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Learning how to build Lotus Seven replicas...together!
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 Post subject: Re: Stalker BMW build
PostPosted: October 10, 2016, 11:08 pm 
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Location: Omaha, Nebraska
You're correct on the rings. You don't need to run lower tension, it's just that you can.

I understand your take on accusump. You're right, not so good for big tracks run with sticky tires.

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 Post subject: Re: Stalker BMW build
PostPosted: October 29, 2016, 4:50 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
It fits!

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It's as close as it can get, the bottom of the bellhousing touches the table and with everything level and square the oil filter cover is about 1/4" from the inside of the hood.

A used Raceline 4 stage dry sump pump is sitting on the workbench. I'm going to use the stock BMW pressure pump and remove the pressure stage from my external pump. The BMW pump is a pretty trick variable volume job and it looks like it has more capacity than the pressure stage on the Raceline pump. I can't find numbers but the rumor is that the modern Vanos actuators take a bunch of oil volume to run so I'm worried about just slapping the Raceline on (probably sized for a small Chevy). This makes plumbing a tad easier also.

Also in the works:

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BMW S54 throttle bodies. They're on the big side but the time savings in not having to make a linkage for a bunch of motorcycle throttles is pretty huge. I'm 20% considering sleeving them down to 45mm but likely will just run it as is at 50mm to start.

I did a quick solid model and got a quote back for a CNC'd aluminum 2.5x1" adapter flange to go from the S54 throttle body pattern to the N52 intake flange and it wasn't bad at all. Around $400 for 3 pieces (total, not each). I figure there are at least two other people in the country who would want to do this and the added cost for the 2 extra parts is almost non-existent.

So, more engine modification than I originally intended, especially the oiling, but it's all fun so far.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: November 8, 2016, 9:40 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
One step closer on the oil pump. I picked up a used Raceline 5 stage pump for cheap. As discussed earlier, I then decided to just use the scavenge stages with the stock pump providing pressure. Shortening it turned out to be a fun lathe project with some cutting, a snap ring groove, and threading. Looks more appropriate for the engine size now.

Original:
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Shortened parts:
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Shortened pump:
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Also finished up the design for the ITB adapter. It's really tight around that first throttle but it fits.
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Next up is the mount for the pump, it's going to involve the steering shaft snaking through there, should be interesting.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: November 21, 2016, 8:58 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
The pump mount was interesting. I test drove emachineshop.com for the first time for the main piece of the mount and I couldn't be happier.

I made an 1/8" aluminum mockup to get everything in the right spot but it needed to be 0.5" thick for strength/stiffness. Making 0.5" thick aluminum parts without a CNC makes them look like you chewed them out of drywall so I wanted to have it made. I dowloaded the CAD software from emachineshop, swore at it for a few minutes until I found which way was up, and then drew the part. I moved the tolerances around until I liked the price (0.005" and 10deg draft angle, I think allowing water jet, 0.001" or 0 draft angle increased the price by about 40%, still not terrible) and hit 'buy.' 6 days later it shows up at my door looking awesome.

I know everyone "knows a guy" with a machine shop, water jet, etc. who swears they can do it cheaper but that turns into a PITA 100% of the time. This was easy, good quality, and a pretty good value. 0.5" ~4x4" aluminum with 4 unique hole sizes and a non-square shape was $61 shipped, would have been $105 for the tighter tolerances.

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There's a second bracket on the back to stiffen it some more:

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So, overall really happy with emachineshop. Also, I sent them a much more complicated model in solidworks format and they quoted it in two days, also for a good price. Not quite as easy as 'click to buy' with their software but still good service and you don't have to screw around with a second rate CAD program.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: November 22, 2016, 12:28 pm 
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Joined: October 24, 2008, 2:13 pm
Posts: 3190
Location: Carlsbad, California, USA
Thanks for the info on eMachineShop. I'd not heard of them before. I've got it bookmarked now.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

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 Post subject: Re: Stalker BMW build
PostPosted: December 23, 2016, 7:29 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
Not much actually completed but some progress and an early Christmas present:

Oil pan on an MDF/steel plate to keep it from cracking during the somewhat violent cutting process:

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Nearly complete pan, need to add the front scavenge port but that one is easy. Keep in mind the engine sits at a 30 degree angle so that front bit doesn't take up any ground clearance. It also houses the stock pressure pump which I am using so it has to stay.

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Early Christmas present (well, not really early, 8 weeks late, actually. Doesn't matter, obviously)

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It all kind of fits:

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Also tried metal spinning some velocity stacks. I learned a LOT about how NOT to do it but it was fun to try. This attempt was massively better than the first one I tried a few hours before so I learned, I guess. The dude on youtube had much more success so I'm missing something. It seems hard on equipment. I think I'll buy them.

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Next up is some composites work for a change of pace now that the engine is sealed back up.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: March 18, 2017, 11:46 am 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
Work has been crazy so I'm in parts collecting mode right now.

Here's the latest e-machineshop.com part. It's an adapter I designed to bolt the S54 ITB's to the N52 head. Looks and fits great, can't wait to get it all bolted together. The ports through the adapter are lofted and perpendicular to each angled surface so there isn't just a chopped bend like it appears in the pictures.

I am sleeving the throttle bodies down from 50 to 45mm which is a PITA but less so than mounting 45mm motorcycle throttle bodies. Hard to figure out why BMW went so big on that engine, they could easily have gotten away with smaller at the power it made. I'm sure having electronic throttle control helped calm down the 50mm off idle issues but I just don't get why (I'm sure there's a reason, though. Being Germans and all).

CNC brake/clutch pedals arrived. Seats and an aluminum flywheel/clutch are also on the way.

I don't anticipate getting even a day in the garage until May 1. :mad:

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Alex


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 Post subject: Re: Stalker BMW build
PostPosted: March 25, 2017, 5:08 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
Managed to steal a couple hours today for some minor progress.

After much back and forth I did decide to sleeve the throttle bodies down from 50 to 45mm. So far going well. Now I just need to trim the butterflies which is not all that easy since they have to be cut on an angle.

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Odd accidental juxtaposition of a hammer and micrometers in this pic. Seems about right for my typical machining strategy :oops:

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: March 25, 2017, 6:19 pm 
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Joined: December 7, 2012, 8:28 am
Posts: 1394
Location: Sarasota
Great build. I am looking forward to seeing how the Miata Stalker kit turns out, especially weight wise.

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 Post subject: Re: Stalker BMW build
PostPosted: May 12, 2017, 7:52 pm 
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Joined: June 9, 2016, 10:05 pm
Posts: 4
Is this build still alive?
I can't say I get that excited about that motor without significant modifications but I would rather it have it over just about any NA 4 cyl.


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 Post subject: Re: Stalker BMW build
PostPosted: May 16, 2017, 8:46 pm 
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Joined: November 9, 2007, 3:40 pm
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Location: Fort Worth, TX
ajmacdon wrote:
Now I just need to trim the butterflies which is not all that easy since they have to be cut on an angle.


I had to make a single buttlefly years ago before I was smart and knew how to use the available tools. I spent hours trimming a little on the belt sander, fitting it to the shaft, trimming more, etc. It took several tries to get a good enough fit so the engine would idle.

A year or two later I saw a mandrel someone made for the lathe - they took a piece of round stock the same OD as the throttle body's ID, cut a face at whatever angle they wanted the butterfly at idle, drilled and tapped two holes to attach the butterfly, and bolted a rough cut piece of sheet metal to the mandrel. In a few passes they had a perfectly fitting butterfly.

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 Post subject: Re: Stalker BMW build
PostPosted: June 29, 2017, 9:29 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
Got a new job that has been taking a lot of time but I've been collecting parts and tools. GM shuts down this week so I'm hoping for some progress!

New Mill - Paid as much as I would have for a used Bridgeport but I just don't have the space. This one is well reviewed and fits great in my shop. DRO and power X and Z are nice features too. I got a quality vice and a rotary table so can't wait to get started!
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Seats by JKComposites in the UK. Can't say enough about these guys, you order from the guy who will be laying the fiberglass and everything is pretty custom. Also quite reasonable prices, a pair of seats shipped to the US is hundreds of dollars less than a single Sparco/Momo, etc and thousands less than a Tillet. No FIA cert but no racecar either.
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One actual project complete, this is the motor controller for my Megasquirt homebrew electronic throttle control. It's a pololu part that does quite a bit of the diagnostics for me. Flame away, I've had enough stuck mechanical throttles that I'll go toe to toe with anyone who says this is dangerous. Makes ITB's driveable since you can vary the WOT position with RPM.
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So, hopefully some seats, pedals, steering column and trans tunnel to talk about later this week!

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: July 29, 2017, 9:03 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
I've had plenty of garage hours, just working through a ton of slow, detail stuff.

Overall getting close to steering, pedals and seat being done, seat mounts are all that's left.

Using a mountain bike headset for the column worked awesome, zero play and super smooth. The whole steering system is 1.125x0.049 tubing. 3 times stiffer than the typical 0.75x0.125 for the same weight (taking a lesson from work, steering shaft stiffness is uber important, too much is not enough).

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Could have done the column mounts in steel but wanted to excersize the new mill:
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Seat mounts, oil pump drive sprocket and gas tank are on the short list.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: August 12, 2017, 3:56 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
Finished a project I've been worried about in the back of my mind for a while. I needed a drive snout for the oil pump belt and the interface isn't super simple (at least not simple to get acceptable runout). Made LOTS of chips on the lathe and got to exercise the rotary table on the new mill, finally getting used to the machine.

Bare snout on the engine:

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Pulley installed:

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Full pump drive:

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In the background I got the full steering shaft welded up. Next up is seat mounts and gas tank.

Alex


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 Post subject: Re: Stalker BMW build
PostPosted: October 29, 2017, 8:36 am 
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Joined: December 18, 2010, 3:29 pm
Posts: 60
No huge milestones but steady progress this fall.

First is the gas tank. Most people put the tank in the 'trunk' but it fills it completely. I am pretty committed to being able to carry two helmets and a weekend bag back there so the tank was going to be impossible to fit. Given my seats don't flip forward there was totally wasted space between them and the rear bulkhead. I drew up a tank that holds 12 gallons (not going to want to sit in the car for longer highway stints than that) and uses every cubic inch back there but nothing in the trunk except filler neck. Before anyone worries for my life, there will be a sealed firewall between the tank/trunk and the seats!

Imagescreenshot.43

I again had outstanding results from emachineshop.com. I exported a drawing to their software, got a price instantly (only $100 more than the raw material for 20 something pieces), clicked 'buy,' and a fuel tank 'kit' showed up at my door 6 days later.

Imagehttps://flic.kr/p/ZTHvDr

I took the time in the model to use the right material thickness and work on the overlap for the joints so it went together so easily. No measuring needed whatsoever, just some blue painters tape on the joints and tack together. Had the whole thing tacked up in 4 hours. It would have taken an entire day just to cut out the pieces if I went the arts and crafts route. (and they would have looked like the dog gnawed them out with his teeth)

Imagehttps://flic.kr/p/ZU4vkF

Probably my favorite part of the project is seeing the computer parts come to life.

Imagehttps://flic.kr/p/CN2uN3

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Fits!

Imagehttps://flic.kr/p/YPpfhA


Got the dry sump tank mounted. The mill makes things so much easier and you get to add speed slots to everything!

Imagehttps://flic.kr/p/ZpFH2i

Mounted on rubber to save the aluminum mounts from cracking and to keep the noise down, dry sumps 'moan' on street cars.

Imagehttps://flic.kr/p/Z1S9fb

Slowly working on the two body pieces I need to make. The LS stalkers just shove headers out the sides of the engine compartment but half my BMW engine bay is not that attractive so I need a couple side panels. These also have a step that looks like venting but actually gives you a couple inches wider footbox. Mold is duracoated now, needs some wet sanding before I can pull the two parts out of it. Yes, there's a draft angle so even thought it's not the prettiest composite design it will at least come out of the mold.

I'm no painter and I did these in the driveway (snatching leaves out of the air before they could rest on the wet paint!) so overall I'm pretty pleased with the finish. A bit of wet sanding should knock down the orange peel but even that isn't so bad as is. The duracoat flows really well, strongly recommended over regular paint for a composite mold.

Imagehttps://flic.kr/p/YPp859

Finally some electrical fun. I've wanted an oscilloscope my whole life. I needed to diagnose the PWM signal from the megasquirt I'm using for the throttle motor so I broke down and ebay'd one. I could have done a digital scope but the inner hipster in me wanted an old analog like we had in high school. Worked like a charm, 10 minutes from hooking it up to fixing the issue. (the Volvo is my test bed for the throttle control)

This is a video if you're a dork and want to reminisce about analog oscopes.

Imagehttps://flic.kr/p/ZRnfQb

Next up is a radiator, driveshaft and then maybe some aluminum panels!

Alex


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