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Starting to get to a fun point where I have enough scans of various miata and GM parts that I can begin virtually laying out some of the more complex ideas of this build that have been brewing in my head for far too long as lightly alluded to in Post #831.
Nothing super earth shattering as far as recent part orders go (lots of research continues), but I'll focus on the really boring decision that I made today... Engine mounts!
As part of the standard V8R front subframe kit, you are provided poly engine mounts that look like this.
Now you may think that's all fine and dandy, until you go to the track and your primaries on your V8R long tubes get hot enough to turn your poly into molten plastic. Ahh yes, the challenges of building a road course car. Temperature!! Shown are photos of Bronson's mounts after a couple hot sessions.
I was able to find that the solution to the issue is pretty simple. Just solid mount the engine to the subframe. Because a V8 naturally has better second order balancing than a particularly vibration prone inline 4 that I've been closely tied to (ahem K24), you can get away with solid mounts on this engine without much for NVH repercussions as multiple v8 swapped track (and even street driving) owners have reported on the facebook groups. You need to order LSx to SBC (small block chevy) adapters, SBC mount spacers, and SBC solid mounts as the magic combo. Once together it'll look like so.... Photo credit: Bronson
As it turns out, the solid mount combo ends up being cheaper than what V8R charges you for the poly mounts, so it's wins all around for my situation and I got the solid mount combo shown above ordered.
While I'm continuing the "boring" valvetrain parts research phase of engine, let's have some nerdy design engineer fun shall we?
If you've been paying any attention, you've noticed I've been doing a decent amount of 3D scanning for Left Lane Designs (my little miata-based side gig). The 3D scanner was bought initially with the intent to help me with some aero and cooling system projects on this car (which I still have intentions to bring to market eventually), but as long as I had the scanner sitting around, it has snowballed into scanning literally any miata component that I can get my hands on and sharing them to the community for what I hope is considered a bargain of a deal. I hope the files help a lot of DIY'ers and professionals alike speed up their design process with whatever they may be making, hence the new LLD business slogan of "accelerate your creativity". As a benefit to this strategy of scanning nearly everything I can think of for the last 16 months and counting, I now have a pretty awesome repository of files to reference and start utilizing for my own selfish reasons
So lets start with the NB unibody scan that I have had available for a few months now. To-date, this was the hardest and most time intensive scan to capture as it took better part of a few hours to scan on a bare NB shell (which on its own is hard to find). Once scanned, it took multiple hours post-processing and cleaning up to mesh into what you see below. It's a small miracle my computer's GPU didn't start on fire during meshing as the scan software is not the most efficient from a processing perspective, but anywayyyyyy.... Options are pretty limitless on what you can use this for, but we are on the LS swap topic in this build thread, so why don't we fit an LS in there? How convenient that I recently scanned the L94 longblock and the LS3 intake manifold that I just bought (it's almost like I planned this or something). Anyway, here is what this looks like.
STL files (which are what the scanner software exports) are not the most friendly to constrain in a 3D space to one another. After making a few reference planes to set a coordinate systems for each component you end up figuring out a process of constraining components together that works reasonably well. Once all assembled as shown above, you can start finding some fun interference points with the truck 6.2L (L94) motor. The truck oil pan sits FAR too low underneath the OEM subframe surface (as shown in green), and the oil pan also is not shallow enough on the front side to clear the steering rack or OE front subframe (shown by red arrow). These are both known interference points that I was aware of with the swap (and already have aftermarket solutions picked out for), but it's cool to see just how bad of an issue it would be if you had any doubts. You can also see how the crank pulley sticks too far forward and interferes with the OEM sway bar location. More on that topic later.....
As if the above wasn't enough proof of why the V8R subframe exists, it is pretty clear as to how little space exists for exhaust routing between where the starter would be (shown red) and where the OEM subframe surface sits. As much as I would love to design an alternative, subframes get complicated to make (or modify), so just buying the V8R subframe that has been proven to work reasonably well is the most effective way to approach this for me.
You may be wondering why I'm going through all this effort of scanning and virtually assembling this car when off-the-shelf parts already exist to build a track capable LS miata. That's a completely expected opinion for you to have, and my only response to that is...
...and with that, you'll just have to keep waiting and reading.
It's been brutal weather the last few days here. Upper 90's temp with relative humidity in the upper 70's. I have been assembling more items into the virtual model to try and stay out of the garage as it is firmly the peak of swamp *** season per the latest weather report.
We did get a set of Paco strong arms installed on the NA in the garage yesterday. As long as we had the car apart, I took the scanner out and got most of the inner wheel housing geometry scanned in case anyone needs/wants it. https://www.miataturbo.net/general-m...3/#post1666773
I did have some small shipments show up late last week. The engine mounts as I mentioned above look really nice. I definitely didn't need the ARP bolts that go through the mount into the subframe, but it was only $10 to add to the order and I don't even think standard grade 10.9 hardware could be bought that cheap at the local hardware store. The bushing you see is from a company called Creative Steel and is for the Getrag diff. The factory rubber bushings don't typically last and the one on my diff is no exception. Replacing with another soft rubber OE bushing that will likely fail over time wasn't an option for me. Creative Steel gives you two options: Daily Driver / Street (black in color) and Race (red in color). They give you zero context as to what the actual difference is other than the color and red being firmer than black, which isn't all that helpful if trying to make an educated decision. Seeing as quite literally everything else on this car is solid or delrin mounted, why stop here? I went with red "because racecar".
Documenting this more-so for my own note keeping (turns out a build thread is good for this). You guys getting to read my gibberish is just a side effect.
I had scanned the 5th gen camaro DBW pedal a few weeks ago along with the factory pedal box (which was a huge PITA given my scanner doesn't like gloss black items). GM pedal is shown red and miata box is green. Marrying the two together is the goal per post #827 where I first hinted at this whole thing. This specific DBW pedal is nice because you can see the mounting base geometry aligns closely to miata pedal box sheet metal all while maintaining OE Miata left/right pedal alignment. That alignment was a critical thing for me as I enjoy the OE Miata heel-toe distances. Checking this alignment is a PITA without a scanner because of the complex geometry, but super simple with a scanner and CAD. I'm sure there are other DBW pedals that can achieve this, but I wasn't about to dive into that rabbit hole when this option already seemed damn close. '
The aspect that I was reviewing tonight was ensuring there is appropriate travel for the pedal to reach 100% TPS. From 0-100% throttle the very tip/bottom of the pedal I have measured to move 2.4". The distance from GM pedal to the carpet (per red arrow below) was measured to be ~80mm (or 3.1"), so this scan shows me the pedal has no problems attaining WOT position with a little bit over 0.5" of clearance to the carpet to spare. The bottom of the miata pedal compared to the bottom of the GM pedal (per blue arrow) is 32mm (or 1.25"), so what that tells me is depending on how firm I'm pushing into the brake, the throttle pedal may feel a bit deeper towards the floor with my heel than the OEM Mazda pedal. I'll take that trade-off as it would be easy to make a throttle pedal spacer in the future if I feel the GM pedal needs some offset away from the firewall. Going the other direction is MUCH harder.
In general, as expected there are no interferences with trans tunnel or other geometry around the pedal. Time to start making some sparks soon with this part of the build.
Up next I started importing the rear subframe and getrag differential scans to the unibody. I have some more alignment to do between unibody and subframe and then subframe to the getrag, but that'll be a tomorrow-me issue and not a tonight-me issue.
Even with my eyeball modeling alignment, it's nice to see the diff line up well with engine centerline already.
One of the items I want to look into is alternative designs to mount a getrag to a rear subframe. The V8R setup is rather expensive. As Wingman mentioned in his build thread when installing a Getrag, V8R quoted $500 for essentially a metal bar with 2 bushings and 2 brackets welded to it. I align completely to his "F That" mentality. To make matters worse, you spend that money and the design hasn't been issue free. shown below is a failure where the welded front support plate for the diff has fatigued and cracked at the weld zone, causing the whole subframe to therefore crack. At the VERY least, the provided plate should be wider to spread out the loads across a larger distance, but that's just my stance on it... like I said, I think there's opportunity to make it better...
If I was to just make a one-off part for myself, all this scan work would definitely not be needed, but anything worth doing is overdoing. I'm going into this one with the mindset of, if I make one for myself, I might as well make it easy to repeat and potentially sell to others in the future that may be equally as frustrated as myself with the V8R product, so here I am now staring at this model wondering the easiest to assemble, most cost effective, least failure prone design is that improves upon my perception of V8R's shortcomings... wish me luck
The less anyone has to deal with V8R the better, speaking from personal experience. Even if your product is functionally identical I bet you'd get a good chunk of business.
I'm sure you've checked already, but keep an eye on the bottom right mounting bolt for the throttle pedal. I ran into some interference with the chassis there, and looks like we've got similar mounting positions.
Burnt the midnight oil doing more engine teardown to see what I'm working with and see just how good of a deal I actually got on my junkyard gamble. Started with removing the valve covers and immediately noticed the lack of engine gunk and grime in the valvetrain of the heads. Removed the rockers and pushrods with no ill reports to make.
Once those items are off, you can remove the head bolts and then the heads. Shown here is Bank 1 (driver side) with Cylinders 1,3,5,7 from left to right. Nothing to report. It needs a clean-up, but looks just fine.
...and here is Bank 2 (passenger side) with cylinders 2,4,6,8 from right to left. You'll notice that cylinder 4 exhaust valve is a bit lighter in color than the others. That "more white" color is due to leaner burn conditions almost always. Cylinder 4 is used during displacement on demand where GM physically shuts down the cylinder to save fuel. GM intake gaskets also are known to leak at higher mileage, so it is possible this slightly lighter color on that valve is due to either of those conditions (or both). No damage to the valve itself, so again, not worried. Just needs some cleaning up like Bank 1.
Next was the most awaited moment, the cylinder bore inspection! In short, the "High Mileage" LS Gods haven't let me down! In order, you'll see photos that I randomly selected of cylinders 2,4,& 3. Cross hatching is still quite visible. Keep in mind, this thing has 198,000 miles on it! The worst of the wear was coincidentally on cylinder 4 (the same as the leaner appearing exhaust valve). The thrust side of the cylinder 4 bore has a little wear where the piston is able to slightly rock at top dead center. I'm sure similar scuffing would be visible on the thrust side of the piston skirt as well. Some may disagree, but with what I'm seeing I do not feel it is worth doing a complete bottom end rebuild for. Current me is quite happy with the state of everything here. Any sort of bottom-to-top end rebuild (if I ever need or want one) will be a future me cost with another short block to build off of.
Here is just one of the 16 lifter rollers. All of them looked, frankly, almost new... I'd be lying if I said I wasn't considering re-using the 8 non-active ones and just replacing the active ones for the displacement on demand delete which would save some cash, but my better judgement says to do all 16 just to be safe here, so that's the plan.
Then that leaves us with a relatively bare short block! The valley cover on the top got removed (more on that later). Currently waiting on my pulley removal tool so that I can start digging into the timing cover and oil pan/system.
Small bit of progress tonight. Got the LS oil pan removed and to my surprise this has GOT to be one of the cleanest oil pans I've ever seen on an engine with this many miles. No sludge or dark residue in the sump of the pan? I'm not mad, but damn... I'm impressed.
One of the first bits that I ordered for the LSx swap was the fuel pump. Tonight felt like as good of a day as ever to get it installed and the tank back sealed up. Forever ago (I'm talking like 6-7 years), I had snagged a spare NB fuel pump assembly that I got basically for free. It had some sort of Denso branded pump on it and some odd looking wiring connections, but free was free. Well, blowing the dust off of my parts storage container, tonight was this parts time to shine (or so I thought). After pulling back the covering on the questionable wiring connections, my suspicions were confirmed. What in the world is this!?
Anyways, fast forward about 10 mins later and I had cut out the disgraceful wiring, reused as much of the OEM harness looming that I could, and used heat shrink butt crimp connectors provided with the DW200 kit. DW has some new branding on their pumps that looks FANCCYYY
Anyways, that success was short lived as I went to install the assembly to the tank and couldn't get the screws through the gasket... Upon closer inspection, the gasket has clearly seen better days as it was hardened and shrunk and distorted. So... another order being made tonight for a new gasket. Hopefully the install of this first new part isn't a sign of what's to come, but who am I kidding, it probably is
FYI I had to cut that liner off a DW pump I recently installed on an NC for fitment reasons, but it’s not something that looks fuel safe/submersible, might knife it off if I were you.
Took the above suggestion, cut liner/film off the pump, slapped the new gasket on it, and I can now say that small piece of the build is "done".
Continuing to forward look, I have to come clean on this one. I'm not yet 100% convinced of my transmission selection... It's a toss-up between the 8HP70 and the TKX.. so let's talk about it a bit...
In corner #1, we have the TKX. I'll focus on the benefits of it. It's strong. It's lightweight (given its tq capacity). It's very compact. It comes in 3 different gear ratio options (omitting the need for 6th gear like say the T56). Due to those factors, it is THE manual transmission to have behind an LS for this application in my opinion. If using the TKX, there really isn't any TCM requirements as your foot/hand/brain are the TCM, so you can pick whatever standalone ECU that you fancy to control the engine. For me, I'm really liking the Link ECU with DBW plug and play LS harness. When you add up the Link / TKX combo that I'm mentioning here with all of the accessory stuff, it's approximately a $7500 bill for general reference. Not really that bad considering the ECU/Harness is $2700 of that and EVERYTHING is new.
In corner #2, we still have the 8HP70 (...yes, an automatic).. It's equally as capable as the TKX from a strength perspective. It has razor sharp shift capabilities (<200ms shift times) without a lot of the complexities that DCTs have. It's consistent, which like it or not, is one of the large downsides of a manual trans. I can focus more on gas/brake/steering inputs and much less effort on perfecting my shifting skillset while on track, which I'm sure would correlate to faster lap times while attempting to wrestle a 500hp miata on a course. Anything to make a 500hp miata easier to drive seems like a good thing! There are 8 gears to use on street with double overdrive, so I fully expect street manners to be better while cruising around. TCM advancements for this trans have come a LONG ways as I've been patiently watching and spoke about here many months ago. MaxxECU offers a complete LS & 8HP plug and play harness setup with their standalone that frankly just works like an enthusiast would expect and want it to if I'm putting it simply. In the end, I would have to source a used transmission for this option, but everything else would be new. The MaxxECU / 8HP option ends up, ironically, pricing out nearly identically to the Link / TKX option after all is said and done... so... pricing isn't really a factor at all here to sway opinion.
So what am I fighting myself over? well, the 8HP is a big chonky boi. It will hold a ~120lb weight penalty over the TKX and is dimensionally much larger, which will make exhaust routing a more painful to figure out AND the OEM trans oil pan is estimated to sit around 0.75" BELOW the frame rails. Low profile oil pans are available and in my cost assumption, but it's still not ideal having a pan sitting that low if one could avoid it with oh... say... a TKX... The 8HP does require a trans cooler to be used and that's built into my weight increase estimate, but it's more complexity that would be nice to avoid having to route past exhaust and to the front end.
I did find ONE guy on the v8 miata facebook pages that did the LS - 8HP combo. He was turbocharged as well, but here below you can see some of the exhaust challenges he was up against. Now envision long tube headers dumping a 3" collector right by the transmission flange instead in my case. The passenger side of the tunnel gets snug quite quickly.
Up until today, I was about 95% convinced that TKX was the more logical path for me.
...so what happened today?
Well....
I drove this...
and GOD DAMNIT if that 550hp supercharged v8 AWD 8HP70 powertrain isn't a freaking riot. Now... I know what you are probably thinking... "is Matt really comparing his v8 miata build to a freaking F Type R?"
...and to you I say "Yes, yes I am"
While I fully understand my miata will NEVER be the grand touring machine that an F Type is by nearly every metric, this was the first time I had the chance to truly go test drive how good a higher power v8 8HP-equipped 2 seater could behave from a performance perspective. You can draw some parallels between my ~500hp v8 build and this car with that in mind. I could talk on this one for a while, but I'll just cut to the chase. It is very difficult to not enjoy the FTR. When in auto/touring mode, you'd barely know it was shifting if you didn't have the awesome exhaust notes playing for you. When in paddle shift mode driven in a spirited manner, the trans just shifts on command in a way that I'd never be able to repeatedly replicate while on track worrying about hitting my fast approaching braking zones or staying occupied with steering on corner exit. You'd need a dogbox or some sort of DCT to compete against how good this is, and both of them are orders of magnitude pricier than what this trans is. You start to learn quickly why the ZF 8HP transmissions are as popular as they are with OEMs globally.
So suddenly, after 1 test drive, the 8HP70 is more on the table than it ever has been. I'm confident that MaxxECU can deliver a similar feel that this FTR had and that I wouldn't be a pioneer or test dummy on unproven software. Seems Legit Garage has a BMW successfully running Gridlife right now with MaxxECU / LS3 / 8HP70 and it's been scary reliable even with them beating the snot out of it. Chris from SLG just finished P3 at Mid-Ohio with a scorcher of a 1.29.x lap. The FTR weighs in at 3638lbs (per Google). If I was having fun with that, how would it feel with a car that makes similar power but is ~1000lbs lighter? What about being hundreds of pounds lighter than that prepped BMW? Does a heavier 8HP transmission (over a TKX) really matter when you are traction limited under 60mph anyways? Wouldn't better gearing splits make up for some (or all) of the weight addition? Angle grinders can make space where space previously didn't exist if exhaust is problematic, right? Am I getting old and now part of the problem as to why manual transmissions are fading away?
I'll have to sleep on this one a bit longer as I keep building this engine up... I don't need to make the decision yet, but that day is coming soon.
Moral of the story here is simple though. Test driving vehicles first-hand teaches you things that a spreadsheet or video never will.
Feel free to check out some of the SLG Gridlife BMW LS3 8HP stuff here. Just look at how busy he is at the wheel on a car like this without worrying about shifting. This is more or less exactly what I'm referring to when I say that I feel automatic will cut faster times. The 4:56 mark has a super stand-out quote "here we are [in paddock], not doing anything, because the car just works".
I'm not going to tell you much that you haven't already figured out, because I agree 100%. We owned a ZL1 with the 10 speed auto for a couple of years, and I've had the opportunity to drive friends' Porsches with PDK (Cayman and GT3). On the track, driver workload is a real factor that absolutely affects performance, and a good transmission with paddles is going to reduce the driver's workload over a manual trans with or without a clutch. The reduction in workload allows more mental attention for braking, turning and throttle application... especially in a high power/weight car. If lap times are the ultimate goal, the 8HP would be my choice. That said, on the street I still prefer the manual transmission, because there more driver involvement brings me more enjoyment, but you're never at the edge of the envelope.
My only hesitation is that 8 speeds is just too many for the track. Even at places like COTA and Road America you'd be unlikely to use more than 6th, and an NA/NB Miata is not a car I want to be going 150-160mph in anyway. A lot of extra weight to only use half the capability most of the time. A manual with long gearing in an LSx Miata would eliminate a lot of shifting on track with hardly any performance penalty. If I was building a max lap time car, I still think I'd do the 8HP...
And I still have dirty thoughts about an LS/8HP setup in my E36 Touring...
If lap times are the ultimate goal, the 8HP would be my choice. That said, on the street I still prefer the manual transmission, because there more driver involvement brings me more enjoyment, but you're never at the edge of the envelope.
Completely align with the street driving sentiment. A manual is more fun to bang gears on the street with when you aren't so hyper focused on all the other driver details like when "in the zone" on track.
Originally Posted by Roda
My only hesitation is that 8 speeds is just too many for the track. Even at places like COTA and Road America you'd be unlikely to use more than 6th, and an NA/NB Miata is not a car I want to be going 150-160mph in anyway.
For track use, you aren't wrong about gear usage. TKX vs 8HP70 tractive force with a 500hp LS power curve through a 3.23 rear gear ends up looking like this where 8HP is red, and TKX is blue... TKX 2nd gear (1.89) falls neatly between 8HP 3rd (2.1) & 4th (1.67). TKX 3rd gear (1.28) is practically the same as 8HP 5th (1.285). TKX 4th is the same as 8HP 6th (1:1). Beyond that (at 147+ mph) you aren't really going to get to on track very frequently. I was getting to 134mph at Road America with the K24, so I'd imagine I'd touch overdrive gears with the LSx at twice the power, but TKX 5th (.81) is quite close to 8HP 7th (.839). I would expect to be using 3 gears (2-4) on the TKX and 4 gears (3-6) on the 8HP for track duties overall, with the 8HP obviously being heavier but faster and more consistent when shifts occur. Both seem like viable contenders, but picking what poison I want to drink will take some mental digging. Exhaust packaging is probably going to end up being more of a deciding factor for the transmission choice than anything. From the limited information that exists out there on the NA/NB platform with this combo, it looks like fitting 3" dual with 8HP would be challenging to say the least.
Selfishly, I want you to pull the trigger on the 8HP, just because watching that project come to fruition will be even more entertaining to read about lol. Also because one day when my good judgement falters, I might look into putting an 8HP45 in my car…
I have even fewer insights to offer that you haven’t already considered. However, to echo what Roda said, lowering driver workload wherever possible in a car that fast sounds like it should be paramount.
I remember when I got my current car, I thought, “I’m not gonna run auto rev-matching, that’s cheating.” And then I got a tune with auto rev-match and was like, “Oh f*ck, that’s really good” as my threshold braking consistency improved dramatically.
Excited to sit back and watch this continue to unfold haha.
To be fair, a huge amount of lap time can be gained by just leaving a car in a gear. I see a lot of drivers spending WAY too much time trying to up shifting and down shifting perfectly, they just end up wasting lap time. I was the fastest driver in Laz during our race weekend, I consistently had 2-3 less shifts per lap than the other guys. My friend probably could have jumped in, eliminated another shift or two, and ran a second faster than me.
I realize that's sorta the point you're getting at, eliminate driver mistakes with a clicky paddle, but with the V8 torque you're going to have, you could probably stick it in 5th or 6th at RA and meet or even beat your K24 times. I think it really boils down to the fab work you're willing to do, chopping up a tunnel to make room for trans and exhaust, or...not.
Personally, I'd go the 8HP route, not only because it's more versatile (in my opinion) but also because the MaxxEcu is just amazing. Extremely flexible, very easy to make do whatever you want. and their support is unmatched.
That's a 200 pound transmission... Yeah, engine torque isn't too concerned in a straight line, but if you're going to the track that's still an extra hundred pounds the tires need to haul around the corners.
an NA/NB Miata is not a car I want to be going 150-160mph in anyway.
Can confirm. The difference between 125mph and 150mph in my NA changed me from excited and confident to nervous and unsteady. The car felt too small, like there wasn't enough structure around me anymore. My mind questioned why I was doing this. I thought about tires going flat, wheel hubs failing, and I thought about my family.
Yet I kept my foot planted while I was catching that Corvette. Pretty stupid.
I honestly forget the safety equipment of this car. I think @Roda has a half cage? This one is just a bolt in bar? I'm a big proponent of anti-intrusion bars, difficult with only a half cage. Sucks for OP, a lot of the tracks in the mid-west are fast ones. At least the ones I can think of.
All build threads need to have a summary for us old folk, like:
pages --- engine
1-10 ------- BP
11-35 ----- K24
36-44 ------ LS
1
