Ford-A-Palooza over the last couple days. Getting pretty efficient at tearing these motors down lol. The "seized" motor was about as useable as expected, but I think we have a good candidate for a future forged build with the second motor uhhh... when the day comes.



The first engine definitely could've been rebuilt, but I figured it wasn't worth it given I had the second motor at my disposal and wanted some spare parts. I pulled the head off to find that the engine had either slipped timing or the thing was overrevved. Piston to valve contact on all four cylinders and all of the exhaust valves were bent. Perfect. I grabbed all of the cam buckets, valve retainers, timing components, and some hardware and gave the core to our metal recycling guys for $15. Carnage pics and then a look into engine #2.



The OEM pistons don't have exhaust valve reliefs, but these ones do now!



Doink.

Engine two, however... we might have something here.

Pulling the VC off showed the engine is as clean inside as the one I just put together. No varnish to be seen. A bit of a coolant leak from the EGR which doubles as a secondary coolant outlet at the back of the head but that's it. I should've leakdown tested it first, but I confirmed the engine had some sort of compression cranking it by hand with the spark plugs installed. With the spark plugs removed, it spun smooth and free. Valvetrain looks clean and has no excessive wear to speak of. I pulled the head and the HG doesn't appear to have been breached anywhere.







Now for the culprit. I think it's pretty irrefutable that the cause of the oil consumption is due to the wear present on all four cylinder walls. Crosshatching is mostly gone and all cylinders have these cloudy patches along the walls. I'll have to look into it, but I'm interested what that could be from. Moisture in the cylinders, fuel washing, or something else? I'm sure a quick Google search will tell but I'm done with the computer for the day after making this post lol.




Now, one thing worth considering with the 2.5 Duratecs is that they can only be bored out 1mm over. And if you're gonna boost the motor, you really shouldn't overbore them more than 0.5mm. Either way, the wall wear doesn't look too deep and I'm not in a rush to build a screamer motor yet. At some point I'll take the bottom end to a machine shop and have them let me know if a simple hone can bring it back to life. I think I'm still ahead for only being $35 in the hole at this point.

 

The good motor definitely looks like a hone it and send it type deal to me. My bp looked about like that with corresponding piston skirt wear and the machine shop (who builds spec miata motors) said it checked out. Cylinders looked brand new after the hone but pistons definitely had wear on the skirts. Motor has been a champ eating 200+ kpa ever since!

Id expect that could definitely be rebuilt with fresh pistons, but the measurements will tell all.

 

Yo, gracias for the input Nate! I forgot to ask at the end of the post, but was hoping to get a little insight from the regulars regarding the cylinder wall situation. If it can be honed and sent, I'd be stoked! Time will tell, as I'm going to abstain from buying more parts and building this thing anytime soon.

But don't worry, I'm still f*cking with other things on the car.

MAP sensors... So the NC's MAP sensor isn't the primary sensor for engine load, that's done by the MAF. The MAP sensor is used to adjust injector pulse width based on the pressure differential inside the manifold. Basically since the NC has a dead head fuel system with no fuel pressure sensor, the MAP does the work that a fuel pressure sensor would. But, the stock MAP sensor on the NC only reads up to 1.1 bar. If you decide to boost your motor, you can either tune around this, or use a 2+ BAR MAP sensor and continue using the MAP in your fueling strategy.

Alright, the facade's up. You guys can already see where I'm going with all this.

Anyways. Here's a GM 3-Bar MAP sensor that was used on their forced induction vehicles in the 1980s and 90's. They're a pretty popular MAP sensor replacement for vehicles that are going to get boost, the NC being one of them.



Setup is easy. Splice in the new connector, power ground and signal. Then add a vacuum line to the sensor and mount it. My vacuum port for the evap system was unused so I pulled vacuum from there. I mounted the sensor to an unused bolt hole location. Unsightly, but it'll work for now until I can make a little bracket and mount it somewhere else on the intake manifold. I just left the factory MAP sensor in place as a plug. I got the new sensor wired and plumbed, then it was just a matter of changing the MAP scaling in ECUtek to get it to read right.



Being that the GM 3 BAR sensor is used across a pretty wide range of tuners and builds, calibration info is pretty easy to find for it on the internet. Pressure range is 1.1KPA at 0V and 315.5KPA at 5V. 315.5 minus 1.1KPA gives you 314.4 total range. 314.4 divided by 5 gives you a MAP slope of .6288 BAR per volt. I was going to put that in but read in a couple places that the cars using this sensor had a 5.1V reference voltage, so if your car uses a 5V reference, you need to compensate for that. I took .6288, multiplied by 5, then divided by 5.1 and got .6164 BAR per volt. Plugged that in and the MAP sensor read the same at key on engine off as my previous sensor. 14.35PSI where I live. The sensor should read 1.61V at 100kpa, and my ECU's reading 1.57V with the engine off. I haven't adjusted it yet and fuel trims are exactly where they were before, so I think it's safe to say the sensor's calibrated correctly.

Another canyon rip early this morning.



Engine's got 500 miles on it and two hard mornings in the canyons now. Oil pressure still looks good, no weird noises, and I can say for certain it's definitely a hair quicker than the last engine was. Every shift now is right into the powerband instead of slightly before it. Very happy with how it turned out, even if I didn't know this would be the outcome with the current cam/spring combo.

Also worth noting, I'm running a catch can now on my exhaust side breather and this is all it's caught since putting the new motor in. So despite the increased ring gap, she doesn't seem to have notably more blowby. Glad to see that.



Also signed up for Global Time Attack finals at Buttonwillow in November. That race will happen after our last NASA event of the season, so I won't be limited by the TT5 ruleset. I think the car will be able to run a faster time than I was able to do in the NA two years ago, but will continue scheming on what else I can do to the car to grab another few tenths before then. Super exciting!

 

I kind of wish FM had gone with that GM sensor on their NC turbo kit. Would have saved a significant amount of labor and it would have been easily accessible for any future issues.

 

Dang, it's been a minute! Guess that's a good thing. Been spending a lot of weekends up in the mountains this season. Car's just been working and I haven't dropped any massive hours or coin on it in a bit. But don't worry, I'm still tinkering.

The recent project I've been keeping myself occupied with is the cooling system. Namely rerouting the heater and degas hoses, and relocating the degas bottle.


I could've photographed this process better but I was working on the project in short spurts over the last week. Bear with me.

But Zak, why would you want to reroute all of the coolant lines aside from the radiator hoses? Because I'm smarter than the Mazda engineers, that's why (that's not why).

Ok, and if I were to *cough* hypothetically turbocharge this car at some point, a couple of the coolant hoses and hardlines need to be relocated anyways. Might as well relocate those and simplify all of the hose routing while I'm at it. I've got a lot of real estate to play with in the engine bay with everything I've either relocated or removed from this car. And while I'm at it, I might as well relocate the coolant tank from above/behind the radiator too.



Quick overview of the stock heater hose routing: The stock heater hoses are both cleverly routed, but are both long and a PITA to get to. One branches off of the thermostat housing on the driver side of the block, wraps under the intake manifold, then curves up over the side of it, before connecting to a hardline that's bolted to the firewall. This hose also includes a hardline with tees for a coolant loop that runs from the EGR valve at the back of the head, around the side of the intake manifold, through the throttle body, and back to a port in the lower radiator hose hardline. I deleted this loop when I initially did the 2.5 swap so didn't need to worry about that.

Heater hose number 2 tees off of a hardline at the back of the head, below the cowl panel, and under an access panel that needs to be removed, then wraps around the head above the exhaust manifold toward the front of the engine bay. It then makes a u-turn and goes through the firewall to the heater core. There's a 5/16" degas line that follows this same path over the exhaust manifold then goes to the radiator. Both of these incorporate hardlines over the exhaust manifold that interfere with turbo fitment... or they would if I were going to put a turbo on the car or something...

For the heater hose coming off the thermostat, I ran some 3/4" silicone heater hose around the front of the engine bay. The front crossmember that serves as a mounting point for the battery, ECU, and airbox from the factory, is now basically unpopulated and made for easy routing. I relocated the battery forward a few inches to make room for the hose to wrap around the front of the ABS module away from the exhaust. Also pictured is the rear heater hose hardline that wraps around the head and over the exhaust.



And here's the heater hose tee at the back of the head. I forgot to bring a pair of long bent-nose pliers home and had a hell of a time getting this one out. Also, note the EGR valve in the background. Not the coolant cap that I JB-welded over for extra safety, but the electrical connector on the valve. I didn't bother plugging it in when I swapped the motor (EGR is all zeroed out in my tune), but it looks like that was actually a good move. No space back there to plug the thing in if I wanted to



So I routed the front heater hose around the front of the engine bay, deleted the rear heater hose and 5/16" coolant hardlines and replaced them with silicone hoses, then I kept the ball rolling and decided to delete the factory coolant bottle and mount my own on the passenger side of the firewall since there's all kinds of free real estate back there. As an added bonus, the selected location allowed me to mount the bottle even higher than the factory location.


Degas bottle doin' degas bottle things. Still gotta relocate my breather/catch can. I've got some ideas for that.

I ordered a generic DNA Motoring aluminum degas tank for $45 along with a couple fittings. The tank I'm using utilizes a standard size GM radiator cap. They come in PSI multiples of two. I figured I'd "step my game up" just a tiny bit and run the system at 18psi instead of the factory 16psi rating. I got two 18psi caps from AutoZone for $15. All in, maybe $80 for the degas tank swap, but the popular Moroso tank I was previously running now retails for $330, so I'll probably make enough back from selling mine to subsidize this whole project lol.

Here's a photo of the mostly finished product. Heater hoses relocated away from the exhaust manifold, degas bottle relocated and no longer taking up space behind the radiator, steam lines from the radiator and back of the head routed neatly (by my standards) as far away from the action as possible. I had a small bit of aluminized heat shielding laying around so I wrapped the heater hoses where they pass closest to the exhaust. I need to order some more so I can just wrap them completely. This pic also really shows how far back the engine sits in this thing. There's a lot of car in front of that crank pulley lol.



So how does it work? Good enough! I bled the system easily last night and put nearly 200 miles on it today with no issue! I'll spare you guys the seven hundredth photo of this car in the mountains.

I... I honestly have no idea what I'm going to do to the car next. The next NASA race at WSIR is on 9/27 so I have until then to complicate things for myself. I think I'm gonna get a pair of SuperMiata Chubs for the front of the car since these current hubs have 20+ track days on them now and I don't want to lose a wheel at 120mph. I also didn't read the Maxxis contingency FAQ closely enough and found out the hard way that there's a cap to how many tires you can get from the program per year. So I'll be switching to Toyo R's for the final two events, as Toyo has a slightly less indulgent contingency program, but theirs has no cap on rewards. According to Grassroots Motorsports, the Toyo R's were a single tenth slower on a minute and a half course than the Maxxis RC1's I'm currently running, so they should work totally fine for me. We'll see if I get along with them.


5:40AM this morning about to text my buddies I'll be at the bottom of the mountain on time as long as all of the coolant stays in the car.

 

Looks good man! IMO the next mod to do is to get Progressive's insurance (not a sponsor) with $0 glass replacement and get a new windshield

Damn, never realized how far back that engine was, almost looks like a front-mid engine now that you point it out.

 

Damn you’re right, new windshield should definitely be the next move. I cleaned the windshield when I stopped for gas yesterday morning and the squeegee now makes an audible clicking/tapping noise as it slides across the glass from how deep the pitting is

 

Why not go for the Fab9 intake manifold? That should be worth +10 whp and give you something to tinker with in the tune lol

 

I've given the manifold a lot of thought, but the cost to benefit ratio is honestly just too slim for me to take the plunge. $999 for the manifold plus $160 for the necessary throttle body, $200+ for a 3" intake, and some change for a harness and you're out the door at $1,400 for 10whp. Honestly the main selling point for me on that manifold is just how much less space it takes up in the engine bay and all of the extra access you get to components on that side of the engine if something goes wrong at the track haha.

Wait, I can't remember, did you grab one of those manifolds for your car? Lol

 

No, I don't have one of them. I really want to get one if I end up picking up my former 2.5 NC from my friend that is trying to sell it back to me. I am in the midst of selling other cars and lots of parts to pay off other debt, so I will see if I can afford to pick it up in the near future.

 

I've been waiting for an update, nice to see you are still prepping for a possible turbo future. That intake manifold seems pricey, but I see parts like that as a 'lifetime" item, I.E. as long as you plan on keeping with the ford motor platform for the life of this car you might be able to come up with an argument for it. And that 8-10 HP might become 20+ in a turbo application!

 

Chili, my bad. Been seeing your name in so many of the NC threads recently that I thought you'd joined the yacht club at this point lol.

Aghhh, why must you make such compelling arguments for me to spend more money? Hahaha, really that is a pretty good point. It's not like the manifold is going to wear out and require replacement... Maybe I will consider it further. Building an intake and splicing in a new DBW connector would definitely keep me busy for a bit as well.

 

Oh trust me, it's a rabbit hole, and stuff like that is how I always convince myself to spend the coin.

I.E. I went for a fluidampr on my BP over the boundry billet gears, since they both address the same issue but the fluidampr won't wear out and can be transferred to future motors when the time comes. Or for my FD, going with the fancy IGN1-a ignition kit I was able to tell myself it will help keep the motor alive (rotaries hate misfires and it could destroy a $8k keg).

But yeah when you are dealing with $400 motors it's probably hard to spend money on anything! Spoiled!

 

Your last big post there really reminds me of the Miataturbo.net days of old, only with 100% more nautical content. Major props to you sir. It's stuff like this you just don't get on Facebook.

Another vote for the fab9 intake. I know this matters very little for your use case, but it also sounds incredible...

 

Dammit, dammit, dammit, dammit, dammit.



Alright, I guess we're doin' it. Thanks for the peer pressure, guys

Had a kinda crazy turn of events turn into this order yesterday. I've been on and off considering buying the manifold for a bit, but it's designed to work with a 68mm generic Bosch DBW throttle body. Yesterday it hit me that some tune parameters might need to be tweaked so that the ECU is happy with the values it's getting from the Bosch unit's TP sensors. I deal with this at work somewhat frequently, and modern cars are very sensitive to triggering limp mode if they don't see exactly what they want to see from the TP and accelerator pedal position sensors.

So I popped a question into one of the 2.5 swap FB groups as well as M.net, asking if the Bosch TP sensor values are plug and play, and if I could make the necessary tweaks on my version of ECUtek if not. Thirty minutes later, I get a call from Bryan Spears at Fab9, who definitely smelled the blood in the water He says that the Bosch TB is straight plug and play as far as the TP sensor values go, and all I'll have to do is adjust my DBW tables to my liking, given the throttle opening is larger than the stock one. He also tells me that there's a few optimizations they make to throttle control for the upsized TB that aren't available in my version of ECUtek, but that if I send over my current self-tuned file that he can apply them, and that additionally he'll apply their optimal VVT and ignition timing tweaks for the manifold while he's in there, while leaving my tune unlocked. That's the abridged version of the conversation. He offered a couple different ways to skin the cat, but that's what we landed on.

"For sure, Bryan. That would be incredible, thanks for going out of your way and trusting that I just want to tune my car and not steal your guys' secrets to use commercially. What am I looking at for tuning charges if we do this?"
"Oh dude, I'd just throw that in for free. You've paid us for tuning before, no big deal."

F*ck it, great sales call man. Sign me up for a manifold haha. Bryan had one of the sales guys send me over an invoice for a manifold and I shot the payment over last night. I ended up getting the wrinkle black version, which is $45 more, but they gave me a small discount on it and Bryan threw in the throttle body adapter harness for no additional charge, so I'm absolutely not going to complain. I originally wanted to spray the manifold the same red that I used on the rest of the engine, but wrinkle black will be just fine lol.


Damn, it does sound really good too...

 

Very nice! It does sound good in that run. As sad as it makes me that you didn't go with ITBs I'm also ok with more NA power and content

 

Exciting stuff man, that IM honestly looks like a great piece. Maybe I've been shopping FD parts for too long but the price isn't terrible for a bespoke 2 piece manifold, and with the tuning tweaks thrown in for free you are winning. Like I said, as long as you are sticking with that engine platform for the foreseeable future, you can't go wrong. Think about it this way, us BP guys throw $750+ (flattop or skunk2 IM + skunk2 TB) for less gains just so that hopefully our **** doesn't come apart and eat TB screws and hopefully our power curve won't fall off near red. And we bolt them to motors that are increasingly >$1500 for decent ones. You are still winning.

I mentioned this before, but since my NA is a lifer, I look at parts like that as lifetime parts that I'll always have for the car. Things like engine internals, transmissions, clutches, even oil coolers, are all consumable and I'm prepared to part with them when the time comes and it's harder to drop major coin on them knowing that. Things like chassis bracing, brake upgrades, ecu upgrades, safety stuff, aero, and bolt-on engine parts like the flattop+skunk2 and my Fluidampr, or fuel injectors, etc. I'm happy to drop more coin on since they won't "expire". These are parts I'll have for the car, forever, unless I motor swap or something. Then there's a middle ground of parts like turbo stuff, suspension, etc. that will last a long time, but might need replacing or rebuilding down the line, depending on how hard and how often the car is used. And logic like this is how you end up with a $25k+ 1990 miata that still has **** paint.

And all that extra flow means you'll be able to make more WHP at less PSI, with less heat/stress, which will be critical for your FI setup on track. Psyched to see what gains you get with this!

 

I LOL'd at that... only because I'm pretty sure I have way more than that in my NA!

I do think it's a good strategy in the long term though. And even if you eventually sell the car, it tells the buyer you were all-in on doing it right. I always scratch my head when I see an LS swapped Miata on V-Maxx suspension, or something similarly silly.

 

Nate, I'm not gonna lie. Your first comment above regarding the IM being a non-consumable upgrade struck a chord with me. It's a great justification for sure. I've spent a good bit on the auxiliary parts for this car (exhaust manifold and midpipe, this IM, tuning software, etc.) but with how affordable these motors are themselves, I don't see myself changing engine platforms probably ever for the length of time I have this car. +10whp now (with either of my N/A motors) and more with FI later seems like a solid investment. If I go FI, I don't have any hard goals, but being able to hit the high-200whp range with under 10PSI would be rad, and less heat and restriction would be a major bonus like you said.

And I agree with you there too Roda. I'm not quite ready to part this car out yet but the IM is still a hot commodity and adds value for sure, lol.

Ricardo, $1k is where I have to draw the line. If there were an ITB kit for this car under $3k all-in, I'd have given it some more thought. Hopefully this is a satisfactory middle ground to keep you engaged in the thread!

 

I get that, and I'm always watching and reading the thread! Plus the way you smash through projects is incredible and motivating