K75 turbo hack

Discussion in 'Hacks' started by Mr.umbrella, Feb 22, 2018.

  1. Mr.umbrella

    Mr.umbrella Adventurer

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    Intro: I built this combo last year from a k75 I rescued out of the back of someone’s garage that had been sitting for 20 years.

    I made my own subframe and thoroughly serviced it (spline lube, coolant flush, new brakes and lines, fuel pump, etc...) We toured all season and loved it going everywhere from Canada to Connecticut, NY, and New Hampshire. I wanted more power and bought a low mileage k11lt for a song thinking I’d get a hannigan for it.

    When it came time to break down and sell the k75/velorex combo my wife and I cringed. We love the look and the size is perfect for us. It was only lacking in a few places: steering sucked, slightly underpowered, and I want better storgae space.

    So we decided to keep the k75s together and make it what we want...

    I’ll update this thread in as little of an erratic manner as possible, but so far I’ve:

    Last week I Installed a unit fork (leading link)

    Since then I’ve Started on the turbo system. I am reversing engineering the luftmeister kit using an appropriately sized turbo from a ford ecoboost 1.0 for better low end. I will use a low pressure system without extra fueling to start, just as luftmeister did and after its functioning properly add extra injectors/more noisy. My goal is 100-110 whp.

    The pan and turbo is currently at the machine shop having exhaust flanges made, and a return bung welded in.

    I’ve received all the parts I need; tubing, wide band a/f, additional injector controller, Vortech max flow bov, external wastegate, intercooler core,and other miscellaneous bits.

    More to come once the turbo and pan are back.

    Attached Files:

    #1
  2. AceRph

    AceRph Affluenza Free!

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    :lurk
    #2
  3. davebig

    davebig Another Angry Hun !

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    Ok but a K11 would be easier deliver a hundred HP and can be sharpened ( improved throttle response) with simple injector change, not to mention they are cheap.
    If your a mechanic,machinist, fabricator extra time hurray have at it. I doubt Luftmeister were a commercial success.
    Then there's the Velorex issue the Dutch build sidecars for 100+ hp rigs all the time they use allot heavier components than your dealing with, the Velorex where designed for 500cc motorcycles there should be folk here who think you may be beyond its practicality already.
    [​IMG]
    Your going to increase the little K power by 25% ? Cool idea as a engineering excercise, seems impractical to me.

    Dismiss me as negative if you like but power generates heat and speed and when your turning left all the force goes onto the sidecar frame, if you have anyone or thing you care about why not use stuff that's built for such forces.

    [​IMG]
    Subrame and fork for what NL sidecar builders think ,subframe ties transmission,engine and steering head together.

    You have a very cute little rig but it's just that anymore power and its a problem looking for a place to happen. Look at all the build threads and see what they did or just start with a heavier platform.
    #3
  4. Mr.umbrella

    Mr.umbrella Adventurer

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    Dave, I was a custom fabricator in the past. The subframe ties in all the motor and transmission mounts.

    The velorex suspension and spindle have been upgraded. I’ll be making my own sidecar frame and suspension to replace the spindly older style 572 frame, but to be honest we really like the style of old Czech design.

    This project is by no means meant to be practical, just a fun experiment and to do something a bit different. None of my projects have been known to be the road easiest traveled.

    Realistically I’ll probably only see a 10-15% peak power increase but with the design of this turbo system should have more torque and be able to move it down in the revs so I can run a taller rear drive assembly.

    I’m not on a hunt for pure power bit more specifically how linear and where it comes in.

    Luftmeister was far from a commercial success which came down to poor business practices. The engineers of the kits (rb racing) had a lot of success in their own right and the kits they designed where exceptionally reliable on the k-bikes (75,100, and 1100) as long as you take care of fueling and timing correctly the bmw block is very stout and understressed as you probably already know.
    #4
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  5. davebig

    davebig Another Angry Hun !

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    I see your an Audi mechanic possibly a race car builder ? A hacks a couple year project, you'll come around or break enough stuff !

    [​IMG]
    100 hp NL sidecar rig weighs just over 800 pounds will spin the rear 175/14 if it's wet at all.
    Maybe a better question would be : How much sidecar experience do you have ? A great eduction would be for you to drop down to Middleburg PA and visit with Claude.
    #5
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  6. davebig

    davebig Another Angry Hun !

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    Please pardon me for being a wet blanket, I've never been a Velorex fan unless light weight is the goal. I'm sure your a clever guy and in search of a project, you could do allot better with minimal research and you'll be allot happier, less frustrated in the end.:-)
    #6
  7. davebig

    davebig Another Angry Hun !

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    Wow Mr.umbrella you gave up to easy we're all looking forward to your build thread ! :-)
    #7
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  8. Mr.umbrella

    Mr.umbrella Adventurer

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    Nope, didn’t give up. Just waiting on the turbo flange to get machined. It’ll be here this weekend.

    Dave I agree the chair is too light. I’m building a new frame with proper suspension for it that is heavier duty than the old Czech stuff. I’m just keeping the velorex tub b/c we like it’s size and style so much.
    #8
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  9. davebig

    davebig Another Angry Hun !

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    K75 stuff modern injectors with much improved atomization way crisper throttle. Do yourself a favor and go visit Claude at freedomsidecars he used to build sprint cars is a great suspension/front end guy.
    #9
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  10. Mr.umbrella

    Mr.umbrella Adventurer

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    I’ve already upgraded to the new style Injectors last year. I didn’t really notice a big difference, but it was a nice piece of mind.

    I’ll being going on a vintage bike trip in the summer down on PA I’ll have to pay Claude a visit. I keep seeing his name pop up all over the forums.
    #10
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  11. davebig

    davebig Another Angry Hun !

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    #11
  12. Mr.umbrella

    Mr.umbrella Adventurer

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    Thanks davebig I thought about a terraplane before but it’s not the right style for my wife and dog.

    I finally got the oil pan, and turbo/flanges that my buddy
    Cnc’d over the weekend. I started on the manifold tonight and got most of the hard part of it done which is always the header tubes. Hopefully tomorrow I’ll have the design finalized and can finish weld all my tacks and have the turbo mounted. I’m really happy the header tubes will be equal length.

    Attached Files:

    #12
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  13. davebig

    davebig Another Angry Hun !

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    [​IMG]
    From the torsion suspension thread a Velorex chassis he converted to torsion bar, the trouble with the little velorex's is they aren't really square or straight. Keep us posted !
    Actually I'm starting to like your idea if it doesn't get too heavy !
    #13
  14. Mr.umbrella

    Mr.umbrella Adventurer

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    Dave I like that velorex setup and did he include a stabilizer bar to the rear suspension too?

    I’m going to start from scratch on the frame. I want two lower mounts perfectly in line and uppers similar so lean in/out is simple. I want my toe and wheel lead to be easily adjustable at the sidecar wheel. I’m probably going to use an automotive front spindle on an adjustable plate. When I get to that point, I have lots to do before that.

    I did get the manifold close to done. The turbo is a tight fit between the case and leading link fork but it just fits. This is going to be a really tight package once the outlet tube and external wastegate find a home.

    Attached Files:

    #14
  15. davebig

    davebig Another Angry Hun !

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    Nice, a trip to Claudes would be very educational about whats easy and whats possible, most builders use trailer spindles to use 1" wheel bearings easy to source. I think Claude has a modular variation with bolt on swingarm mount to raise and lower etc etc.

    [​IMG]
    EZS sidecar frame simple but works very well.
    [​IMG]

    [​IMG]
    As I was cleaning and taking apart. Did I see Unit forks add a brace wherever you can. My images are just for you to get ideas from though you don't seem to have any trouble cooking up your own :-)
    #15
  16. Mr.umbrella

    Mr.umbrella Adventurer

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    You did spot some unit forks. I picked up a set and a k1100 subframe off Facebook over the winter. I added a steering stabilizer to make things smoother last summer which luckily works with the unit fork assembly without modifications.

    I had a cross brace that triangulated both uppermounts, but it was In the way of the turbo. I’m going to rear work it and tie it in to the steering head assembly just like the eml’s.

    I also have a car rear tire conversion for it on the shelf. I just need to mount some new rubber and the wheel along with a Fox twin clicker. I’ve got a lot of work left but this rig should be really dialed in once I wrap it up.

    Perhaps I’ll apply all this useless information I’ve learned to build a real hp sidecar out of my Ducati 748 that’s just been lurking in the corner waiting for some love.
    #16
  17. davebig

    davebig Another Angry Hun !

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    Having been a Ducati man in the past (bevels and newer 2v) that would be cool, a 4v Ducati motor would make a hell of a sidecar power plant given they have both torque and hp.
    [​IMG]
    My old best girlfriend a 944 SS Elefant anything worth doing is a pain in the ass !
    #17
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  18. Mr.umbrella

    Mr.umbrella Adventurer

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    I toyed around with getting one of those elefant duc’s, but I ended up with a multi 1100s. Loved the bike, but I sold it to fund buying our house and got hooked on the sidecar.

    I wish my 4v bike was as easy to do valve jobs on as a 2v. I need to pull the cams and probably replace some flaky rockers.
    #18
  19. davebig

    davebig Another Angry Hun !

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    The brotherhood of the shim is not for folks without mechanical aptitude, I have love hate relationships with 2v's they are obsolete junk all of them but are really fun and fairly simple, 4V are all fun but pretty much require a real mechanic, I have a buddy with an ST2 for sale I always thought they would make a nice sidecar tug.
    Here's an Englishman's very cool Elefants http://www.companytroubleshooters.c...ll&id=1227710847&archive=&start_from=&ucat=1&
    #19
  20. Eddieb

    Eddieb Long timer

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    How much ground clearance does the K75 have in that setup?
    #20