Steps to scratch build a VW

Discussion in 'Hangar Flying' started by Little Scrapper, Aug 13, 2019.

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  1. Aug 18, 2019 #121

    fly2kads

    fly2kads

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    Yes, there is, AA Performance Products makes them. John at Aircooled.net stocks them.
     
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  2. Aug 18, 2019 #122

    Pops

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    Anytime you go to a stroker crank, you are adding more work and problems. Some of the smaller stroker cranks can be used without grinding for clearance on the inside of the case. On larger strokes, what length rod to use, etc, etc. Will always have to make custom length pushrods and they have to be just right in length for the proper rocker arm geometry. Also you will have shims under the cylinders against the case surface to space the cylinder out for the correct deck height for the CR you want, ( you will need to measure the CC of each head chamber along with the deck height to get the CR. You will be doing all of this on every engine except of the case clearance.
    Lots of work, but just like building an airplane, can be a lot of fun and you WILL know your engine.
    I believe Hot Wings knows far more about the VW engines than anyone on this site. I just know enough to know I don't know much and still learning.

     
  3. Aug 18, 2019 #123

    Little Scrapper

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    I really like this thread, appreciate the knowledge and how everyone.is civil and helpful.

    Do most people assembly these on a bench or on a stand? I could weld up a quick stand but they are pretty light.
     
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  4. Aug 18, 2019 #124

    Hephaestus

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  5. Aug 18, 2019 #125

    TFF

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    Case halves crank and cam are usually on a bench. Then a stand is helpful for cylinders and heads and accessories. All can be bench though.
     
  6. Aug 18, 2019 #126

    dmar836

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    I made a cradle of cross crossed 2x4s for benchwork but it isn’t ideal.
    Pops didn’t mention that many strikers end up with rod bolts that hit the cam. This requires clearancing. Many cams can be ordered clearanced. I started doing it to a cam but it isn’t exactly intuitive. I decided to save that cam for a later build.
    Anytime you mention a small stroker crank most all advice will be to go bigger for no additional cost,etc. you just can’t avoid that type of hijack to your questions on the web. Go small!
    Dave
     
  7. Aug 18, 2019 #127

    dmar836

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    All this talk has me thinking maybe I’ll remash my parts mix and prop formula to see what I can do with the 69mm crank!
    Dave
     
  8. Aug 18, 2019 #128

    Vigilant1

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    While we're talking about small engines and displacement/bore/stroke options: As mentioned before, sticking with the 69mm stroke has advantages if you can get by with the available HP. Looking at the displacement/bore/stroke chart, I had wondered why more folks don't choose 1915cc instead of the 1835cc engine (5 more HP!). I started a thread and got lots of helpful answers from Hot Wings and Pops here: https://www.homebuiltairplanes.com/...-1915cc-why-is-the-1835cc-more-popular.30794/

    Bottom line: Some folks have experienced problems with the thin-wall 94mm cylinders. Also, as mentioned previously, the case gets very thin at spots when machined for the 94mm cylinders. So, that's probably why the 1835cc is more popular (and among stroker engines, it's probably why the 2180cc engine is more popular than the 2276cc engine). As tempting as the additional HP would be . . .
     
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  9. Aug 18, 2019 #129

    Hot Wings

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    More? Probably not. Different bits of the puzzle? Probably.

    You have more experience with flying VW's and here that is worth a lot.

    << >> In this we are the same. I'm still learning too. Fear the day when that stops..........

    I don't know about most people but a stand makes things soooo much easier. Less frustration = better build.
    You can put a VW engine on a standard V8 style universal engine stand. The 2 leg engine stands are kind of marginal. The 3 leg is much more ridged.
    [​IMG]

    One of these is worth the money = if you are building engines full time:
    [​IMG]
     
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  10. Aug 18, 2019 #130

    blane.c

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    I am curious what is the down side of building a larger cube VW and limiting it to less HP, for example a 2180cc is normally rated at 72hp@3400rpm what if you propped it for 60hp@2840rpm and cruised around 45hp@2200rpm?
     
  11. Aug 18, 2019 #131

    Vigilant1

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    These videos are great--thanks for posting the links. I'm amazed at (and thankful) for the work people do to makes these types of videos. Sure, sometimes there's a commercial motive, but that's not a minus in my book.
    That cutaway case is fantastic.

    Tricks--tricks for everything. Its cool, but it's frustrating because they seem to be spread everywhere over the internet. Same with recommendations on parts - (Hey! This head looks like it will cool better than the one in the standard build! I'll use this" Surprise! The valve geometry is slightly different and now all the instructions you were going to follow on the rocker-arm setup and all the pushrod lengths are wrong). To have everything pulled together in one reference would be a very handy thing for someone building an engine. In 2019, maybe a well-organized Wiki would be a good way to keep up with changes with regard to new products, in-service experience with various approaches, etc. But, for now, a good kit with clear instructions (hopefully with a "why" for each step, as required) can take a lot of the risk, head-scratching, and frustration out of this process.
     
    Last edited: Aug 18, 2019
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  12. Aug 18, 2019 #132

    Pops

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    What I done, on the SSSC I'm cruising around at 2650/2700 rpm at 80 mp burning 3 gph ( about 33 HP) on a 1835 cc, 60 HP engine, but can go to WOT and climb my 230 lbs at 1200+ fpm.
     
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  13. Aug 18, 2019 #133

    Pops

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    Looks like you are the man :) Bet you could make a good video.
     
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  14. Aug 18, 2019 #134

    Vigilant1

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    Because this jump (1835 to 2180 cc) requires going to a stroker crank, many would probably choose to stick with the 1835cc engine >if< they only needed 60HP. The 1835cc can get by without a Force One prop hub and the machining that comes with it (I'd personally use the Force One anyway, but it is less important). Also, the case needs to be clearanced for the 2180cc, it's not required for the 1835cc. If you can get single-port heads for the 1835cc engine and also use 1.25" intake runners, you'll get good volumetric efficiency and maybe lower fuel consumption than if you use dual-port heads and larger pipes on 2180cc engine that is only making 45HP. And, if you will really be needing only 60HP for TO and 45HP in cruise, then neither engine would be under a lot of stress and either would live a long time.
    >IF< the engine isn't making a lot of HP, then the minor differences in cruise RPM between a 2180 and 1835cc engine will hardly make a difference in how happy they are and how long they last.
     
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  15. Aug 18, 2019 #135

    Little Scrapper

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    Question.

    If I were to practice and just build a non aviation VW Type 1 engine just to build some knowledge what would be the cheapest total kit I could get. So nothing for aviation, simply for the education. A simple 1600 to just run on a stand and educate myself would be worth it for me.

    I know a VW guy and I think I can get a case. If I could order a budget rebuild kit with a cast crank, rods etc I'd do it. It would be worth the investment to figure things out.
     
  16. Aug 18, 2019 #136

    Pops

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    I agree. I still say, you are the Man for the job :)

    The difference would mostly be in the WOT rate of climb and take-off distance. I like both.

    Can buy new single port heads and have milled for the 92mm cylinders.

    Like you , if I was to build another 1835cc non-flywheel drive, I would use the Force-One just for the peace of mind.
     
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  17. Aug 18, 2019 #137

    Pops

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    Last winter I bought a 1965 1200 cc, 40 hp engine and a 1966, 1300 cc , 50 Hp engine for a total of $50 for the two. Both engines were as just removed, with everything to run. Both with one piston stuck from setting. Bet you can find an engine in your area.

    I have the lower end of the 40 HP engine rebuilt setting on the bench. Need to rebuild the heads and buy an oversize 83 mm piston and cylinder set. Stock is 77 mm, will make it a 45 HP engine.
     
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  18. Aug 18, 2019 #138

    TFF

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    If you know someone with a complete practice engine, just get it. 1200,1300,1600. If you just want to make one run, take it apart and put it back together. If you decide to make that the airplane engine, the differences is only new parts and machine work. Spending money on those for practice not worth it as it has nothing to do with you putting it together, unless you are the one boring and milling.
     
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  19. Aug 18, 2019 #139

    Vigilant1

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    Sorry--not what you asked, but just my 2c: Since you've indicated that saving money isn't a primary goal, that you are doing this for education/personal development, I think in your shoes I would build the aero engine I want, and I'd do it with input from the folks here who know a lot (me excluded!). Some of the techniques and choices for the airplane engine are sufficiently different that you won't be covering all the bases if you just rebuild a base car engine. And when you get done, what will you do with it? There are a lot of choices to be made in building a VW based airplane engine, and if you have the patience to lay them out in a build thread, you can make each one in a deliberate fashion and it can serve as a blueprint for someone else who has similar requirements later on, even including sourcing for the parts, what to watch for with installation, etc.
     
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  20. Aug 18, 2019 #140

    dmar836

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    Agree. Usually those building the cheapest engine out there end up with the cheapest engine out there and the expected results of a cheap build. Even the hackiest car guys don’t like modern cast cranks. The stock German crank is good as-is but a forged crank is only a couple hundred bucks and they are pretty high quality. VWs aren’t expensive to build well compared to V8s or any aircraft engine so not much money to be saved IMO. That’s why I suggested disassembling one for a potential rebuild. You’ll then be confident you aren’t forgetting a seal or plug or whatever and you’ll know exactly how it falls back together.
    Dave
     
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