Full cage... and I feel a lot more comfortable pushing things on track with full safety equipment. Still wouldn't want to go 150mph in my car...

 

I have nothing to add that hasn't already been said, but cool to see you lay out the comparison between the two trannies. It really just comes down to your absolute goal. Absolute lap times vs having a manual shifter/better exhaust fitment. I would choose the manual shifter/better exhaust fitment because for me personally half of the "journey" would be building the car, and absolute lap times would be 2nd. The car's gonna be a handful regardless, so the "refinement" of an "auto" LS swapped miata is sort of an oxymoron to me. If you're going LS miata might as well stay full insane and stick with a manual. Just my 2 cents.

 

You seem to be more oriented towards "adding lightness" so the TKX would have been my guess. Simplicity, driver enjoyment, ease of installation. I don't think the 8HP is going to make the Miata into an F-type. We like to think that certain upgrades will dramatically change the car.... but it's still a Miata.

My interior already gets hot (black car, like you) and I already scrape the exhaust in many street scenarios with a T56 and dual 2.5" exhaust.. so cramming an exhaust where it might not fit doesn't sound like it would be an ideal fit for you.

But we're all fans of <insert known technology here> until we spend time with <new technology over here>. You shoulda never drove that F-type.

 

Appreciate all the feedback/discussion guys.

I did some deep soul searching over the remainder of my holiday weekend after the FTR test drive and gear ratio comparisons... and there are 2 ways I've thought about to make driving a high power/weight ratio car easier.. 1, shift in a more automated fashion (ie automatic) or 2, just shift less... Curly is on top of bullet #2 so let me jump there...

I spoke to 2 people that have high power/weight ratio RWD track cars (both manual dogbox or TKX cars), and they seem to mimic this feedback while on track. The ONLY place the 8HP has a gearing advantage over the TKX is a small window under 70mph as shown in the green range below where you can see the red line (8HP 3rd) is above the blue line (TKX 2nd). In practice, Bronson (LS3 TKX owner) just stays between 3rd and 4th which would say it seems the realistic limit for what tires can handle is somewhere around 2000lbs of tractive force per this plot.


In a huge majority of those circumstances under 70mph, the car is traction limited. Having more gear ratio like 3rd in the 8HP would offer would very likely NOT be a benefit, because you can't put down the power on the longer ratio of the TKX anyways as shown by in-car video I've been sent. At higher speeds, the ratios are the same between the two transmissions so the only benefit is the shift time, but I've been shared logs of power shifted TKX transmissions completing shifts in very close to the same time as the claimed 200ms of the 8HP. Is that debatable shift consistency improvement of the 8HP worth the weight increase, additional trans cooler complexity, challenging exhaust routing, and additional calibration required to tune the 8HP to behave in a desirable manner? Oh, and you also give up the "gear slamming" fun that comes with street driving a manual. I think the writing is on the wall that the TKX makes more sense for me. YMMV on your own use cases, but I think you nailed it here curly.

To be clear, I can run MaxxECU on either transmission, but if 8HP I must use MaxxECU as Link doesn't have 8HP integration.

This is definitely one of the negatives of the 8HP that has been considered. I'm going to gamble a bit here and say that the corner speed improvement I can hold with the TKX being ~120lbs less will outweigh the shift time improvement the 8HP could provide as far as a lap time is concerned... so I think I'm convinced TKX is still the right path overall.

Safety on a dual duty NA/NB is definitely probably the hardest compromise out of anything here with this car. Small car means light weight but minimal space. I am currently on just a bolt-in bar, which I will completely admit, feels inadequate for the speeds this thing has ran on the local big tracks. I was doing 132mph into T1 and T5 at RA with the K24 and the "what if" thoughts do run through your head. Likewise, I'd have the same "what if" thoughts if I had a full cage and was driving it to work in traffic with a jungle gym of bars around my un-helmeted head. In general, I trust myself on track more than I trust random drivers on the street so I've leaned a bit more towards street safety. Door bars eliminate my windows, which is a no go for street car scenarios. Any step towards more track safety makes for more awful street driving and vice versa. That said, for right or wrong, the car is staying where it is for this next phase of the build from a safety perspective as I truly drive the car in both scenarios in equal amounts. Who knows, that may change in the future and I can adjust accordingly?

...must be my settings because this thread only shows 15 pages for me. Time for another spreadsheet referring to post numbers?

I feel you here (see above). Building a dual duty NA/NB sucks when you get to this point because the car is small and space is very limited. it's a blessing and a curse all the same.

I cliff noted your response to an abbreviated version and I can't say I disagree. TKX is winning out here for reasons I outlined in my response to Curly in the second quote

 

Staying true to the vanity plate, I think you are right. Exhaust clearance was an issue on the K24 with the crossover that I pancaked (...like everyone else does with the swap). It will be nice to mitigate that from happening as much as possible with the new driveline, which is a win for the TKX path and a massive negative on the 8HP.


Driving more cars is never bad as long as you understand their usage case. In the case of the F-type, maybe the wife wants one for date nights?

 

For me, the 8HP just doesn't fit the ethos of a modern Cobra. Sure, the 8HP is probably going to be better for performance and driveability, but I don't think that should be the overriding factor. 400+ WHP/TQ in an NA/NB is well into ridiculous territory and sort of past the point about talking about optimum performance or ease of use. In my mind, if you spend too much time thinking about the engineering of making this thing as fast as possible, or doing it comfortably, and at some point the answer needs to be a newer and larger chassis, not the individual components you put in it. Obviously that's a value call that's going to be different for everyone though, especially the guy plunking down the coin.

Perhaps a more convincing argument: Making a convertible tin can with 40 year old chassis design roots better at accelerating to 150+ MPH without a roll cage or ABS seems to be asking for trouble. That said, a TKX isn't exactly going to be a boat anchor to your acceleration, so maybe it's not that convincing.

IMO, do whatever you think will be the most fun. Maybe an 8HP will do that best for you!

 

You aren't wrong...

Enter the C6... The value for the vette is strong (I considered it heavily) knowing it makes up for a lot of the older/smaller miata RWD chassis shortcomings when at the edge of capability, but it's an expensive avenue to commit to. Take everything we are used to with miata pricing (parts and consumables) and easily double it to get to vette cost territory. You can very quickly get to the point of diminishing returns for your dollar by switching platforms to something like a vette. In some sense, I guess what we are talking about here is where do those diminishing returns occur on the NA/NB miata platform? I think it goes without saying that what I'm spec'ing out here is well within that range of discussion.

full disclosure, I'm estimating that I'll be right around $40k into this NB build by time all is said and done. That is literally EVERYTHING you've read about in this thread including purchase price of the car and 2 sets of wheels/tires. For that all-in dollar value, I don't see how you could build a stock $25k base C6 up to be faster and it definitely wouldn't be cheaper to maintain. It would likely be subjectively safer, so the extra size has that advantage. Even if it was as fast as an LSx NB for the same $40k all-in cost, I'd take the keys to the LSx NB purely from the "being different/unique" factor and not owning another cookie cutter bolt-on C6. Everyone's opinions will differ on this one and none are wrong, but it's a fun mental exercise to work through when starting a build that is this involved and costly.

MK60E5 ABS is part of this build phase, which I have only briefly touched on. I've already encountered plenty of scenarios with the BBK where I've said to myself "man, proper ABS would be nice to have here" and it would be really dumb to not integrate it now. I will need wheel speeds for traction control strategies anyways, so ABS is not just wanted at this point, it is needed.

 

I could have sworn I edited my post to say "currently without", but you get the idea. I figured the Mk60 was happening and look forward to another deep dive!

 

I also considered a Corvette before starting my project. It's objectively the better platform, instead of putting 300-500WHP through a chassis designed for like, 100 on a good day, you're starting with a car that's designed to handle the power (and everything that comes with it). It makes a ton of sense.

But it's not nearly as cool. A v8 Miata is silly in all the right ways. I think it's easy to get caught up in the mindset of "car A is faster around a track so it must be better". Last time I checked everyone here is paying to race, so we might as well have fun while doing it. That's sort of the whole idea behind the Miata, isn't it - it's not how fast you get there, it's how much fun you have doing it. That's my (unsolicited) opinion, at least.

 

A corvette is the obvious choice for RWD big power and performance on the track. Almost too easy of a choice, actually. Which is why I hate it. I could never do a 'vette and in my eyes the lsx NB is infinitely cooler. I see 'vettes on the road all the time, I barely turn my head most of the time. Something about the little dick energy old man boomer mobile just never left my mind and that's all I can see. Plus, I've driven one and the seating position, visibility, and nimbleness of the miata makes it more fun.

I too think the manual trans is the right choice for this build. Though again the 8hp is almost definitely faster on track. But agreed that the ethos of a "modern cobra" needs to have a manual trans.

 

Funny you should mention that - ever since I got a reasonable-quality sim rig pieced together my "Cars I lust after" list has shrunk exponentially.
"Man, the De Tomaso Pantera is an awesome looking car - I've always wanted one"
<Downloads one on the sim rig and takes it for a drive>
"Ugh, this thing handles like a 70's muscle car (big shock there) - doesn't corner for crap."
<Scratches Pantera off of the Dream Car list>
At this point the only car I would be willing to buy in Real Life would be a Miata, a Porsche 996, a Lotus Evora GT/400, or a Ferrari 488 Challenge Evo.
Hmmm, maybe I should start looking for a DD Miata... >.>

To bring this back to the actual thread, playing with different transmissions in the sim rig basically reinforces what's been said - if you're looking for the best possible lap times there's a valid case for paddle-shifting, auto-blipping (ok that's more of a throttle thing but work with me here), do-everything transmissions. For pure driving shenanigans, though, welllll...

 

What makes sense is always a fun and debatable topic... I ran my first CTSV [the one that started this thread on post #1] on track once and it was (unsurprisingly) stupid expensive to operate. The operating costs on just brakes and tires took away from the fun I was having in a big way, which was the learning point for me that I hadn't previously thought about seriously. Not everyone feels the same, but their budget is clearly higher than mine. The C6 is more capable than the CTSV from a track perspective without a doubt, but the costs challenges remain similar. Being blunt, you've got about 4 track days to enjoy your $2k set of tires and $600 set of pads. A couple events later, you can do rotors and fluids for another $1k+. This is just basic necessities, not even including entry fees or breaking anything. None of us are here to make money on track. It is an expensive hobby and faster speeds costs more money, but I just found myself not enjoying the "big car" costs, which brought me back full circle to the light weight miata platform. Even at LSx swap power levels, I fully expect tires and brakes to last orders of magnitude longer with a car that will weigh far less. Ignoring the uniqueness factor, spending less money on consumables and more money on events is a big reason I chose to stick with the swapped miata path. The car ends up being the "cheap part" long term.

Regardless of how common they may be on the street, I love me a well prepped vette on track. I do quickly realize it is not something I want to pay to operate on track however. I'll bucket many Porsches or Mustangs or Camaros or BMWs in the same category. They make fantastically capable cars, but cost of the car in addition to the cost of track operation is not for the faint of heart, which leads many of us cheapskates to these light little roadsters to do questionable things with

 

This is the same conclusion I came to with our ZL1... tires and brakes were essentially double the cost of the Miata, and I wasn't fully comfortable with the speed it was capable of with just 3 point belts and airbags. The question becomes how fast do you need to be to be happy? Our K swap NA runs lap times right in the ballpark with some pretty expensive stuff that shows up at our tracks, and I'm competitive in our TT events. I'm also closing in on 60 years old, and I've just decided that I really don't need to go that much faster. The builder in me, however, is always looking for that "next step".... that's the guy I need to get under control...

 

For right or wrong, I've made the somewhat overkill decision that it's much easier to reliably detune the LSx with DBW (if needed) than it is to try and add notable reliable power to the N/A K24 powerplant (which I wanted) to answer this question. That builder personality in me has definitely played a factor though I must admit...

 

The most important measure is dollars per smile.

 

Yup, this is exactly why I put 2k track miles on my CRX (before I sold it). I had way more fun driving a slow car slow but doing it as often as I could. One of my instructors said something that stuck with me - the cost of the car can vary a lot but we're all having about the same amount of fun.

 

Ya the new ZL1's are nuts. I think another thing that varies a lot amongst people is how many events you actually do a year. If you're only doing a handful of events a year, then your consumables bill may not be horrible (even for a heavier car). Also tire selection makes a big difference (obviously). My buddy that has tracked his Mustang GT (2016 I think) a lot runs 305 square, and found a set of tires that has been lasting much longer than he expected compared to some faster tires that cut ~2+ seconds off a lap time (I'm not even talking about hoosiers). I'll have to ask him exactly how long his brakes/tires last, but it's not horrible I remember.

Cost wise you buy a Miata, spend $15k+ modifying it, I'm not sure I'm really "ahead" in the total cost of ownership game and I think it really comes down to how many events you run a year. I've said it before but I've been mighty impressed with his Mustang and the Coyote V8. It's definitely no Miata, but I was impressed with how capable it is on track, and it turns much faster times. The other thing that's impressed me is how reliable his car has been on track. He's beat the s**t out of his car for years and it's been running like a champ. I think he's probably within a second or two of similarly prepped vette times so it's nothing to sneeze at. I guess what I'm saying with all this rambling is sometimes the bigger/heavier cars don't necessarily "cost more" in the long run, depending on how much you spend on making a miata "fast".

I'm 44 and definitely learned that you gotta draw the line somewhere and be happy with it. I tell friends I have almost as much fun going karting with a group of friends and it costs a whole lot less, so the law of diminishing returns most certainly applies to going fast on track.

 

To add more reverberations to the echo chamber, I think it's also worth noting that after the initial investment in the car itself, we're all modifying it and spending that money as we go, as opposed to all at once. Both of my Miatae were bought for cheap, and were out turning laps on track for a sub-$10k initial investment including initial maintenance, mild mods, etc. Hell, I probably had less than $5-6k into my NA when it turned its first track laps. I'm sure the same could be said for most of you, some might've even spent less. Eventually, both cars started coming close to, or surpassed, what would've been the cost of a decent condition C5 with supporting mods, but at that point they'd already turned hundreds of track laps. Basically, the way I think of it is that you can make one of these as quick as a C5/C6/M3/etc, and even spend the same amount of cash doing so, but you don't have to spend all that money up front. I'm sure there's a flaw somewhere in my thinking, but that makes me feel warm and fuzzy at night.

And all of this is before you factor in the cost of consumables.

 

The other thing to keep in mind is that while a fast track-prepped Miata might cost as much as a used Z06, it's not like the 'vette is ready-to-go when you buy it either. Coilovers, brake upgrades, aero, safety gear -- you'd be buying all of that for the C5 as well.

--Ian

 

I appreciate all the dialog the last few days on why we all like building happy stupid miatas in all sorts shapes and sizes for the variety of completely logical and absolutely nonsensical reasons. While conversation was scattered, it did make me realize that at my core I dont really care if someone in a similarly prepped automatic car is faster than me. I'd be happier slamming gears a majority of times as that's part of the modernized Cobra ethos I'm chasing after here. I'm already expecting the full LSx swap to take me a while and the risk of project scope creep with the 8HP due to learning how to tune the TCM and the physical install of it with nightmare-ish exhaust routing potential has pretty concretely sealed that transmission idea in a tomb that I'll let someone else uncover for the LSx NB platform.



Back to LSx stuff shall we? Or at least that's what I thought.

Having connections in the local gearhead community is both a blessing and a curse. This week is one of those weeks. Friends know I scan things. Old retired friends have some wild cars. So one call led to another over the weekend and this showed up in my driveway. I'll be honest, as a proud U-Haul sponsored track day hauler, just this trailer has stemmed more jealously in me than I care to publicly admit. Maybe one day....


Now when you open the side access door, you get a peek at what is currently diverting me from LSx miata things..... Mopar things!! I managed to get shore power hooked up to the trailer and it makes for a pretty awesome office setup that isn't hard to handle...


....but why own a stock 797hp challenger hellcat redeye, when you can mod one to around 1050whp and run 8's in the quarter mile with your full weight boat? He put a larger 2.65L blower on it because the factory 2.4L is too small and "while your in there" you might as well put a 130mm throttle body on it. A 130mm throttle body (if you haven't seen one as shown below) could swallow a small child I'm certain. It is nuts to see something like this on a car and it makes everything about my LSx build seem logical, tame, and sane. That is, until you realize the miata will have about the same power:weight ratio as this


Anyway, the ask from the old friend was to design an intake system that adapts the new 130mm TB to a ram air hood scoop / headlight duct fed OEM airbox that is modified to hold a 7" ID (no typo, SEVEN) air filter. Some guy apparently makes an intake for this, but I'll say it nicely; his design sucks. I still can't get over how obnoxiously large this **** is for a car, but I'm all for obnoxious so let's party.... Packaging space is extremely limited and this would be a complete pain to attempt to measure and form by hand, but this is all where having a scanner is coming in clutch. I scanned the whole space and virtually assembled the airbox in place. I then had two very easy to reference circles that "simply" had to be connected together via CAD tools. In the end, you are left with something like this



This friend conveniently owns his own dyno locally, so he's already mentioned that I need to drive the miata down when it's ready to turn the rollers and take as much time as I need to get the ECU calibration dialed in. I guess this Mopar stuff is just a way of paying it forward for now, which I'm all for. Hoping to lock in the rest of the hellcat intake design tonight, 3D print it tomorrow, test on dyno later this week, and then he's off to some big Mopar challenge event with it later next week. From what I hear, he's already got a few buyers lined up for this intake system, so I wouldn't be surprised if this design effort ends up putting some cash towards LSx parts for me if it sells, which I won't be upset about.

This is also good CAD practice for what I need to do on the miata [[foreshadowing]], but more on that later....

Also #savethemanuals