When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The engine bay is pretty much a playground of open space for activities again
The interior is... well... an interior that is a continual work in progress
To the MT brain trust, I've got some questions for you to help me ponder through.
The only part of the HVAC system that I want to keep is the defrost. I've been caught needing it on cold/rainy days where the windshield would otherwise fog up and anticipate that need in the future for both track and street driving. I don't need (or want) the eyeball vents or foot vents functional. Simply put, I only need the (single speed) fan on when I need heat and defrost running to the windshield. If I don't need defrost, I'm cruising with fan off and windows down (and/or top off). Knowing this, I really don't want the large multi-speed OEM blower motor, the crossover tube, and the OEM HVAC door assembly with OEM heater core. It is quite bulky/heavy, takes up vital interior packaging space for other electronics that I'm planning on, and requires me to mess around with routing coolant through the firewall. Is anyone aware of an assembly that contains an electric resistive heating element attached to a fan that would work well enough for this type of application? I'm thinking UTV cab heaters or something of the like? I have a concern on getting enough flow to the windshield with a fan that is likely much smaller... the secondary concern is if the air actually gets warm..
There appears to be a stack of cheapo units on amazon for this, but I trust them about as far as I can throw them (maybe less). Ideally, a 2-port system like shown below would be best so I can connect one port to each defrost duct on the dash.
In my racecar I used a mini water radiator, came with a fan and two outlets. That after trying and ditching an electric heater. The radiator worked ok, better than nothing but nothing to write home about either, I should have gotten the next size up - I got the smallest I could find, because weight, y'know? . Only demisting the drivers side helped, but it struggled still. IIRC I got it from one of the US or UK race supply outlets, and there were several sizes. I'm the Amazon et al will have them.
If it's just hotter-than-ambient air you're after, seems like there's a lot of places on the car to grab that without having to deal with a resistive heater and\or coolant. Maybe a duct from inside the trans tunnel and a bilge fan to the windshield?
Stock blower draws air from the cowl, which is typically dry and semi-warm from engine bay. I’d keep it, just duct to both defrost vents, blocking off any other exits.
we made a little piece to adapt the blower motor to x2 ~2.5” pieces of pipe, and clamped some brake duct hose to it. The plastic defrost vents are roundish enough to lightly clamp the ducts on.
If it's just hotter-than-ambient air you're after, seems like there's a lot of places on the car to grab that without having to deal with a resistive heater and\or coolant. Maybe a duct from inside the trans tunnel and a bilge fan to the windshield?
"only hotter-than-ambient" is more or less what I'm searching for. I'm not positive just how much hotter you need the defrost air to be in order to be effective. I reached out to the "trackable miatas" facebook group with this question and received hits on an interesting concept
Apparently the BMW E30 convertibles had a rear defrost fan assembly that also has a resistive heating element within it. Think of it as a glorified hair dryer, which is perfect for the hairdresser jokes! I've yet to see how the heating element actually looks inside of this unit, but it seems potentially promising to mount something like this in place of the factory miata HVAC setup. For the $50 it costs to buy a functional used unit on eBay, I might just have to experiment with it. I really like the idea of not having to run coolant through the firewall if I can avoid it in the name of keeping coolant routings simple!
Originally Posted by curly
Stock blower draws air from the cowl, which is typically dry and semi-warm from engine bay. I’d keep it, just duct to both defrost vents, blocking off any other exits.
Thanks for sharing that helpful photo. With whoever's setup you just shared, do they have positive feedback with operating in the rain where windshield fogging is likely? Seems like a very viable option as well.
That BMW thing is a cracker find, it is likely sized for the job from the get go. If you are focussing (sorry) on only the driver's side I'd expect that to work well.
It is certainly a much better solution than my first go, which was similar in concept but poorer in execution.
Take inspiration from another German manufacturer and do it old school air cooled VW style - just pull air from around the exhaust manifold. In all serious, interesting find on the BMW heater. That's the sort of stuff I was talking about when I said I was looking forward to learning from the next stage of the build.
I'm not sure how the LS coolant path works, but it seems like most engines use the heater core loop as the coolant bypass loop to prevent total coolant stagnation while the thermostat is closed. What's the plan to address that? Maybe a dual acting bypass style thermostat? Pretty sure you've got this one figured out, given your day job!
Thanks for sharing that helpful photo. With whoever's setup you just shared, do they have positive feedback with operating in the rain where windshield fogging is likely? Seems like a very viable option as well.
That's our enduro setup. Haven't tested it beyond a ~40* morning when the windshield was completely fogged up. With engine running, it cleared up the fog quickly. No, haven't tested it in "anger" yet.
I'm not sure how the LS coolant path works, but it seems like most engines use the heater core loop as the coolant bypass loop to prevent total coolant stagnation while the thermostat is closed. What's the plan to address that? Maybe a dual acting bypass style thermostat? Pretty sure you've got this one figured out, given your day job!
With this post, you're giving me an excuse to explain cooling system design for this system in detail... so here we go...
Starting out with fundamental layout, here is a good image that I found online that describes the high level architecture on "most" OEM LSx setups. Note the pressure/surge tank is at the high point in the system, and the steam tube and radiator vent ports allow air to flow upwards and burp out to that high point, which is following 'best practice' to a T as far as I'm concerned. Air doesn't like flowing downward!
Now, for the LSx miata layout that I'm reviewing, I want to delete the heater core. The heater core ports on the LSx are unfortunately on the passenger side front corner of the engine (the furthest spot from where I'd ideally want them to be). Packaging space is always at a premium and if I can avoid having coolant lines routing down the passenger frame rail and across the firewall to the OEM Mazda heater core ports, that's a win in my book. The new diagram to look at turns into what's shown below... Note that the pressure cap moves from the surge/pressure tank to the radiator. Without heater core (a relatively high mounted component in the system) you have a pretty reasonable chance at making a radiator mounted pressure cap be level with (or higher than) the steam ports to give air bubbles an upward escape path without jacking the front of your car up like crazy.
So now we get to the question of, how do you manage the LSx water pump manifold/casting when you don't need the heater core ports. The LSx water pump manifold/casting is actually quite clever in how it is fundamentally laid out. Here is one angle of how coolant is fed into and out of the pump manifold...
But where it gets interesting is here (where the thermostat bolts up). When the engine is cold, the thermostat naturally seals against the machined bypass port (as shown below in blue) and noted by line #6 in the diagrams above. There is very light preload spring pressure that the thermostat uses to seal to this port when the vehicle is cold. During standard "cold" operation, the pump generates enough pressure to overcome the preload spring and bypass flow from the hot engine outlet passage on the manifold back to the pump inlet passage as shown by my red line. Pushing open the preload spring is basically easier than trying to push fluid through the radiator (and fluid always picks the path of least resistance). As the coolant heats up, the wax expands on the thermostat and increases the preload on the spring to the point where the pump cannot overcome it anymore, therefore causing all the coolant flow to go through the radiator (and not the bypass port).
The heater core lines are simply on either end of this bypass passage as shown in yellow, so regardless of the preload on the thermostat spring, some amount of flow will go through that passage.
OE thermostat example shown here with the light preload spring on the left
So now it becomes pretty obvious that the heater core isn't needed to provide a bypass route on this system as there is an integrated bypass passage built right into the water pump manifold by design.
The "proper" way of deleting a heater core on LS is to tap/plug the ports on the manifold, like this. This forces all of the coolant through the radiator for optimal performance when the thermostat is hot and the bypass port is sealed off.
The "easier but much less effective" way of doing this, is to loop the inlet and outlet barb fittings like shown with a commonly used $5 hose. While it is easier than tapping/plugging holes, this creates a flow bypass route regardless of the thermostat position, will reduce the flowrate through your radiator, and therefore reduce heat transfer out of your system! Could it work? Sure... but if you are trying to get the most out of your system this is not recommended. For street driven cars, it's very likely that the hose solution works just fine as you aren't straining your cooling system while cruising on the street. This story changes as you get to more demanding track scenarios.
NPT plugging it will be for me! Not only is it more effective, but it looks cleaner and is marginally more lightweight. Yes, I'm counting grams for weight loss already...
Not much more to show for this as far as photos go, but got the cowl finish panel removed so that I could get the cowl mounted coolant overflow bottle removed and added to the pile of sell parts.
Also got the shortened throttle cable removed. What a giant PITA getting the plastic firewall clip released is. Not only are you upside down working under the dash (questioning if you know up from down and left from right correctly), but you are in a constant battle with yourself trying to get both top and bottom tabs pressed in simultaneously to release it. Sad to say, but this was probably the most frustrating part of removing the entire engine swap (which might be a compliment to how good the swap is to work on overall?). Honestly, if considering a kswap, they are quite nice to wrench on... lots of open space, so compliments to that swap for that.
Speaking of PITA (and potentially obvious) items, the hardline to AN compression fittings that you use for the fuel line adapter are definitely not intended to be removed without damaging the fitting... I told the swap package buyer that I'd do my best to remove it with the PTFE fuel line to the rail, but that's a pretty futile battle. The line itself came off without a fuss, but props to whoever designed the compression fitting. That thing is ON THERE!
Ideas (both good and bad) are flowing as I do the classic 'car guy stare' at the empty engine bay. The latest idea is related to the future intake. I've got enough components for oil and coolant systems to keep the front end as crammed as I'd like it to be, and that is before routing an intake up there in that ducted region as well. ITB's achieve that goal, but don't easily achieve the secondary goals of being cheap, easy to tune, or great to cover up when you know you'll be driving the car in rain. I wonder if you could re-route the intake elsewhere via some creative overthought means?
Running into a couple delays on some kswap sale details, but more on that for a future post.. Not much for further miata progress until that's sorted.
Sold the 4.3 Torsen with axles, driveshaft, and PPF to a local spec racer, which didn't take long at all. Hover mode is officially engaged for good for a while!
Been spending the last few days completing some much needed garage deep cleaning, putting away the winter toys, and taking out the summer toys. There was (and still is) things that haven't been put in their new place since moving in Sept, so it's been good to finally focus on getting those items put away before I create an inevitable mess once again around the miata.
As part of cleaning, this week is supposed to be the first 60-70F average temp week with limited rain. Seeing as the miata is out of contention to play with, I had to put some focus into the summer vehicle that I did have available as an option (the ZX6R). First order of business was the dreadful chain and tire grease cleaning, which I never did since I initially bought it. 30mins of swearing later, you have this nice clean setup. A quick tension adjustment and the rear end is good to go!
Working my way forward, the coolant overflow was a little low so that got topped off. Will have to play a close watch on if there's a seep/leak somewhere as the hoses are showing their age.
The oil needed to be changed, so that's quick work as well. I can't confirm if this was done intentionally by design or not, but the fact that the oil filter when loosened drips PERFECTLY though the bodywork airflow duct is super satisfying and an incredibly convenient 'design for service' easter egg.
Lastly, I managed to find a tail light supplier that still makes some nice parts for these 22 year old dinosaurs. For whatever reason, it gets hard to find lighting suppliers that keep making model specific parts for this gen bike. After waiting for about 4 months, I received a light smoke sequential LED integrated tail light and got that installed. It has brake multi-flash features (for extra visibility) as well as amber LEDs that scroll to each respective side when the turn signal is activated. Pretty slick piece worth waiting for and does a good job of tidying up the rear end. The bike will need tires within the next few tanks of fuel, but I'm excited to at least have this to ride for the time being when the miata is 'under the knife'
Man, I freaking love throttle therapy season (especially after how the last few weeks have gone.... foreshadowing to later in this post). The project bike is being a typical project that will need a little money tossed at it (the speedo is having some intermittent functionality issues to dig into), but it's been great getting wind blowing past the helmet again. Leaving for work in brisk mid-40 degree weather and coming home when it's in the 70's has made for some nice riding this week. The new house has some twisty roads on the way to/from work that aren't a very long detour, so that's been great to explore. I may not have 8,500rpm in a kmiata to use anymore, but 15,500rpm in this quickly makes you forget about it and eases the temporary pain of being miata-less.
Other "car guy" events in the area are starting to heat up for the season as the weather warms up (pun intended). The local circle track just down the road had a cars and coffee event on Sunday. Much to my surprise, I ran across an LSx miata owner. The owner had an extensive list of parts on this thing that I picked his brain on for a while. It didn't seem like the car was built with any specific purpose in mind (and he confirmed it was more of a memorial build to his late-father), but it was obvious by the 3 gal dry sump tank in the trunk and built 6.2L / T56 / 8.8 combo that the owner stuck a serious amount of time/money into it. Got a lot of pointers from him on what to watch for and what he'd do differently if done again, which will be valuable I'm sure in the coming months.
To raise money for a suicide prevention fundraiser, the event also had $10 photographs on track with your car and as part of the deal you could take two 45mph laps around the track. While most parents decided to sit on the stands with their kids to watch the cool cars do this, I took a different approach.... "Load up kids, we are doing fliers in the cammed family suburban!"
After signing about every safety/insurance form known to man, I built what will likely be a core fatherhood memory of taking the wife, 16mo twins in car seats, and a pile of stroller junk in the trunk around a 33-degree banked oval track at a "45mph" un-audited speed that I may or may not have exceeded. Both kids in back were uncontrollably giggling as my wife was 10/10 questioning the person she married, but it was all 100% worth it. Being a dad has its very cool moments and this was one of them.
Anyways, back to this..
Running into a couple delays on some kswap sale details, but more on that for a future post.. Not much for further miata progress until that's sorted.
Right now is that "future post". Brief backstory.... Met buyer of kswap through a kmiata facebook page. The buyer consisted of Nephew (whom I'll label N) and Uncle (whom I'll label U) who want to build a n/a kswap track focused NB2. N is more of the mechanical guy to build it whereas U is more of the one funding it all. N made a post complaining about new part lead times and whatnot, and was looking for clarity on all the parts required as many kswap buyers do. I DM'd N mentioning I had quite literally EVERYTHING he could want for a turn key swap plus a bunch of "nice to have" add-ons as you've all seen here in this build thread. We spoke on the phone for a couple hours of the next few days, N and U chat about it, and I get an excited call back from them that they'd love to proceed with the deal. Zero red flags.
I told them that I'd need some time to remove the parts and in the meantime N&U were going to sort out pickup as they were a couple states away. I took them for their good word and didn't ask for money down.
Fast forward to EVERYTHING being removed from the car, and I get a blindsided call 48 hours before the pick up date.... N had some "personal life" things pop up (which I won't disclose here) AND got laid off. U (whom still wanted to go through with the deal) needed N's mechanical abilities to be able to able to install this swap, and N was in an understandably not-so-great mental state given what just happened to him. U called me and basically said "I'm super sorry, but I dont know if we can do this deal anymore if N can't help me". well f*%&, that's great considering my once functional car that I could be driving right now is now a completely stripped shell.
[[insert me questioning life's purpose for an evening over bourbon here]]
U and I continue chatting over text and decided it was best to let N just take a week to let the turmoil settle down a bit in his personal life. We've all been there, **** happens, but man did it suck seeing my car in pieces with a deal that could fall through. U still wanted to do the deal (which was promising) but really needed N's commitment to installing this kit into their NB2 rolling chassis. Well, a week goes by and thankfully N came full circle. He took the optimistic approach and realized the layoff just gave him more time to get this install done quickly.
So the deal was back on (yay), but they changed their tune a bit and preferred to have a carrier pick up the swap kit instead of driving themselves. No worries, I can support whatever you want, but I need to get paid! We continue discussion and opt to go the next-day "cashiers check" path. U sends cashiers check, I get it Wednesday, and it cleared today.
So that whirlwind of emotion brings us to today. Glad it all is ending up working out, but it's not been a stress free situation (see first part of post on why throttle therapy was needed). I also need a celebratory bourbon.
The shipping carrier is supposed to be calling me on when they want to pick this up. It's a carrier that supposedly does the crating/palleting and freight work for you on-site which seems damn slick. I've not heard of this type of service before but if it works well I will have to keep it in mind in the future large shipments. Throughout the last few weeks I've been piecing together the LSx parts list in preparation for kswap payday. Now that kswap is officially sold, I can get serious about the order of operations for what parts to get first will be.
Nothing like a high stress deal to get the blood flowing!
When I bought my FD Rx7 I had to commit to driving 1800 miles and picking it up, without a title in hand, with only a promise from the lady I was dealing with that she could get the title once we had the car here. I had bought a miata from her, so had some level of trust, but seriously lost sleep over the whole ordeal. That and the roadtrip being in a mystery van that I had never put any hard miles on. On the flipside I'll never forget the whole deal!
Sometimes you just gotta chance it! Glad it worked out, excited to see the LS build come along.
Pretty sure I shared this here before (maybe not in great detail or the idle video), but jumping into this as a daily driver for the last 2 years may or may not have emotionally influenced the miata direction a bit
When my wife and I found out twins were on the way, I needed a 3rd row vehicle while keeping the ability to tow/haul things. Naturally a suburban hit the top of the list pretty quickly for those needs. Bought this one with 228k on it and minimal rust (what really matters here in WI) for a very reasonable price at the time. Didn't want to spend dumb dollars on anything new because we were saving for the house we now have and twin costs were unknown so I kept it cheap on the older gen stuff. It's the last of the gen4 LS engine architecture SUV's before they went to GenV LT architecture that is more complex, more expensive, and (most importantly to me) less reliable. The Achilles heel to these gen4 LS generation trucks from a high mileage reliability perspective is the active lifters for displacement on demand (DOD).
As "preventative maintenance" I decided to just jump in and replace the lifters right away.
...but if I'm replacing the 8 active DOD lifters, I might as well upgrade all 16 of them to LS7 lifters
...and if I'm doing LS7 lifters, you might as well do a healthy cam and hardened pushrods
...and if you are doing a cam, you should remove the VVT to provide you the best cam options
...and if you have the heads off and exhaust manifolds disconnected anyways, you might as well put long tubes on it and stiffer valve springs to support the cam
sooo scope creep may have happened
Preventative maintenance led to essentially an entire valvetrain refresh with some "sound good" exhaust goodies to support the chosen cam, but for a stupidly cheap ~$1500 in parts and a full days worth of work, I absolutely love how the truck sounds/performs as a budget friendly beat around dad-mobile. It's still on a factory catback/muffler with some fancy SLP tips on it for flavor. Just turned 254k on it on it last week without a hiccup and fully intend to have this be the first 300k+ mi vehicle I've ever owned.
A lot of the positive experiences working on and tuning these gen trucks (this being my 4th one over the years) has very much helped persuade the decision to go down a similar v8 build path with the miata.
Ahhh and now we see the inspiration haha. That's kick ***. Didn't realize you had previous experience with the LS platform prior to taking on the swap. That makes all the more sense.
Also $1500 and a day's work for that substantial of an upgrade. That's way less time and scratch than I would've guessed. Killer.
What'd you use to tune the thing post-upgrades? Is HP Tuners what most people are going with? My roommate wants to do something similar to the LS in his truck but most of his experience is with carbureted stuff so EFI tuning is new and scary for him lol.
Didn't realize you had previous experience with the LS platform prior
Have you read this build thread title? haha
I believe this is my 7th GM v8 vehicle that I've owned (5 trucks and 2 cars; ranging from a 4.8L regular cab truck up to heavily modified 6.2L LSA Cadillac sedan). I'm nowhere near an expert on all the variants out there, but I know enough to be dangerous and damn if they aren't easy to make power on and simple to work with. It's honestly a small miracle that I convinced myself to try out the kswap given how much I've enjoyed these older v8's over the years.
Originally Posted by Z_WAAAAAZ
What'd you use to tune the thing post-upgrades?
Every GM V8 I've tuned so far has been through the factory ECM on HPtuners. It's very hard to justify the costs of aftermarket ECM when $100 in HPtuner credits unlocks the existing ECM and you don't need to worry about BCM integration points, your dash not working right, or throwing random codes on what has always been a daily driver for me. Depending what generation engine/transmission you are tuning, the ECM can range from very beginner friendly to a bit daunting. Earlier gen3 engine stuff is pretty rudimentary and well documented online if you follow "sloppy mechanics" at all. The gen4 engine stuff (like my Suburban and CTSV) gets a bit more advanced with overlapping torque based tables, closed loop idle tables, and torque based transmission tables (if you have an auto). The HPtuner forums help answer a lot of questions once you dive into it.
Haven't checked this thread in a while and excited to see the new direction! While it might feel like a step back removing the K swap, I think it's one of those "one step backwards, two steps forward" kind of things. I'll be interested to hear your comparison of the LS vs the K when it's done. With the cost of K swaps going up, it's harder to justify the cost of a K swap + other mods over an LS. I think my personal fav v8 these days is a coyote, but they're just not nearly as compact and affordable as the LS motors.
0
. Only demisting the drivers side helped, but it struggled still. IIRC I got it from one of the US or UK race supply outlets, and there were several sizes. I'm the Amazon et al will have them.
