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Discussion Starter · #1 ·
G'day Guys, I'm new here my name is Paul.

I run a cnc machine shop and as a personal side project I intend to build a 2000 liter V8 using two ZX12R cylinder blocks and heads. I'll make the case and crank myself. Bore 83 mm and stroke 46mm (hi revving). I went with Kawasaki as the base on the assumption that compared to say the Hayabusa the parts may be more plentiful and cost less. Set me straight if im off on this.
Anyway I'm looking for the following information if possible.
1. ZX12R cylinder spacing C/L spacing.
2. Cylinder block height ie from the case face to the deck. (Ignoring the cylinder spigots).
3. If anyone already had a cad model of the head and cylinder block Id be happy to pay them for a copy.

Attached are some screen shots of some parts I've modeled to date.
 

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Discussion Starter · #3 ·
Thank you! Was thinking even a measured sketch or a scan of an old head gasket and the base gasket that goes under the cylinder block assuming they use one, these would be very helpful. And the depth of the cylinders and cylinder C/L spacing as I said earlier. That would give me most I need to complete the case.

Once I have the bottom end arranged I'll start buying some used top end parts but not until I'm happy with the case and cam drives.

I've designed and built a few engines from scratch in the past. So this is well in my sights.

There will be a chain drive for the cams at each end of the crank. The rear chain drive sprocket will have an idler between it and the crank to reverse the direction for the rear facing head. This puts all the intakes facing each other down the center tunnel and keeps the cams rotating in the correct direction for each head.

Feedback good or or not so good is always welcome.

Cheers Paul
 

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Discussion Starter · #6 ·
Does Solidworks do FEA or mass calcs? It may be useful to analyze various parts for stress/strain and for weight.
Solidworks does have FEA. But from experience the engine will be plenty strong enough, and besides its just an excuse to build a racing V8. Most of the components will be stock Kawasaki, rods, pistons, heads, cylinders etc. So the case, crank, and cam drives that will be my own.
 

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Discussion Starter · #7 ·
I If the heads are facing each other, you could just make a set of gears for the ends of the crankshafts and run them, as they will be running in opposite directions. The end result would be a much lighter engine, one less very complicated crank to grind. You would only need cut off the bottom transmission of one engine and Tig weld it to the other, and you would have the cranks driving each other with big fat gears. This would solve all your cam gear drive issues. Just an idea to try and save you a 100 hours or so.

Is that a scale drawing? I would guess not, if it was, you could all the data you need from them. :)
Drawing is scale yes, but far from finished. Being CAD I can quickly juggle things about. The pot spacing’s are now 88 mm for the Hayabusa. But I will change that for what ever the ZX12-R cylinder block is. Once I have that info.

I think your idea is to effectively run two engines Siamese, with two separate cranks geared together? That would work, but what I’m shooting for is a small traditional racing V8, with one flat plane crank. Much like the H1V8 layout attached, but instead using ZX12R bits.
 

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Discussion Starter · #9 ·
I primarily work with Rhino3D. The reason I asked if your drawing was to scale was that if it was, using parametric scaling, you could get all the answers to your questions. Of course this differs from having ac actual crankshaft in hand, and the components, mostly the components, as you will have to make your own crankshaft. So the dimensions from your crankshaft will have to match the bearing sizes, etc.. There's a guy in England who has done this on a few different bikes. He did a superb job, though I felt that the horsepower gain he achieved made the project kind of not worth it. Why not design your own V-8? Using the components of one that exists, how much more could you gain, as you will be bring into the melding the deficiencies of each motor, and doubling them.

Just wondering, I programmed CNC machines 4,5 and 8 axis for over 15 years, designed the fixtures, even end mills. I have no doubt you could do this project.

Have you ever seen Allen Millyard's work? Videos well worth watching. He's done what you are planning to do, and a lot more. :)

Link =
This link takes you to all his videos plus the one below.

Hi yeah, Ive seen all of Millyards work. Its brilliant! That man can do anything with a hacksaw a file and a welder! His V8 uses a stock Z1 crank pressed together. He thinned the big end rollers and rods and squeezed two on to the stock crank pin. It worked but the rods are now very thin at the big ends. To me this is not opitimal. So I will make my own crank and use stock rods. Im assuming the ZX12R heads, clyinders, pistons and rods of high qulity and performance, and so all those qualities should transfer over. The rest will be my parts.
I'll be using my own oil, scvenger, and coolant pumps. Bearings? The crank big ends will use stock ZX12R bearing shells the mains Ive made 40 mm using my own shells from my own engines. The larger mains gives me more crank pin overlap and stiffeness.

If anyone here has old ZX12R bits, even if blown, I'd be interested in them.

Cheers Paul
 

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Discussion Starter · #17 · (Edited)
Do you have a crank grinding machine, or will this be a pressed/welded crankshaft?. By the way, I like the CAD drawings and Renders. I work with Rhino3D and have made many parts for aircraft, motorcycles, cars, etc. I programmed 4 axis and 8 axis cnc machinery for 16 years, designed jigs, end mills, etc. It's really exciting to see someone take on such a monumental task. :)
I run a business called Rotec. We design and manufacture radial engines for experimental aircraft. In our machine shop we have a large cylindrical grinder, we make offset fixtures for grinding our crank shafts (80 mm stroke). The V8 crank here only has a 46mm stroke (crank pin 23 off C/L) the counter weights are bolted on, so the entire crank will fit easily inside 100 swing well within my grinder's capacity.

Crank press?
I did look at pressing the crank together much like we see in the Z1. But as my stroke is so small the crank pin and mains overlap would make this problematic. Being that the crank is small in diameter, I sould have no trouble roughing it from solid 4340 billet.
Im building a poor mans F1 engine, thus very high revs from the dramatically oversquare design. I suspect valve float will be my limitation. I expect I to get around 12,500 rpm which I understand the ZXR12 can achieve in stock form.
 

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Discussion Starter · #22 ·
Will you by any chance be posting any youtube videos about this project? Would be awesome to see the crank being machined or ground. Do you expect to go through several stress relief cycles on the crank during machining?
Hi, I'm still in planning stages now, I have a few projects to clear first but this engine has been on my bucket list for some time. As per my other engines, we would typically rough out the crank, then send it out for stress relieving and then finish machine with grinding material left on, send out for heat treatment then final grind.
Yes once I start cutting chips you can be sure I'll post some vids.
 

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Discussion Starter · #23 ·
Dude, my respect for Rotec, and your engines is as far up there as it goes. I have flown planes with your engines, and felt as safe as possible. Just a sample of the engines from you guys, for the people unaware. If you were on my forum, I'd have a special header and section for you!! You are a world renown engine manufacturer!! I will be following this thread. I'd love to see pictures of your shop! :)



The radial is mine (Rotec) the flat engine is a Rotax similar name differant product. RotecAerosport.com is us
 
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