Let me just reiterate again how cool all of this is. And how envious I am of you having the knowledge, tools, and time to devote to such projects. Thanks for taking the time to post everything as you go, too. I find it very interesting. :cool:

I meant it in a good way... It is quite incredible, a definite one-of-a-kind FrankenCar. Do you plan to register it or keep it competition only?

Appreciate the comments.

I don't plan to register it. It won't have any emissions controls and I'm running an aftermarket ECU so it won't have OBD-II diagnostics. When it's old enough that I can get Historic plates for it I may tag it just so I can go play with it more often. But that's several years off (20 year rule in Maryland, so 2024)

One of my big concerns on this project was whether the Miata steering rack would fit. It does, but there is a fitting on the rack that interferes with the front pulley. It's one of the directional high-pressure lines from the spool valve. These are hard lines (basically brake lines but carrying PS fluid) that run from the spool valve to the rack. Pic below shows the fitting with the line removed. When the line is installed it sticks up about two inches, because you can't really make tight radius bends with brake lines.

https://lh3.googleusercontent.com/vq...=w1382-h777-no

Other than that, the rack fits perfectly and doesn't interfere at all. I think what I'll end up doing is converting that fitting to a banjo fitting with crush washers and then running a flexible, braided line to the spool valve. Sort of like this:

https://v8roadsters.com/wp-content/u...Product-52.jpg

Anyway, when I had the rack out I noticed that the two bushings on the driver's side are super soft rubber. I hate compliance in steering and suspension when it comes to autocross cars, so I made up a couple of delrin bushings and re-used the stock Miata metal inserts from the rubber bushings (with the rubber burned off :) ).

https://lh3.googleusercontent.com/t-...=w1382-h777-no

https://lh3.googleusercontent.com/rP...=w1382-h777-no

Today was a day I was kind of dreading. It was to be ABS module relocation day. The location of the RX-8's ABS module (pump) is unfortunate. It's on the driver's side of the engine bay, next to the shock tower. The problem with that with a four-cylinder in the engine bay is the intake manifold wants to occupy the same space. So it had to move. The intake manifold is off in this picture because, well, it doesn't fit with the module there.

https://lh3.googleusercontent.com/qX...=w1382-h777-no

I had a couple choices. One, I could move it about three inches towards the shock tower but keep it in the same general area and orientation. Two, I could move it rearward (towards the firewall) and next to the master cylinder. First I marked all of the lines and pumped the brake fluid out of the system, then disconnected all of the lines. Then I re-installed the intake manifold to see what I had to work with.

https://lh3.googleusercontent.com/Ms...=w1382-h777-no

I realized I had another problem. This intake manifold is designed for a Miata engine bay, and the Miata fuse box is much smaller than the RX-8s. The throttle body would be right where the fuse box is. You can see the black plastic top for the fuse box in this picture, in the lower right.

https://lh3.googleusercontent.com/u6...=w1382-h777-no

The intake manifold I picked up was really designed for a naturally-aspirated application, but it looked like a good, high flowing design for a turbo application, so I picked it up used from the prior owner. The manufacturer had problems with the runners cracking where they met the flange that bolts to the cylinder head, so for this particular manifold they cut the runners and mated them with silicone joiners (with a weld bead run around them so the hose clamps would have something to shoulder up against. This is kind of handy for me, because I could cut the runners a little more and move the manifold closer to the engine to gain more clearance. I'll have to TIG a bead around the runners again at some point, but I gained 1.5" of clearance to the fuse box, which should be good.

https://lh3.googleusercontent.com/Rm...=w1382-h777-no

That problem solved, I started putting the ABS module in various places and orientations to see what would work best. It looked like option 1) made the most sense - I could re-bend each brake line to fit, then make a new bracket for the module. The two lines coming from the master cylinder were easy - I could remove them from the master cylinder and the ABS module, take them to the vise, straighten various bends and re-bend them around a 19mm socket without risk of kinking them. The rest of them were kind of a puzzle. Once I had the ABS module where I wanted it, I started mapping out where I wanted each line to go. I needed to reduce the height coming off the module and move all the lines closer to the shock tower so they wouldn't interfere with the plenum. I didn't take a ton of pics, just a couple of the final product. All the lines fit great and I can get the intake manifold on and off with no issue now.

https://lh3.googleusercontent.com/yV...=w1382-h777-no

https://lh3.googleusercontent.com/2b...=w1382-h777-no

Last task was to install the control arms and shocks. The lowers had spherical bearings installed by a guy who does that for a living. The uppers just got offset delrin bushings for more camber. The shocks are Penskes that I picked up for a song off of a Miata guy (valving is all wrong, but I got a guy for that). I put the brake rotors on and mounted up a couple of 315/30 Hoosiers to test fit those.

https://lh3.googleusercontent.com/a-...=w1382-h777-no

Pimpy spherical bearings. Yum.

https://lh3.googleusercontent.com/S9...=w1382-h777-no

Couldn't resist throwing the front fenders back on and seeing how it looks. Ride height is a few inches too high, but it still looks badass, I think!

https://lh3.googleusercontent.com/OH...=w1382-h777-no

Long day working in 90 degree heat, so I'm done for the day...

Oh, wow!

a) wow


b) Was keeping the ABS required? or desired?

I can't think of a reason that I wouldn't want it. The RX-8 has one of the best ABS systems in existence (even today). It would be really challenging to drive without ABS.

Still following closely, excited for the finished product!

Man, July? I need to get back into this. I've actually done a lot of stuff in the past couple months.

I got my bellhousing and transmission installed and realized quickly that I would have to stand the engine up rather than run it with the 10 degree tilt, like in a Miata. The reason for this is the bellhousing that adapts the transmission (3rd gen RX-7 twin turbo) to the engine (Mazda 6 / Ford Fusion) is designed to have the engine perfectly vertical. This actually helps me, because it solved a minor interference issue I had with the steering rack near the front of the motor. I test fitted the transmission and made a strap to hold the tail of it in the right place.

https://lh3.googleusercontent.com/FI...=w1036-h777-no

Kind of amazing that the shifter hole lines up just about perfectly. The transmission will move forward about a half an inch from where it is right now, and a stock FD RX-7 shifter should work well.

https://lh3.googleusercontent.com/mI...=w1036-h777-no

Like the new oil pan? It's from a Ford Ranger, which came with a version of this engine. Perfect clearance all around. And uses a stock Ranger pickup, dipstick and dipstick tube. Really simple. Only downside is it isn't internally baffled, but I can have some baffling done later on.

https://lh3.googleusercontent.com/Sc...=w1036-h777-no

Oil Pan clearance to the steering rack is good.

https://lh3.googleusercontent.com/Ms...=w1036-h777-no

I think I have everything in place to fab the engine mounts. The engine is about an inch from the firewall at the closest point. The engine is as low as it can go and still clear the steering rack and the subframe, though just barely. The oil pan is not hanging down below the subframe. The transmission is at roughly the right angle relative to the differential. A side note that makes all this challenging is that the transmission and differential need to be at the same but opposite angle. In other words, if the transmission is pointed five degrees down, the differential needs to point 5 degrees up. U-joints only operate at constant velocity if both angles are equal. CV joints (like in a car with independent suspension) don't have this requirement.

I made a couple of plates to bolt to the engine. I'll join the plates to the (stock Miata, for now) rubber engine mounts using some 1.5" OD, 3/16" thick steel DOM tubing.

https://lh3.googleusercontent.com/YX...=w1036-h777-no

I ordered an electric power steering pump from a Toyota MR-2 Spyder to power the steering rack. The factory Miata steering pump won't fit with the turbo plumbing, and the electric pump lets me move weight to the trunk to improve the weight distribution. I ordered it from a salvage yard and it should be here this week, so I can start making a mount for it.

Which brings me to my newest toy... a MIG welder! I haven't welded anything in a long time, so I'm way out of practice. Mostly I just need to tack stuff together so one of my talented friends can TIG it the rest of the way, but having a metal glue gun is essential for engine mounts and other brackets. Fun!!

https://lh3.googleusercontent.com/K9...=w1036-h777-no

Incredible... I've always loved the body shell, the handling and feel of the RX-8..

I got my engine brackets made. It took me pretty much all day Saturday to get them cut and tacked in place. It was a lot more difficult than I thought it would be. I think the first issue was that I made them out of much thicker steel than I probably should have. I bought 3/16" steel which is pretty hard to work with, especially since I don't have a professional tubing notcher. I could have made them out of square tubing but round is stronger for this application and well... it looks better.

Anyway, I started with a piece of 1.5" OD steel tubing and made a riser off of the engine mount on the subframe. I welded a bottom piece to it that I cut out of a flat plate of 3/16" steel. I drilled a hole in the bottom for the engine mount stud.

Then I notched another piece of tube to mate up with that vertical tube. This was tricky since the bracket on the engine is about three inches forward of the engine mount, and about an inch and a half up. I ended up having to tweak the notches I put in the tube quite a bit to get the angle right. Then I had to cut the other end of that tube so that it would line up with the engine plate. I cut an oblong hole in each plate for the tube to slide into so it could be welded from both sides.

Anyway... lots of words. Here is what I ended up with on the driver's side (passenger's side was too hard to get a picture of).

https://lh3.googleusercontent.com/H7...=w1036-h777-no

Ugly tack welds but my machine really struggles with 3/16" steel. On the other side I pre-heated the brackets with a torch which helped a lot and gave me stronger, smaller tacks.

I took the brackets to my buddy Larry who is an expert TIG welder and he finish welded everything. I was pleased that the gaps were all tight enough for him to TIG, and that the tacks I made had good penetration.

https://lh3.googleusercontent.com/BO...=w1036-h777-no

https://lh3.googleusercontent.com/3d...=w1036-h777-no

This week I'll clean these up and paint them so they don't rust, but I'm really happy to get this step done. The engine has been supported by a above-engine support bar and it's in the way of getting a lot of stuff done. Tack welding these with that bar in place was a bear. I ended up doing what I could from the bottom with the car on the lift, but access wasn't great under there either and I'm such a novice welder I'm nervous doing anything not on a bench.

Next up... transmission mounts and ... a turbo!

Those suckers are long!

Yeah, about 5 inches long each.

I couldn't resist going out to the shop and making sure they fit correctly. Driver's side:

https://lh3.googleusercontent.com/6a...2=w583-h777-no

Passenger's side:

https://lh3.googleusercontent.com/58...=w1036-h777-no

I'm surprised by the black thing that it attaches to - in the first picture. Is it braced from underneath and I just can't see it? It looks so long that the torque would rip it off the frame.

The black thing is a factory Miata engine mount, and yes it's braced from below but will be getting another cross brace. The aftermarket subframe I'm using is not known for being super strong.

Speaking of, are you going to gusset the engine mount arms?

Yes, but I need the turbo, manifold and downpipe first so I can be completely sure where things will end up. I should have all of that this week and I can start mocking all of that up.

I made good progress this week. I removed all the emissions crap from the wiring harness. I made some brackets to fit the NC radiator and fan in the RX-8. Not planning to use the stock radiator, but it's convenient to be able to make off the shelf parts fit wherever possible. I got the input shaft of the gearbox cut down, which is required to work with my bellhousing (which is designed for an FC TII transmission with a shorter input shaft). I got the driveline angles correct by shimming the front diff mount, and I got the slip yoke and pinion flange for the 8.8, which means I can start building the driveshaft.

Today I spent most of the day wrestling with the intake manifold, which wants to share space with the ABS pump and the belt tensioner that replaces the belt-driven steering pump that I'm not using. Eventually I'll use an electric water pump setup as well but for now I'm just using the factory water pump. I do need to machine a spacer or find one from a Mazda 3 tensioner because the pulley is about 5mm inboard of where it needs to be to line up properly with the alternator and engine pulley.

The tensioner that came with my 2.5 actually worked once I milled off about 30mm of material from the mounting bosses to move it closer to the engine. The stock NC intake manifold is pretty restrictive and also doesn't fit with the engine straight up in an RX-8, so I got a used Moto-East intake and cut down the runners to move it closer to the head so it would clear the ABS and the fuse box. I relocated the ABS pump to under the master cylinder and re-routed all of the lines. I modified the Mazda 3 alternator, which sits low on the driver's side to make room for the turbo and exhaust plumbing, so it would clear the steering coupler. I spliced in the wiring for the alternator, and finished the battery routing. My hands were filthy all day so I didn't take any pictures of that stuff, but I did take a picture of the "finished" product.

I really want to get this thing fired before thanksgiving to stay on schedule but I need to pick a clutch and flywheel first...

https://lh3.googleusercontent.com/5N...=w1036-h777-no

Awesome. There seems to be a ton of room up front, not so much on top.

So... why not pick something that's in the ballpark and move froward?

Suggested under the assumption that you'll be in/around there again soon enough after its first competitive run anyway...

There is room in front, but not as much as it appears. As it is a standard straight front anti-roll bar will not fit because it would have to go through the front pulley. So either the ARB has to move forward with spacers, or I have to have one made with a bend in it.

The issue is I'm not even sure what will work. The clutch / flywheel assembly thickness from the crankshaft to the clutch fingers is a critical distance. It needs to be within a certain range to work. If this was an off-the-shelf install it would be no problem but because of the mismatched transmission and engine it's trickier.

I finally got someone at Clutch Masters who had half a brain, and was able to in almost no time give me the diaphragm thickness of their dual-disc clutch setup. And, as it turns out, it's 2mm too thick to work with my bellhousing.

I mentioned this to the tech on the phone, who said that they had a "short" pressure plate that might help. It cuts 3mm off of the stackup height. Success! So I'm $1,450 poorer, but I have what I believe is a clutch setup that will work. Which means I'm one setup closer to getting the car running.

I had a super successful run to the pick 'n' pull yard this past weekend as well and nabbed a few parts I need for the build. I'll post up more of what I got done this weekend when I'm home.

Cool!

$1,450 for just the PP? Or does that include the clutch disks?

pressure plate, discs, and an aluminum flywheel. Not a bad deal, really.

So I mentioned I had a productive trip to the pick and pull yard. I initially went there because my RX-8 was missing the front crash beam. The local yard had an '08 RX-8 and it didn't look from the pictures like it had been in a front end wreck. Turns out the car was pretty nice, and the bumper was already gone. So I nabbed the crash beam (four bolts per side, literally took a minute to get it on the cart). While I was there I saw that someone had removed the front wiring harness but left the bottom part of the fuse box. The one in my car had two broken tabs that I had planned to repair, but when I saw this fuse box I just grabbed it. Score.

https://lh3.googleusercontent.com/Qu...K=w583-h777-no

While I was there I noticed that there were a bunch of Mazda 3's around. I remembered that the belt tensioner that came on my 2.5L engine was for a Ford, which uses a different belt (different number of ribs) than the Mazda engines. I deleted the power steering pump from my car and am putting a tensioner where the pump used to be. On a Miata with the power steering pump deleted, this would just bolt on.

Unfortunately, because of some packaging weirdness with the RX-8 and this engine, the intake manifold and the fuse box want to occupy the same space in the engine bay. Moving the intake manifold closer to the engine by shortening the runners would solve that problem, but then the manifold would hit the tensioner. The solution was to take the tensioner down to the milling machine and remove a bunch of material from the mounting legs, re-drill the outer legs so I could flush mount the bolts, then re-drill the inner part of the legs for the dowels, and reinstall everything. The result is just about perfect... but was a ton of work.

https://lh3.googleusercontent.com/eZ...=w1036-h777-no

https://lh3.googleusercontent.com/Af...=w1036-h777-no

It also bothered me that the aftermarket subframe didn't have provisions for securing the factory brake line clamps nor the ABS sensor wires. So I went out to the boneyard and cut those tabs off of the factory subframe and hammered them flat so they could mount up just like stock. Eventually I'll just tack weld these onto the subframe, but since I also cut the factory control arm mount with the tabs, they're secured just like stock.

https://lh3.googleusercontent.com/tD...=w1036-h777-no

https://lh3.googleusercontent.com/nl...=w1036-h777-no

I also finished up a bunch more with the wiring. I ran the hot lead from the battery (re-located to behind the driver where the rear seat used to be), deleted all unnecessary wires from the engine-side harness, ran new wires to the alternator, re-pinned the factory harness for the Mazda3 alternator (moved from the passenger's side of the engine to the driver's side to make room for turbo plumbing on the exhaust side of the engine), and ran the wiring to avoid possible contact with any moving parts. The engine bay actually looks pretty put-together at this point.

https://lh3.googleusercontent.com/mC...=w1036-h777-no

I got the MX-5 radiator installed with some custom brackets I made... I'll end up running a better radiator but I wanted to use MX-5 parts here rather than RX-8 parts for reasons that should become apparent later. I verified the stock fan fits. I started measuring for coolant hoses. It's starting to come together.

I ordered a bunch of metal for the transmission crossmember, so it's sort of a race now whether that stuff arrives first, or the turbo setup, or the rear suspension arms. Or the clutch and flywheel. Either way, lots of work yet to go.

I needed a way to plug the factory EGR tube at the cylinder head. I could have ordered a blockoff plug for $10 or so, but then I realized I could just cut the tube short, crimp it over in the vise, then weld the opening closed. So that's what I did. I don't know why, but this little task was really satisfying.

https://lh3.googleusercontent.com/FF...=w1036-h777-no

I've been doing small things here and there on the RX-8 but nothing really worth posting about. I had been noodling ways to support the tail of the transmission since the RX-8 never had a transmission crossmember and I needed to fabricate one.

I started with some flat steel to bolt to the bottom of the transmission tail housing, then made two ears to capture a round tube and bushing which will bolt through it. My welding is still only sorta okay, I get good heat penetration but I tend to move too slowly when I start to pull the pool.

https://lh3.googleusercontent.com/tg...=w1036-h777-no

Next I used a piece of 2" 12ga steel tubing, cut it to 4" long and made two delrin bushings for it.

https://lh3.googleusercontent.com/sC...=w1036-h777-no

I gusseted the two ears of the bracket that bolts to the transmission side and drilled the ears for the isolator bushing and tube. This is the test fit.

https://lh3.googleusercontent.com/27...=w1036-h777-no

I'm using a piece of 1" x 3" rectangular tubing to connect to the bushing and span the width of the car. I notched the 1x3 to prep for welding. It took a while to get the fit right, which when you kind of suck at welding, makes things easier.

https://lh3.googleusercontent.com/SQ...=w1036-h777-no

https://lh3.googleusercontent.com/XP...=w1036-h777-no

I tacked it, then checked that everything was still square, and drew some beads. I feel like I'm gradually getting better at this. I got a bit of blueing on the inside of the tube so I feel like the heat penetration is good. Everything stayed square which is nice.

https://lh3.googleusercontent.com/Sp...=w1036-h777-no

Underside, actually a harder joint to weld but it turned out better.

https://lh3.googleusercontent.com/ZB...=w1036-h777-no

That's kind of where I'm at for now. I need to repeat this for the other half of the span, but I ran out of time today.

I can only imagine how cool this is going to be to drive once it is complete.

Still room to grow, for sure, but I've seen a lot of welding that doesn't look nearly that good.

Impressive skill developing.

Haha that's not how I intended it.

It's so fun learning new skills, there are lots of "a ha!" moments. I don't know why I didn't get a welder sooner and just start screwing around with it.

OTOH, just because it looks good doesn't mean it is good.

I finished my transmission crossmember. I got a better feel for the welder and got better penetration on the later welds.

https://lh3.googleusercontent.com/Jl...=w1036-h777-no

https://lh3.googleusercontent.com/up...=w1036-h777-no

https://lh3.googleusercontent.com/_I...=w1036-h777-no

https://lh3.googleusercontent.com/0K...=w1036-h777-no

A little primer and paint and they're pretty much done.

https://lh3.googleusercontent.com/Wg...=w1036-h777-no

https://lh3.googleusercontent.com/rr...=w1036-h777-no

https://lh3.googleusercontent.com/94...=w1036-h777-no

I recessed nuts that I tack welded into the reinforcement plates, so it's super easy to install and remove the crossmember.

https://lh3.googleusercontent.com/pq...=w1036-h777-no

https://lh3.googleusercontent.com/62...=w1036-h777-no

I also got my rear suspension parts from the fabricator. Converted to spherical bearings, and the toe and camber arms changed to turnbuckles to eliminate the cam bolts, which tend to slip. Simple to make.

https://lh3.googleusercontent.com/P_...w=w583-h777-no

https://lh3.googleusercontent.com/v1...=w1036-h777-no

Turbo setup came in as well. I had some nervousness about it not fitting, but everything cleared. Bonus.

https://lh3.googleusercontent.com/ZO...A=w583-h777-no

https://lh3.googleusercontent.com/rG...=w1036-h777-no

And I got a limited slip diff to put into my Explorer rear end. DIdn't change the gear ratio, so I just pulled the bearings and installed them on the new LSD, and swapped the ring gear over.

https://lh3.googleusercontent.com/n-...=w1036-h777-no

Starting to figure out the cooling system. Nothing really lines up the way it did in the Miata. Annoyingly, the hot side of the radiator is on the opposite side of the engine bay as the coolant exit from the engine, so the coolant pipes have to cross over. I could probably change this, but it would require a custom radiator to make the air bleed and overflow piping to work correctly, and I'd rather not re-engineer that.

Anyway, coolant exits the cold side of the radiator on the passenger's side, then uses this short section of steel pipe to carry water to the water pump inlet on the driver's side. Because the engine is so far forward relative to a Miata the bend was entirely wrong. So I cut it and re-welded it in a different orientation. Nice little half hour job that saved me a lot of time searching for the perfect cooling hose.

https://lh3.googleusercontent.com/jU...=w1036-h777-no

https://lh3.googleusercontent.com/jc...=w1036-h777-no

I don't think anyone is reading this thread anymore, but what the heck :)

I have made progress on a bunch of little things over the past month. I pulled the engine so I could finish building the oil and fuel systems, install cams, swap the crank pulley over, and re-time the engine. No pictures of any of that, because my hands were covered in cam lube and I didn't feel like getting my phone dirty.

I finished the important part of the wiring as well. The MR-Spyder power steering pump is wired in with a dedicated 4AWG wire from the battery, which will be behind the driver's seat.

Most of the interesting stuff was finishing up the fuel system, which was something I'd never done before. I ran E85 on my last car, but I never changed the fuel system (other than the pump and injectors) to accommodate it. The RX-8's stock fuel lines are about 5/16, which is probably sufficient for the power levels I'll be running but I wanted to create a return-style fuel system that never existed on an NC or an RX-8, so it necessitated some plumbing changes. I ended up deciding on a new 3/8" (-6AN) PTFE feed line from a new fitting at the fuel pump, to a 10 micron filter, to a flow-through fuel rail with an external rising-rate (1psi fuel pressure increase for each 1psi of boost pressure) fuel pressure regulator. I also wanted an ethanol sensor in the return line so I picked up a standard GM (Continental) sensor.

The PTFE fittings are a little bit weird to work with until you're used to them. Lots of band-aids were needed.

Flow-through fuel rail with 6AN fittings on each end.

https://lh3.googleusercontent.com/3C...=w1002-h751-no

Feed line is 6AN through a 10 micron filter mounted in the trans tunnel, and 6AN all the way back to the pump. The stock feed line is used for the return. I put the E85 sensor in the return line.

https://lh3.googleusercontent.com/GZ...=w1002-h751-no

https://lh3.googleusercontent.com/yi...=w1002-h751-no

I turned a simple plug to defeat the pressure relief valve in the RX-8 fuel pump assembly. This is normally where the fuel pressure is set in a stock vehicle.

https://lh3.googleusercontent.com/XM...=w1002-h751-no

Bulkhead fitting with a 3/8 barb inside the pump assembly and 6AN on the outlet. The barb connects right to the barb fitting on the pressure side of the pump. The stock siphon mechanism is preserved.


https://lh3.googleusercontent.com/m_...=w1002-h751-no

I'm still reading! This is fascinating.

Me too :cool:

Hell yeah, me too.

Ok well thanks for making me feel better. :lol: