Lol, thanks!

Like I said, not our first rodeo with an NC, the first being a Club PRHT in red.



We probably would not have let that one go, except at the time my wife was commuting 150 miles/day on busy rural two-lane and wanted a little more comfort and more power for passing. Compared to an NA/NB, for street driving, the little bit of extra room, more power, and more modern features make it much nicer day to day. The power hardtop is just the cherry on top.

And if I were starting over on a race car, I would absolutely pick an NC over NA/NB.

 

About a month ago, I tested the NA at the local AutoX to see if my CPS wiring fix had worked. I didn't have any cutouts, but the logs still showed a couple of signal errors. I pulled the CPS connector apart, and put a slight crimp in the female side of the connectors for a tighter fit over the pins. A street test drive showed zero CPS trigger errors. Yesterday, I ran the local AutoX again, and again, did not have any cutouts. Going to pull the logs today and check for CPS trigger errors.

As much as I enjoy the driving at AutoX, it was a pretty miserable day. 9 hours for 6 minutes of driving. I was in the second run group this time, so 3 hours standing in the sun at 95* chasing cones before driving. Sitting in the grid between runs choking on the exhaust of the two carbureted cars I was gridded next to (which they left running the entire time in grid). And roasting in the car... if not for my coolshirt, I'm not sure I would have been in any shape to drive. Of course, a caged/harness car doesn't help... the time between runs was just short enough to make getting in/out of the car impractical. Ugh...

In any case, the car ran well and I put up respectable times. Still waiting for results to be posted, and I need to look at the data. I think I got some video this time...

 

This is my one hesitation with signing up for a true autocross. I've done a few autocrosses on go kart tracks and the seat time was alright, but those were no-work and were pretty small events, maybe 50-60 cars max. It seems like there's a large variance in seat time depending on the event, but I'd better be getting a lot of driving in if I'm going to stand outside for hours in the summer sun haha.

At any rate, glad the CPS issue is solved! Can't wait to see the video.

 

Glad to see you got your CPS sorted. That's the sort of issue I hate, but I've encountered loose wiring pins often enough now that it's one of my first suspects for issues like this. I need to do the same to my clockspring airbag connection, it regularly shows a fault, but reseating that connecter fixes it most every time for a few weeks.

Once I started doing track days I could barely tolerate going to an autocross unless it was a test and tune. Hours of work for minutes of driving, and usually the time in grid is so short that you can't hardly compare notes with your competitors while you're actually driving. Plus, gonna be honest, I'm not that good at it. I drive too much by feel and feedback from the car rather than sight. On track I'm running in the advanced groups. At autocross I feel like novices are nearly running the same pace as me, which gets frustrating and demoralizing.

 

AutoX results posted, logs pulled...

No trigger errors while on course! I did have a few trigger errors when the idle drooped, I think when I nearly stalled the car a couple of times coming on/off grid. Still getting used to the clutch when idling around the pits. All trigger errors occurred at RPMs below idle speed... I think the errors were more related to nearly stalling than an electrical issue.

Came 9th fastest overall of 45 cars, 2.1 seconds off FTD (CAM-S C5 'Vette). Plenty happy with that.

Max sustained lateral g's in the 1.0 range... definitely low grip compared to a real track! Max speed on course, a reality shattering 47mph...

 

Only got one run on video, and it started late... looking into an external power fault with the camera. First, and slowest run....

 

47mph, holy hell that is a tight course! Does look like fun though haha. Congrats on the result.

 

Sweet video, looks like a hoot. Other than the standing around in the heat all day, that is. Looking at the video I can only imagine how hot that big 'ole slab of concrete gets with no shade in sight. And I thought it was hot in Grand Junction!

 

I'm very glad that your CPS issue is resolved! The car seems like a lot of fun in the video. I too agree about the cons of autox but I would be lying if I said I didn't enjoy it. Granted, I wasn't choking on carb smog and didn't have a cage to hop over when getting out of the car. I look forward to seeing your car in action sometime soon(ish)!

 

Thanks, guys.

No new NA news, except we'll be running at INDE this weekend. First real track since the AutoX testing... fingers crossed.

I did take a 'family photo' early this morning. Last chance because the NB is off to a new owner in Alabama...

 

Had a great day at the track yesterday (FINALY!!)... more to come. Need to unpack the trailer, and download data and video....

 

TL;DR...



Car ran perfectly. Even with grip down, went 4.5 seconds faster than my previous best. Won my TT class.


The deep dive...

INDE Motorsports Ranch, our favorite AZ track and I guess we can call it our 'home' track now since it's the closest to home. Because of moving, and the swap, and life, etc. it was our first time there since March of 2023. My wife and I were both driving HPDE, and I was competing in a time trial class of 6 cars including another Miata, Veloster N, Mustang, Firebird, and a Corvette. For this organization (ProAutosports) the TT classes are based on power/weight with a tire modifier.




I spent the first session trying to work out shifts and braking points, as things had obviously changed a LOT since the last time we were there. By the end of the first session, I had things basically worked out, though I noticed a lack of grip in the longer, sustained corners. I ran a 1:48.93, compared to my previous best (with the BP engine) of 1:52.57 with better conditions. Everything was working properly, I was getting good data, and video seemed to be recording.

Second session, I decided to carry 4th through a corner where I was previously using 3rd, and fine tuned a couple of braking points and dropped to 1:48.09. With this being the first time out (other than AutoX) where I got more than one lap without the engine cutting out, I was just happy to drive it and get used to the car again.

With the day warming, I figured things weren't going to get better, and I was right. Our first TT competition session wasn't 'till noon, and it was approaching 90*F. We try to grid according to lap times, but it doesn't always work. I talked to a GT500 Mustang driver that ended up gridded behind me, and told him to just go by on the warm up lap, and when we went out he did. Unfortunately, we bunched up a bit on the out lap, and while we were trying to spread out a bit, some dimwit in a Mustang GT passed about 6 cars and then held us all up as we got up to speed. That cost me three laps before I finally got clear, and ran a 1:48.93 on my only traffic free lap. When I got back to the pits and looked at the results, I breathed a sigh of relief... I was leading my class by 3.5 seconds.

Our second session wasn't until 3PM and it was a little over 90*F. I didn't expect a quicker lap, but went out anyway, hoping for the best. There was also a car in my class that didn't run the first session, so I was worried he might lay down a fast lap. I screwed up big time on my first hot lap, and overcooked turn 1 at the end of the longest straight and had to take the escape road, which put me out at the back of the pack. And behind the same Mustang driver.... and again, he would give a point by, but not let out of the throttle, so it took a few laps to clear him. I got lucky again and got one clean lap, a 1:48.83. I needn't have worried, because no one in my class went faster than the #2 driver in the first session, so it was a win for the day!

 

The deeper dive...

Looking over my data, everything looks really good. Coolant temps peaked at about 190*F on track, and oil temps were even lower, topping out in the low 180s after 7-8 laps. IATs remained at ambient temps, so my 'cold air' inlet is working.

Grip was definitely down, .1-.15g in the longer sustained slow speed corners. I am comparing two different data systems (cell phone app vs. AiM), but even my wife commented on the lack of grip, and the corner speeds back it up, so I believe my previous data was reasonably accurate. Whether it was track condition, or tire age, I'm not sure. One thing I was happy with is I was much more comfortable with driving the car on the slip angle than previously. Since I haven't had much actual seat time in the car in the last year, I attribute some of that to the online SIM racing I've been doing over the last year.

So, speed deltas... here's a track map with the actual speed deltas, peak straight speeds and minimum corner speeds. Black numbers on the inside of the track are previous best with BP engine. Red numbers on the outside are from yesterday with the K24. There was also about a 20*F difference in ambient temps... 63*F afternoon high for the BP numbers, over 90*F for the K24.



Obviously, the K swap made a huge difference in terminal speeds on the straights, and even between some of the corners. 15 mph on the main straight, 11 mph on the back 'straight'. Obviously, those required big changes in braking points. The back 'straight' was flat with the BP, and there are now a couple of spots that require a slight lift. You can see the lack of grip in some of the lower speed, sustained corners, and even coming on to the main straight. That makes the K24s terminal speed on the straight even more impressive.

Anyway, after finally having a good day with solid data for comparison, I'm super happy with the performance of the car at this point. I'm going to keep looking at the data, as I think there was at least another .5 second in my driving if I can dig it out. I've also got a bunch of video to go through and I'll try to have that up later today.

 

Video

 

Nice driving, Chris! That track looks like SO much fun, one of our locals took a driving school over there and was raving about it. I'd love to make it that way sometime.

Very glad to hear the cut-out issues seem to be gone and you were just able to drive the car. All good stuff. Car looks great as always.

 

Thanks!

And I need to keep better tire notes in my log book. When I pulled the wheels today as part of my usual post-race inspection, I realized I had already flipped them on the wheels. I dug through my receipts and this set of Toyos went on the car in February 2023. So they were brand new for the old best discussed above, and this weekend were on their 8th event. That explains my lack of grip.

 

Dude, nice job laying the rest of the class to waste! Haha, it sounds like the car's just getting better and better on track (and you too of course). Glad you were able to get a full day with no issues after figuring out your sync loss concern.

Also, 190* CLT and 180* oil temp on a 90* ambient day? Damn, that's impressive (says the turbo BP guy).

Stoked to see what times you can pull in the future on fresher tires. For now, I'd be stoked on your current result!

 

Thanks! This car has always run pretty cool. I've had a couple people tell me the radiator inlet in the air dam is bigger than it needs to be, and I could reduce drag by making it smaller. Maybe... but I also think it's one of the reasons I've never had temperature issues.

Some pro pics from Saturday... my wife is driving in most of these...

 

I gave the car a good once-over, since this weekend was the first event post-swap where we really put any laps on it. I was happy to find nothing loose, and nothing leaking*.




*A note for anyone doing a K swap... the KPI oil pan comes with plasticky drain plug washers. I think these are made by Dorman and they're crap. Just throw them in the trash and get copper washers. I'm embarrassed I was stupid enough to use these...

 

Glad you didn't find anything loose or leaking. I agree on the stupid plastic washers - absolutely the wrong part.

While you were going over the car, did you look for clearance issues?

• Exhaust to subframe
• Exhaust to transmission
• Engine mount bolts (engine side) to engine mounts (chassis side)
• Oil pan to subframe
• Valve cover to hood

Glad you're enjoying the swap!