After that disastrous day at Road Atlanta(that kept alive its streak of breaking my car, grrrrr) I had exactly one month to the day that the car did not *need* to move, so I was able to address a BUNCH of stuff that had needed doing very, very badly for awhile at this point, including a bunch of stuff yall have been(rightfully) yelling at me to fix(not brake ducts).First in talking with Bronson about brake things, I mentioned I was running the "budget" option rotors, the AFCO 9850-6020 straight vane rotors. And he said... wait lemme find the quote exactly...

"Yeah at your power level you're insane for even trying those at all"
.
Alrighty then, noted. I had been using them because they were cheap... at $40 a rotor I didn't mind if they didn't last that long as the next option was a $120 coleman rotor that I guarantee it wouldn't last 3x as longer as the $40 rotor, and a rotor per brake pad was a cadence that was easy to keep up with. Bronson suggested a better option, the GT48 rotors he's been trying out and getting great life/results out of.
https://www.wilwood.com/Rotors/Rotor...emno=160-13499
They are fractionally thinner(1.21" vs the 1.25") but still fit all the 11.75, 8 bolt templates SM/Brofab/Jerfspeed use. An eye watering $150 a rotor("Yeah at your power level you're insane for even trying those at all" echos in my head and I press buy) but they should last significantly longer and cool much better(Bronson claimed 30% cooling jumping to a curved vane from a straight, don't ask me where that number comes from).

Definitely a lot more thermal mass and structure here compared to what I was running. I'll burn off my last two sets of straight vane 1.25" rotors, then jump to these.



So about that fireballing... best I can figure is when I last installed the turbo, the metal sealing ring between the turbo/manifold got pinched juuuust enough that it caused a leak when really hot. Enough it didn't leak when cold(er), but would dump exhaust gasses into the bay when hot. My welds had NOT actually cracked. Unfortunately it seems the stress of the Vband trying to pull the turbo onto the manifold, along with the heat, warped and cracked the turbine flange pretty badly.



And I realized I had a turbo manifold that was being warenteed... and a scrap turbine housing...(I'd have to take nearly 3/32" off the turbine flange to make it sit flush, it's worse than it looks)... so I said **** it and welded the turbo right to the manifold. Remember this is the turbine wheel/exhaust housing that's already made contact with each other so basically everything in this setup has some sort of damage to it, and has a replacement waiting for when it finally chokes.

Per Artec's suggestion, I added an additional flex joint immediately after the turbo to completely isolate it from any downpipe stresses, and prevent any heat induced stresses. Thus far, the repaired manifold is holding.
To strengthen the screamer pipe, I welded "ribs" to the inside and outside of the bend. It hasn't cracked again, but the amount of vibrations that I see in the tip poking through the hood is frightening. At certain loads/RPM ranges it vibrates so much it appears to be phasing, full on "beam me up scotty" style. I really don't want to know what the rest of that assembly looks like.
At long last, all the turbo lines were converted to 6AN stainless PTFE lines and wrapped in heat sleeve. I had to remove the rear water return pipe and weld on aluminum bungs, and weld a steel AN bung to the fitting in the block, with nessisated removing everything on the hot side which is why this change kept getting kicked down the road. But the days of melting turbo coolant lines(3 seperate occasions) should be over.
Additionally, all the EGT sensors got heatsleeved, as well as the(repaired) wiring for all the sensors that had melted. The turbo blanket had turned completely to ash from catching on fire so we are back to exposed tubing housing. Shouldn't be an issue now that everything sensitive is wrapped.





I also went waaaaaaaay down the rabbit hole and did some deeeeeeep diving on cams and came out the other side spouting gibberish like "overlap is the enemy" "backpressure go brrrrrr" and "scavenging effect is for VE nerds, feed the spinny wheel the energy it craves"

And now it has some BC Stage 2 cams that I scooped off of FB marketplace. Inital testing has been... very promising and a step in the right direction for expanding the powerband of this car and managing all the bad things I've been trying to avoid. I'll need to hop back on a dyno to fully optimize, but even with my somewhat limited sensor package I'm liking what I see.



And um... I hate to say this but... car feels dialed. I have 4-5hrs of street time on the cammed, heatshield'ed setup and honestly the car feels the best it's been to date, from a driveline/powerplant perspective. The heatsleeving is working wonders and so far all EGT sensors have survived, which is the longest lifespan I've gotten out of a set. The month of inactivity really gave me the the time needed to fix all the little things that were piling up and replace temporary fixes with permanent solutions. Haltech even rolled out their newest IC-7 update that allows you to FULLY customize the dash instead of only using presets, so I spent hours setting up my dash how I wanted and adding warnings, greatly reducing the mental workload while hauling the mail around.

Which is good, because next weekend I'll drive 14hrs to Reading, PA for the Pagoda Hillclimb, and then the weekend after that, its 6hrs to Norton, VA for the Flag Rock Hillclimb. Never been to Pagoda, never done back to back events, so either this is gonna go great, or everything is gonna fall apart day 1. No in-between.

 

I appreciate your duplicated efforts posting here in addition to the videos, which I always watch. Way to send it, rip your wiring harness

 

Take a poscat for the fire prevention measures.

In your cam rabbit hole, what did you end up learning that led you to the BC S2? I assume your goal with the cams was to help lower EGT?

 

Good to see she's running well and you're still at it. Entertaining video as well! That's shitty luck on that v-band washer but for sure those things can be a pita to align while holding the turbo in place and aligning the v-band clamp and tightening it. Sometimes I wonder if the good old t3/t4 4 bolt flange is actually better.

One suggestion I'd have and I'm sorta shocked you haven't added it is any reason you don't have some heatshielding around your downpipe/manifold/etc? Just to keep some extra heat out of parts that don't like heat. I'm sure it'll be a little tricky to fab up but looks like you're pretty skilled and should be doable for you. I see the turbo blanket got destroyed pretty quick, likely due to the flames, but I'd consider getting another one. Firesleeving is a good precaution to be safe for wiring/things that can melt but I'd seriously do some kind of heatshielding to all the hot bits to keep heat out of parts because there's gotta be a crazy amount of radiant heat with the exposed manifold/dp/turbine housing. I guess one "downside" of heathshielding of some sort is you won't as easily see cracks/etc in parts but I think it should help wiring/other stuff see significantly less heat. Just some thin gauge bent sheet metal in certain areas should do the trick.

Those K vibrations are nasty.. hopefully less cracking in the future. *fingers crossed*

 

"Haven't seen a post from Wingman in a while, I wonder if he's been doing anything big on the car."

*Opens thread*

"Holy sh*t!"

Every time man. Damn, you stay busy haha. Can't wait for the recap vid of the upcoming events (hopefully it's a long one ).

 

Yes, EGT was certainly forefront in my mind, as well as improving how this motor breaths at the top end. I bought these particular cams making a few assumptions about what the motor and turbo were doing EMAP and turbine speed wise and how it would behave when not in "full boost". I've since added both an EMAP and turbo speed sensor and found that making assumptions about these items is NOT always the correct move as these numbers, as well as off boost behavior, were... not completely as anticipated in reality. This is an ongoing project that will get its own technical deep dive eventually, but is still an ongoing experiment.

Its absolutely something that's needed, but hasn't been tackled yet because I lacked the proper tools and material to do this properly. I've experimented with trying to secure head shielding to downpipes in the past and nothing held up for very long. Fiberglass wraps fall apart in mear hours. Even when secured with stainless wire heatcycles loosen it up and it disintegrates into an itchy mess. I've tried welding nuts directly to the downpipe and using bolts though layered/dimpled aluminum, but vibrations woller out the mounting holes and these quickly become nothing but sources of sharp rattles that eventually also fall off.
I think the end solution will be stainless sheeting. I've seen this style on higher end professional GT cars, but didn't quite realize it was literally spot welded in place to prevent it from falling apart. When the list of *critical* items gets shorter, or during the off season, this is something I'm absolutely going to explore.
It was actually Daniel from Bofi Racing that saw what I had previously attempted, the failure modes, and suggested this style of shielding and spotwelding it in place, going as far to secure a personal spotwelder and test out a few different methods/style to see if this idea had any merit. And I think it does.
-Disclaimer, this wasn't the test piece, just a reference images found while exploring this option-




Wow, called it. I said this tongue in cheek as a joke, but holy ****. This was a no good, terrible, absolutely awful weekend.

Pagoda Hillclimb, Reading PA.

The weekend started off sub-optimally, but innocently enough. It was an estimated 13hr tow from Atlanta GA to Reading PA, so I initially planned to leave at 3am Friday morning in order to arrive before 5:00 the same day, leaving ample time for traffic, fuel stops, ect and arrive well before 6:30, which is when I was required to be there for the novice orientation and registration. However I was either so tired from work the day before, or I turned them off in my sleep, but regardless I slept through two alarms and woke up with a sense of panic and unknown dread at 5am. A nice shot of adrenaline from the "**** I'm two hours late already" combined with a redbull was enough to get me moving and off to PA it was. I lucked out, as somehow avoided almost all traffic and had 10/10 clear weather and roads, making excellent time on my trip up the eastern seaboard. I rolled into Reading at almost exactly 6:00pm, perfect timing to park the tow rig in whatever paddock space was left and attend said novice meeting.
A point that was stressed repeatedly during the novice walk was that this course was VERY slick and did not rubber in much at all- a local speculated it was due to the polen/sap the trees lining it dropped nearly year round. Additionally, when previewing video of the course it *seemed* very smooth blacktop, but upon arrival found it was filled with frost heaves, asphalt patches, and generally was not exactly an FIA grade circuit. Nothing new there, as no hillclimb location I've ever been too has perfect pavement- these events are held on roads that are public use for 363 days of the year after all.

One quirk of this course is there are two paddocks. The "upper" paddock a mile past the finish line for trailers, tow rigs, and cars, but only during non-comp times. During competition, your car, and only your car(no tow rigs or trailers, limited support vehicles due to space), is parked at the bottom of the hill. If you need it while in this grid, you need to pack it into the car and bring it down with you. Fuel, tools, spares, jacks ect- pack tightly and wisely. You can make a trip back to the upper paddock after a run, but the turnaround time can be tight and if you go up at the end of a run group, you don't have time to return down with your group and will need to wait for the next group to cycle though. You're not going to be running back to paddock to fuel up between runs is what I'm getting at.


Saturday morning dawned and the shitshow began in force. On the drive from top paddock to bottom grid, battery voltage dropped from its normal 14.5v to 12v. Thankfully, I had both brought a spare alternator, and packed it into the car along with tools. I wasted no time putting the spare alternator in, only for this one to do the same thing, only 12v and dropping at idle. wtf? I did some poking at the wiring into the alternator and found the exciter wire had pulled out of the plug. It was a pigtail I had bought off of ebay several years ago as none of the junkyard motors came with alternators or the respective pigtails. I stripped the wire, wrapped some .20g safety wire around it, and shoved the whole wiring abomination into the plug and it worked.

Just in time, as at 8:00 they had all the novices line up for a sighting run. This was *supposed* to be at "80% speed" as it was led by a local- in a dually. Apparently this was too much pace for the Legends car two cars ahead of me though, or he had some kind of mechanical issue, as the pack had gapped us by T2 and we made the ascent at a crawling 15mph- well below the local speed limit. So instead of a proper sighting run I practiced my clutch slipping skills keeping the car moving uphill.

Back down the hill, wait an hour or so for first runs of the morning, finally leave the line at speed- and I don't even make it past T3 before I put the car into a guardrail.

All those warnings the day before of "this course is slick" went in one ear and out the other apparently. And honestly, I went full retard. The car pushes like crazy exiting the corner, I give it a bootfull of throttle to rotate, rear slides out as requested, and I don't lift to get things straightened out. Car does on big wiggle, then snaps 180* on me, sliding across the fairly narrow road and making first impact into the guardrail with passenger front. Rotational momentum makes the car bounce and hit passenger rear to cap it all off. I'm given the ride of shame on a flatbed to the top paddock where I get my first good look at the damage- its not exactly fantastic.




The guardrail hit right above the front turnsignal and completely destroyed the fender and hood. The turbo itself was fine, but the inlet piping and filter had crumped like a coke can. The rear passenger tail light was also completely shattered, rear quarter panel bashed in 3" along its entire length, and trunk tweaked.
I went to work trying to get it into somewhat of a workable condition. Out came the hammer and pry bar, bending metal out of the way as able. I was fortunate enough that none of the suspension or steering was damaged- although I think if I hadn't added in the strut tower support bars to my cage, the strut tower would have moved as all the sheet metal around it was wrinkled.
A few hours later and I had something ugly, but functional.


I wanted to take it up and down the road before I headed back to the lower paddock just to make sure nothing felt terribly off, but when I tried to start it, the starter just went *click*. I furiously jabbed the start button a handful of times, whacked the starter with a hammer, stuck the car in gear, rocked it back and forth trying to unstick it, but *click click click* was all I got. Annoyed, angry, and hot, I held down the start button for 4-5 seconds of *cliiiiiiiiiickcciiiiick* until the Noco lithium battery freaked out about the huge amp draw and disconnected itself. Starter was 100% cooked.

I pulled the starter out and went into town to find a replacement- one perk of this hill is its literally right on the edge of town so there were three auto parts stores within 20min. And I know, because I played whack a mole trying to find a damn K24 starter. Each location I called said they had it, then when I showed up, turned out they *didn't* have it, until I found the local advance auto hub store that *did* have it. I spent over two hours chasing down that stupid overpriced starter, but I got back, threw it in, and the car started right up.


By this time I was miserable- all day beating on the car in a gravel parking lot, absolutely baking hot. I threw on my firesuit and hustled my way to the start line to try and at least make one run for the day just to have something to show. But just as I reached the gates the final group rolled past me heading back to paddock, done for the day.

I hunted down tech and got them to re-OK the car from a safety and class legality standpoint. Exhausted from the day I grabbed a bite to eat, shot the **** around someone's campfire, and finally passed out.

Sunday dawned and I actually made a run! It was dogshit slow, almost embarrassingly so, but dammit I made it to the top and was on the board, only a measly 12 seconds behind the next guy in my class. Don't care, I can improve from there, I was just happy to have finally made it to the top!


ngl, this fenderless ratrod look kinda started growing on me...

I made another pass and cut 5 seconds off my time- still not exactly impressive, with some missed shifts and hesitation, but was on pace with the competition's first runs from the day before, so I wasn't completely lost in left field anymore.


And then it rained.

I made one more pass in the hopes that the course would still have some speed, but it was pouring by the time I made it to the top and the course was completely soaked. Those with a full day of runs already completed stopped running all together- the course was slower now, so there wasn't any point. Disgusted and tired, I threw in the towel, packed up, and began the trip home.

 

**** man. Sorry to see this, but I know you'll be back better than ever! I think the lows in motorsports are what make the highs so good. I've definitely had that moment after putting my car into a wall where I think "****, why do I even do this?". Fortunately that usually passes pretty quickly and I get right back at it. Kudos to you for making the car track worthy again and making it up the hill.

 

F*cking grit, man...

 

For reals. I'd have thrown in the towel long ago. Pretty damn inspiring.

 

I had cannonballed my way up to PA, but on the return I had a little more time to spare, so drove 6hrs Sunday, slept for the night somewhere in NC, and finished off the return drive Monday morning.

The return trip towing a bent up car gave me a lot of time to sit and think, and I targeted a few key weaknesses and setup issues with the car that, while not the cause, were contributors to the whole guardrail debacle.

1. At 16psi, I'd estimate the car makes around 450whp, and trying to put that down in 2nd/3rd gear is a near impossibility, even with 275 hoosiers. The wastegate spring is 16psi and thus, is the bare minimum I could run. As a result corner exits are... tricky, trying to find that fine line of "I'm spinning to much and losing time" and "I lifted and just lost all my spool, now I'm basically dead in the water"
2. This car is sprung for track. Getting weight to transfer and rotate at ~40mph is like trying to jetski on stilts. Corner entry it pushes, and corner exit... well we know what it does on exit. 1400F/600R on the Xida triples is a touch light for track yet, but its waaaay to stiff for hillclimbs, especially as we have to contend with potholes, asphast patches, you know, normal public road stuff.

#1 was fairly easy to adress. It's an adjustable turbosmart wastegate with several springs inside, so I removed a spring, dropping base pressure closer to 11psi. All my duty cycle numbers for boost control were now off, but that's a future me problem.
#2. I still had my old set of normal Xidas, but they were sprung with 1000F/500R... closer to "track use for a low-aero car". But by purchasing a set of 300lb springs and moving the prior rear springs to the front, I now had a set of 500F/300R Xidas... "I only street drive and don't want to spill my coffee" soft. Thankfully past me had bought these springs a few weeks ago with this very thought in mind, so they were waiting on the shelf already. The laughable softer rates *should* allow me to roll the weight around the corners better at slow speeds, and not be upset by bumps anywhere near as easily.

By the time I crossed back into Georgia, I had a replacement NA hood I bought off a buddy along the way, and a plan of attack for the car. Pagoda had taken place June 21-22, and when I arrived back home June 23rd, I had 3.5 days until the car needed to be loaded back onto the trailer for the Flag Rock Hillclimb in Norton, VA. I called in some assistance and we got to work same day. By the time we called it quits, the car had a full "new" suspension setup installed, and body panels mostly in place.


We had to max out the Xidas to even approach 4.75" of ride height with these super soft springs... I was targeting a higher ride height to allow more suspension movement, and again, deal with rougher roads better. The first go-round was NOT at maximum and I remembered quickly why my fenders have those god-awful vents/flares/pulls in them. Stock fenders do NOT cover 275's.


I gave the bent sheetmetal a few attempts at pulling it out, but in the end, it was easiest just to cut out all the damage. Between the actual impact and me beating the metal out in PA, sections had become so pancaked and compressed it wasn't worth the time it would have taken to try and peel it all apart. I'm better with an angle grinder then a panel puller anyway. The replacement hood I bought off a buddy in South Carolina on my way home, and the fender had been sitting in the attic for several years- I think I picked it up as part of a deal where the seller was just getting rid of stuff, and tossed it in? Its time finally came and about... 4 bolts on it actually still lined up to the car.

I was somewhat glad to ditch my old hood- so much structure had been cut out it would literally bend in half if you weren't careful how you picked it up. At speed it would flap and vibrate around and was, frankly, a huge piece of garbage only just holding onto the car. With this new hood I made an effort to leave as much internal skeleton intact(which still wasn't much as the K takes up a ton of room) and change the style of vent to something that didn't remove so much of the skin integrity. And thus, I went for more of a "waterfall" approach. CFD results pending. Holes still had to be made for the valve cover and turbo bits, and more venting will be added over the hot side to help extract heat from the volcano, but this was a rush job knocked out in a day or two.


Rest of the week was a blur, and I wasn't able to load the car onto the trailer till almost 4:00pm on Friday, but if you didn't look at the dented rear, ignored the mismatched fender and hood, you almost wouldn't believe the car had been crashed the weekend before(that's a joke, the car always looks like it just came through a blender).



Drove through the night and arrived in Norton at 2am. Fortunately a buddy had saved me some paddock space in proximity.


Flag Rock Hillclimb, Norton, VA. Second stop of the SCCA Appalachian Hillclimb series.



Where as Pine Mountain is a hill I don't really enjoy due to the many, many off camber 180* turns and not much flow or chance for momentum cars to shine, I do very much enjoy Flag Rock. While it also has its share of 180* hairpins, including a double 180* or "S" hairpin, it also has two sets of esses, each with its own straight. I haven't driven this hill since 2023 and after my first run I was like "damm... forgot how good this hill is".

Right off the bat I could tell the wastegate and suspension changes were huge steps in the right direction. Car no longer plowed like a bulldozer in every tight corner and I actually had traction. I ended up turning the boost back up to ~20psi by the end of the weekend and really didn't struggle with corner exits- weather this is due completely to the suspension changes, or weather Norton just has better pavement, needs more data points, but this definitely felt like an improvement. A loooot more body roll then there was with the other suspension setup! This was with the front swaybar set full stiff, rear full soft, and compression/rebound set in the middle.



2rd run on Saturday the car kicked the radiator fan on while pulling up to the start line, and... got weird. Voltage fluctuated up and down for a few seconds, I heard some rapid mechanical clicking from my fuse box, then an oddly familiar smell of burning plastic made itself faintly known. Before I had a chance to really think about it, the starter gave me the "Go" signal and I was on my way. About halfway through the course, there was an alarming bellow of grey smoke from my fusebox/main buss/switch panel area. Since I knew fire support would be better at the top then along the course, I slapped all non-essential electrics off and continued to the top. By finish the smoke had cleared and only the smell hung around... until while turning around my "coolant warm but not dangerous" alarm kicked on and I realized my radiator fan wasn't running.

Upon investigation I found another completely smoked fuse. You might remember my fuel pump fuse killed itself at Pine, well this was the exact same failure mode, except worse, because this smoked a fuse, relay, and melted most the insolation off all the radiator fan wiring. Like, it's literally 14g wire with the insolation literally slagged off, as if it got hit by lightning or something, and the fuse looks like it was at Chernobyl.


Thankfully the slagged wiring hadn't taken anything else out with it despite running in the middle of a large bundle(tefzel ftw), so I just ran the rest of the weekend without the radiator fan, being very strategic when I started the car in grid to avoid overheating at standstill.
I have a few theories about what the hell is going on with these fuses and why things keep going into meltdown, but that's a later post.

I wasn't the only one with issues, my paddock mate and longtime hillclimb buddy had some classic K24 headgasket issues. Supercharged K24 BRZ, makes around the same power, and we often come up very tight to each other in competition. We had a headgasket party till the early morning hours, 3/4 of the group just getting sloshed and being as helpful as drunk mechanics can be, but we did have the car back together and running the next day. Although I'm not sure any locals in town appreciated us firing it up at 2am and bouncing it off limiter a few times as an operational check.


Sunday came around and with the course properly rubbered in, times started falling. Second run of the day I dropped the clutch and left the stageing line to do the traditional, tire warming rolling burnout up to the start line, and heard a very loud "WHAPP" from the rear. No idea what it was, but decided since the car still had drive the most prudent course of action would be to do my run and figure out what the noise was later. This ended up being my fastest, and last run of the weekend.


When back in paddock I jacked up the rear and it didn't take long to find the cause of the "WHAPP". Drivers side diff mount had snapped clean in half.




Only welder I was able to find in paddock was a tiny harbor freight one running flux core and powered off a generator, so with minimal access and no welding helmet, I gave it a shot. It was a mess, the welder would only weld for a few seconds before the generator would overload, and since I didn't have a shade helmet I was guessing what I was currently welding together. Needless to say the end result was... pretty bad.



I tossed my firesuit back on and rolled to staging, but before I even made it there I heard a "WHUMMMP" as the garbage welds let go at walking speed.
So that ended that weekend. A little disappointing as I had just loaded up a full sauce tune and was ready to full send, but it is what it is.

On the bring side, it's a mount that I built, not V8R!

Sparks!

 

Some responses are better left as memes... so here is my continued contribution to this thread that I love so much.

 

Good on you for getting it back together again man. I liked the design of your old hood, but this new one looks good too.

Just saw that BRZ on Gears and Gasoline. Looks like a wild ride.

 

Damn... I am in awe of your persistence. If I had crashed like that I'd have driven home and curled into a ball for a few days, wallowing in self-doubt, anger, and frustration. Good on you for getting back out there so quickly.

I'm stunned that you managed to melt tefzel insulation off of a 14awg wire. You must have had a dead short somewhere - did you find anywhere where the insulation wasn't melted?

By the part number, that's a Type II circuit breaker, ie non-resetting, so it should have failed and stayed failed once the current exceeded the breaker limit. I couldn't find your earlier posts about melting a fuel pump fuse, but looking at that breaker, I wonder if you had a weak connection at the breaker and excess heat from that melted your fuse box and let the terminals touch, bypassing the circuit breaker. Do you have a way of testing whether it still works? I struggle to think it could have failed "closed".

 

10/10 banger as usual. Memes keep me sane sometimes so keep them rolling.
Yeah, I'm equally as stunned. The only place wiring wasn't melted was the last 6-7" going into the fan, just after the connector(I think its an OE Mazda AC fan connector? It's not a deutsch, but it's nothing I recognize) so best guess is the connector was internally melted and shorting. I was unable to disconnect it to inspect the insides. I don't know what happened to the CB itself, I don't think I threw it away, but the garage is a packed out mess currently so it might just be stuck somewhere weird.
This isn't the first time I've had one of those CB's fail/do something weird on me, but this is the most dramatic failure for sure. I think it has something to do with packing a bunch of heat into the relatively small area of the bussman, as the solid state relays in it have also done weird things in the past as well. After that pump failure at Pine, I added a forced air duct off my driver blower fan to help move some air around it, but this is a bandaid solution that apparently doesn't fully stop the bleeding. This car is getting a PDM soon as I don't/cant trust this electrical setup. Which makes me happy because PDM things, but also makes me really sad because I loved the Bussman setup when I first installed it. Compact, serviceable, and fairly inexpensive. Unfortunately it currently resembles a cratered warzone with both of fuse 3 slagged out from the fan, pin D6 smoked from the fan, and relay A10 burned from the pump.



What isn't broken anymore is the diff setup. Dropped the diff out, welded the broken halfs back together, then added a 3/16" steel reinforcement plate to both sides from the mounting ears to the subframe pickup points. Splash of fresh paint and hopefully she holds. Like it never even broke in the first place...


While dropping the diff out found the diff side drivers axle had a torn CV boot, so had to wait around a few days for a replacement boot to show up. I took this time to tear apart the front of the motor and swap the OE K24 RBB 20* intake cam gear for a RBC 50* cam gear. Double the VVT movement range to (hopefully) allow for more aggressive spoolup and torque down low.

Side note. I always reference these K24 vibes and blame half my problems on them. Well this is what I noticed while rev'ing the engine in the garage with the hood off... the screamer pipe literally phases out of existence at certain RPM's. And this is what the ENTIRE turbo/manifold/downpipe experience. I've seen similar, if not quite as pronounced harmonics in the alternator mounting brackets.

"Rebuilt" that axle, stuffed it back into the car, and dropped it back onto the ground two days prior to dyno day. Did an hour or so of street tuning to reset all my boost control duties for the different wastegate springs, quick nut and bolt on the car and....

Dyno Time

I'll keep this short and sweet as I'm still playing major league catchup for many things. There *is* a technically post coming with lots of squiggly lines, back to back run comparisons, cam information, and datalogs.

But the TLDR: 609whp/535tq. 500ft/lbs available as low as 4500RPM.




For reference, this is my run overlayed on a stock BP4W with a 2871r strapped to the side, running 14psi. Its very much a "you vs the guy she tells you not to worry about" senario... Over double the peak power, and the BP makes more power/torque for exactly.... 0% of the graph.



Like I said I'm playing major league catchup. I haven't even started editing a video from the Flag Rock hillclimb. So quick cut of a 600whp dyno pull...

 

Chroist. Six miatas’ worth of power in one miata.

Brave man tempting fate by saying “one more dyno pull”

 

today's read is a simple one. I see 600whp miata, I hit that poscat

 

The Data Deep Dive

So lot of information and interesting things to dive into after that dyno day and the events leading up to it. Be warned, this is going to be a post with lots of squiggly lines and tangents.
First off, cams. I recently installed a set of BC "Stage 2" (P/N: BC0042-2) cams after having run stock cams for the life of my Kswap. My goals with these were primary to decrease EGT/EMAP and secondly, get the turbo online as quickly as possible. The BC cams have a great deal less overlap to them, which will help goal #1, but hurt goal #2.
And this is where I found out the hard way that making guesses about what's happening inside your motor... probilby isn't always going to be an accurate guess.
To backtrack and explain some, the boost curve on this motor has always been atrocious. It would come up to 200kpa around 4800 RPM, hold whatever pressure requested for a few hundred RPM, then taper off till redline with the boost controller trying to fight it. This made for a powerband that came on hard, spiked, then died off and has been kind of a gnarly car to drive in low gears. Pulled is a 3rd gear segment where you can see this exact behavior, targeting 240kpa, spiking to 250kpa, then falling off to 215kpa.


I attributed this behavior to a motor with high EMAP, assuming the pressure in the exhaust manifold was shoving the wastegate open despite the boost controllers attempts otherwise. Lowering backpressure with less cam overlap was one of the reasons I selected the cams I did.
However, after dropping these cams in, this behavior didn't really improve much(but EGT did!) so I was a little puzzled as to what was going on.
It wasn't until I was perusing some EFR data about their integrated compressor recirc valve that I realized the EFR CRV could be run solo without a BOV accompanying it, and it would actually help the turbo maintain speed off throttle. So a week before the dyno day, I chopped off my turbosmart BOV(which had passed several previous pressure checks) and suddenly, boom, boost control was on point. Little overshooty in the beginning and a little more oscillation then I would really like, but I almost cried when I saw this nearly dead flat boost curve targeting 250kpa. Drivability is going to be soooo much better like this.


So I don't know how that BOV passed pressure checks then leaked while in use, but respool times during a shift(200kpa-shift-respool to 200kpa) dropped by .5 of a second(1.8 compared to 1.3) and compressor speed stays higher by about 10,000RPM showing that valve really does work as advertised.
I also added an EMAP sensor shortly after the cam installation, so I now had the full suite of sensors to monitor all the turbo things- manifold pressure(MAP), turbine pressure(EMAP), and compressor speed.
With boost control sorted and allthesensors now feeding me information, I hit the dyno. Last time I was there was with the R40 single port head, a smaller G25-660, and put down 527whp with smoking hot EGT's. With the larger EFR 7670 and 4 port RBB head I suspected the car was going to put down much more.
First baseline pull at wastegate pressure of 200kpa(14psi) the car put down a respectable 380whp/300tq.


However, note the HUGE dip in power around 4500RPM, which interestingly enough corresponds exactly to where I had guesstimated the Vtec crossover point...
I hopped into doing Vtec crossover and VVT tuning. First pull with no Vtec, car pulled fine. Then I set Vtec to engage at 3000RPM, began a pull, and car damm near stalled out on the dyno. I attempted this twice and the same thing happened, car lost nearly all power, the RPM flatlined, and VE dropped off a cliff as soon as Vtec engaged. I thought something with Vtec and oil pressure must be going on, so I set Vtec to 5000RPM, tried again, and the car made it to redline but VTec caused a HUGE drop in power everywhere, exactly as it had in the baseline pull. You can even see the VE drop in the tune as well as the dyno.



Completely baffled as to what was going on and not wanting to spend expensive dyno time troubleshooting, I disabled Vtec completely and carried on. Yup, you read that right, ALL numbers put down after this were with NO VTEC ENGAGEMENT.
In hindsight, I have a theory about this. BC bills these cams as "high boost(18psi+)" which I assumed was some marketing nonsense and didn't put much thought into. But now I wonder... are the larger vtech lobes somehow optimized for high inlet pressure in a way that completely nuters power if there isn't lots of positive pressure? I'd have to hop back on the dyno to test this further, but I don't understand how this could physically be the case.
Regardless, I hopped into VVT tuning, and after a half dozen runs was able to get the turbo up to speed/pressure about 1000RPM sooner then no VVT. Shown here, 0* VVT everywhere vs optimized VVT advance- look at that massive difference in low end torque! Over 100ft/lbs difference at 4000RPM! These VVT runs also had some more boost thrown into them- all these runs were done at 220kpa.


With that set, I started adding timing until MBT was hit for a certain boost level, then adding boost, then timing. I found I could add nearly 5* of ignition advance over the map I had in it before power hit MBT, which was the R40 spark map I'd been running. Was this due to the better flowing RBB head allowing more spark angle, the bigger turbo allowing more flow, or a tuning error from me last time around? Who knows.

Numbers kept going up until it hit that 609whp mark. This was achieved at 280kpa(26psi of boost) and ended up being a very convent place to stop, as looking through the logs afterwards I peak at 85% injector duty at 8000RPM, and overspeed the turbo's maximum RPM of 138,000 hitting 141,400. ID 1700's are essentially maxed out, and the turbo is DEFINITELY maxed out. Something I didn't notice till now while reviewing these logs is the fuel pump is struggling... It's a Walbro 350, and while the Maxx is calculating my peak fuel flow rate at 82 GPH(310LPH, below the Walbro rating of 350LPH@50PSI)) fuel pressure follows a downward trend, peaking at 75psi(pretty sure this is what the internal pump relief is set at) and falling to 58PSI at redline. Dieing pump? Out flowing the pump? Leaking pressure regulator? Unsure.


On the bright side, I NEVER tripped an EGT alarm, and reviewing the logs shows a maximum of 1480* F on cylinders #1 and #2. The #3 sensor is currently dead and #4 is installed post turbo(Note the 400* drop across the turbine section!). This is a HUGE change from last time, where for around the same inlet pressure and RPM I was tipping 1800F*. Due to cams? Due to head? Combination? Probably.


The pressure ratio across the motor also isn't half bad. Under 4500RPM it maintains a 1:1 ratio or less, 6500 RPM its only at 1.3, and not until 7500RPM+ is it touching ~1.5(280kpa inlet pressure for 445kpa exhaust pressure). Really good numbers and the efficiency of this EFR turbo is honestly staggering.

So. Jeez. 600whp Miata. What now? I turn it down obviously. Dyno queening it at 600whp was super cool but...

I did a few pulls in front of the dyno shop and 4th gear evaporates from under the car with frightening ease. I immediately setup boost by gear so that it only targets 260kpa in 5th and 6th, with the rest of the gears easing into a lower boost peak, but feeding it in constantly to redline. Otherwise that 250ft/lbs jump from 3500rpm to 4500rpm at maximum spool just blows the tires out from under the car.
Seeing how the turbo is maxed, the injectors are maxed, fuel pump is struggling, and 1-4th are useless at full tilt, I decided I simply don't want to run the car consistently at the peak boost level. I'll save that map for biiiiig tracks when I realllly need a little extra spice, but for hillclimbs and anything smaller than Road Atlanta it's more of a hazard then a help. I guess the ideal option is to go DBW and setup some TC wizardry, but that's a future me project.

For now I'll just "limit" the car to 250/260kpa and work on keeping it away from guardrails/walls...



(This is not editing trickery. This is the actual manifold complexion after a pull)

 

These results have me a bit confused as well... Having done so much research on LS camshafts recently, I'm a bit confused at how BC (or other k-series companies) spec out these Honda camshafts. The specs on your cams per BC website are below.. Note: they only show one set of cam profiles even though technically vtec cams have 2 profiles.. which one is shown? good freaking question...


In my online digging, I found this link, which is a neat comparison to keep handy for future-you: https://docs.google.com/spreadsheets...it?gid=0#gid=0

I also found this link, which if you go to the BC0042-2 cam, you'll see a dyno graph: https://www.briancrower.com/makes/honda/k20ak20z.shtml


uhmmmm... 45 psi of boost and 9500rpm and 1100WHP is a wildly different built K24 spec than what you are building here on pretty much every front. I can only assume these 2 power pulls in the above chart are with VTEC on and off, which showcases the VTEC transition point at ~6100RPM. Interestingly enough, your study of VTEC on/off showed the transition at 6500RPM which is close to this chart! This is making me further question if this cam is right for what you want... I'd probably call BC and ask what they mean by "high boost". 304 degrees of duration & .525" of CAM LIFT is a ton of valve lift with a 1.75" rocker ratio (0.918" to be exact!). I'm not nearly as well spoken on k24 cam specs as LS ones, but this BC cam seems overly large on the VTEC lobes for what you are building.

I'm going to take a stab at this one.... If this pump spec sheet is correct (Click Product Info Here), Walbro does a dumb marketing play and rates their 350LPH when at 0psi relative pressure and 12V. I really don't like when companies do this because there is no system in existence that operates with zero back pressure, but whatever, at least they provide the spec sheet. Loads of companies rate water pumps and fans this way online without spec sheets just to sound better than someone else... but I digress....

If this pump performance curve is true, the pump is not quite as big as you think it is. Your flow is actually going to be based on (rail pressure - manifold pressure) and depend on the voltage being applied to the pump (12V-13.5V usually). Think of the boost pressure as pushing back on your fuel from wanting to come out of the injector.. so let's start with the red lines below... if you are at 75psi gauge pressure in the rail at start of a pull, and 26psi in the intake manifold, the fuel has a relative pressure of ~50psi from tank to manifold. Referencing the 50psi flow line, you get a range of 270-330LPH depending on voltage (which lines up nearly exactly with your 310LPH Maxx calc). It looks like you are operating around 13V if I was eyeballing things here.. Now if you stare at the blue lines which are reflective of redline conditions at higher injector duty cycle, you are operating at 58psi gauge rail pressure. This makes sense as the injectors are open more often so you should see pressure drop with flow increasing. Subtract the boost pressure off of 58psi, and you can see that you are working on a relative pressure of ~30psi (320LPH @12V to 370LPH @ 13.5V), which is very near the upper limit of where the pump performance chokes out.

In dummy terms... I'm quite certain you are just right at the limit of what this pump can offer. I don't see anything particularly concerning, but it's a good observation to be aware of.

 

TL;DR: Paddocks bored again

don’t you have a LS swap to finish??

im in “vtec is broken” and/or “cams are too big” boat.

 

Oh man, if your waiting on the completion of that project, you're in for a looooong wait
Yeah general consensus among several is cams are too big.
This leaves me with a bit of a quandary though. I don't really feel like shotgunning 2-3 sets of cams at the car to find the "perfect" set. Also considering that a different cam might bring back the EGT issues. The fact of the matter is that I'm at the limit of the pump, limit of the turbo, and limit of the injectors, so I'm... probably just going to leave it alone for now. Car definitely isn't hurting for more power, and while a less extreme torque ramp in would be nice, the current curve is very useable.