also I've witnessed an oil pump explode at 7500 after being fine for years at sub7

Did that engine have a harmonic damper? Any more info? Very curious!

Ok so here are a few common KNOWN failure points:

Throttle body shaft/screws
Valve damage from spinning too high with stock valve springs

So if you upgrade the throttle body and valvetrain, what's next?

No, it was a stock 94 engine. On a couple of our 01+ vvt engines that were revved out to 7500 we had valve seats that were pounded in pretty hard. also stock engines

Just to be sure, you're saying was a stock engine that had the factory harmonic damper installed, right?

I think I'm going to at least check the valve lash on my VVT head. I set all the valves to exactly minimum spec when I built it, it's got 700 miles and a lot of 8 to 8,800 pulls on it, so I'm curious to see if it tightened up after that abuse.

correct. completely oem long block

I know it's not much, but you all have convinced me to lower my hard limit to 7,400, 7,200rpm soft limit.

What's the longevity like with the BPs that had a factory 7500rpm limit?

That's a good question. I know at the very least they have a few interesting little tid-bits that US cars don't: like a balancer thingie on the throttle body.
And I guess they have the old school bp05 head with hydro lifters?

If you have to change any of the shims, aim for the maximum tolerance this time. My engine went from all intake valves at .009 and all were under that, one of which was .004. But thats a motor thats built and spent a lot of time above the stock redline. Jury is still out on my bearing wear, motor is still new enough that blackstone couldnt say conclusively if the motor was in the final stages of break in or if it was wearing quickly. When I do my next analysis in June it'll be more conclusive.

As far as i know, i thought they had 4W heads? BP5A?

Great question actually! Actually I can add to that, were they 7,500 indicated or actually 7,500? Like how U.S. shows 7,200 but it's really 6,900.

Yeah if they are tightening I'll shoot for looser! Kinda curious now what they are. I did all the machine work so I'm hoping I did a good job! My seat widths were .060 and I cut them so the seal towards the outer edge of the face for more size/area.

US hard limit is not 6900.

I'll be able to answer that question in a couple weeks, though.

Interesting, so what is the factory U.S. rev limit? I thought it was 6,900 fuel cut on my 99.

Apologies if i'm wrong, but i'm pretty sure it was 7200, as the cluster indicates. Cluster being in accurate, though, you'll see 7500-7600 on the factory tach. (I saw about this during one of the burnouts on the way home with the new purple car.)

We discussed jdm engines recently, I'm looking for the stupid thread can't find it. But yeah I thought they were 4w's too but someone said no. Rev? Ben? One of the aussies? Someone

I mean... they kindof have to be. Or at least have solid lifters, because BP5A cam.

I would have literally thought it was the same head package we got on the MSM.

You're more than welcome to prove me wrong. I don't think we have too many discussions about it so I'm sure others will benefit. I'm just repeating what others posted. I don't know much if anything about the JDM-Tyte motors. I was surprised too

I'm just musing out loud. HLA vs. SLA cam profiles and all that. The cam is used in SLA head.

After seeing what Mazda did with some of the later KLs, i don't think i'd be surprised in the slightest if they used a shitty old BP05 head with SLAs and better cams because reasons.

Stupid question from my own paranoia incoming.

When I had the OE bp4w in my 99 on the stock ecu the rev limiter came on at 7k indicated on the tach. Now that I have my vvt motor in the car on ms3 with a 7200 hard limiter the rev limiter kicks on at 7200 indicated (confirmed via data logging in the ms3)

1) what was the rev limit on the bp4w? I had no way of getting a measurement when I had that setup.
2) is 7200 a relatively safe/conservative track car redline for an NA vvt motor car? I will say that the motor takes on a different hum and resonance in that last 100ish rpm before red line. I rarely hit it as I try and shift at 7000-7100 but its nice having it there for certain straight always.

Just looking for some opinions here in the realm of, if this were your car and you had a very healthy junk yard lottery long block, what would you do?

At the very least the JDM/EUDM 01+ motors are NB heads because the flatops manifolds fit the NB head.

nope. ok now I'm really gonna look for that thread.

Actually BP5A has to be NB head because it has VICS manifold.

I just asked the guy selling this if he knows:
99 00 Mazda Miata MX 5 1 8L DOHC Engine 6SPD Transmission ECU JDM BP5A BP 5A BP | eBay

JDM/EUDM/USDM NB engines all use the same castings. NB1 has a different piston (.5 more cr), and the 5A intake cam. NB2 has teh square top and .5 more cr pistons and the little mass damper on the TB. I have crosschecked just about every part in both against USDM and those are the only differences.

What's interesting, particularly in the case of the NB1, is the 7500 rev limit the JDM variant gets. It's no different than ours and we recess valve seats if we do that for a bout 6 months on a stock NB1. The conclusion is not that the JDM has secret sauce, but that Mazda knew they would not be driven as much as a USDM car and was OK with the accelerated wear for their home market. Mazda has never been an "engine company". Honda would have given the JDM variant better parts for an actual improvement but then failed by sticking it in a wrong wheel drive mobile.

wow, so the other thread is way wrong then.

ok well I need to save this post to avoid confusion later.

Thanks for that Emilio, very helpful.