Brunton Stalker M-Spec BMW N52

1/02/19

Lots of work ongoing but nothing too interesting. 

Finished exhaust aside from final welding and, well, finishing. 



Mounting the bike mufflers was a pretty big challenge. There's really no attractive way to mount them to the side of the body with any kind of rubber isolation (I also don't know how they're going to sound so didn't want to build a big mount right through the carbon panel if I might switch to a normal muffler someday). Also, to clear the fender they are probably 6-8 inches from the side of the car so, again, it wouldn't be pretty. I'm happy with the solution, though. It's a cantilevered mount with 4 silicone mounts. The inside pair are flipped one way and the outside the other so that all the mounts are basically in compression. Then there's a stand off that the cans bolt to.



Next up was the parking brake. This sucked because I don't even want the damn thing, it's just for legality. Also, no matter how you do it it takes up a bunch of valuable real estate. A normal Miata pull handle would kill the tiny amount of center console space so instead I used an old school under-dash pull and twist handle but put it between the driver and passenger. That takes up a small amount of trunk space which I'm also trying to keep sacred but seemed like the right trade. Oh well, it works great and is out of the way. Still need to make a nice handle.

You can also see I've been busy with interior aluminum paneling. Going very well. Everything held together for now with #4 sheetmetal screws which leave a smaller hole than you need for a rivet so I can get it mostly assembled before painting and then go through and rivet everything. I think clecos have been usurped by the advent of the Li-Ion drill, no idea why I would monkey around with them when I can drill and shoot screws nearly instantaneously.





Alex

OK, that's caught up to current.  Spent 4hrs on hood pop springs today, typical of the current list of tasks.

Hopefully it's a fun read, seems like my average gap is a post every couple months.  Gives me time to catch up on all the awesome cars in the builds section here!

Alex

i love my N52 (2007 525xi), but there are a couple of things to address:

Crankcase Ventilation system hoses get brittle.  If you're keeping the BMW system, replace these hoses.

PCV Heater can short out and set engine on fire.  There's a recall.  I just had the recall fix done over Christmas break.

VANOS solenoids get weak and set cam timing codes.

Electric Water Pump fails anywhere above 80k miles.   Mine went 140k and I was told that's about +2 sigma.

I think that's about it.  They're really good engines as far as i can tell.

In reply to AngryCorvair :

Thanks for the tips! PCV will be taken over to the dry dump tank so that BMW stuff will be gone.  I've heard about the water pump, probably will start fresh.  Vanos is a concern since the engine was out when I bought it.  We'll see, they're silly cheap engines so I can spend a bit on parts and still come out ahead.

Alex

Very cool, Jason Minehart is a friend of mine and I love his stalker. They're awesome cars!  

Wow! This looks great, but I'm not going to get any work done today if I look too closely. 

This thing looks awesome! I've had three N52s, great engines and relatively trouble-free for me other than silly leaks in the valve cover and oil filter housing.  The 2009 engine (N52n I think) you have has the plastic valve cover that can supposedly crack, though I never had that issue on my 2009 or my 2011 328's.  My 2006 had a magnesium valve cover, but it leaked when one of the aluminum bolts holding it to the head broke, so it might not be a better alternative.  

I'm curious what the dyno will look like for this engine with the ITBs, one of the best things about the N52 is the torque curve that starts to plateau at 2000 RPM and stays pretty flat throughout the rev-range.  I'm not sure how much of that is due to the valvetronic or if its due to some other intrinsic design of the engine.  Not that you need a whole lot of torque with a super light car.  

So what's the plan with the suspension on this thing? I see pushrods, did you set those up or is that part of the kit?

That thing is Awesome!  Thanks for sharing

Yes thanks for sharing this!  I’ve always liked lotus 7 type builds.  I never knew about this kit so now I have something else to dream about.

Awesome awesome awesome!

rothwem said:

This thing looks awesome! I've had three N52s, great engines and relatively trouble-free for me other than silly leaks in the valve cover and oil filter housing.  The 2009 engine (N52n I think) you have has the plastic valve cover that can supposedly crack, though I never had that issue on my 2009 or my 2011 328's.  My 2006 had a magnesium valve cover, but it leaked when one of the aluminum bolts holding it to the head broke, so it might not be a better alternative.  

I'm curious what the dyno will look like for this engine with the ITBs, one of the best things about the N52 is the torque curve that starts to plateau at 2000 RPM and stays pretty flat throughout the rev-range.  I'm not sure how much of that is due to the valvetronic or if its due to some other intrinsic design of the engine.  Not that you need a whole lot of torque with a super light car.  

So what's the plan with the suspension on this thing? I see pushrods, did you set those up or is that part of the kit?

Thanks!  I'm also curious on the torque curve with the ITB's but the cool factor and the sound were worth it.   I had plenty of room for length so that should help.  Tuned for the 2nd pulse at 6000 RPM so there's still a few good harmonics left for lower revs.

Suspension is from the kit.  Miata based and pretty standard but well designed SLA.  Scott's cars do very well in autocross and the one I rode in was great on the street as well.  That was a big part of why I wanted the kit.  You can think for years on SLA geometry but in the end, no matter how clever you get with it, it doesn't make or break the car and this one is quite good.

Really interesting on the valve cover!  I thought they were all plastic.  I need to clean it up with fill panels and bodywork since it's super ugly right now.  I'll look at a mag one and see if it's any prettier to start with.  

The other thing I'm thinking about is that the N53 (EU/UK only) ditched the valvetronic for DI (might just be an N54 head??).  That would be a lighter, simpler head with a prettier cover.  However, I would have to plug the DI ports somehow.  Looking for any experience on that one!  Can't just leave the injectors in there since they're cooled by the fuel running through them.

Alex

I really like your bicycle headset steering column. Do you have a picture of the hub hinge? Awesome work, this thing looks great 

GoLucky said:

I really like your bicycle headset steering column. Do you have a picture of the hub hinge? Awesome work, this thing looks great 

Thanks, it really worked perfectly, would do it again every time.  

No pic yet of the mtb hub, I fiberglassed it into the hood and I need to do some trimming/sanding before you can see the forest for the trees.  Works great, just fuzzy right now.

Alex

When were you at MTU? Myself and another friend who do One Lap left about 2000 and I keep running into techies from about then to now when I do autocross and track days. 

Also details on the motoped? That's nine kinds of cool. 

mazdeuce - Seth said:

When were you at MTU? Myself and another friend who do One Lap left about 2000 and I keep running into techies from about then to now when I do autocross and track days. 

Also details on the motoped? That's nine kinds of cool. 

I was there from 97 through 01.  Pretty much lived in the student projects building downtown the whole time!  I really miss that place, what an awesome town and school.

The motoped was originally a kickstarter thing that I bought quite a while ago.  Looks like they still make them in a bunch of new varieties.  Even though it is 'adult' sized it was way too small for me and the head shake was unmanageable with only one tube holding the headset in the factory frame.  I drew up a new frame in solidworks, did a bit of FEA and shipped the design to Cartesian tube in Canada.  5 days later I got a package of perfectly fishmouthed chromoly that nearly snapped together, it basically jigged itself.  

Here was the motivation for the whole thing:  I really want to like motorcycles but I just don't.  I'm more comfortable on a mountain bike than I am walking, pretty decent at it, and absolutely love every second riding. However, for some reason I cannot get along with any bike that's heavier than I am.   I've tried all the tricks that bikers recommend. I tried buying a used Honda nighthawk for nearly free to learn on, rode it for a season and hated it.   I then tried a friend's F4i and it felt no better on the street.   I then tried a track day on the F4i.  The track day was interesting but I just didn't love riding enough to invest in it.  The motoped was an attempt to make the lightest, simplest, most mountain bike-like motorcycle I could.  Still didn't work.  I guess I just don't like bikes with engines.  It kills me, they are the coolest machines on the planet but I just can't figure them out.   Next up is to try an e-bike mountain bike someday, can't get much lighter and simpler than that.

Alex

eBikes are cropping up all over now, I moved aside on a climb to let a guy past me as the closing speed was impressive, then discovered that that was in no way representative of how he then proceeded to descend. He had the good grace to pull over as soon as he realised he was blocking the trail, which was good of him.

In reply to esuvee :

Well, if you were ever at the climbing wall at the SDC, you probably met me. One of my biggest regrets was not joining the motorsports stuff at Tech. I was there 94-00 so we had about the same experience as far as the town goes. Great place. My kids do summer youth and my niece is there now. If only there were jobs..........

Thanks for the bike info. That's on my to-do list. 

Any updates to the project? I just bought a 62 MG Midget shell and love the idea of an N52 but have no physical dimensions - have any handy? 
Beautiful work. 

Missed this orginally. Tagged for following.

I would also like to know the N52 physical dimensions.  I'd like to put one in my Triumph TR6 but am wondering if this engine is taller than the BMW S52 that I have in it now.   

I'm also wondering about engine mounts to the magnesium block (trying to avoid galvanic corrosion).  Did you modify the stock engine mounting brackets by welding new ends to them or fab up new brackets?   

Great build thread!   Is the Stalker on the road?  

java230 said:

Missed this orginally. Tagged for following.

ditto! thanks for sharing. still on page 1 for now.

Love the build, your attention to detail is top notch!

Where are you located in MI?!

I'm in Livonia.

I have been considering one of these for awhile and would love to check it out in the steel.

Obviously can coordinate post Covid/summer if you're willing/able.

RACEC4R and esuvee,

You both need to come out (post Covid) to a GRM Michigan meet-up when we next have one. There's a bunch of forum regulars in SE Michigan.

Man, sorry for the lack of updates, I kind of got forum'd out for a while.  Let me see if I can catch up with some copy/paste.

3/17/19: 

Been working steadily but literally nothing to take a picture of.  Just a lot of details and aluminum panel pieces.

After a few months of little stuff it's clear it's moving along, though!  I took these the day the wheels showed up.  I went with my least likely option, 16x9 Advanti Storm S1's with Toyo R888's.  This combo was on my short list with about 5 other options but then I saw that Tirerack had the wheels at 58% off.  14lb 9" wide wheels for $95. The suspension is pulled up to ride height.

I could have set it down when the wheels showed up but that would have been 30 min of work for no real reason, soon enough!

Lots more details ongoing.  Idle air circuit, brake, fuel and oil plumbing, still too many to list, really.

Alex

I'm thinking about doing a Cursed Engine swap and want to know if a Iron Duke from a Old Camaro would fit inside a 1995 Mazda Miata. Would it fit?