This project has been around for many years. My son was in the womb (now 9 1/2) when I pulled the trigger and build it. It's got miata front spindles, miata rear drivetrain, and 4age 20v engine with toyota T50 trans. I was (and remain) a total amateur, but I've learned a lot refining and refining (and refining).
Latest project was to redo the header. I replaced the original silvertop with a blacktop, as they were actually cheaper at the place I was purchasing. $600 got me a damn near perfect engine- oil was gold with no visible black sludge like my OG silvertop (which ran fine for a few years before I moved to Hawaii, and it magically E36 M3 the bed when someone drove it from HNL to Ewa to deliver it to me).
So the header- the original was 1 3/8 od mild steel- find for the silvertop, but undersized for the blacktop. And I was using a flux core hobart to weld it up. With no previous welding experience. New one is shown first below. It's 1.5 x .065 304- bought an Everlast 185 Micro Tig and it has been great.
Pictures:
This motherberkeleyer sounds like a formula car now with the open exhaust and revs like a motorcycle (stock silvertop flywheel). I've got a magnaflow welded stainless turbo with an ebay polished stainless resonator that I'll weld up tomorrow. Hopefully it's not too loud. I'd record the current sound but it would blow your mind.
Ok, screw it:
I guess I can't imbed video:
https://picasaweb.google.com/Brust.Roethler/BrustsCarIII?authkey=Gv1sRgCK-qtsW6_6TvlQE#5824873570933799170
That's going to like 2500. I think I killed cockroaches across the street when I pushed her to 5500. Still haven't seen 8200 rev limit. 
Cool! I have a midget, most likely, in my future. A previous owner pulled the 1300 for a 1500 and I would love to pull that boat anchor for a 4AGE. Did you have to custom make everything? Just curious about the details.
NOHOME
SuperDork
12/22/12 8:44 p.m.
Welcome back! Been following since the start.
Thanks. It's been a long journey. Single- it was all custom. The engine install required only simple motor mounts, but everything has been a problem to solve. Header, intake, radiator, transmission mount, etc. I'd stick with keeping it as simple as possible. My project was made much more difficult by my desire to have independent rear suspension and big miata front brakes. Keeping away from that would have saved me a lot of time, effort, and money. Use an RX-7 solid rear axle, and get a big brake kit for the midget spindles.
Let me know if you are really interested and I can give you a head start and lots of opinions!
Ok, dammit, I'm re-doing the entire independent rear. I'll do some pictures. It's snowy outside and I'm past the age where no heater, convertible, rwd, lots of power, and snow = fun.
ransom
SuperDork
1/25/13 5:29 p.m.
When I saw the thread title, I clicked, and I got panicky waiting for the page to hurry up and load so I could 'favorite' it...
Looking forward to the rear suspension re-do!
Ok, started the rear suspension. I thought I'd made a lot of progress, until I took pictures. I've got the top part of the subframe welded up, including the front mounts.
From Rear Suspension
The big "flange" type things on the sides bolt in to the stock rear shock mounts. The diff mount here:
From Rear Suspension
I'm using suspension bushings as isolators on the sides there. I'll be building a mini powerplant frame that will connect to the front lower part of the subframe with another bushing set.
Here is the actual mount to the diff housing. One of the "wings" was broken when I got it, but it actually worked out to my advantage.
From Rear Suspension
So that's that. One more gratuitous picture:
From Rear Suspension
I'm getting better at Tig welding, and having a lot of fun with the engineering problem solving. Stay tuned.
BG- I only want the aluminum calipers for the cool factor... big brakes in this car would be silly!!
Edit: I'm so dense that I didn't realize you were being facetious, even with the smiley. They're positively HUGE for the MG, even though they are NA standard brakes.
Ok. Weekend update. No photos because camera battery dead.
-upper a arms done. 2.1 lb vs 3.1 lbs of stock miata piece.
-Subframe at 85%: 18.1 lbs vs 39.5 of previous version.
Stock miata lower a arms are 10.1 each- very hopeful of reducing that to half.
Some unsprung weight numbers for comparison:
Fully loaded spindle with bearings, caliper, and pads: 24.1 lb
Daisy wheel and aquatred tire: 28.8 lb
Upper a arm: 3.1lb
Lower a arm: 10.1 lb
Shortened miata axle: 11.4 lb
Yzf-r1 shock/spring: 4.9lb.
Excellent! I love this project and stoked to see it moving along. The midget I mentioned earlier is my FIL's. He also has a tr8 and mentioned selling the midget. I claimed first dibs, now I just hope I can afford it.
Gotta love a nice blacktop, are you using the stock ecu? I had one in an ae86 with an exhaust, headers, velocity stacks and a tune and it really brought the engine to life. Its crazy how restrictive the stock ecu is. I used a megasquirt ecu they arent very expensive and it is perfect for your setup. If you have the money to spend try it, even with stock cams it might be plenty fast with just basic bolt ons and a tune. :)
That's interesting to hear- you'll croak when I tell you what I've got controlling it- a silver top ecu with afm. The original swap was a silver top and I already had it wired up, so when I replaced the engine with the BT, I just kept the ST electronics.
Still, it is near frantic. I could make it franticer with a megasquirt, aluminum flywheel, and maybe cams.
I've been back and forth on the MS- it runs so well stock that I'd hate to dick it up, and I understand tuning with ITBs is challenging, let alone for a first time tuner.
I actually heard somewhere that the silvertop ecu is less restrictive, i cannot say it is the truth though. But if it runs good than thats awesome!. With the tuning issue, i would bring it to a reputable tuner, and ask questions, they have to learn it from somewhere and sure your very capable of learning how to tune 
That's interesting- I don't know any evidence either way, but I've never heard of anyone using the silvertop ECU to run a blacktop- seems stupid to me ( 
)
This weekend's progress:
From MG Rear Suspension II
From MG Rear Suspension II
From MG Rear Suspension II
From MG Rear Suspension II
From MG Rear Suspension II
From MG Rear Suspension II
From MG Rear Suspension II
Still need to weld up toe links (see the picture with my hand in it), shock mounts, front diff mount, and finish weld all brackets. The shocks will be Yamaha YZF-R1, with some swivels to adjust height/corner weight the whole thing.
So the lower a-arms weren't too bad. I used FK bearing spherical bearing weld cups with 1" OD/ 1/2" id sphericals instead of using rod ends, as I didn't like the shear load on the shank of the rod end. Don't know how much/if this will be better, but I'll feel better about it.
That looks great! Light and strong. Are you going to utilize the PPF mount on the diff as well, or just use the four bolts across the top.
For the top, just the four bolts. This is how I did it on the previous version and it worked fine. I do plan to make up a stabilizer for the nose that will tie into the front right vertical tube- can't leave that unconstrained. Starting to get excited- still have to put the e-brake tabs, the brake line tabs, etc. Then blast and paint. Then align, then test..... then realize that 4.5" travel isn't enough, and buy longer travel shocks.
So I slid it in today. Good news and bad.
Good:
It fits. My measurements were well within the adjustment range, and it seems like it's going to all get under the stock fenders. Win.
Bad/Challenge:
Travel is going to be limited. Dunno what/how I got away with it in previous iteration, but now upper a-arm looks like it's going to hit upper bump stop after 2.5" bump travel. That doesn't seem right. This isn't thoroughly scientific measurement, but I'm a little disappointed. Don't want to do a bunch of cutting to get what I need out of it. The travel of the heim joints gives me almost 9" of theoretical travel. I would like to have 5", but I'm limited by the body, and by the shock travel I'm working with.
Which leads to challenge #2: I'm using YZF-R1 shocks. They have 2.8" travel and 500lb/in springs give or take. Layed over at 45 degrees I get almost 5 inches travel, and close to ideal rate, but upper mounts might be a challenge. I certainly won't be able to get the height adjusters I'd like in there (like a pushrod suspension in reverse- the "pushrod" doesn't move but does allow suspension height adjustment without altering preload or anything like that).
I desperately don't want to spend money on shocks- looking at $500 between single adjustables with springs (I'm on an AFCO kick with 16 series midget shocks). Got nothing material done this weekend, which bothers me, but I've got a lot of thinking to do. Input welcome. I'd take pictures, but it's so hard to get an idea of what you're looking at.
Ok, toe links welded up. agonized over shock placement, but settled on 10.5/17 (10.5 is from inner joint to shock, 17 is to center of tire). Program I'm using says my stock yzf-r1 500 lb/in springs will be too light for 6" travel, but I can fix that when I get it all together. The frequency calculated is pretty high anyway (2.4 hz), so maybe it'll work out. Will have adjustable height and adjustable preload, so we'll see how it comes out.
Came out pretty great. Been driving the past few months when the weather allows. Haven't gone on any extended drives- some minor driveshaft rubbing and outside tire rub- going to have to do something about that regardless- may mean some minor flaring, or swapping to circular rear wheel arches. She's definitely a runner though. Making a rear suspension subframe mount that will go in the trunk and stiffen everything up a bit, but really having fun with it now.
Hi I emailed you as i am looking to do something similar with one of my Twin cam midgets!!
Cheers
Peter
