Help me to not blow another BP
 

I'm currently building a BP with supertech 84mm 8.6:1 and a BP05 head
I built the bottom end with the "moderate turbo/nitrous" ring gap, and after that I took some measuraments:
actual compression ratio is 8.5:1
the top of the piston is under the block, 0.4mm under
with a 1mm oem headgasket the piston to head gap (squish) is 1.4mm
Is this a good gap or I have to shave the block?

pics from my diy thread

https://www.miataturbo.net/attachmen...ine=1424992213

https://www.miataturbo.net/attachmen...ine=1424992213

sorry if you already mentioned it, but why oh why on earth would anyone in their right mind downgrade a 99+ head to a bp05? that is like.....beyond words crazy

my old head was gone, and it's near the impossible to find a good used bp4w head in Italy.
Seems like ALL the mx5 in Italy are 1.6l
Even the NB/Fl
I asked to a ebay uk seller for a good used head for "my bp 99-00 mx5"
they said "we have 5 spare bp05 heads in good shape"
I didn't know bp05 != bp4w, because as I said there are NOT 94-97 1.8 mx5, and the few are imported

I spent MANY hours of porting work on that head before I noticed the fail, so here it is: I will use that head because fuck threes and horses, I want lemons.

also: I found a bp-ze head + oil pump combo for 300 €, but I have an ms2, so I can't control vvt :vash:

Why not ARP main studs?

--Ian

Hey, more power to you either way. I have a bp4w head but it's chewed up a bit. If you can do some fancy port work and surfacing, you're more than welcome to have it.

Shipping to Italy seems expensive.

OP, glad to hear you are ready to stop blowing them up.

I've got a bp4w and bp6d head I could ship you if you want. I need to get home first but if you're not in a real rush we could work something out

You should not need to deck the block.

Good luck.

Thank you all for the answers, as I said I will use that head. If that means 30 whp less, I can live with that
It was my mistake, but now is too late to going back: to many hours of work, also I bought the hondata gasket, so what is done is done.

Talking about reliability, I have the bolts that came with cx rods. I know that most of you are using arp2000, are these a "must to have" or I can leave cx ones for a 250-ish rwhp goal?
What about mains?

Main studs will require machining of the main bore. It won't be necessary to use them for your goals.

Many people use the bolts that come with the rods without issues.