Potential 89 Build Up
 

So, I'm pretty sure this isn't the right place for this thread, and I apologize. I looked around and didn't see anywhere else that looked like this thread would go. So if it needs to be moved, I understand completely.


I've been eyeballing an '89 Miata for the sake of doing a V8 swap and making a fun little drift car to play around in. It has to be 25 years old for ease of passing inspections in my home state of Texas. What I have thought about is gutting it completely. Stripping all the wiring out and running a carbeurated 350 sbc with a 5 speed. This way, the only electronics I will have to worry about is the lights/horn/wipers/etc. I would fabricate a new aluminum dash panel to install mechanical gauges. Reuse the stock steering column. No AC, no radio. None of the standard creature comforts. Just a stripped down toy.


Where I have concerns is what all is required to actually fit the motor. From what I've seen, I will have to modify the gussets by the firewall to make I clear and sit properly, and I might run into issues with header clearance and the steering linkage. I don't plan on buying a kit to do this because I have a pretty extensive background in mechanics and vehicle fabrication, as I used to build armored trucks for a living. So Im hoping to find a little guidance and tips before I pull the trigger on this car and this build.


Again, if Im in the wrong spot for this thread I sincerely apologize. Thanks in advance.


-Mike

I have been working on a DIY build for about a year and a half now. I have over shot my time dead lines and budget twice over by now. I could have thrown a turbo on the 4 banger and been doing burn outs a year ago with alot of money in my pocket. Or I could have bought a V8 kit and be done by now. DIY project are very time consuming. If you have the patents and long term storage necessary then go for it.

Armored trucks? Any chance you are in DFW and know a guy named Joe that did simular work?

Yeah I am actually in the DFW area. South Ft Worth to be exact.

Long term storage might be a problem for the time being snice I live in an apartment, but I'm sure could be worked out. I haven't lived without a garage in 5 years and luckily my apartment has one too. Just don't know how long I'll be staying here. Patience I've got cause fabrication tends to relax me in some weird way. Lol

I've seen price ranges from anywhere from $2,500 to $25,000 and that's my only concern. I don't want to spend too much on this project. In my mind it seems pretty straight forward.

-Buy the car and gut it completely.
-Make room for the engine and weld in some motor mounts and reinforcements.
-Fab a cross member to hold the trans.
-Reinforce the sub frame.
-Mount a rear end.
-Plumb the brakes
-Wire the necessities
-Install gauges and finish up an interior.

Considering I'm going old school with a carb'd SBC motor, it just seems straight forward in my mind. I figure between the car and motor/trans/rearend I can get started for about $1800. Then the price of metal for fabrication. Fuel cell. Exhaust. Wiring components and fuse block for the basics to pass a safety inspection to stay street legal So I can drive it to car shows.

But what am I really looking at price wise?

I stopped keeping detailed records of what I have spent for fear my wife would find it. I can guesstimate what I have spent thus far...
5.0 sbf ground up rebuilt ... $1000
T5 tranny. $300
Headers. $350
X pipe $150
Flowmasters. $150
Ecu. $120
Clutch & flywheel $250
Differental 8.8 $85
Driveshaft mods $250
Alternator $120
Mini starter $80
Axles $550
Radiator. $350
Coil overs. $1200
Polyurethane bushings. $200
Ball joints, tie rods, bearings $200
Modified wire harness. $350
Broched hubs. $150
Rotors pads. $250
Roll bar. $550
I'm sure I forgot alot of things but I'm a $6655 and I still need alot in new rubber, wider rims, fender flares, paint. I think I'll be in around $100 by the end.

Well I figured I'd go with an older motor so I wouldn't have to use a harness and ecu. It would be a lot easier that way, save me countless headaches, and it's cheaper. As far as hubs, I figure if I can get a complete rearend with hubs included then I'll just run mismatched rims. I'm not too worried about rims matching on something I'll be doing donuts and stuff in. That will save me money in the long run. I'll get fender flares and for paint I'm just gonna spray bomb it. Interior wise is gonna be stripped down to basically gauges, steering wheel, seats, gearshift and pedals. I figure where the most money will be spent is on fabrication. I'll build a roll cage on my own. I may not even worry about fenders and a hood either but I'm not sure yet. I'm probably going to even go with a fuel cell to give me extra room to accommodate all the new stuff under the car.

One thing I've been thinking about and haven't seen much in the way of in other build threads is the frame of the car. I don't know what all needs to be reinforced and what doesn't. I've never even seen a miata without a body on it so I don't know what their frame looks like.

Maybe you should consider building something like the Ghetto-cet since you have the fabrication background. Have you seen this? https://www.v8miata.net/advanced-eng...etto-cet-2112/

Well miata's are unibody. they don't have a "frame" per say. There are a lot of areas that can be reinforced using seam welding. Also, there are lots of braces that you can buy, or in your case fabricate, such as strut towers, frog arms(bolt under the front fenders), "frame channel" reinfocements (stock miata frame channels are very flimsy) this also gives you something to bolt the trans mount too. I could go on and on.

Personally I think your biggest issue would be fabricating a front sub frame that will fit the car and the engine. Modifying the stock one may be possible, but I've not seen it done and it's very large and would likely suffer a loss of strength as much material would have to be removed. And fabricating a new one would be pretty difficult as it provides all the front suspension geometry and such.
I would suggest buying a subframe that is naked and doesn't have engine mounts on it.
Mount-less Subframe - V8 Roadsters

I'm the self anointed King of Cheap, however if I had a do-over todayknowing what I now know (after owing and building/rebuilding my car for 4 years) I'd buy the car attached below. Even though I haven't seen it in person, it may likely be daily driver quality and you can take care of the details required for perfection (always a very personal thing) as time and money allow. It's listed on this site in the classified section for 10K, is a very low mile car and billed as an original Monster Miata.

Miata V8 5.0 Mustang 302 Conversion Monster Miata

Hey wait I thought I was the king of cheap!

Mike I'd like to suggest you start by reading a couple of build threads end to end. A close look at guys that have done what you want to do will answer so many questions for you and many that you probably don't even know you need to ask yet.

https://www.v8miata.net/v8-miata-bui...uct-tape-1460/

https://www.v8miata.net/v8-miata-bui...na-texas-1535/

This fine build used a kit but it is so good you just have to watch it anyway so grab your popcorn and enjoy! https://www.v8miata.net/v8-miata-bui...-process-1643/

Give that a go and come back with your thoughts.

Edit

I'd say from a purely financial perspective, its hard to beat buying one already built. Plus, instant gratification.

I'd still consider a 4.8/5.3 swap to be nearly as economical as a SBC with carb, honestly. Worrying about $200-300 on the motor cost is pretty minor, but for me its worth it going with efi for the efficiency and ease of servicing. I have had two carb'd v8s and I won't bother again. They need to be tweaked often in my region due to temperature swings, and they smell, hah. To me, mileage and better performance of the 5.3 is the way to go. I found iron examples for as little as $400 in my area, and complete pullout aluminum w/harness for $1200 or so.

DIY subframe I've only seen 1 or 2 successful examples I would trust. I have seen a few people mod the original one and give up, not sure if anyone has done it successfully, but It can be done. Bossfrog's subframe allows you not to cut the firewall, if that bothers you, it just sits higher than the V8R one.