Update time! Quite a bit to go over.

I see why tuning is a professional's job, it is tough! I'm still working on the dying issue. Its pretty tough to get locked in with the light flywheel. Changing to Initial Values for the IACV instead of Last Value helped a ton and I think next is tuning Idle VE and Idle Advance.
I still need to get my Raspberry Pi wired in so I don't need to drive everywhere with my laptop in the passenger seat lol. Also need to figure out how to setup oil temp sensor and flex fuel sensor still. Still no blowby issues at 7psi so soon as I get some free time I'll turn boost control back on and see what happens at 14psi.

Finally got around to the fans! I was procrastinating since I didn't know what to do about the relays. I fabricated new fan mounts and installed them for the two new Spal fans, one 13" and one 5.5" (show me someone else that has a motorcycle rad fan on a miata ). I wired them into the stock relays since Flyin Miata said they use the stock relays for their spal fans that are 12". So far no real issues I've noticed other than when they kick on theres a RPM/voltage drop but it recovers quickly. They definitely cool the car off promptly. That said, I'm running a 195F thermostat and the fans come on at 208 so not much room there and they come on a lot. I'm going to install a 180F thermostat probably this weekend.

Look at those PERFECT welds . That used to be flat rusty sheet of 16ga steel.






ow that the car is driving, I want to go do mountain runs but I have to hop on the highway for 30-40mins. As I'm sure you're all aware, a 4.1 in these cars mean high revs on the highway. I'm having a really hard time finding a 3.63 ring and pinion. I was going to try to find a full diff from overseas but then my mazdaspeed axles won't fit. So I'm leaning towards the Mfactory 3.3 instead now. Should be about 3246rpm in 6th at 80mph, which sounds awesome. It should also allow only a 1-2 shift for a 0-60. 3.6 would've brought it down to 3565 but I've heard thats kind of the drone area of the BP motors and given how hard they are to find its kind of a moot point.

With a 3.308 this would be my speeds in each gear with 205/50/15 tires:

First Gear: 39.8 mph
Second Gear: 64.4 mph
Third Gear: 89.4 mph
Fourth Gear: 110.9 mph
Fifth Gear: 143.3 mph
Sixth Gear: 176.9 mph

At 130+ I think a wing is pretty much required to not feel like you're about to lift off lol.

I saw the superpro bushing kit was on sale so I picked that up but I likely won't get to those until next spring or over winter. I also grabbed the IL motorsport diff housing bushings for when I do the diff work. I need to get a list of all the parts needed for a diff rebuild. More intimidated by this than the engine build lol.

And last but not least, the LRB radiator cooling panels. Not sure these do a whole lot, but they look nice and they can't hurt anything! And it might be placebo but I felt while driving the temps did stay a little lower so maybe they help.



Yes thats a gatorade bottle. On the agenda is welding up a custom overflow tank that will hold pressure and also modifying the power steering fluid reservoir so I can put the air filter right there or tuck it down behind the rad fan since theres so much room for activities now!

See y'all next update, have a happy 4th of July!

 

Looks like a nice setup. The tuning can take a bit, but if you're fighting something specific, I would look at the hardware or setup. The idle can be tough, I'm running a larger single spal fan, have AC and power steering so idle droop was a challenge. I would start with a slightly higher idle target maybe 1100rpm and then work down to 950-1k. I'm using a pwm fan controller from a c6 vette/fusion/milan and have it start coming on at 192F. IMO 208 is too high. There is no issue running a 180 stat with a normal operating temp of 180-190. This will give you more headroom if you run in hot weather or on track.

 

Hey Leo! The flywheel is from FM's happy meal level 2 kit, which I think is about 10lbs. And my idle target is 900rpm. Doesn't leave much room to catch before it dies and the lesser inertial mass is tough for a street car. I've tried a 1k idle but the NVH is a little too much for my liking so I'll deal with a fickle beast lol. Its really only a problem when the fans or headlights are on and I'm coming to a stop with a little steering or something. Otherwise its good 90% of the time. When you say targeting higher idle, what do you mean? The only curve I know of is the warmup idle target so once you're at a certain coolant temp you can't have a different idle target dependent on load. I hope I'm wrong. I do use the idle up for the fan already, upping 65rpm with a .1ms delay.

At 208 fan engagement, it only hits 213 before coming down and stock headgaskets don't blow until 240 area if I recall correctly. Shoot, stock miata fans come on around 215-220 for the AC fans. Can't remember exactly but I did see it in a thread about this. I also believe Supermiata mentioned 200 is the best temp for power in the BP motors. Regardless, I agree with you and I do want my operating temp to come down to the 185 region so I will go with the lower thermo.

 

Gatorade bottle catch cans are king.

Glad to hear the car's running well after everything, dude!

You'll be so amped on the Pi once you get it in. Been street tuning with mine the last couple weekends and it's so much more comfortable than playing with a laptop in the passenger seat.

 

By target I meant set to 950-1k . I run AWR motor mounts and 900rpm is rough, not an option and 1krpm is much smoother.

Sure 200F might make more power, maybe 1-2hp, but you will sacrifice the ability to run in hot weather. Ideally you want it to stay below 210f.

My old setup would run up to 230+ on the track and then it would stay above 200. My theory is that it would bleed off some volume of coolant and then the average system pressure would be lower. In theory it should pull some back in and recover, but that was not the case. The lower pressure reduces the boiling point and the system’s efficiency. Also these are average temps and not the highest temp. The coolant around the exhaust valve might be 10+ hotter and temps deep into 200’s could allow boiling at these points. High coolant temps on engines with different block and head materials wear out head gaskets at a higher rate and higher coolant temps increase this rate. My daily is a C8 Corvette and it rarely gets over 175f on the street. I have to drive it hard to get the water to 185 and the oil to 180. GM did this for more head room on the track.

 

I use 1100 RPMs as an idle target because the A/C performs better at idle and the droop is lessened. I also added additional grounds and positive wires from the battery to the alternator and from there to the fuse block. That aided with the amount of burden immediately placed upon the alternator when my giant Spal fires up. It allows the battery to better "help catch" some of the immediate load.

I also added a 3 second delay relay between when the compressor engages and the giant Spal joins in, which is really nice.

All together it makes things pretty good.

 

Thanks man!! Mind sharing a picture of your mounting set up? I took the radio out a long time ago and was going to 3d print a "case" for it. Just need to figure out what power wire to tap into.

 

Interesting, I'm on the softest AWR mounts as well and 900 feels really nice. Seems like the consensus is a higher idle for less stalling so I'll bump it to 950 for a bit and just see how she does.

Tons of valid points there. Wow 185 when pushing it is really surprising, nice job Chevy!! I did throw the 180 in there over a few hours this last weekend and it did make a very substantial difference. It only saw 205 after pushing hard and coming to a red light hard. And it might be anecdotal but it felt like the temps came down much faster too but idk how to explain that lol.

 

Very interesting, I'm guessing you're on a light flywheel as well? What gauge wire did you use for those additional ones? Idk if I can fit anymore wiring at the passenger fuse block since the MaxSpark coils were already a pain to fit lol. But that honestly sounds like a fantastic solution so I may see what I can do. No AC so I don't have to worry about that extreme of a voltage drop but it certainly could help.

 

Can't believe its been 6 months since I posted here! I've been enjoying summer and driving the car, however that might be coming to a hiatus (and not due to our currently warm winter here). Even got to go on a sick Miata club cruise with 50+ cars up a mountain pass.

Here's a little vid I made of a drive, taking the car through a canyon in a mildly spirited fashion:

Lately though, the car isn't doing good. It really hasn't ever been GOOD, but I assumed it was me learning how to tune and dealing with that. But now that I have learned and practiced a lot more tuning I started looking at hardware. I'm smoking at idle, alllllll the time. Like can't go in a drive through or I'll cause a health department crises.
I took the car out today, got it up to temp and did some pulls. I feel like for 15psi, it should be faster than what it is? Or maybe I'm getting used to it, I don't know but I'm paranoid. Got the car home, popped the hood while it idled and I could feel the air coming out of the catch can. It's probably always done this but I've never really checked this before.

Engine hot, dry compression test looks horrid.
Cyl1 - 87psi
Cyl2 - 80psi
Cyl3 - 95psi
Cyl4 - 80psi

Leakdown results seem pretty ok. And the marks on the cylinder walls don't seem to be getting any worse.
Cyl1 - 14%
Cyl2 - 10%
Cyl3 - 8%
Cyl4 - 9%

Also, the tops of the pistons have far less carbon on them than they did in the first build. I noticed a little bit of oil right where the spark plugs sit. Not in the threads, kind of in the well. Not a puddle or anything, but some droplets. I think the smoking is probably coming from oil getting past the turbo seal but from my understanding, the excessive blow by could be causing that, since its happening at idle only. So I'm thinking this is probably something with the valves or valve stem seals. I had a shop do the head work so I'll most likely have to pull it and take it back to them to see what's going on. Better than a full rebuild again...I guess?

Can't catch a break with this thing lol. A v8 swap sure is sounding nice right about now. Just need to sell a kidney

Took a few pics of the spark plugs and cylinder walls but I don't feel the need to post them unless someone really wants to see them.

Taking a break on the car while I ponder what to do and do some research as well. Shouldn't be another 6 months before I update again though haha.

 

EFRs are very sensitive to crankcase pressure. I had the same issue on my last build - still in the process of finishing the rebuild, but I'm switching to a -12 drain, running a pressure sensor in the pan to monitor it, and making a custom catch can. I have half a mind to switch to -12 bungs on the valve cover too. You should chase low hanging fruit before you decide to pull the engine again - make sure the CHRA outlet is perfectly vertical, check fitting IDs in your drain line (looks like you have NPT-AN at the pan, a lot of those fittings have a pretty nasty step down in diameter at the NPT side), get your drain line as smooth and short as possible, go overboard on crankcase venting, and consider monitoring crankcase pressure. Sometimes death by 1000 papercuts is an effective way to fix issues like this, and even if they're not, you've still improved things.

When you do a leakdown test, pay attention to where you can hear/feel the flow - it's often audible through the throttle body, exhaust, or oil fill port. This will clue you into where the leak actually is.

Don't pay too much mind to the compression test nominal value, just look at % difference and trends over the life of the engine.. Compression testers are notoriously inaccurate, and when you combine that with variations in engine setups and ambient conditions, it makes the nominal reading basically worthless. But they're fairly consistent reading to reading.

anyways, cool build, I think I've seen you post on CMC, hoping I get my car finished up some time this summer and can join on a few cruises.

 

Hello again MT.net people! It was too close to the 6 month update deadline but I made it in time lol.

After my post over winter, I decided to redo the tests, poke the camera down into the cylinders to take a look and document what I did quite a bit better. This was how I tested the compression and leakdown tests...

Started with exhaust valves fully open, rotated piston to bottom to close exhaust valves, then back to TDC with all valves closed. Warm test was a short drive and radiator fans came on a couple times. 3 second crank at 400rpm. Current engine health is warm idle is -15 to -16 inhg and decel pulls -20inhg. so slightly less vacuum than I would like but not awful.

1:125cold/140warm/3% leakdown, sounded like air came out rings
2:130c/145w/3% rings
3:130c/145w/3% can hear in valvecover and rings
4: 130c/150w/2% rings

I also picked up a spare block on the cheap for a backup. I have not driven it since mid January because life and its been on jack stands getting some work done!

I bought the SuperPro poly suspension bushings when they were on sale a while back and as of today, all bushings are installed. I chose to do the all thread method and that worked quite well. Progress was quite slow since I had to fix the caliper paint that I half-assed before. Additionally, I replaced the upper A arms in the front, tie end rod and lower ball joints. The rear caliper driver side had a brake fluid leak so that caliper needed lots of TLC. Turns out I forgot to put a copper washer on one side of the brake line, whoopsies! I did not due any zerks fittings so time will tell if I come to regret that.

Next up was the differential bushings. I initially bought these since I was going to do the ring and pinion down to a 3.3 or so but decided the cost isn't worth it at this time. But I went ahead and tried to install the IL Motorsport diff bushings.
That went super poorly. I spent probably 10 hours fiddling with those things. The old bushings came out super easy, the cradle area was clean and smooth but I broke the 12ton HF press trying to get them in. I ended up getting them out and just ordering poly bushings, which were a cake walk to install.









Last weekend I redid my rear subframe brace, it got dented when I pulled off from a steep curb and just hung too low. I removed the portion going towards the mount of the chassis on the passenger side since it just was too much "stuff" going on down there with little benefit. So now its just perpendicular connecting the two control arms.




I also ordered some hood vents and am planning on an oil cooler as well. In order to install the latter, I need to get my CarPi figured out and then get a two-in-one sensor for oil pressure and temp and figure out a new oil feed location for turbo.
Right now I'm thinking of removing the stock oil pressure sender and using that port on the block for the new 2in1 sensor and oil feed. I'm not thrilled on losing the dummy stock guage which is why I need to have my TunerStudio and raspberry Pi set up inside the car before I get rid of that.

Thanks for the comment Nick! Good to know about the sensitivity to crankcase pressure. I suspect the pressure is causing the oil to go out the turbo seal and/or possibly related to the drain. I will consider moving to -12 drain line. I was also looking at those oil caps with AN bungs and putting an additional catch can on there too.
Yeah would love to see you at a meet sometime! I'm in the south metro area if you ever need an extra hand to get it back on the road! (although my track record is clear that I have no clue what I'm doing haha)

Little bonus too, was I stopped at Flyin Miata on a road trip a couple months back and it was so awesome, Mike was a great tour guide and super knowledgeable! I will make a short update post once I have the hood vents installed and hopefully start making progress on the CarPi!

 

Nice progress, enjoyed reading the thread! There are some oil coolers that have ports on the adapter block for oil sensors/feed if needed, you could do a two bird one stone.

 

Hey Y'all!
Been a minute, so here's a little update...
I did get around to installing the hood vents. I spent a good two hours measuring and adjusting over and over and over and I think it turned out great. The instructions said to cut it 1/8" wider for the rubber trim but I was afraid so I cut it to the template and had to do some grinding. I ended up not putting the rubber trim on the vertical front portion since I like the look more that way. And holy crap did these things make a massive difference in heat management and helping the car cool quicker.






On another note, I started randomly seeing really wacky reading on my wideband. It was very slow to react. I ended up replacing the sensor and adding a really small straight spacer to get the sensor out the direct flow of the exhaust. I know its not ideal but with the blow by issues I'm seeing I believe the sensor didn't last as long due to the oil hitting it so this should keep it alive for a couple years.

Next thing...I was talking with the DIY AutoTune folks about idle instability after longer (1+ hour drives) in the summer where it would lean out due to heatsoak. We discussed the MAT/CLT correction table but what I was experiencing was the opposite of what that table was intended for. https://diyautotune.com/blogs/tech-c...rrection-table
Thats the link on how to do it. You can see where the flow goes up the correction % goes down but my correction % would need to go up as the flow went down. I decided I wasn't going to try to make this work because I had a hunch it was heatsoak of the fuel, injectors or just radiant engine bay heat. That table would just be a weird bandaid.
Randomly, I stumbled on a forum post that mentioned the GM flex fuel sensor can also do fuel temperature on the same signal wire and it was correct! I started researching and learning e85 tuning and enabling it in TunerStudio. Turns out, my hunch was bang on! Over the summer, I was seeing fuel temps 30F above the intake air temp after driving for a bit in 85+F weather. I added the Temperature Adjustment (Primary Fuel) table and started at 100F where I add 2% up to 19% at 135F. Unfortunately, summer was winding down and I haven't had a good test on this but I did make mental notes when driving on how far the EGO adjustment was out when idling in hot temps, so it should be pretty close.
I found the new gas station by my house has e85! I've been working on that tune quite a bit following OGPedXing's videos on youtube and its working very well EXCEPT for a new issue that started, that I would love some advice on if anyone knows anything

Here's the situation: light flywheel, 1k rpm idle target. When my Spal fans kick on, idle drops hard. I have the correction tables in for this for voltage drop and idle advance and it saves it on pump gas 9/10 times unless I have cabin fans and headlights on, then maybe 6/10 times. I believe the root cause is the electrical surge when kicking the fans on and the battery voltage drops (seen this in logs). It was annoying on pump gas but now on ethanol I have a new and arguably bigger problem. When the fans turn OFF at 197, my GM Ethanol sensor goes into a fault state and the car dies. Now, I found the fault state assumes e10, which is 40ish% less fuel than it needs, so that's why it dies. The workaround for this would be to set the default e% up around 70 or so to allow EGO authority to keep it alive since my ethanol is actually e75-78. I think the problem here could be something where the electrical draw dips quickly and the sensor is very sensitive, where it throws a reading the ECU interprets as invalid and so it shows as a fault. So now I'm trying to figure out what to do. My Flex Fuel sensor signal is Pin N, power is to the cigarette lighter 12V and the ground is Pin A at the ECU.

Maybe some noise at the ground or something? Maybe upgrade to RX7 alternator? I really don't know much electrical but maybe there's something I could do with the relay or a capacitor or something like that. Would love some input from some smarter people than I

 

my spals also kill my car, it did it even before i was boosted when i was on regular gas. Wish I could figure it out as its very annoying to deal with. I was planning on upgrading to the rx7 alt whenever I get around to getting a new alternator, I need one anyways. I've never had an issue with my Flex fuel sensor going haywire like you described, though I get power from a sensor around the engine bay fuse box, and ground inside of the fender with a rivnut because my wires are tucked behind there.

 

Dang, love the look of the hood vents with no trim on the leading edge! I'll do that on my next set. Though hopefully that won't be for a long long time haha!

Great find on the fuel temp logs! I had the same issue with idle droop after ~1hr of driving my NA8, but it almost completely subsided after I switched to E85.

How many amps do those Spal fans pull? IIRC, all NA/NB alternators max out at 70amps or less, with the RX7 alt putting out over 100.

 

According to chatGPT, the cig lighter is a very noisy circuit and on the same as the fans. I'm not sure thats 100% accurate but I don't have the time to comb through the wiring diagram. I'm going to try moving the flex fuel sensor 12V up to the steering column ignition wire. Need to doublecheck exactly which one that is tho.

The lack of rubber trim and the black rivets (with sharpie touchups) I think look so good, thanks Z! I'm sure its not a true representation of the fuel temp since its getting lots of residual engine bay heat temp but I am very confident its going to help next summer.

SPAL 30102044 looks like 21.3 amps and I have a little Spal 30103011 that draws 5 amps. So those two plus all the other stuff the car is powering. Google says stock NB fan is 6 amps lol shoot no wonder its so drastic. Sounds like RX7 alternator needs to happen and maybe some additional wiring from the battery per sixshooter's comment: "...I also added additional grounds and positive wires from the battery to the alternator and from there to the fuse block. That aided with the amount of burden immediately placed upon the alternator when my giant Spal fires up. It allows the battery to better "help catch" some of the immediate load."

 

Missed your comment about the power, any chance you could see what wire that is? I'd like to not re-invent the wheel if you already have a working solution!

 

According to years of experience using Spal fans, air conditioning, and other fun stuff, I ran additional ground cables to the PPF from the battery. I ran additional hot leads from the battery to the starter, and from the starter to the main fuse on the fuse block. I also ran an additional wire from the alternator to the fuze block. I used an ebay high-amp NA alternator to further supplement the system. Yes, lots of things. But it worked fine when done.

 

Yes, this is a good thing to do in the longrun to be fair, my spals almost kill the car when they come on because their draw is too much and tune is too little, and aside from thickening the wiring for the fans I've kept the stock relays and controls.
It is important to bare in mind that better fans generally means more amperage draw especially without a soft start feature. fd rx7 alt is in my future. Boy do they move some air and cool **** down.