[DZheng]

I have an 08 E90 N52, Can someone educate me on the difference between the N51 motor compare to the N52? What are the specs... Thanks

[Cscat]

http://www.e90post.com/forums/showpo...08&postcount=3

[driverman]

Originally Posted by Cscat

http://www.e90post.com/forums/showpo...08&postcount=3

In late 2007, I made my decision to buy an N52KP equipped 328 based on this table. I wanted the 10.7:1 compression ratio of the N52KP (ULEV) not the 10.0:1 ratio of the N51 (SULEV).

I knew that the N52 engine in 330's had the 3 stage intake manifold, the N52KP engine in US 328's had 1 stage and this table shows that N51's also had 1 stage. But since then I've read on this forum that N51's have 3 stage intake manifolds and that's how they make up for the difference in compression ratios.

There are other differences between ULEV N52KP 328's and SULEV N51 328's that are described in other threads.

[UKBasketball]

My E92 has the N51, and coming from a N52B30 powered BMW, the N51 feels quicker and smoother to me. I don't know if it is the 3-stage intake, but there is a great power surge from around 3,000rpm on that my N52 certainly did not have. Also the N52 just sounds lower pitched, meaner and all around better than my N52 did.

[thegr8grizzly]

I know from repairs that the cooling systems on these two engines can be different. Since the N51 is a SULEV, it naturally runs hotter to burn more emissions. This requires special components in it's cooling system that tend to more expensive such as radiator hoses with special temp sensors, much more powerful cooling fans, and a radiator with a "PREM-air" coating and an EAC sensor on it.

[apc3libras]

My previous 328i was a SULEV (n51). The differences are emissions related. Some states require a certain number of vehicles imported be SULEV. Differences in cooling system (radiator) and other parts. The dealer even told me the fuel pump is sealed in the gas tank and said if it needed to be repaired, it's about a $7000 fix. Not sure if that is true or not. Also, the emission warranty that goes to I believe 80k miles or so is only valid if you reside in one of the SULEV required states.

I honestly don't notice any performance difference in my current n52 vs the old n51 (both 2007 E90 models).