Bottom End Limits M50 Non-Vanos Turbo

[NEOe30]

Hey all,
After damaging my first m50nv block, I picked up another one in pretty good condition. I would love to get 450-500 WHEEL hp out of this setup if possible. I know this has been discussed before, and I'm pretty sure that the rod bearings are the weak point on the NV block (because pistons are forged I believe?) at around 550hp... not positive though, that's why I'm here.

My question is, what is the weakest point of the bottom end and at what (estimated) HP or boost levels does it start to become sketchy/unreliable.

My setup in progress is as follows:

M50nv Engine
Hx35 turbo (56mm)
44mm Wastegate
60lb injectors
.140 MLS headgasket
ARP headstuds
Megasquirt 3x full standalone
Stock fuel pump (walboro upgrade soon)
POSSIBLY water/meth to keep temps and detonation down.

Let me know!

[pazi88]

Weakest point are the pistons. The ring lands crack from the slightest detonation. The pistons are not forged and those are really old design anyway. To make that 550 hp from wheels you need low compression forged pistons. The stock pistons might survive with e85 but not with pump gas. Stock connecting rods and bearings have worked fine even on 800hp engines. There is no need to change those but on the other hand chinese forged rods are really cheap. Also ditch that 0.140 headgasket. The thicker the gasket is, more likely it will blow. And with low cp pistons you don't need that anyway and you can use stock thickness. I recommend Athena Coopperring headgasket.

With megasquirt I also recommend ditching stovk vr sensors for crank/cam and use hall sensors. The vr sensors with bmw trigger wheel are really tricky to get working reliably with megasquirt.

EDIT I also noticed that you plan to use holset hx35. It's not big enough for your hp target. With pump gas that can maybe support 450hp from cranck and that's about 400 from wheels. With e85 and stock compression ratio, you can acheive 500 hp or even more from crank. You need hx40 with at least #16 exhaust housing to get to 550 from wheels using pump gas. That's more than 600 from crank so even that might be at limit.