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.