I’ve been quietly working on Hyper in bits of spare time here and there. Lots of cool stuff in the works. Debated about how much to share because inevitably once I start showing stuff others start to copy it. But I’ll risk it, want to bring you guys along on the journey.
Let’s start off with explaining that this update is specifically and only happening because of where this car competes. Global Time Attack has evolved to now require a spec tire model in each class. The tire for Limited class is the A052 and that is not available in any wide sizes for 15″ wheels. Fitting larger wheels on a Miata properly is not an easy feat, and this likely means we’ll see less NAs/NBs competing in GTA events. But unlike others who run their cars for fun in many different series, the HyperMiata is a single-focus car that is all about trying to earn that top spot at the largest time attack event, and that is GTA. So I’m doubling down and committing a lot of time and money to converting this car to run some big rubber.
Left: our old 15×10 with 245/40/15 Rival S 1.5. Right: 18×11 with 295/30/18 Yokohama A052.
Custom 5×114 front and rear hubs get the wheels bolted to the car:
Brakes have to be changed to work with the new hubs. I’ve got half the parts or so for that already with drawings done and parts in the works for the rest.
Now let me be clear: our recommendation has always been and will continue to be that you NEVER want to put large 17″ or 18″ wheels on an NA/NB. Don’t do it! This car’s situation is so specific, and even then I agonized over whether to pull the trigger on this for a while. The new tire offers a larger contact patch and stickier compound than the smaller Rivals we were running, so the potential is there for more speed, but there are some massive challenges caused by the larger wheels that all have to be overcome otherwise it’s just a big step backwards.
Custom hubs and brakes are the easy part. The real mountain of work is in providing room for the massive wheel’s range of motion.
Current state of things is I’ve been cutting… and cutting… and cutting. Basically cut out as much car as needed until full range of motion is there, and then see how much car is left and rebuild around that. This is cutting into some rather critical parts of the tub so as I’m cutting I’m planning how I’m going to rebuild these areas to keep load transfer through the areas that need it. Otherwise the car would end up a floppy mess.
This is where the front is at, with still some more cutting to go. Those holes go into the interior of the car. If the fiberglass blanket wasn’t in the footwell and someone was sitting in there, you’d see their feet through the hole.
The rear is nearly done in terms of cutting and I’ve started some of the new pieces.
Yep, that’s the rear wheel tub protruding through the rear parcel shelf into the interior of the car:
When the sheet metal is done, the bodywork will be a whole separate project because new fenders will be needed. Feels like I’ve been at it for a while already but there’s a mountain of hours ahead. Right now I’m just putting my head down and keeping on plugging away at it day by day. We’ll get there.
Some fancy new rear hubs with 5×114 lug pattern just arrived, courtesy of Miatahubs. For those who noticed that we took one of the GWR NCs to Superlap Battle USA in February, waiting on these hubs and a couple other custom parts is the reason Hyper didn’t make it.
Jerico 4 speed dog box with Roltek shifter. Built with road race ratios, input shaft, tail housing, shifter location, etc. all to my specification.
Been saving for this for the better part of a year, since I had the trans failure at COTA in February. Credit goes to Emilio for bringing up this idea when I mentioned a sequential was out of reach. When I looked deeper I realized this could tick all the boxes I need: lightweight, shifts fast, reliable/durable, and can hold any power I throw at it. I can build a flywheel to take a common clutch so I’m no longer at the mercy of just a couple obscure options.
Going to use a Tilton aluminum bellhousing and make an adapter plate. Custom flywheel for a Tilton 7.25” twin and custom carbon fiber driveshaft are both already in the works.
Already pulled apart the spare MV7:
Got the bellhousing to a CMM thanks to local LFX gear head and CNC extraordinaire Chip, and blueprinted the LFX bellhousing pattern:
I’ve just finished up drawings for the adapter plate, sending those to CNC after the holiday.
Much excite.
Captain Crunch approved:
Regarding gearing selection:
I labored over gearing spreadsheets for quite a while. The one thing you can’t change is that 4th is 1:1, and for most Miatas that would be a problem (too short). However, I’m on a 3.42 Getrag rear end, with alternate Getrag 3.23 and 3.73 options. That helps.
The road race ratio approach, when you only have 4 gears to work with and assuming no standing starts, is to gear 1st to be usable at relevant track speeds. I went back and forth over making 1st short for use just for pits/trailer loading/etc. which would make it 3 usable gears on track, or say “to hell with putting around in the pits easily” and make all 4 gears exactly what I want at speed. I watched a bunch of on-boards with Trans Am cars and realized they all go with the latter approach; they are using 1st in every slow section of the track. They also run a 5.5″ clutch… But they get towed around the pits with a hopped up golf cart… and I need to be able to run the car without a support crew pushing me around. I was at a crossroads. So I went long with 1st gear, but with a clutch that I think I can get around solo on. I looked at data from the tracks I am aiming at with this car, min speed in the slowest corner and how long I’d want that first gear to go before a change up, and picked 1st gear based on that. With enough power, frankly, that low gear goes by so fast I wanted to stretch it out so that it wasn’t just instant wheel spin. So 1st gear goes to ~ 75mph. That’s going to make getting around the pits at 10 mph tricky. For that reason I chose to do the Tilton cerametallic 7.25″ because that can be slipped a bit and should make it juuuust possible to give it a footfull of revs and slip the clutch to get going around the pits… more so than a metallic 5.5″ at least (I hope). Keeping in mind the factory clutch/flywheel are 52 lbs. The custom flywheel and 7.25″ twin should come in well under 20 lbs.
The result of the gearing choice is that whereas with the Camaro trans I only had 3 relevant gears (1st and 2nd too short for anything, 3rd gear in slowest sections and top of 5th in fastest sections with 6th a useless overdrive with too far of a drop), now I will have 4 relevant gears, with a better spread between each than I had before. So I cut the weight of 2 gears and yet ended up with a closer ratio transmission.
Solving the fuel starvation under high G loads. Surge tank is needed, but the stuff on the market doesn’t tick every box. I want a swirl-pot style surge tank. The energy of the fuel swirling inside the tank at least partially counteracts the G forces acting on the fuel, so there is much less sloshing, and it ensures every last bit of fuel makes it to the outlet until the tank is dry, unlike a more conventional surge tank that’s just a tall static volume. So as it so often seems, the only way is to make it myself.
I hand cut a bunch of pieces:
The inlets and outlets have a shallow slant cut inside to shroud the in/out flow from the swirl flow in the tank:
Welding it all together:
Went with 1/4″ NPT rather than AN so I have the flexibility to change hose size if desired down the road:
Finished tank:
Installed with AEM 400 in-line pump, Radium in-line filter, AEM high pressure regulator. Bracket against the forward bulkhead supports the tank since it will have a bit of weight to it once full of fuel.
Now with two fuel pumps, the external post-surge tank pump does the heavy lifting and the pump in the main tank is relegated to lift pump duty, so I’ve put a DW300 back in the main tank since that works properly with the pump fixture. I added a second fuel pump circuit on the wiring side, with a dedicated fuse and relay. Relay is activated by the same fuel pump switch on the dash, so the single switch turns on both pumps, but if I need to troubleshoot one pump or the other I can pull the fuse for the other pump so I’m just activating one.
Dyno Friday to make sure it’s all flowing as expected, then on to track testing.
The only issue is I’d like to anodize the tank both inside and out for longevity. But the inside can’t be anodized if it’s an enclosed tank. I want to make the top of the tank removable with a bolt-on cap, but that requires sealing the cap with an o-ring which means the cap piece needs to be cut either by CNC or waterjet and then have the o-ring groove done in a lathe, neither of which I have the ability to do here right this moment, and I wanted the tank done and start testing immediately. I have drawings off to the waterjet to get those bits made though, once they are done I’ll cut the top off this tank and weld on the new flange that takes the new bolt-on cap, then get both pieces anodized.
Fuel surge/swirl tank report: it works a treat.
Tested at Buttonwillow on Sunday, ran the car round and round till it read completely empty in the main tank, got another half lap out of it and then it started to sputter and came to a stop a few turns later. Towed back to the pits, pulled the top fitting from the surge tank and ran a dipstick down it to see how low we ran it. There was only about 3/4″ of fuel left in the bottom of the surge tank. That’s like, 1/20th of a gallon. Yep, it’s working.
Awesome to get the “band” back together since COTA. We went in hoping to make it a third year in a row of wins at this event. Lots of excitement, with more power and other improvements we expected to be on a very good pace.
Day 1 morning had an open practice session so the plan was to do a systems check and a quick warmup lap then back to pit lane to get tires dialed for the first timed session.
Half way around the track going through Riverside, the highest speed sweeper, the engine cut out and the throttle pedal ceased to work. I coasted to a stop off-line trying to figure out what happened. Engine was idling, pedal just didn’t work. I figured out I could limp the car back on idle speed and got around the track at 11 mph in 3rd gear, thankful for the torque of the engine.
Back in the pits we tried to figure out what had happened. First thought was wiring or a bad pedal or throttle body but nothing immediately jumped out at us. The first timed session started with us still in the pits. Suddenly after cycling the power off/on again the pedal was back. I jumped in the car and rushed out, only for it to cut out again at the exact same point on track. Got the car back the same way, first session gone.
During testing last year I had encountered something that manifested itself the same way… but in that case it had been due to a fuel pump sock that had been left in the E85 for too long (should be changed once per year) and it only happened when I was running under 1/2 level in the fuel tank. The result – engine cutting out briefly and losing the throttle pedal – was identical, but here we were running a full tank. Regardless, with that as our one solid lead Greg and I jumped in and pulled the fuel pump fixture and replaced the fuel sock while Moti made setup changes based on the few notes I could come up with from less than one lap. We noted that the fuel sock seemed to be trying to come out of the DW400 pump (this pump is universal, not designed for a Miata pump fixture or sock), so we did some zip tie magic to help it stay put and got it back in.
Afternoon, session 2 – I coasted through the high G areas and made it around the track! Seemed like we had an improvement.
Got two laps in taking it easy through the high load areas and then tried to pick the pace up in the third lap. This was our first year with radio between the car and someone on pit lane. Coming through the first section of the track I wanted to get on the radio and yell to Moti “this thing is really fast!” but the car kept me so busy and everything comes so fast through Cotton Corners and the Bus Stop section I couldn’t even lift a thumb to the push-to talk button. Coming around Riverside, the car stumbled, then going into a hard braking zone it cut completely. I got myself out of the way and cycled the car several times and eventually got the pedal back, but the session was done.
Speaking with others I got confirmation that the cutout and pedal loss is the result of the GM ECU going into limp mode. There was a definite correlation between fuel level and triggering limp mode. The sock replacement had helped, but the car was clearly very sensitive to fuel level. There was just one more session for the day and we hadn’t yet even had a chance to get tire temperatures/pressures. We needed to just get a full lap in and get back to the pits so we could get that data while it was hot. We filled the car completely to the brim for session 3.
Went out for session 3 and the car made it through Riverside! I got a full lap in at some pace without it cutting out, and brought the car back in to get tire temperatures. Track drama from other cars having issues ended the session.
That night we went back and forth over just about everything. The orientation of the sock on the pump fixture was in question but there’s no sure way to check that as once the pump fixture is installed there’s no way see into it. A thank you to Supermiata / 949Racing for some consulting and offering what they knew of the subject, and we spoke to some others who have big power Miata setups who even question the flow rate of the factory sock – they said they found the sock to be a restriction – the problem is that the factory sock is the only one with the right geometry – the aftermarket socks don’t reach to bottom of the tank, so you trade one problem for another. We knew the way to kill it with fire would be a surge tank, but that just couldn’t be done trackside. We scoured the track for anyone with fuel cell foam or hydramat that we could possibly stuff in the tank… we even came up with several squares of fuel cell foam that someone had ripped out of their own fuel cell because they were having starvation issues and suspected the foam was breaking down and gumming the filter. Upon close inspection, the foam was breaking up. We thought better of it.
Based on what we had found on day 1, we figured we could get two solid laps in before the fuel level got low enough that we’d have issues, so the plan was simple. Run full to the brim, two laps, then refuel.
I like to run the full session. There’s a big difference between leaving a margin and pushing the car hard and it takes me a few laps to feel comfortable pushing, especially with this car. I tend to get faster through a session, and similarly, faster through a day. There’s some crossover point when the tires are better early in the session and I’m better later, but always more laps are what I need to find where I can really cut time. Day one I had something like 2 laps at decent enough speed that I had an idea of what the car was doing. This definitely wasn’t how I like to normally do things. Hoped for better in the morning.
Day 2 morning is when temperatures should be ideal. We got filled up and went out for the first session. Naturally, everybody is thinking the same thing; now is the opportunity to get that fast flyer… and so there were a ton of offs, people pulling dirt on the track, yellow flags, etc. Both laps aborted. Back in for fuel, got topped off, and the track was black flagged.
Back in our pits as we were making some minor changes we found the car was making so much downforce it’s starting to warp the chassis, break spot welds, etc. The perils of a 25 year old chassis. Moti jumped into fabricating reinforcements. At the same time, I noticed the passenger side muffler had more movement in it than it should. The bolt holding it in place had come loose and allowed it to flex more than usual, and tracing things upstream I found that as a result of that extra movement the downpipe had cracked ⅔ of the way around.
Greg and I got the downpipe removed and I jumped on the scooter and blasted over to Sevens Only to see if we could get it repaired. They obliged. It’s not the prettiest weld… actually, I’m definitely going to grind it out and reweld it myself later… but it was no longer cracked. Much thanks to them for being available on the spot to glue it back together. I rushed back to the car and we checked the time. 15 minutes to the session. We jammed to get the downpipe back on, I got suited up, and we were on the ground and fired up 1 minute before the session started.
Out on track, we had multiple cars with issues. The track was black flagged, session over, never got one flyer in.
With so little opportunity to get laps at pace in, and distracting issues, I felt I wasn’t getting in sync with the car. I tried to think back to partial laps, brief sections where I had been able to push a bit and feel what the car was doing but it was a challenge. It was definitely harder to drive now than it had been previously. Much more twitchy, and I had to be very gentle with the throttle in a lot of sections where I was previously just rolling into it and full throttle much earlier. We softened the rear sway bar and added some low speed compression damping in the front to try to help.
We had fresh tires on stand by, and the tires on the car until now were older 2017 build dates. It takes at least one session to dial in the tires; ballpark the cold pressures, then take hot temperature and pressure after a session and adjust pressures accordingly to hit your target hot pressures. With the downforce and power this car makes there’s a very large rise in pressure over a session and a large stagger between the predominantly outside front tire and inside rear, so it’s really important to get those pressures all correct. So this was our last chance to put the fresh tires on – use session 3 to get them set right for session 4. We put the fresh ones on.
Session 3 started off well, tires felt a little better than the old set but the balance had changed, I had a little more front bite and a little less in the rear. Sliding through Riverside at 115 mph and catching it juuust at the outside edge of the pavement had my heart rate up and on the radio saying “we need more rear wing”. Despite the tail happy balance I kept pushing and the lap felt OK… twitchy and bumpy, but it was feeling like the best lap of the day.
But then, going over Phil’s Hill and coming down the back towards Star Mazda I was quickly catching another car that was on a cool down lap. Unfortunately they didn’t notice me until too late so instead of staying off-line and slowing on the straight they cruised into the next turn on-line. I set up wide and tried to keep my pace up and go around the outside but found a ton of dirt and debris as soon as I was out there off-line and the car slid juuust enough to pull me off track. The lap was gone. I aborted and got back to the pits for fuel. Back out and the rotrex temperature warning light started triggering, with the numbers spiking up and down. I pushed through the lap but was distracted with worrying about and what that meant and what would cause it. Lap felt OK, but the car was fighting with me and felt really twitchy.
Back in the pits between sessions we figured the only culprits that would cause erratic temperature spikes at the sensor on the Rotrex are either air pockets passing the sensor or a bad sensor/wiring. We got the nose off and topped off the fluid, which was just a hair under the disptick.
We had just the final session in the fading light. We executed our plan; 2 hot laps, in for fuel, then another 2 laps. With less cars on track we had some clear track and I finally got to push the car without interruptions. But it was a real challenge. The car just felt unsettled almost the entire lap. I pushed as much as I felt I could, had one brief off on the outside of Bus Stop but got three solid laps in this final session. Drilled down to a 1:48.0 but couldn’t get much more out of it.
1:48 flat turned out to be good enough for 4th place in a 26 car field. We were just 0.07 seconds off the third place car. SO CLOSE to the podium. But with all our trials this weekend I must say that I’m massively thankful and proud of our team. We busted our butts for two days straight, didn’t miss a single session despite everything trying to stop us, and in the end got things together enough to take a very respectable finishing result home.
I’m not one to say later “we looked at the data and it shows we could do X time”. That means so little. What matters is what you actually put down out there, the rest is just noise. But, what I did find Monday night when going through data and video was a big realization – sitting at home with a clear head I immediately noticed in the video that I was bouncing all over the place, way more than the car usually does. It was suddenly obvious – we were still running largely the same setup as we ran at COTA. Specifically, lower and stiffer than we ever have before at Buttonwillow. My only recent test day on a similarly bumpy track was at Streets of Willow where I was largely engrossed in working through early boost issues, but when I think back now the car was far too stiff that day as well. I should have caught it then.
But, every step of the way I learn, and you can bet I won’t be making that mistake again.
We fought, we overcame, and we come home with a ton learned and a game plan for how to improve. You can’t ask for more than that. There’s a lot of teams who dream of a 4th place at this event. We may have our sights set much higher, but I remind myself to appreciate the struggle, because that’s how we get where we are aiming.
Rules for next year just announced. Limited class cars will have to run Yokohama Advan A052. It may make things really difficult for us but it was a necessary growth step for the series, so I get it. We’ll figure things out.
I don’t expect them to have any decent width 15″ tire through 2020. By the time 2021 rolls around, maybe.
Also, realistically I don’t think we can hope for wider than 245. We can (and have) told them they should go wider, but it’s a different culture and mentality with Japanese brands. We can’t get Enkei to make a 15×9 for crying out loud. They will look to what currently exists and is successful, I don’t think they’ll pioneer a new size.
Pretty stoked to be cruising SEMA, come around the corner and see the HyperMiata on Stoptech’s wall! We were on the wall, on their TV, full centerfold in their brochures, and at the top of all their application guides for race kits getting handed out at the event. Much love. Very flattered.
So a stock (Luk) clutch isn’t up to the task once a supercharger is added to the mix. Go figure. And the car was down on power with the undersized intercooler.
Point of complete failure was on a downshift at the end of the front straight, but that only means the downshift was the final straw, not necessarily the root cause.
Hard to say whether the rivets sheared or the disc broke apart first.
For GTA Finals I have a gamble on my hands. Put another Luk clutch in which we know shifts well but we can assume is a ticking clock until it inevitably fails like the one above… or put the SPEC clutch/flywheel back in which will not fail like the Luk but it never disengaged right on the MV7, so we’d be hoping that it works better in the MV5 (the Luk was always better than the SPEC in this regard, but it was still not perfect in the MV7 and it improved when we switched to MV5).
Laguna Seca flew by! We had an amazing weekend, filled with meeting lots and lots of fellow enthusiasts.
But what about the HyperMiata? On Friday we set out to take a crack at the Miata lap record. I had just got some heat in the tires with one warmup lap and did a single flyer and saw a 1:35.25 light up on the display. That’s a new record! Going into turn 2 on the next lap the clutch failed. Man, I was just getting warmed up! There was definitely more in it. But in true Time Attack fashion, I didn’t know it but I had just the one lap to get it done and I did. Will have to go back some time and drill that record down further.
The rest of the weekend the car sat proudly on display in front of our garage:
Had a great time giving rides in the Budget NC Saturday and Sunday. It’s not neck-snapping like the HyperMiata but it extracted a lot of passenger “Wow”s and “Holy Crap”s as we chucked it through corners and dove deep into braking zones. This car is a riot, it shouldn’t be possible to build such a fun and capable car for so little.
By the end of the weekend I was aching to get back in Hyper and get just one more lap in. After so many laps that weekend I felt so much more ‘up to speed’ on the track than I had when I did those first couple laps Friday morning. Aaargh! Ah well, gotta have things to look forward to!
Got a shakedown in at Streets of Willow, working out some kinks and relearning the car. Even over weight with the Laguna Seca exhaust and a passenger I was thinking the car felt quick, drag racing with an Audio R10 down the straight, and then in a later session I switched over to a secondary page on the dash display and saw I was only making about half the boost I should’ve been.
Worked out several other details while there, and towed home with a new top priority: find my boost!
Made some DIY caps for the intake piping so that I could pressurize the system and started the hunt. The primary issue was immediately obvious; there was a significant leak in the intercooler core itself. I couldn’t put air in fast enough with the shop air to even build up any pressure.
Pulled the intercooler off the car and tested it alone, and found there were a dozen or so points in the core where pressure was leaking out between the bars significantly. So I had put a chunk of hours into building this custom intercooler, not knowing that the core was defective from the start. We suspect it was leaking less initially which is why it made pressure on the dyno, and then worsened after being bounced around and stressed. Not the news I wanted, but I was glad to have something in my hands that I knew was the cause (the worst part of an issue is
I dove into making intercooler #2, and because we had seen super happy IATs with the first intercooler I decided to take this opportunity to use a smaller core for #2 to try to cut a few pounds. This time I used an off-the-shelf intercooler that already had endtanks to try to cut down on fabrication time a bit… but the inlet and outlet still had to be modified so it really didn’t save much.
Intercooler #2 held pressure perfectly:
With the new intercooler in place I was able to pressure test the full system and pinpointed a few more smaller leaks. The seal between each coupler and pipe can be quite finicky. I’m using a combination of Murray clamps on the thin wall aluminum tubing and T bolts clamps on a couple of the thicker wall connections, like the outlet of the supercharger. The T-bolts actually deform the thin wall aluminum tubing, which I saw first hand on one of my pipes, so the Murray clamps are better in those locations, but they aren’t without their finicky nature either. The one connection that never had any issues was the Vibrant HD clamp in the cold side piping. I also found a small leak in the blowoff valve fitting.
A quick side note, this highlights one of those inherent differences between turbos and superchargers that you don’t really think about until you’re dealing with it. A supercharger is far more sensitive to boost leaks than a turbo; up to a point, a turbo will compensate for leaks in the system by just spinning more until the wastegate sees the target boost achieved. A supercharger has no way to compensate, it spins exactly the same as it did without leaks, and any pressure lost to a leak is just lost. All in all, this was a good learning experience about how sensitive things can be to leaking, and I’m making pressure testing a routine step in the future any time anything in the charge pipe system is disassembled and reassembled.
Switching to fuel, at the track datalogs showed fuel was struggling a bit more than before. Then a few days later while idling in the shop the pump quit completely. Rather than swap in another Deatschwerks DW300, to be sure the low pressure side of the fuel system could supply anything we asked of it I decided to switch from a DW300 pump to a DW400. The DW400 is a big pump that doesn’t really fit the Miata, but I modified the pump fixture and brackets to make it work. Then I redid the high current pump circuit with heavier gauge tefzel wire, larger fuse, etc. so that we can run the pump properly, even at the 20+ amps it draws at high pressure if needed.
Booked a local dyno to verify everything was sorted. Numbers didn’t matter, just wanted the data logs from a few pulls. Everything is back in the green, but seeing 1.0-1.5 psi less now than in our first round of tuning at UMS, with a small but definite delay in the ramp up in boost when plotted by RPM.
Leading theory at the moment is that the smaller intercooler is causing a more significant pressure drop. To test this I’m going to add a second boost sensor in the hot side charge pipe so we can see the delta pre and post intercooler, and depending on what we find I might have a third intercooler build in my near future. We’ll see.
But for now, it’s running well and making decent power so it’s buttoned up and going in the trailer tomorrow for Miata Reunion at Laguna Seca.
