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Looks like nice welds on that repair! Looks like it will hold up to me
Excited to hear about this weekend, it's puking snow and I'll probably go snowboarding if the winds hold up and the lifts run! But I have the itch for brap things and am just about ready for spring, so living vicariously through you!
Every time I click on this thread, I interrupt myself while reading your updates, and check marketplace to see if there's a beat up NC available. This is turning out to be such a great build. Your NA build was also great to follow.
Congrats on breaking into the sub 2s. Looks like a blast to drive. You know how to build a car.
Wow. This was exactly one year ago and this weekend I'm picking up beat up NC with a 2.5L swap.
This is your fault. I hate you.
I just hopped on to see how your build is going. Keep up the great work.
Pulled a 1:54.61 on Saturday and a 1:54.46 yesterday (with fuel starvation in one corner), good for 4th and 5th place respectively out of 9. The TT3 bar has been raised. When I raced TT3 here two years ago, I got a 1:59.7 which was good for 6th of 9. This weekend, that would've placed me dead last. F*ck. The two TT3 national champs (in an LS-swapped RX8 and 240whp Lotus Elise) mopped up on the rest of us, but the car and I are on pace for podiums at the next event so I'm stoked on that!
Despite being way out of contention for a podium this weekend, the racing itself was f*cking great. Natalee Wiebe has been at the front of the pack for the last couple years in her aero-equipped GT350, and we were neck and neck all weekend, being separated by less than 0.3 seconds during multiple sessions. Our lead instructor Fulton was right there within half a second of us on Saturday (results not pictured) in his less-modified GT350, making for a nail-biter finish. It was about as thrilling as things could get for a mid-pack battle.
Pre-session 1 grid on Saturday, sitting next to Joseph in his K-powered Elise and our lead instructor Fulton.
Saturday morning also yielded something pretty exciting. Our lead HPDE1-2 director pulled me aside and gave me a special assignment for the weekend. Two sets of parents were working on fast-tracking their respective son and daughter into Spec Miata racing, and this was their first day on track. Both kids were in their late teens probably and had been racing karts together for 10+ years. I'd be working with one of them all of Saturday and the other one all of Sunday. It ended up being a total blast. Both of them ripped right off the bat, using the whole track, getting on throttle early mid-corner, etc. They just needed lots of help with shifting and vehicle dynamics because they'd never driven with a gearbox or suspension. They wound up improving bigtime on the couple new additions to their skillset and are going to jump into HPDE3 at the next event. I hung out with both families throughout the day and talked to our head instructor at the end of the weekend and it sounds like I'll be paired up instructing them at the next few events until they get their TT licenses in the later part of the season. Stoked.
Saturday morning started off without a hitch. I was off-pace in the morning, running a 1:56 right out the gate and landing close to the back of the pack, but the car felt good and wasn't doing anything alarming. Before the second session, I added a tiny bit of fuel at WOT to the tune, upped the boost from 7 to 8 psi, and dropped my tire pressures which were way higher than expected at 37psi hot. The next session, I went out, now gridded with all the cars I was racing against and... actually hung on. The two Shelbies and I as well as a TT2 Supra were all running laps within spitting distance of each other. I pulled out a 1:54.91 on lap four and pulled off before I could mess anything up for myself. Ended up just barely edging out Natalee and Fulton that session but it wasn't over. Session three was warmer but I was driving better, and so were the other two drivers. I think each of us ended up shaving almost exactly .3 seconds and ended up in the same finishing places as session two. Session four was much warmer and most TT3 drivers didn't go out but I wanted to get some more laps in so I pulled into grid. Managed a 1:55 flat before the tires got greasy and pulled into the pits sitting 4th of 9 for the day. Pretty solid all things considered!
Saturday night was great as usual. The boys and I cooked some chicken sandwiches then harnessed all the technology we had to watch some episodes of Top Gear. Wireless projector onto the side of the van tethered off my buddy's laptop with WiFi from his phone and audio bluetoothed to the van speakers.
Sunday would go pretty decent as well but with a couple more hiccups. I'd been slowly feeding in more boost throughout Saturday, starting at 7psi and ending around 8.5 based on the logs. Saturday night, I gave the MBC another half turn to try and land at 9psi in the morning. What I didn't think about was the fact that the first Sunday session would be almost 30 degrees cooler than the final Saturday session. We go out for first session Sunday and an LMP-looking car up front loses a wheel on the out lap, causing the rest of us to do pace laps for the next ten minutes while they loaded it onto a flatbed. Finally with just over 5 minutes left in the session, the green flag gets waved. I get on the gas and the Supra that was outrunning me in the straights yesterday starts getting closer to me. We're making 10 pounds of boost now lol.
I wish I could say that I harnessed this extra horsepower to set a PB and clobber the competition. Unfortunately that's not what happened. That extra 15-20 horsepower was too much for my pea brain to adapt to in two laps and I ended up running a 1:56 despite both laps being open and clean. Oh well I pulled the car into the pits and turned the boost back down to 9psi for the rest of the day.
Sessions two and three were timed, with the fourth session on Sunday being a fun run. My two Mustang compatriots and I from the day before would wind up turning some pretty close laps again, with my car just barely edging them out at the end of the day. Unfortunately another super fast Mustang that had broken a tie rod the day before was back, and ran a 1:50 pushing me back into 5th place, and out of any Maxxis contingency for the day. Bummer, but it was still fun sparring with our little pack from yesterday.
At some point on Sunday, my buddy Ricky bought three sets of old tires off a guy in the paddock for dirt cheap. Unfortunately, he drove his Mustang to the track so I ended up becoming delivery service to get them home for him.
With session 4 being a fun run, I turned the boost down a bit more and swapped to those two year old, semi-hammered Toyo RR's I got for $150. Figured most people were packed up and I could just go out and slide around for a little bit. I get on track and consciously try to differentiate the tires I'm on versus the fresh RC-1's I'd been running all weekend. Guess I suck because I couldn't tell much difference aside from the Toyo's seeming to want a little less slip angle. Otherwise, they felt perfectly grippy. About six laps in, though, I go to shift from 4th to 5th, the clutch pedal sticks to the floor and the trans gets stuck in neutral. Dawg, another trans issue? You gotta be kidding me. I coast to a stop and turn the car off. Trans goes into all gears. Ahh, dude my "new" slave cylinder that came with the NC2 trans probably gave out or something. No biggie. I get towed back to the pits and check my transponder times before leaving the car, as my Aim was dead at this point. Best lap was a 1:55.11, only .7 seconds slower than my PB for the weekend. What the hell? On two year old, less grippy tires in higher ambient temps? Maybe it just took me eight sessions to get warmed up lol.
Got the left side of the car in the air. The slave side fitting of the braided clutch line I installed last month had come loose. I love when the mechanical is my fault lol.
After the fun run, we had one more instructing session for HPDE 1-2 then a final session for HPDE 3-4. I couldn't give my students a ride in my car, as I'd yanked the passenger seat out, but my buddy David graciously tossed me the keys to his Boxster so I could take each of them for a few laps. Needless to say, they were pretty hyped. We pulled back into the pits and both dads said they wanted the ride alongs instead next time
All in all, pretty damn good weekend. Got a month until the next round and am going to try and get the 3.7 R&P installed as well as figure out some sort of downpipe bracing solution so I don't have to continuously worry about the turbo to manifold V-band cracking. Also got a potential solution for brake cooling on the way this week, and some other bits and pieces for the car coming in. Onward!
Last edited by Z_WAAAAAZ; Feb 23, 2026 at 03:08 PM.
Smoking dude! The car looks sick out there, glad it's holding up for you still in turbo form. So cool to see it out there battling with GT350's, even if you didn't podium you gotta take a step back and see how ******* impressive that is.
I'm also glad I'm not the only one that usually goes slower when I turn up the wick. I can't think of a single time that it actually netted me a faster lap flipping that high boost switch. If I left it on high boost all the time I'm sure I'd acclimate and go faster, but the switch it power throws you off more than you'd think, ruins my braking points, adds tire spin/overheats tires/etc. It's usually a hoot though, until you munch a transmission.
Yo, thanks Nate! There's definitely been more work involved than when I was N/A last year, but I'm happy with how things are holding up. I'm not taking the result for granted either! Super amped that the car's able to hang with the big boy cars.
Dude I'm glad to hear you've had the same experience with flipping the high boost switch. Braking zones are what killed it for me. You'd think it'd be easy-ish to anticipate where they're gonna be but... it's not.
Finally got the PB lap on YT. Weird coincidence, the Supra ahead in this video is the same one I was following in my PB lap video from Phoenix last month. The 1:54.46 lap was way more exciting than my second fastest one. The dude ahead of me charged in and blew the T1/T2 corner entry, then I followed suit and kinda did the same thing. Then the car fuel starved in T12 from 1:27-1:30. D'oh. Not gonna think about what could've been if I had a bit more gas in the tank.
Two sets of parents were working on fast-tracking their respective son and daughter into Spec Miata racing, and this was their first day on track. Both kids were in their late teens probably and had been racing karts together for 10+ years. I'd be working with one of them all of Saturday and the other one all of Sunday. It ended up being a total blast. Both of them ripped right off the bat, using the whole track, getting on throttle early mid-corner, etc. They just needed lots of help with shifting and vehicle dynamics because they'd never driven with a gearbox or suspension.
That is wholesome and I am not jealous at all, no sir.
Sounds like a great weekend! I need to get a passenger race seat as well.
Lap looks good on the video! Stiff competition, lots of fast times on that sheet (relative to me at least lol). I also miss having a passenger seat sometimes, but what can you do.
Awesome job Zak! Definitely fast with the wrench and on track haha. Cool story with instructing the kids and driving the Porsche around. Keep it coming!
Thanks dawgs! Hoping the next one will be as good as last weekend. Great times for sure.
Buckled down and knocked out a bunch of work on the car yesterday, but first, my fiance's flawless birthday gift to me.
Yeah. That's staying in the van as a conversation piece haha. So sick!
Alright so the car's had a bunch of teething issues and inconveniences since installing the turbo, and I've been trying so hard to keep the car running that I haven't addressed any of the smaller ones. I've got a list of the ones I need to take care of and some proposed solutions:
-Manifold to turbo v-band breaking every few track events ----> Downpipe brace
-Turbulence in the MAF tube at WOT/high RPM causing noisy readings & slightly jumpy AFR's ----> Air straightener in MAF tube
-Front rotors filling with large stress fractures and needing replacement after every ~5 events ----> C6 Z06 Corvette brake ducts
-Shifting like a mad c*nt while on track ----> Swap the 4.1 R&P for a 3.7
-Intermittent smoking at idle that seems to happen less when my crankcase breathers are clean ----> Add another breather port to the block breather plate
-Other things I'm probably forgetting as per usual...
So I started with the diff ratio solution first because an opportunity presented itself. A few weeks ago, Prestige Spares posted up some NC stuff they were selling, a couple open 3.7 diffs being in the mix. Said diffs were being sold for $175 apiece, and a 3.7 R&P from Mazda Motorsports is $446 before shipping and tax. I bought one of the diffs and it showed up last week. Super crusty on the outside, but the internals looked good.
Yesterday, I took the car into work to pull my 4.1 torsen out of the car, and swap in my spare 4.1 open diff for the time being. I'll be having a local shop do the R&P swap this week then will pop the "new" 3.7 LSD in the car next weekend.
After swapping the diff, I got to work on my proposed brake cooling solution, a set of C6 Z06 molded brake ducts, running to AWR backing plates at the hubs. I initially thought that the AWR plates aimed air directly at the rotor face, but was wrong. They shoot air directly at the center of the hubs. Sweet.
These Wilwood Superlites and 12.7" RX8 sport rotors have served me well for the whole time this car's been on track, but post-turbo they've killed a set of pads and rotors about every four to five events. Not horrible, but I'm sure they'd do better with some form of cooling.
This was my first attempt at making the Corvette ducts work. The C6 duct inlets are 4.5", tapering down to 2.5" at the outlet. I couldn't find any 4.5" AC duct flanges, so I grabbed a pair of 4" flanges and am going to finish connecting them to the ducts with some 4.5" to 4" silicone reducers. Zip tied the ducts to my splitter mounts and radiator ducting then attached some 2.5" AC ducting at the outlets to get air to the AWR plates.
Mocked up. Still waiting on reducers and experimenting with ducting length. I'd have liked to get the duct inlets closer to the center of the airdam, but was limited by the splitter mounts being in the way.
Ducting just barely contacts the wheel at full lock. They're 17x10's, what're you gonna do?
Finished off easy. The Duratec/MZR has its PCV valve/baffling built into the side of the block. When I popped in my 2.5, I got rid of the factory PCV plate/valve assembly (which is known to leak under any amount of boost) and installed one of these nifty Radium plates that allow you to run the breather VTA/ Unfortunately, if running the stock NC intake manifold, all that you can fit on the Radium breather ports are 6AN swivel fittings. I ran a single 6AN swivel when the car was N/A, in addition to the 10AN fitting on my valve cover, and it was fine. However, with the car being turbo'd now and these engines creating a boatload of internal windage due to their long stroke, I figured adding some more venting should be a priority. The Fab9 intake manifold I have on the car creates a ton more room on the intake side of the engine, allowing for easy removal of the breather plate and plenty of room for bigger ports to be installed.
Previously, the port on the left was just plugged.
Next week, I've got an air straightener coming in for the MAF tube and will run some before and after logs to test if it stabilizes the MAF readings a bit at WOT. Also gonna try to figure out a solution for downpipe bracing, probably mounting some sort of support from the bell housing. Trying to get all of this dialed in before NASA WSIR on March 20-21 so I have fewer things to worry about on the car and can spend more time enjoying it and less time being scared I'm going to have to deal with a failure or hiccup at the track lol.
Driving the car with an open diff tonight was actually a good experience. I've never driven one of these cars without an LSD, even my NA came with a Torsen. Trying to mitigate wheelspin on corner exits was... actually kinda entertaining.
Gotta finish up the brake duct solution this week still, then it's onto building a downpipe brace and getting the MAF straightener installed. Then by next weekend, the car will hopefully have a 3.7 LSD in it and be ready to punish at WSIR!
Can't wait for it! Swapping from a 4.3 to a 3.6 on my NA (after the turbo obviously) was a game changer. Big improvement on both the track and street.
Unfortunately the shop where I dropped the diff off called me back on Tuesday and said they'd do the r&p swap for $580 so I'm picking it up tomorrow and am either gonna drop it off elsewhere or do it with my buddy at his shop next weekend.
Other things are happening, though. Holy hell this little MAF straightener makes a huge difference in smoothing out the readings at WOT. Ever since installing the turbo, the MAF readings would start to get noisy at 5k rpm to redline, causing a lean-ish spike at 5.2k relative to the rest of the rev range that I couldn't tune out no matter what I did.
Highlighted above are MAF readings from a pull on the dyno back in January. 4k to 6.8k rpm. As soon as the engine hits 5k, MAF readings get turbulent as hell and start bouncing around all the way to redline.
And here's a pull from 4k to 6.8k on the way home from work today (formatted differently as it was recorded on my phone instead of the laptop). No bounce at all. The ECU has a smoothing strategy that accounts for a little noise in the MAF readings, but AFRs are noticeably smoother with the straightener installed and the MAF readings more stable. Even at idle and steady cruise, fuel trims only fluctuate 1-2% where before they'd jump back and forth 3-4% before
Somehow I didn't take any pics of the straightener installed. Just imagine this little doohickey secured into the MAF tube about 3.5" in front of the MAF sensor. After reading up on a bunch of installs, I started out by using friction to hold it into the tube, then spreading a little high temp JB weld around the OD. After finishing, I didn't really like the idea of only friction and JB weld holding the thing in place, despite plenty of folks saying that had worked well for them. Ended up drilling the tube and straightener and using a few very short screws to hold the straightener in place. JB weld on the screws as well to seal the holes.
I'm not too worried about the straightener and slim layer of JB causing a restriction. The MAF tube is already a 3" ID pipe, where the rest of the charge tubing is 2.5" and the throttle body opening is 2.75".
I should also mention that installing the straightener immediately made a huge difference in the MAF readings. Fuel trims pegged 20% rich after starting the car and I had to scale my MAF tables down the corresponding amount to get them back in check. Tonight I confirmed that it was partially due to the sensor orientation and orientation of the charge tubing. Started the car and monitored fuel trims on my phone while playing with the MAF tube. Was able to get MAF readings to swing up to 10% just by changing the depth of the MAF tube in the cold side intercooler coupler.
Made a little progress with the C6 corvette brake ducts as well. The inlets are 4.5", but if you trim off the lip on the leading side, some 4" silicone tubing can be slid over the ducts to connect them to the airdam.
Don't mind that bendy splitter rod lol. The stud bent when I got towed off the track and the tow strap was wrapped around the wrong side of it.
Duct tract is decently straight! Just need to slap some hose clamps on and they're ready to rock.
Second local shop recommended to me by some Miata buddies wants $650 for the swap. What the f*ck?
Think I'm just gonna slam the 4.1 LSD back in as is, grab another torsen unit (diff only, no housing/etc), and install the 3.7 R&P with said LSD core into my 4.1 open diff with my buddy at his shop. I figured I'd pay someone a couple hundred bucks rather than bug him to work on a Saturday (he offered and I'm still gonna pay him of course), but I guess that option just isn't on the table. Thought this would be a hell of a lot easier to get done and I guess it's another good lesson to just learn to do things yourself.
Yeah, that's what I'm saying. Seems like the "f*ck you, I don't wanna do this" price, except the second shop ecstatically told me that they do plenty of Miata diffs.
There's a couple partial videos of NC diff rebuilds on YouTube. Anything over 3 hours labor seems like a stretch.
Sure has gotten expensive. When I did my R&P swap in my 10AE i used a shop up in Oregon (was living there at the time) and it cost me $365 and that was over 10 years ago. I'd have expected more than that now, but not nearly double.
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The two TT3 national champs (in an LS-swapped RX8 and 240whp Lotus Elise) mopped up on the rest of us, but the car and I are on pace for podiums at the next event so I'm stoked on that!
so I'm picking it up tomorrow and am either gonna drop it off elsewhere or do it with my buddy at his shop next weekend.
