concluded that this will be my next project, but I will be driving the Miata for a while...whilst I sell my kids to fund the Porsche conversion project haha

Also as the Porsche is a 1295kg car so the LS3 conversion will also be technically legal in Australia

Enjoy!