Ls1Mx-5

iTrader: (3)

Hi, first build thread on Ls1Tech so here's the story: Two years ago my father and me decided to put an f20c into his Miata after seeing it done in an issue of super street. However, after a botched k-member modification attempt using a stick welder, we sort of gave up and moved on to build a b20vtec Crx. Recently I sold my Crx and my Mustang to buy a Miata with which I planed to put an ls1 into (My dad still hadn’t officially given up and relinquished the f20c). I found a super clean 1990 automatic Miata on Craigslist and lowballed the guy $2500. Needless to say he accepted and I brought the car home. It had only 94000 miles, and not a spec of rust anywhere. After tearing it completely apart, my thoughts were confirmed. To my satisfaction it had never been in any accident and truly was rust free.

After seeing what a superb car my Miata was, my dad fronted me an Idea: Buy off him the jdm f20c engine and trans, spoon ecu, full engine and interior wiring harnesses, s2000 gauge cluster, interior pieces (s2000 starter push button), and everything else that came with the jdm front clip for only $2900. I gladly accepted. Soon I sourced an rx7 turboII rear end and half shafts for only $700. Over the summer I seam welded the entire chassis, painted the engine bay and most of the interior black. During that time period I also concluded that it would be unwise to sacrifice positive handling characteristics that would come with mounting in the f20c due to its front sump oil pan and the requirement to move the steering rack foreword, (and imprudent to be a ricer). I sold the majority of my S2000 parts to purchase an Ls1/T-56, along with a v8 roadsters kit.

The v8 roadsters kit is superbly constructed and designed. Not only is it stronger, and smaller then the stock K-Member, but lighter weight. It also ties together the frame with its frame rail braces and transmission mount. A stock Miata has all of the drivetrain components tied together as one piece by way of the ppv. This allows for the chassis to flex around the whole drivetrain a negative feature not prevalent in my redesigned Miata.

Here's where its at now: its sitting on four wheels with the engine mounted less then a 1/4 inch from the firewall, the trans is in securely mounted to the crossmember, the rx7 TurboII rear end is in place, anchored by a home fabricated torque arm that bolts to the 3 studs on the case, and attaches upfront around the transmission crossmember. Also the brake system and clutch system are back together and cooling system is almost completely in place. What’s left (sort of in order): Put in the headers and finnish fuel system, test run the engine, put in the steering column, the carpeting, dashboard, the starter, alternator, put in the driveshaft I’m going to order tomorrow, finnish the installation of the summit mechanical gauges, make an exhaust system, install the wheel hubs from MiataRoadster that allow for the rx7 half shafts to fit in place, put in the half-shafts, put in the rest of the interior after it runs, along with the fenders bumper and hood.

Ohh yea, sitting on top of that 346 is an Edelbrock high rise intake manifold accompanied by a 750 Edelbrock Carb...

I occasionally like to cruse the internet and see how other people modify cars, so I can acquire new Ideas for myself. But most of all, I used to envy all those people who had really cool threads and builds. I thought someday I’m gonna have one like that where I completely build my dream car from the ground up, and now I do… a set of coilovers is next on my shopping list. They need to have adjustable ride height, and be as ridiculously stiff as possible. Any Ideas? Tell me what you guys think so far

















What size engine did I buy?
Ohh yea...

Ls1Mx-5

iTrader: (3)

What am I missing? Hmm...an engine stand would be quite nice



Took the oil pan out so Shandelle at V8roadsters could modify it

Came out terrificly













We decided it would be a better idea to take one out of the 'factory' page and lower the chassis onto the engine







Fits in there like a glove. The shifter even comes up through the center of the trans tunnel, right where the stock unit did.

Ls1Mx-5

iTrader: (3)

As close to the firewall as possible



Weird camber angles anyone? Someones gonna need an alignment. Luckily the ingeniously designed v8roadsters k-member allows for all the stock alignment adjustment properties



Nice ground clearance

Painted the rear end

Torque arm, we filled it with foam to prevent rust





Looks good if I do say so myself






Stay tuned, should be on the road soon

dark_dementshun

iTrader: (2)

What kind of welder are you using? Some of those welds look kinda scary. If you have not driven an LS Miata, you have a lot to look forward to! Just be warned, you get used to the power fast and only want more. haha

Ls1Mx-5

iTrader: (3)

I know man, my gasless-mig produced some unattractive welds, but they're strong and will serve the purpose I want them to by holding the thin layers of sheet-metal that make up the unibody together. For the Torque arm however, I used a true MIG welder at my High School for some exterme penetration, overkill welds. The fastest car I've ever driven was a 2008 Porsche 911 (less hp and more weight then my Miata) owned by a traffic court judge, so I think I'll have allot of power to get used to.

Ls1Mx-5

iTrader: (3)

Well, everything is connected, all fluids are in, and the engine is ready to fire up. We hot wired the starter and it spun, but didn't make contact with the flywheel. So we pulled it out and hot wired it outside of the car. The gear slid out and spun fine, so we thought that because we swapped from an automatic to a manual transmission that maybe the starters are some how different. It seems that is not the case. So here is the question, what's wrong? Why is the starter working but not connecting to the flywheel? If you guys can imagine, we are sooooo close to making this sucker run for the first time. We really wanna see and hear this happen. Any help would be greatly appreciated, thanks.

Ls1Mx-5

iTrader: (3)

It was late last night, both my father and I were very tired. It turned out we were simply hot wiring the starter incorrectly. The engine cranks fine now, should start up tomorrow.

LS1-450

iTrader: (33)

Made some helpfull comments about the build in your thread in the "External engine" section regarding the starter issue. Thought I was posting the comments here, but somehow got posted in that thread. Have a look.

Ls1Mx-5

iTrader: (3)

I'm using an 87' Rx7 Turbo II rear end. The way I have it mounted is extremely strong, why do you think my set up is unstable? This is how they are mounted in Rx7's that make in upwards of 700 hp, except for the torque arm which will add even more stability. Think about it, the rear end is going to want to torque upwards, meaning the torque arm will also. The downward weight of the transmission as well as the strength of the trans mount will prevent the upwards movement of the arm. I don't want to sound like a douche, but I haven't seen a stronger set up then mine in a Miata with a TII rear. As for suspension, I have to get my 1.8L sized Torsen LSD sold to fund the purchase of the coilovers I want, and I'll cross the water pump bridge if I come to it. In any case, thanks for the input.

LS1-450

iTrader: (33)

Well....guess you don't need us then. My LSX powered Miata has been in service for 7 years now. Long before the recent influx of too many Miata swap kit companies & "swap experts." I promise you that my rear end strength & set up puts yours to shame. Your mounting is weak & wheel hop will be an issue.

Ls1Mx-5

iTrader: (3)

I'm not a "swap expert" I'm looking for advice which is why I'm posting this thread. How did you mount your rear end? Do you have a turboII? You told me to strengthen my set up but didn't tell me how. How would you do it if you were me? I'm pretty sure that with my torque arm I will not have any wheel hop issues. I'm looking for a friendly discussion/debate here

Shinsetsu

iTrader: (2)

are you not going to metal finish ANY of those welds?



"exterme penetration, overkill welds"

you know having to much penetration creates a stress riser and makes it actually weaker than a weld that is properly done?

Ls1Mx-5

iTrader: (3)

I got the welds on the torque arm just right. The box steel I used was very thick

blk96406

iTrader: (18)

Reading through your post and looking at your pics, the car will be an absolute blast to drive when its done!!! I dated a chick that had a Miata and always wondered what it would be like w/an LS under the hood........

Couple questions and some constructive criticism--- I know that your young, we all start someplace, with something. I am by no means an expert or self proclaimed expert, I learn something everyday. I gotta ask what is up with those welds????? Looking at the pics of your tunnel from the front, blows my mind. The windshield frame and lips around the doors are another one I cant figure out, how are you ever gonna get the trim to even snap back on???? Welds SHOULDNT LOOK LIKE THAT!!!!!! It looks like you have a decent shop/garage that your working in, pick up a grinder w/a flap disc, an angle grinder w/a couple roloc discs, sandpaper, anything and prep the area before you even attempt to strike an arc. In one of the pics, I see what looks like the T-handle to a grinder laying on the floor.......The welder should sound like "bacon frying in a pan" when your welding. Take your time, go slow, and practice. Like I said we all start somewhere, but welding up a car, chassis and suspension parts isnt always the best time/place to "learn". You said that you took the torque arm into your highschool to weld it up, are you taking some welding classes???? You should try getting some scrap from school and just practice prepping, setting up the welder, and work on laying nice beads. The torque arm looks like its just three pieces of box tube that a beaver knawed off...... You should take your time and make that piece again and make the pieces "interlock" instead of just stacking them and butt-welding the gaps. That is a major suspension/chassis part......what would/will happen when it comes at a 5 grand clutch drop??? Filling the torque arm w/foam wont keep it from rusting, it will actually promote rust. Any moisture that gets sucked into the foam will stay there and will rust from the inside out.
Like I said, I am not an expert, but know enough that if someone around me tried thinking that was "good enough", this just wouldnt fly w/me at all.......it is a major safety concern.
Best of luck w/the rest of your build, again not trying to be an *******, just trying to make you look at things a little bit.

Shinsetsu

iTrader: (2)

have an upclose pic of one of the welds? how thick was the material

Ls1Mx-5

iTrader: (3)

Thanks for the input man. I spent easily 20 hours practicing welding different sizes, shapes and thicknesses of steel on different settings before welding the Torque Arm together. I know about the foam rusting theory from reading about people filling their frame rails with foam. No moisture was in the torque arm when I filled it with the foam. I did chuckle at the beaver comment, but I assure you, that Torque Arm is ugly, over built, and extremely strong. It will never break. The chassis welds were all done with a crummy gasless wire mig. I did the best I could with what I had so all the welds are ugly, but strong. By the way, the trim does fit back on, and the transmission tunnel was welded on the inside and outside

blk96406

iTrader: (18)

Right on, man
Best of luck w/the rest of the build..... Ill be checking in to see how its progressing. Youll have to get some 0-60 times, etc with it.........

Shinsetsu

iTrader: (2)

that much heat, you prolly weakened the material around the weld and did more harm then good, welding on one side with the proper penetration is plenty.

Ls1Mx-5

iTrader: (3)

Guess you've never welded with a gasless mig

Shinsetsu

iTrader: (2)

No I havent, but if that is the way it turns out then I dont want to, those look like crap. I would have atleast done some metal finishing to make them a little more astetically pleasing.

proper mig weld on 3/16 steel



the penetration from a proper weld, why would you need to weld again? all it does is weaken the metal


and incase you were wondering this is a tig weld


are you taking any classes on welding or are you just doing it yourself?