I am assuming the labor/basic fabrication to be free, or about beer-99, since I know enough people interested in something like this to assist. I'd probably start with an older chassis for the sake of cost, and I've managed to find several junkyard LS1's with trannies local to me, so that isn't a big deal. I'm beginning to think I might actually attempt this, instead of just dream about it.
Just FYI, the older chassis has some extra costs involved. I'd guess $500-1000 worth of extra parts to deal with the speedo, fuel system and a lack of space at the front. Turns out the engine bay is a crucial inch shorter, which means new fans and a few other things. If you get a 1999-00 for your chassis, the engine is more valuable than the one from a 1990-97 so you get more back out of the car.
Good to know.... thanks for the heads up. I may consider going that route, as it will allow me to recoup some initial investment cost, as well as perhaps drive the car a little before I decide to tear it apart.
One advantage of the Miata build is the chassis cost. Depending on what you have planned for the car, this might be relevant. Body damage or replacement of a Vette or FD might be a lot more expensive than a Miata.
Hmmm.....resurrecting a thread that's been dead since before Christmas
Why not take the difference and spend it on instruction?
I love taking an obviously less-fast car and squeeking past a faster car on track. Taking the new 944-Spec, '88 924S around a prepped STi with mediocre driver at Infineon was just awesome.
Practice, then take your buddy to an auto-x, and walk around him in a Camry. Then laugh.
Salanis wrote: then take your buddy to an auto-x, and walk around him in a Camry.
Last year at our mother's day autocross, the novices driving the Ferrari 360 couldn't stay on course and, thus, did worse than my mom in my geo.
http://n.b5z.net/i/u/6145553/i/results/2009-05-Results.htm
JoeyM wrote: Hmmm.....resurrecting a thread that's been dead since before Christmas
OMG, the horror!
Thanks thread police. I felt I had something to add that hadn't been mentioned.
Having bought a near perfect 02 Z06 Saturday, all I can add is, best of luck to the Miata builders. The car is amazing for the money.
In reply to Rusnak_322:
That's assuming one has the restraint to leave the E36 M3 alone. In my case it was a clean, straight one-owner CPO '98 that is now a race car with a license plate, and I've got late-model e46 M3 money tied up.
That says it works really well and as I have no affinity for gold chains or buying 315 and 295 Hoosiers Vettes are out...
JasonZ wrote: Having bought a near perfect 02 Z06 Saturday, all I can add is, best of luck to the Miata builders. The car is amazing for the money.
As a fellow Z06 owner (and Miata owner, for that matter), I have to 2nd this.
Can you change everything on a Miata in order to equal a stock Z06's performance? Probably.
Can the Z06 change parts too and negate everything you just did? Likely.
Local Corvette autocross: LS1 Miata vs stock Z06. Margin of victory for the Miata: somewhere around 4-5 seconds. 
It's amazing they let us come back, although we do have to rely on spies inside the organization to find out when the races are taking place now...
Resurrection! I came across this thread while looking for something else, and thought I'd throw in a data point from the 2011 Targa.
There was a C5 Z06 there. It was being driven by Jud Buchannan, who had been to almost every single Targa Newfoundland (he may have missed 2010) and is the only person I know of who has a platinum Targa plate. He's probably finished on the podium at least a half dozen times. Let's just say that a lack of driver skill or experience was probably not a factor. He's not a pro, but he's quick.
The Corvette was running Level 2 prep. That allows modified heads (from the original castings) and camshafts, 10% displacement bump, engine management changes and just about anything you want to do to the suspension short of changing the fundamental setup (transverse leafs stay transverse leafs, for example).
I was driving the Targa Miata, of course. Modified 5.3 L33 engine, AFCO suspension - basically, Level 2 prep if the Miata had come with an LS1 from the factory 
Also not a pro driver or navigator!
By the time we rolled up to the penultimate stage on day 4, we were ahead of the Z06 by 27 seconds. That includes some very fast open road stages where, interestingly, we were pretty much neck-and-neck. Through the long, high-speed Garnish, he was 5 seconds faster. On the same stage in the other direction, I was 6 seconds faster. I have to say I was surprised when I started looking at the numbers. Being the Targa, we're looking at a wide range of types of driving and that also included some pretty wet stages. Maximum speed was 125 mph, but I only had to lift for that a few times and only once for more than a few seconds.
You can play with the numbers all you want for price- used Miata plus junkyard parts, used Z06 that needs love, etc. But there's a good test of the end result. And I'll bet my car could be duplicated for $20k if you did the work yourself.
Gotta love long-lived threads! 
Just thought I'd add my own data point, since I own and autox both my LS1 '00 hardtop and my '99 NB LS1 conversion.
The Miata accelerates harder when the tires hook up, due to being 500+ lbs lighter. However, the Miata has problems hooking up 225 series RA-1s vs. 305 RA-1s for the Vette. I know that autox courses are always different, but I've closed in on FTD about 3 seconds vs. the Vette, and I doubt if my skills have improved that much.
The Miata conversion has been a blast in itself, and like all projects it's never really finished. Still need to improve oil cooling and get some cooler intake air (thanks to Keith!), and wish I could get some wider rubber on the rears.
Y'all have a good one, Mike
Vettedrmr wrote: The Miata conversion has been a blast in itself, and like all projects it's never really finished.
That's the rub, in general, I think. Many people here just love wrenching as much or more than they love driving the cars, and they would tend to see time spent in the garage as fun enough that they'll happily give the garage time a value of $0 in the comparison, because for them it is fun.
For others, myself included, if the $ situation is about the same, and the Z06 allows you to spend your time driving rather than wrenching, we'd happily pick the Z06 any day of the week, because the fun for us is the driving, not the wrenching. We would place a money value on the time we spend in the garage, because that time is being spent doing something that we see as less fun.
Maybe if rust were never a factor, or parts didn't break, or bolts wouldn't round off, or it just wasn't so dang dirty, I'd enjoy wrenching a bit more.
I suspect that if you're the sort of person who builds a V8 Miata, you're going to be tinkering with anything. Once the Miata is on the road, I'd expect tinker time to be equivalent between the Z06 and the Miata. Sure, you can improve the air intake on the Miata. Or you could improve the air intake on the Z06. Rust, rounded bolts and dirt are going to be present in both cars if that's how you treat them
However, you can pick up a Z06 today and drive it home. Instant gratification.
So Tom... how's your LSx Miata coming along? 
Keith wrote: I suspect that if you're the sort of person who builds a V8 Miata, you're going to be tinkering with anything. Once the Miata is on the road, I'd expect tinker time to be equivalent between the Z06 and the Miata. Sure, you can improve the air intake on the Miata. Or you could improve the air intake on the Z06. Rust, rounded bolts and dirt are going to be present in both cars if that's how you treat them
For the most part I agree with you, but the only way to not get rust or dirt on the car is to not drive the car and keep it in a climate controlled garage. Well, in Michigan anyway.
I'd take a zo6, or any corvette, in a heartbeat. Don't get me wrong... But a v8 Miata with a quiet exhaust would be just so much fun! No one expects the Spanish inqu- I mean a v8 Miata!
Joey
Looks an awful lot like an inline 6 in a Jeep Cherokee at the moment. And an mx6. DAMN this thread is old lol.
Vettedrmr wrote: Gotta love long-lived threads!
I didn't quite follow that, what is the difference in time between your vette and LS miata?
In reply to Keith:
I know Jud, he has known my father longer then most people here have been alive. I will ask him about this on Monday when I see him @ lapping.. Seem to remember he had some car troubles...
PS his Acadian trumps all Nova's or Miatas
before the simmons wheels.
You can make any car faster then a z06.. All you had to do was change the engine, tranny , rear diff, wiring, cooling, brakes, wheels tires... So your really modified car beats a stock one... yeee haa .
The flip side is, spend $30k modifying a Miata (that's the turn-key Flyin' Miata price, I'm not making it up) and you have a car worth a LOT less than $30k. Spend $30k buying a really nice Z06 and you have a car worth $30k. That's nothing to sneeze at. I'm not really playing in that price range but if I was, resale value would be a significant factor.
The Miata's great, but I would pick the Z06 every time.
Good thing there are mass-produced options and interesting custom ones, then.
Your $30k Z06 might be worth $30k today, but what's it going to be worth in 5 years? 10? It's still depreciating. It'll never bottom out to the $5k level, but it is going to keep getting lower and lower.
And what's a custom car built to your particular specification worth? I think it's notable that we've been building LS3-powered Miatas as fast as we can for 2.5 years, and none have come up for sale on the aftermarket. So it's impossible to say what they're actually worth.
The purpose in comparing Jud's Z06 and my Miata wasn't to brag. It was offered as a data point in this comparison: a modified Z06 and a modified V8 Miata, in competition over a long period and a wide range of speeds/environments. Jud's car wasn't stock, but was modified according to the class rules. As I said, other than the fact that my car had the "wrong" engine, it had been given a similar level of modification. I knew he was running about the same speed we were based on the fact that we were usually grouped together at the start.
His Acadian is bad-ass. It was a shame he wasn't driving it in 2012, I enjoyed that beast.
So random that I was just having this comparison to myself today after watching the "best cars for 20k" on Road Testament on Drive. I do wonder now after reading this where the 20k FD RX-7 comes in even though for some reason I still love FC's
http://www.youtube.com/watch?v=pvT_BLK3Z8s&feature=g-all-u
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