Intake for N51

[racer_951]

Hi, I am new to 128i. I just bought a 128i M Sport 6MT. I will be selling my 135i to my daughter. I'll pick up the 128i on Wednesday. But I already got my mod machine running in my head . Looking through this forum, there is definitely a lot more discussion on N52 which is the mainstream engine whereas N51 seems like an unwanted step child. Fortunately, it does come with the 3 stage manifold. I noticed all of the intake mods listed in various sites like Turner Motorsports listing intake systems, even the silicone elbow, for N52 only. Why's is that? Is the N51 intake much different. I plan to delete the secondary cats and while we are at it, have the muffler shop fabricate an axle back. I know deleting the secondary cats will increase performance some like like the AFE mid-pipe for my Z4M roadster (for sale by the way). But I doubt any axle back exhaust will make much difference in performance. Forgot to mention, I also plan to get a tune either from AA or StageFP.

Going back to the intake, I hope to get your comments and suggestions. Any N51 performance mod suggestions are also welcome. The car will be used as daily (I am in my retirement) and track. Headers and MILVs will be considered down the road.

Thanks guys and gals!

Litko

[RaddDroid7]

You can use almost all N52 mods on the N51.

I installed the silicone elbow just fine.

For the intake I just have a K&N drop in filter but i'm going to purchase the AFE intake soon.

I'm considering headers as well cause I'd like to get a tune but that's after I buy the intake and get the headers installed.

EDIT: People also like the Injen intake, only thing that concerns me is heat soak due to there being no cover like the OEM and AFE intake.

[racer_951]

Hi RaddDroid7,

Thanks for your reply. Very helpful indeed! That’s what I was thinking regarding applying N52 mods to N51. I guess these websites mentioned N52 as a general term for both N52 and N51. I’m going to do charcoal filter delete, drop in K&N filter and silicone elbow first. These are easy mods though it doesn’t really do much with performance but definitely gain a little induction noise ��.

With your N51, aside from secondary cats delete, what other items should I consider deleting? I understand that N51 has an additional air injection? Am I correct? Is there any performance benefits by deleting that and how?

Thanks!��

[RaddDroid7]

Originally Posted by racer_951

Hi RaddDroid7,

Thanks for your reply. Very helpful indeed! That’s what I was thinking regarding applying N52 mods to N51. I guess these websites mentioned N52 as a general term for both N52 and N51. I’m going to do charcoal filter delete, drop in K&N filter and silicone elbow first. These are easy mods though it doesn’t really do much with performance but definitely gain a little induction noise ��.

With your N51, aside from secondary cats delete, what other items should I consider deleting? I understand that N51 has an additional air injection? Am I correct? Is there any performance benefits by deleting that and how?

Thanks!��

That sounds like a great idea, and for deleting the air injection I have not done that or heard anything about it(I'll do some research). You can do a resonator delete and replace the muffler.

[racer_951]

Please share your research on the air injection pump delete. Love to hear back from you!

[Papa Popov]

Most of the aftermarket intakes are trash. Just do silicone intake boot/K&N/charcoal filter delete, and a Euro box if you can find one for cheap (please don't drop $300 on one).

If by some miracle another stash of BMWP intakes in uncovered it might be worth picking one up. The gains are minimal (but there, unlike the aFe box) and there's not as much noise as an open intake, but its much less prone to heat soak. Plus its sexy af and will hold its value well. Definitely not worth the crazy retail price BMW charged, but for $400 I'm pretty happy with mine.

[racer_951]

My current plan is silicone elbow, charcoal filter delete and k&n panel filter

[Thunderguts]

I would look at the Turner intake. It's not as impervious to heat soak as a true box, but it's not as bad as some. Being semi-open, it's got to improve induction noise. If it had existed before I got my BMWP intake, I definitely would have tried it.

The filter and charcoal delete won't do anything for sound, but you might get an extra 5 hp. The silicone elbow does enhance the sound above 3k.

[racer_951]

Thanks Thunderguts!

[wootloops]

Regarding the n51 secondary air pump delete..

Someone mentioned a while ago that Bob @StageFP might be able to disable it in the tune so that it doesn't throw a check engine light, but I'm not 100% sure.

Physically, there is an OEM part ( 11727511542 ) that is used to block off the hole for the valve on the head. The N51 and N52 share the same head design, so they just block it off from the factory on the N52. Makes it easy to remove the secondary air valve.

[racer_951]

Is there any advantage from performance perspective by deleting it?

[wootloops]

Originally Posted by racer_951

Is there any advantage from performance perspective by deleting it?

No. Just one less thing to break, and gets some clutter out of the engine bay.

[Tuxedo]

I have BMW performance intake and StageFP on an N51, I recommend

[chris82]

You should be able to get 260hp at the crank with the AA tune. This is what mine did and the engine was otherwise bone stock. For intake, can't go wrong with the euro box or AFE closed intake and silicone intake hose. For exhaust, I'd look no further than Supersprint, they make the entire exhaust system for this car.

[chris82]

Originally Posted by wootloops

No. Just one less thing to break, and gets some clutter out of the engine bay.

Exactly this. I was trying to install an oil cooler, and this damn pump was right in the way of where I wanted to route my plumbing to the cooler.