Few more pics from this weekend. The NASA SoCal director emailed everyone involved this morning and said this past weekend's instructor program went spectacularly. They set a personal record, with 28 HPDE 1 entries, 47 Toyota GR/Intro entries and 34 total instructors attending this weekend. The attendance was high enough that they're going to hold another GR/First-timer group at the Buttonwillow event this month. I'll be instructing again for that event and was told I can get my instructor's license afterwards, assuming none of my students roll their cars. Super stoked. By then I hope to have the car dyno'd and classed so I can enter it in TT6 and actually race this puppy.

eBay Motors was having a 15% off promo on certain items until the end of September, so I took advantage and ordered myself an 84k-mile 2.5L Duratec engine out of a 2015 Ford Fusion on Monday. Total came out to $456 shipped to my work. Absolutely bogus pricing for a whole motor lol. It won't show up until next week and I still need to order hotter cams, a Fluidampr, and handful of small and one time use parts for it. Stoked to start on that project. At least I can get it torn down next week, do a leakdown test and get my eyes on the internals before proceeding to confirm it's ready for action.

I don't have any other major projects lined up for now. This weekend I'm planning on installing a set of poly diff bushings and sealing up the gaps around the radiator with foam (shoutout @SimBa and @Gee Emm for the discussion on expanding weatherseal foam in Sim's thread). The car ran super cool all weekend, didn't see coolant temps get up above 200*F even as it approached 95*F outside. Still, I figure it's best to optimize the setup with the time I have, and the small gaps in the factory ducting are low-hanging fruit.

 

thats so cheap for an engine - i still find it weird you can buy an engine sight unseen from ebay though!

 

Looks like you're having fun out there man and moving! That's always great to see! I'm definitely watching this build as I think the NC has gotten a really bad rap over the years which is completely undeserved. It's not nearly as heavy as some think it is compared to the NA/NB and has some serious upgrades over the older chassis (stamped steel control arms are no more). On that note how much does a 2.5l swap cost? For the money that seems like the swap to do over the K swap, especially if you can give it some boost in the future. I like these guys' channel and thought this was a good/related video:

 

175 HP on an easily swapped $500 engine? Doesn't sound half bad. Any idea what kind of horsepower is expected with the cams and tune? Are you going to run E85 in it (or already are)?

Interested to see what you come up with for radiator sealing. $30 at the HDR weatherstripping department goes pretty far. Or just get really wild like my roommate and grab some expanding foam in a can

 

That price for a motor is hilarious. That alone makes me want an NC, if I didn't have way too many cars already I'd be shopping. Very interested to see what the motor looks like when it comes in.

Dear god, no. Thats fucked. I mean it works, and im usually function over form, but heĺl no!

 

Ya anyone who's used expanding foam knows that **** makes a mess and is a giant pita to remove as it sticks/bonds to whatever it touches. I'd at least put a plastic bag or some kind of barrier and not just spray it directly on things.

 

Right? It's pretty hilarious. You can find these engines for up to $800 on the upper end for a real low mile one, but I figure I'm going to hammer it anyways and will probably just buy a spare one in the future to have on deck when I add a turbo to the car. The company I bought it from on eBay does vehicle part outs and the Fusion that it came out of looked like it got rear ended pretty hard. Hopefully I don't find anything amiss once the engine lands here. Have talked to multiple guys that bought their NC 2.5 engines the same way with success so I'm not too worried.

Thanks, Teg! Yeah, I'm stoked on the pace the car carried with stock power. Should just get better from here. I was super surprised after putting my car on the scales this weekend. ~2,425lbs with 3/4 of a tank of gas in it! Not bad at all. Should end up under 2,400 once I pull the A/C out.

So the 2.5 swap basically costs just the engine and some one time use parts, and a tune. The cheapest I've heard of someone doing it for was just over $1,200. That was with stock cams, most people will upgrade cams when they do the swap though. I think I'm going to be in it for a little over $2k all in. Will be upgrading the cams and adding a Fluidampr to mine, both of which cost more than the motor itself haha. The cool news is after doing this, any future motor replacement will be around $600 all in.

I'm actually hoping to make 175whp on it with cams and a tune, so another ~35whp over what the car's making right now (without a tune), but with a fatter torque curve too. Above that, the dollar to horsepower ratio gets kinda silly. Apparently, e85 is only good for about 10whp on these motors naturally aspirated as they can be tuned pretty close to MBT on pump gas. Fab9 just came out with an intake manifold that adds ~10whp without sacraficing low end torque. That's $999. Bigger throttle body is good for around 5whp, those go for $380-500 depending on which model you decide on. I'll save my money and run that ~175whp for a while before slapping a turbo on and aiming for ~240whp haha.

Haha, I used so many cans of that expanding foam to insulate the hard to reach places in my previous Econoline van. Worked great for that application!

 

IIRC that is what he did, either that or aluminum tape. He can still pull the radiator with it like this. I'm not sure on all the details, it's been a while since his car got any attention

 

Interesting, who knew that slapping a turbo on a car was the cheap(ish) way to big power gains. I almost forgot what site this was for a second

 

So how are the drivetrains of the NC? I thought I read the stock 2l motor is weak but the 2.5l can make good power w/o being built? What about the transmission? Can they hold 300whp reliably? Seems like a moderate upgrade in many respects over an NA/NB.

 

Ah ok my bad.. couldn't see it in the picture, thought he might have just sprayed it in there w/o protection.

 

Sounds like it's time to make him a lowball offer and get yourself a parts car

Long live MiataNaturallyAspirated.net!

The numbers are a bit higher than NA/NBs, depending on who you talk to. The 2006-2008 2.0L (Mine) did not get forged internals and are supposedly good to the low-200whp range. 2009-2015 2.0L's got a forged crank and rods, but not forged pistons. Those are supposedly good for more than the early 2.0L motors but there's no definitive consensus on the most power they can handle unopened. 2.5L's vary, but I'm following a couple guys on FB running up to 340whp on unopened 2.5L motors. The 2.5L seems to be ok into the high 200whp range in most cases, though. The general consensus is that max power is mostly limited by the stock ring gap being on the tight side. Some guys open up the 2.5L and regap the rings for boost then run the engine otherwise unmodified too. I think the rods in the 2.5L are good up into the low-mid 300whp range.

Excessive RPM is what seems to kill the 2.5L motors quickly. Running them above 7k seems to shorten the lifespan significantly. I was surprised to find out that during the swap, the crank damper from the 2.0L needs to be used, since the 2.5L trigger wheel has a different number of teeth. Fab9 claims the new Fluidampr they sell helps the 2.5s live a lot longer at high rpm since the 2.0L balancers that have always been used aren't tuned to dampen the vibrations of the larger 2.5.

Transmissions are similar to the NA/NB. 5 speed seems to generally be ok into the low-200s, although I've read a couple guys running them into the low-300s on boosted cars for street use without issue. The 2006-2008 6 speed is not much stronger but the 2009-2015 NC2 6 speed is. Apparently Mazda Motorsports makes a more robust gearset that can be dropped into either generation of 6 speed as well.

 

Quoted for truth, cat given. Plastic bag FTW.

This stuff is a last resort in my book, I haven't needed it - yet. The other options all seemed cleaner and neater.

 

Track day looked sick! always enjoy reading your updates man, pushing me to look for ncs nearby 😂

 

Man loving this thread. Makes me think about ditching the NA and moving to a NC as more of a street/hpde/autocross build. Maybe just add another miata to the stable.

 

Thanks, gents! Definitely haven't had enough time with the car for any sort of long-term review, but so far it's been a hoot!

 

You've got to be looking at the tippy top of the performance spectrum to find engines that come with forged pistons. The standard cast hypereutectic pistons most engines run are more dimensionally stable with temperature changes. Forged pistons that are properly sized at operating temperature give more piston slap on cold starts. Customers hate funny noises. Just think about the sheer number of people you see wondering about HLA noise and piston slap on older vehicles, and imagine that off the lot brand new. It'd be a customer service nightmare. '

Regarding the 2.5L swap, I'd definitely keep the redline lower than "it won't blow up immediately". Remember what these larger stroke 4 cylinders are designed for - moving a heavier sedan with more authority in the midrange. I really believe a lot of the problems people have with K24s come with treating them like they are a standard K20 that was meant to rev to most of 9k. My theory is GLTC folks seem to chew through them because they take a junkyard engine that's now almost two decades old, delete the balance shafts, and rev them to the limit of the head rather than the rotating assembly. Understand where peak power is, and don't rev it too terribly far beyond that.

 

Yeah, good point. I should know that of all people, working in a service position at a dealership. We get lots of new car owners coming in for clicking noises from high pressure fuel pumps, evap purge valves, etc or faint turbo sounds that the manufacturer already did everything possible to keep quiet. Some of these noises I can't even hear myself without popping the hood and putting my ear right up to the valve cover so yeah, makes sense the manufacturers wouldn't want to subject themselves to more of that haha.

In regards to the 2.5L swap, yeah I'm gonna run a lower redline than most guys. Probably gonna cap it at 6,900rpm. Most dudes seem to be running them at 7,200-7,500rpm. I'm sure the extra 300rpm would be nice but I'd rather be safe and lose a tiny bit of top end instead. The car's still gonna get a turbo eventually anyway and then max rpm will be even less relevant. I'm actually supposed to sell the original wheels and tires of my NC tonight and a bunch more stuff off the NA tomorrow so I should have camshaft and Fluidampr money next week. Gotta go back and look at some dyno charts to figure out what cams to grab. The powerband on the 2.5L is already so low in the rev range with the stock cams that I don't think a set of mild cams is going to move peak power above the 7k range. I'm already going to go with a milder set anyways because I don't want the setup to require upgraded springs as well. Trying to keep things simpler on this go around (for now lol).

 

Weekend update! Plenty of fun and interesting bits to review from yesterday and today.



I took the car into work yesterday morning to swap out the diff bushings and start pulling the A/C components out. Did a bunch of reading on the bushing swap this week and decided to try doing it the lazy guy way. I disconnected the rear coilovers and dropped the rear subframe down an inch or two (backed the nuts out to their last 4 or so threads) and used that tiny bit of clearance to access the 4 nuts holding the bracket onto the carrier. It worked! But I was in for a bit of a surprise. The PO swapped the diff in this thing with an OEM LSD out of a 2011... and already upgraded the diff bushings to poly. What an idiot, I took a quick look at them during the week and thought they looked like OEM rubber ones. Luckily, one of the bushings was pretty warped and the steel insert just fell right out of it when I removed the bracket. The other bushing wasn't much better. I replaced them both with the new ones and the shifter is now a tiny bit more planted... i think.



After swapping the diff bushings, I went to work on starting to remove the A/C components. I hooked up the A/C recovery machine and the second it started recovering refrigerant the condenser sprung a leak. I'm going to take that as a positive sign from the racing gods haha. Took the condenser and all the lines out but I was still waiting on the idler pulley to delete the compressor, so that stayed in. With the condenser out, it looks like it had been slowly leaking onto the radiator as well.

I started adding foam to the radiator cavity during the week, and was going to continue once the condenser was out, but forgot the rest of said foam at home. I think I'm going to add some foam to the right side and then wrap it all in foil tape to make sure absolutely no air is passing through the foam itself.



Then, after finishing work on the car, something else awesome happened. The gentleman who bought my ZF transmission in August came back over and grabbed all the rest of my ZF trans and Getrag diff drivetrain swap components. I made sure the sale was ethical. The guy who bought everything owns an auto repair shop and was confident he could make everything work. I gave him the rundown on all the vibrational issues I originally had with the kit as well as the realization that the flange adapters and driveshaft flanges were not perfectly self-centering. The guy's running 356whp through his MSM and has spun more wrenches than I have so he seemed like a perfect candidate.

He's also an NC guy and has done a handful of 2.5L NC swaps. As a part of the deal, he included this NC2 6 speed transmission. Don't know if I'll have time to install it before the next track day, but it's one more piece of the puzzle procured! Ignore the current state of the NA...



After that escapade, I took the NC up to the mountains for a little rip (see first pic). The car ran great the whole way and I was pretty amped on its performance. Drove for around two hours and then turned around to go home. Now, the battery light has been coming on at high rpm for most of the time I've owned the car, along with a voltage drop to ~12.9-13v for 5 or so second, before recovering to 13.5-13.7v again. I chalked this up to being some weird side effect caused by the AntiGrav battery and its independent BMS. This was not the case, the alternator was on its way out. On the freeway, about 40 minutes away from home, the alternator gives and voltage drops to 12.8v. Sh*t! I should've seen that coming.

Well, I didn't see any point in calling it quits early and making the tow truck drive longer, so I killed my headlights and kept on trucking. Surprisingly, I actually made it another decent bit before the car died. I had pulled off the freeway and was on the surface streets about 10 minutes from home when the battery decided it was game over. The low voltage protection came on and everything died. I honestly wasn't even mad at this point. I gave my roommate a ring and luckily he was around. He came over with a pair of jumper cables and we got the car running again. Only needed to jump it twice to get it all the way home. Could've gone worse, right?



Didn't think I'd be working on the car more today but so be it! Grabbed and popped in a new alternator this afternoon. Problem solved, the charging system works, although I still have yet to see what charging voltage does at 5k rpm. I'll keep an eye on that this week.

The A/C delete idler pulley and the accompanying belt (whose length I guesstimated again) showed up today too. I already had the tools out, so I figured I'd toss those on too. As when I pulled the power steering off, I figured I'd buy a belt that I thought would be close to the right length, then swap it out once I figured if it was too big. Well, I'm two for two on my educated guesses. The belt I ordered snapped right on and was the right length. Score! I was able to drive the car out to a parking spot.



There's not really any good angle to show off the A/C delete parts. You can see for the mounting points for the A/C compressor and then that idler in the bottom right just bolts in where one of the front cover bolts goes.

Not sure what next week holds. I'm sure I'll find something to stay busy!

 

I'd say that's very wise. Rod/stroke ratio is a factor for sure with the larger stroke 4 bangers and it definitely adds more wear and tear when you rev them higher. I'm not familiar at all w/ the 2.5l but I'd guess it's gotta long stroke and thus limiting the revs is probably wise (esp if you got boost later). On top of that I'd guess the cam profiles fall off hard on the top end and/or it's running out of air regardless. Regarding the K24.. ya it's wild that people remove the balance shafts and rev them out like crazy. I'm not sure what the GLTC cars push them to but to my understanding even spinning them to 8k (with the oem balance shafts) is really pushing it.