[Letsrunem8]

I did my research and found the topics covering my area of interest but didn\'t find the direct answer and the threads were quite old. How reliable is actually the n51 engine (328i sulev). I know as far as performance it\'s inferior to the standard ULEV (compression ratio, manifold, etc.) but has anyone found any problems with reliabilities for this particular engine. Any input would be great. Thanks

[driverman]

I don't know about reliability, but regarding performance....

I researched this topic extensively when I ordered my 328i in late 2007. At first, I thought the ULEV (N52) would perform better because it has a higher compression ratio and less emissions equipment. But I later read on this forum that the SULEV (N51) has the 3 stage intake manifold.

Therefore, who knows which model performs better? I'd love to see dyno test results comparing N51 and N52 models, especially since I originally ordered the N51 but changed it to the N52 after I learned about the compression ratio difference.

[Majikthese42]

I just had a 328i loaner with a slushie this week -- since I'm in NJ, the chances are about 99% it was a N51 SULEV.

I thought it was significantly quieter than my N52.

My E91 is a stick so I can't comment about the relative performance of the N51 vs. the N52 (all other factors being equal, the car would be less responsive just because of the slushbox).

I'd look at how BMW approaches this. If SULEV motors were a really good thing, they'd be in the M1, M3 and M5 -- and they're not.

[3_runner]

I have a SULEV, 62k+ miles on her. no issues.

[driverman]

Originally Posted by Majikthese42

I thought it was significantly quieter than my N52.

Could the loaner have been quieter because it had a closed trunk instead of the open space in the back of the E91?

[Propagator]

Originally Posted by Letsrunem8

I did my research and found the topics covering my area of interest but didn\'t find the direct answer and the threads were quite old. How reliable is actually the n51 engine (328i sulev). I know as far as performance it\'s inferior to the standard ULEV (compression ratio, manifold, etc.) but has anyone found any problems with reliabilities for this particular engine. Any input would be great. Thanks

Performance-wise, the fact is that BMW is able to quote the same HP and torque figures for both N51 and N52. This means, despite our desire to interpret statistical fluctuations from a handful of samples as a real difference, that most likely the actual difference in performance is marginal.

Reliability-wise, I would guess that having lower compression and more complex intake is slightly less taxing on the engine than the other way around, but again, the difference is probably marginal. Either way, if you have an N/A E90, it's very unlikely that the problems you'll have will be engine related anyway.

[Majikthese42]

Originally Posted by driverman

Could the loaner have been quieter because it had a closed trunk instead of the open space in the back of the E91?

Could be. Plus the E90 loaner was 4 years younger.

To my ear, the E91's exhaust note is raspier, and I do like it more. It sounds more like a BMW.

I think the N51 has more exhaust plumbing than the N52 but don't quote me on that.

[Letsrunem8]

Perfect. Yeah I was reading practically the same things and found the same results. I just wanted to see if there were some people with over than 60k miles and what issues they have run into. I read that replacement parts would cost an arm and a leg!

[328i M-Sport]

Is there an easy way to tell whether you have N51 or N52?

[Letsrunem8]

Originally Posted by 328i M-Sport

Is there an easy way to tell whether you have N51 or N52?

You can check on your VIN or also if you open the hood, the top would say SULEV on the hood itself.

[328i M-Sport]

Originally Posted by Letsrunem8

You can check on your VIN or also if you open the hood, the top would say SULEV on the hood itself.

Is there a specific digit/letter in the VIN or would I need to have the dealership look it up? Thanks

[DontHait]

Originally Posted by 328i M-Sport

Is there an easy way to tell whether you have N51 or N52?

Type the first 7 characters of your vin into realoem

[Numark318i]

My SULEV performs well. I have had a 328 loaner (assuming ULEV) and it was not any faster than mine. No issues with my car thus far either. 45k miles. Will update as problems come up.

[accel]

Originally Posted by DontHait

Type the first 7 characters of your vin into realoem

It's easier to just read the sticker under the hood - it says n51 or n52

[Letsrunem8]

Originally Posted by Numark318i

My SULEV performs well. I have had a 328 loaner (assuming ULEV) and it was not any faster than mine. No issues with my car thus far either. 45k miles. Will update as problems come up.

Yeah Ive driven both as well, no significant power difference. However, mine has 27k miles on it, just thinking if I should keep it for years or get rid of it once it hits like 50k lol

[DontHait]

Originally Posted by accel

It's easier to just read the sticker under the hood - it says n51 or n52

Does it really?

I looked several times..there's definitely something I'm missing

[JamesM3M5]

Last 7 of the VIN into realoem.com will indicate N52K or N51 engine. Or you can pop the hood and look at the head on the exhaust side. If there is a valve and a 1" air pump hose, you have a SULEV. The N52 has no air pump.

[M5007]

Mine has that configuration. I am currently at 99,670 and happy to report I have no issues.