[R1d3r]

Hi everyone,

I'm in the process of upgrading my N55 engine to around 500hp and have been reading mixed opinions about the durability of the stock cast crank at higher torque levels.
I’ve come across some claims about people snapping cast cranks due to torque, but I’m wondering how common this really is.
I’ll also be working with a tuner who knows the limits of the N55 platform and will ensure the engine stays within safe parameters, which is a priority for me.

From what I understand, the main issues with N55 engines seem to stem from oil starvation and poor maintenance rather than inherent flaws with the crank itself.
For example, I’ve heard of bearing failures due to oil starvation during high lateral G forces, especially in track situations.
So for that I will replace/upgrade :

Rod bearings
Timing chain
M2 oil pump and sump upgrade.

Some shops have recommended switching to a forged crank, but the cost of such a replacement is quite high.
At that point, I’d be breaking the bank and might as well move to another engine, but I really don’t want to, as I love the N55 platform and just want to push it a little further while maintaining reliability.

For context, I’ve seen N55s run reliably for a long time when properly maintained—some with 150k+ miles. My goal is to ensure my build is both powerful and reliable.

Are there documented cases of cast cranks failing at ~500hp or under high torque?
If so, what are the typical scenarios leading to such failures?
For those running similar setups, is the cast crank sufficient if the engine is properly maintained and balanced?
Is a forged crank really necessary for this power level?
I’m looking to learn from the community’s experience to make the best decisions for my build. Thanks in advance!

[Boostedphil698]

Nobody breaks cranks unless you're money shifting. Honestly, if someone broke a crank from sheer power, I'd be impressed. I've seen the N55 stock cast crank take 650whp.

[wheela]

I think I've heard (2nd hand) of 1 n55 crank breaking, but it was on a poorly maintained non-tuned car. The only other instance I've seen was a pic of broken crank from a dubious source. Even if the forged n55 crank is stronger (which I don't think has been conclusively shown) than the cast n55 crank, I don't think there is any evidence to suggest the cast n55 crank isn't up to the task. Cast crank is last thing I'm worried about on my build.

[R1d3r]

Originally Posted by wheela

I think I've heard (2nd hand) of 1 n55 crank breaking, but it was on a poorly maintained non-tuned car. The only other instance I've seen was a pic of broken crank from a dubious source. Even if the forged n55 crank is stronger (which I don't think has been conclusively shown) than the cast n55 crank, I don't think there is any evidence to suggest the cast n55 crank isn't up to the task. Cast crank is last thing I'm worried about on my build.

Thank you man!