Yo, thanks for the input, Ian. Honestly, the fact that the visible splices on those tires didn't open all the way up on you makes me feel better. I got ~10 sessions on the tires this weekend and have yet to see any signs of the splices so my nerves are calmed haha.

 

Success! 1st place in class both days, new PB for myself, 5th of 20+ cars overall, fastest non-V8 car on grid, and two murdered throttle bodies. If that's not an ideal weekend, I don't know what is!



Set a new PB yesterday morning with a 1:29.49. Botched T1 and got on throttle way too late, but I was pretty stoked with my 100+ MPH oversteer correction coming out of T9 at the end lol.


I was anticipating this weekend for a while and was stoked to race, but the icing on the cake was that a bunch of my buddies were going to be at WSIR this weekend too. Our usual gang of five would be instructing and racing with NASA both days, then my buddies Hamza and Tim were also going to be out there working on getting their W2W and TT licenses respectively. In addition to that, the Supermiata MTTC was going on this weekend at the neighboring "Streets of Willow" track, so ALL the rest of the SoCal track Miata gang would be around. Our core group all linked up in the paddock Friday night and knocked out around midnight after hanging out for a bit.


The ol' claptrap posing for a photo early Saturday morning.

Saturday morning was dang near perfect out. Zero wind, maybe 65*F ambient temps, and not a cloud in the sky. I had done my homework and found it was going to basically be a one on one battle for 1st place in TT5 this weekend. Team Rotary heads was there with their 155whp/aero/Hoosier-equipped NB1, and they were aware of my presence after the previous race. Their car is piloted by one of our TT drivers, and also our lead HPDE4 instructor John. John does all of the test rides for HPDE4 drivers trying to get their TT license. He's a really seasoned driver, and also a bit of a no-BS hardass, who isn't afraid to offend anyone by speaking his mind. It comes from a good place, but you probably wouldn't get that impression your first time meeting him. He had plenty of colorful things to say about me and my buddies' driving when we first got into the NASA program, but apparently he had good things to say about me in the HPDE4 classroom this weekend, which was sick to hear. He came over to our pit on Saturday to check out the NC and we chatted for a bit, and exchanged a few competitive jokes. Maybe I'm dramatizing this whole situation after watching the new F1 movie recently, but it felt good all weekend to have one specific competitor (or pair of drivers) to have some back and forth with.


Fuel from the Japanese market to drive my Japanese rattletrap.

Saturday started out pretty well. First session was a practice/qualifying session, and the following three would be competition sessions. I gridded near the front of the pack and got a few traffic-free laps before the pack started getting mixed up. The Toyo R's handle way different than the RC1's, or maybe it's just been three months since my last track event and I forgot what semi-slicks feel like. Just like Toyo stated in the bulletin, these things like pretty minimal slip angle. I spent a lap and a half getting a feel for them, then went for a flyer and set a 1:29.84, under 0.3 seconds off my PB here. Next lap, I passed the start/finish and watched the predictive timer on my Aim slowly start decreasing from last lap. By turn 7, I was on track for a 1:29.3 or 1:29.4. The airdam and miniscule of additional power were making a noticeable difference in comparison to last time I was out here, and I was having to relearn shift points as well. Exiting T8, I was already banging rev limiter, which I've never done before in this car. Unfortunately, I started catching a Spec Miata in T8, and he decided to pit just as I was getting close. I ended up having to let off through T9 and stay inside at the exit to pass, and watched my 1:29.3 fade into a 1:30, before catching up with some traffic. Oh well, the 1:29.8 was still good for a really good grid spot and P1 out of everyone in my class.

Session two got a little dicier. I pulled out of the pits, got through the warmup lap, and pulled a couple mediocre laps before getting on a good flier. It was warmer out now, and I was at a 1:30-something on the predictive timer, but felt really good. I exit T9 at 100+ using all of the exit, and my throttle goes limp. I ended up coasting across the finish line to a low 1:31. I already knew what was happening. Throttle body was beginning to fail and the car was in limp mode. I turned the car off and bump started it and was able to finish the session, but had wound up in traffic and didn't get any more good hot laps. I pulled the car into the pits and wiggle tested the TB wiring to make sure I didn't have an issue there. Couldn't make the car go limp with the wiggle test so I figured one of the TP sensors in the TB was starting to die. After three weeks and one track session. That sucks. I'd forgotten my spare at home but luckily Frankie had brought his and was at Streets with the MTTC guys a two minute drive away. Him and my other buddies were on track when I went to find him so I decided to come back later and just chance the car going into limp mode because I'd survived another 15 minutes after the first time.


Mitchel, Frankie, and I hanging out at Streets later in the day.

Session three comes up and I'm 0.2 seconds behind Rotary heads. With a failing throttle body. Tight. I pull out of the pits and get two laps in before the throttle goes limp again. Yeah, this thing is done. I cycle the key and the throttle comes back to life for long enough to complete my lap and drive the car back to the pits. Thankfully, Frankie and Mitchel are standing at my van, throttle body in hand. We get it swapped out and I tell Frankie I'll warranty his spare if I kill it as well (foreshadowing). Session four I go out and there's dang near nobody on track. It's warm out now but I manage a 1:30.01, good for 1st place on the day! There was an instructor-only session right after so a few buddies and I played musical cars and did some more fun laps after. I ended up taking my buddy David's Boxster out which was fun and way more comfortable than my NC. No further throttle issues from my car .

Saturday night, we celebrated with some hole in the wall Thai food and hung out around my car (and not the fire pit we set up) while I did the world's longest and most distracted tire rotation.





Sunday went a little smoother. Sessions 1-3 would be competition runs and the fourth would be a TT-class fun run . Session one, I pulled two great laps, a 1:29.69 and 1:29.49, and pitted before I could ruin anything for myself. This put me back in P1 for the day, and 5th car on grid! I ran a little slower on sessions two and three, then my throttle started cutting out again at the beginning of session four. I pulled the car off the track and loaded it up for the weekend. I'd done plenty of driving at that point.

John, the HPDE4 leader was ok with the result, but the other driver was not. I ended up going to talk to our TT leader about something unrelated and heard the other driver saying he wanted my classification sheet checked over and that he had some issues with my car. I went over and introduced myself, and told him I'd love to jack up my car and check over anything that was questionable. I wasn't joking either, we're all part of this organization together, right? I don't want to be the guy causing any trouble or grief, I'd rather everybody be stoked on each other. Anyway, we ended up looking over my car. His main interjection was that he thought my splitter was mounted too low, and shouldn't be lower than the front subframe. I told and showed him that the rear of said splitter bolts to a couple holes in the subframe, but has separate mounts up front, so I could chop the rear off and raise the whole a half inch if he really wanted me to. He said that was fine, and was ok with the car after checking everything else out. We ended up chatting about Miatas and general track/TT stuff after and all was well.

I later found out that our class was going to be pretty slim, and he went out of his way to hit up another guy or two so that there'd be enough drivers for the tire contingencies to take effect. So yeah, I'd probably be pretty upset if I were in his shoes



So now I've got a car that's basically ready for the next event in three weeks aside from having a pair of dead/dying throttle bodies. I briefly came up with a plan to design a makeshift throttle body isolator like the K-series guys do, but is it really worth the 1-3whp increase people claim this thing nets you? At this point, I don't think so. I ordered a new connector for the OEM throttle body and am going to reinstall that this week. Maybe later on, I'll revisit the isolator idea and bigger TB. At this point, I don't think it's much of a restriction and I'd rather not have to worry about my car going into limp mode.

More fun updates coming soon. Onwards!

 

That's Absolutely Fantastic! Congratulations! I'm glad everything held together well enough to top the podium twice! It's also really cool to see that video of your fast lap of Big Willow - I've only driven it in simulator so it's really educational to see what it looks like for a Real Life Miata.

 

Great result! Congratulations! And good catch coming onto the straight from T9...

You know you're doing it right when the competition is asking questions about how you're so fast...

 

Hell of a nice save out of 9. You're buzzing bro, fun to watch. Congrats on a solid weekend.

Frankie saved our asses this weekend too haha

 

Sounds like one of those weekends we all live for. Great save there and good work on P1.

I absolutely agree, having some close competition to go back and forth with makes it so much more fun, not to mention pushes you to improve your driving.

 

Haha, thanks all! Still just trying to learn and improve my consistency, but the car and I are definitely getting along well. Hopefully I can keep the streak going for the next event.

Ed, he wound up giving you guys his spare degas bottle, yeah? Heard yours cracked in a really strange location. Sorry to hear. I saw Kaiko driving through the Streets pits during one of my laps. I shouldn't have been had my attention there but the big ol' slab of orange was hard to miss haha. I'll finally link up with you guys and see it in person someday.

 

Congratulations on the result and the epic save! Hahaha that was an awesome update all around, especially when you drive so well someone doubts the car... Nicely done!

Regarding the DBW throttle isolator: I understand it is a must on K swaps that see track, and the one K swap I worked on has one and it is happy. I don't follow the 1-3whp portion though. Are people claiming the isolator nets power, or the throttle you're using nets power? I don't see how the isolator can affect power if designed to the right diameter.

 

Are the 2.5's really as buzzy as a K to kill TB's that fast, or is something else going on? Two in a weekend is an aggressive rate even by K standards.

 

Yo, thanks Ricardo! Much appreciated man.

I should've elaborated further. The supposed 1-3whp gain is from the throttle body itself. The Bosch is a 68mm inlet vs the OEM TB which is 60mm I believe. I don't think it's much of a restriction right now, if at all. When I was creating my "low power" tune a couple weekends ago, I had to limit the throttle opening angle to below 45* before seeing any drop in the MAF readings at all.

Pretty sure I could make a makeshift isolator out of a couple 3" A/C ducting flanges and a short piece of silicone tubing, but I'm at least gonna see if Bosch will warranty my $350-worth of dead throttle bodies before I jump back into this haha. Plus I got some other things brewing in the next few weeks or so...

Wing, I'm not gonna rule out a pin fitment issue with the TB connector. However, both TB's started out going into limp mode very intermittently and got progressively worse the longer I ran them, suggesting an internal TP sensor fault that just kept getting worse. We have a handful of vehicles that exhibit common throttle body failures at work and they all do the same thing as this. Intermittent at first then they get worse fast. I pulled the connector and didn't find any burned pins or evidence of damage to the connector. Wiggle testing the connector and harness didn't produce any results either. From all the other reports I've heard, it seems like the TP sensors in these TB's are just delicate.

I'm obviously biased but I don't think the 2.5's are as buzzy as K's based on the couple I've been in and all the reports I've read on here. My current engine only feels a little buzzier than the 2.0 did and I've never had any fasteners back out on me.

I just sent a warranty request for one of the TB's via Summit Racing. We'll see if I have any success or not.

 

Nowhere remotely near as buzzy as an NA/NB Kswap.

Seems to me an isolator should be pretty easy to draw up and 3d print no? or am I over simplifying it?

Yup, weird Moroso tank failure. Overheated the car bad enough to hurt the engine again, so it's coming out.... again.

 

Ed I was thinking the same thing. Printing in TPU should give it some ability to absorb vibration while still being strong. I've heard of people printing swaybar bushings from it with good success depending on the settings. Might be more of a project than desired, but I'd probably at least attempt that now that I have a printer and an itch to use it for everything I can.

Not sure that it would hold up to boost, but I guess that's not a concern here... for now

Z if you want to play around with that let me know and maybe we can exchange some measurements. Better yet, open a new thread and have a competition to see who can make the best design.

 

What a weekend! Way to go, awesome video, and amazing pace out there. Looks like you are right on the edge of grip everywhere, seriously good driving man, love to see it. Makes me that much more amped to see you throw some power at this thing and watch you try and harness it.. should be fun.

I gotta second the guys on this, those back to back failures make me wonder if something else isn't outta whack causing them to break down like that. It can't just be the vibes, can it? And if so why would the OEM one last longer, it's a bosch unit as well, probably mostly identical but a smaller diameter - right?

 

Ughhh. Gutted to hear that man. Fingers crossed for no more issues after this. Hey though, I've got a spare 2.5 laying around if you guys wanna use that for a bit in exchange for a few stickers! I'm sure the juice isn't quite worth the squeeze, but someone might as well use it since it's just sitting in my garage haha.

Shucks man, don't lead me down another rabbit hole I was gonna tell Ed that 3D printing a solution would probably be easy except for the fact that I've got zero knowledge about doing something like that lol. Seriously, though, maybe I'll hit you up about it later on. I already clipped my Bosch connector off last night and reinstalled the OEM TB. If I come back to it, it'll be after Buttonwillow the third weekend of October. The fewer factors I have to deal with before then, the better. I'll be in touch, though. I'm sure my isolator idea would have all you guys shaking your heads lol.

Haha, thanks Nate! "Try" is going to be the key word there. I've got a good feel for this thing now and the aero/suspension balance makes it pretty easy to drive at the limit. Add another 100 horsepower though and I suspect I'll be back closer to square one lol.

Yeah, I wasn't expecting either to fail so quickly, but the second one lasting only four or five track sessions is suspect. Before I make any more assumptions, I gotta check if the one Frankie gave me was brand new or one of the ones he used a few times.
The OEM unit looks quite a bit different than the Bosch one. Dunno who makes it, but I don't believe it's a Bosch. I know both units have about the exact same TP sensor voltage sweeps and the same bolt pattern, but that's it. I've seen/heard about numerous failures of the Bosch units, but have yet to see anyone say they killed an OEM TB.



Pic of the TB's side by side.

 

Good result man! And a good vid - I wondered if you felt any aero effects from the traffic ahead? It's a great thing to have the opposition questioning your car, just about a 'I've made it now!' vibe lol.

I am watching with interest the DBW issue, my interest is dormant for the moment, the shop doing the quote for the install faded out and I have been doing other things than following up. Like Fire, I am running a BP though I think these lessons have cross-platform implications, even if only on a 'just in case' basis'.

 

I've been told printing a manifold and TB adapter, and using a silicone coupler between the two is the move for ultra happy TB's. No first had experience... Yet...
Frankly I have some doubts about the longevity of a fully printed setup, it seems like a normal aluminum adapter plate would be stronger, but that's yet to be determined.

 

Thanks Gee, much appreciated! The perspective in the video is kinda hard to judge because of the wide angle, but the cars ahead had enough of a lead that I don’t think they were affecting me. Or at least not to the point where I could tell. Unfortunately they were both big V8s that dusted me in the straights so I couldn’t catch a draft lol.

How come you’re considering a DBW conversion on your car? Auto blip? Hell, I’d almost be game to add DBW just for auto blip.

Wing, that’s exactly what I was thinking next, if I were gonna pursue it further. Was gonna copy something like this, just like you described.



Lots of buzz on the 2.5 NC Facebook group today. Apparently two more guys had issues with their Bosch TB’s at the track this weekend. One sounds like it might’ve just been a wiring issue but another guy seems to have killed two TB’s just like I did.

Good bits of info getting tossed around, though.



Stock TB ftw I guess. Still thinking I’ll come back to the isolator idea later on when I get bored. I have a little extra weight I can pull out of the car for the next event if I end up dyno-ing below my power limit, so I’m not gonna trip about three horsepower for now.

Better yet, I’ll take some logs with the stock TB and see if my MAF and MAP readings change at all.

 

Zak, I am doing it for ... wait for it ... cruise control (because not just racecar), though there are other advantages not just auto blip.

That's interesting about the failure mode, I wonder if the potentiometer unit can be remote mounted? That would allow suitable isolation I'd imagine, while simplifying the TB mounting itself. If the whole unit is remote mounted (ie on a rubber sleeve) I wonder if these will provide sufficient damping with adequate structural properties for the intake's integrity. I'm not sure that the sort of silicone and rubber sleeves I have seen wouldn't be too stiff ... although if it is too sloppy I'm sure supports above/below could be made to work.

 

Ahh, creature comforts! I almost forgot about those. Haha, no I totally understand wanting cruise control, among other DBW advantages. Coming from a cable-actuated throttle, I really didn't like how the NC's throttle felt at first. After a month or so of driving it, though, I started to like it. Definitely feels like you're less "connected", but tip in and other small throttle adjustments are a lot smoother. Plus being able to map out accelerator to throttle position is sweet. I'll be revising the throttle tables for 1st and 2nd gear once this car gets enough power to spin tires haha.

In regards to the isolator situation, the points you brought up are some of the reason I don't want to dive in head first yet. I feel like two flanges with a very short run of 3" silicone tube would provide enough damping to save the potentiometers. That's already gotta be leagues better than solid mounting it to an aluminum manifold. From the ones I've seen on K-series cars, supports don't seem necessary although I'd be bummed to build one and find out the TB causes movement and sagging of the intake. Again, just stuff I don't want to be fussing with before the event in under three weeks.

While we're on the topic of 3D printed stuff, though. I got this sweet little number in the mail last night.



ARHindrichs LLC is a performance shop out in TX that has documented and performed tons and tons of 2.5L NC swaps. The owner, Armand Hindrichs, is very active on the 2.5 FB groups and forums, and has an extensive YouTube channel for engine swapping/building DIY'ers, along with some really solid performance-related vids in general. Everything from how to completely swap a 2.5 into your NC, to engine teardown analysis and assemblies, to hour long heat exchanger and fuel injector studies.


I realize this sounds like I'm plugging the guy, but honestly I just like his content and find it interesting. Of course I do, it's directly pertinent to my car lol.

Anyways, a couple weeks ago, Armand posts a YouTube short overviewing some 3D printed oil cooler shrouds he's been messing around with, and says he wants a few guys with temp sensor data to use them and see if they have any effect on oil temps. I messaged him and although I'm not running the oil cooler in the video, he said to shoot him some measurements and he'd make me a prototype. I sent over some measurements and photos and a week later, he sent me the completed duct. It's made out of PA6-CF for all you print-savvy folks out there, and he said he thinks he needed to run the printer at a higher temp to get rid of the little fuzzies on the inside corners. All of this is just an experiment to gather data, though, so I'm not too worried about it. Actually, my oil temps on track aren't even outrageous. I rarely see temps above 230-235* even if it's in the 80s-90s outside. I'm gonna do some back to back sessions with and without the duct in the mountains this weekend (where my oil temps actually get the highest), then at the track at the next event, and will report back if it drops temps substantially.



The duct is definitely gonna steal some cold air that would've been going to the radiator, but coolant temps on this thing are completely in check on track so I'm not worried about it becoming an issue.

 

We can all say, "I knew him when..."


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