Rb25 Bearing Clearance Recommendation

[Selli160]

Rb25 Bearing Clearance Recommendation

 

Currently Building a rb25 NEO for my stagea. At the stage of checking my clearances but have a few questions for some more experienced engine builders or hobbyists than myself.

My over all goal for the build is a RELIABLE 600-700HP within a street application. Key word is reliable here I don’t plan on siting on limiter every time it starts im building it as a street car and plan to treat it as such, but obviously I still want to have my fun with it occasionally.

Now the FSM states clearances between 0.02-0.04 mm (Big End)  0.028-0.46 (Mains). This is all well and good but as you can imagine Nissan chose these numbers based on a stock application needs. So I feel its fair to assume that using aftermarket race bearings, double the HP and a slightly higher rev limit would require a slightly different clearance.

I’ve done some looking online surprisingly hard to find much info on recommended clearances. Even when I did they contradicted each other so here I am. If anyone has any advice, recommendations, stories and or numbers I would greatly appreciate it.

[Dasmbo]

Hi i cant remember what the exact clearences i used for my rebuild im am pretty sure it was the std settings for the engine but and bearings used were kevlar type cant remember the brand when you do the building of the engine i suggest you use plasti gauges do your bearing clearences much more accurate its a bit more of a pain in the ass. The clearences you have after you have torqued the rods and crank into the block that is most important at high horsepower. I also had my engine block line honed to keep clearences uniform and used new forged h-beam con rods but its all about the clearences you have after bearings are torqued that is important i have been running a street car for 7 years with 473hp at the rear wheels with no probs i would also recommend an after market oil pump with the oil pump adapter fitted to the front of the crank which makes the the oiling system more secure and less chance of blowing the engine at high rpm