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Twin cam head for the L6 from Derek at Datsunworks


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Sorry, I dont come on here as much as I should And have not read through the past 13 pages.  I am super busy in other parts of automotive racing that takes a lot of my time compared to when I could be on here reading every post.  Yes I have 5 full CNC mills and 5 full CNC lathes.  My mills are all at least 4 axis and one of them is a big five axis, so I have a fair amount of machining capability compared to the old days when I first started. 

 

But the cam cores on this would be fairly simple all things considered.  Just would take a fair amount of time, but in a CNC lathe the material can be ripped off fairly quickly.  Email me a print to bryan@blakemachine.com and I can take a look.  I use Crane for my grinds on billets.  I have built billet roller cams for buick straight 8's at roughly 3 feet long and even cut the distributor gear myself with live "A" axis on my mill. 

 

If I wasnt so busy, I would offer to do the head work on my Flow Bench and bet we could get more flow than anyone else could.

 

I am going to be building the Paeco-Goerz Head  For the guy who ended up purchasing it.

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This is all Tony D’s fault:)   Hi everyone. Some of you know me from my  DIY EFI manifold project http://forums.hybridz.org/topic/63445-making-my-own-efi-intake-the-first-casting/ &#

Machine work finished!   I can relax a little:) Just got done with their first bath. Still need de-buring and edge finishing but the majority of the work is done.    

Yes, the exhaust port 'could' use some work, the as-cast cleaned intake is flowing within 10cfm of a 4 hour port job on an OS Giken head.   Those numbers outflow most max ported SOHC heads

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I am going to be building the Paeco-Goerz Head  For the guy who ended up purchasing it.

 

This man has balls of steel. I machine a lot of castings and I wouldn't touch that :)

 

And now that "that cat is out of the bag" will the new owner allow you to post pics of the process?  I would LOVE to see that happen.

 

 

I'll PM you about the cams.

 

Derek

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Well it's out of the mill!

 

20170707035859-3473637a-me.jpg

 

 

OOPS

Not enough clearance for the tool holder. 

 

20170707035908-e67574a7-me.jpg

 

 

 

 

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Well that's it for a week or two. Got a bunch of pattern work that backed up so I have to get a handle on that.  Also realized I need the front timing cover done before I have the head surfaced. I may machine that out of billet 6061 as I'm not too sure if the production heads will have the water outlet coming out of the front.

 

I guess I could have cleaned that block up a bit :)

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Looks surprisingly like my KA 6 cylinder head.....

 

How about now :)

20170707035911-3085181c-me.jpg

Well, that's it.  It's ruined.

 

Send it to me and I'll dispose of it properly.  I'll even waive the disposal fee.

So nice of you. It'll go out today

 

Looking even better. Any chance of a 4 cylinder version?

Probably not 

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Cam scan

 

Well everyone in the brain trust agreed that the numbers on the K20A2 cams would be a good starting point for my motor. I bought a used set of cams off of ebay. I used my structured light scanner to capture the lobe data.

 

The scanner projects a light pattern against the object and photographs that pattern The software creates a mesh from the pictures. Here is a shot of a single pattern to give you an idea. I painted the cam white for a better scan.

 

20170707035924-73c5764b-me.jpg

 

This is the resulting mesh. The mesh has holes as I only capture as much data as I need.

 

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I run a plane through the lobe so I can derive curves.

 

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And use those curves to develop a solid model.

 

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I can then use the deviation calculator to see where I'm at but I can usually tell if I'm off or not as I'm drawing it. On a larger project it's nice just to make sure I didn't miss a feature.

 

20170707035609-377fbbb5-me.jpg

 

 

Now I can start designing the cam core blanks and patterns. 

Edited by Derek
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iVTEC would be awesome on this head. The lift portion would make for more expensive cam design among other things, but what about the continuously adjustable cam timing? Is there room for a tuna can on the end of at least the intake cam? It's amazing how much broader a torque curve you can achieve with even one cam being adjustable on the fly!

 

I am not able to offer another solution, but the cam profiles (presumably low cam) of the K20A2 cams were arrived at assuming that the cam timing would be variable. I wonder if the "ideal" cam profiles would be different in a fixed cam timing scenario. Maybe more aggressive?

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If you plan on mass producing the DOHC L28 head, what price ( or price range) are you aiming for?

A(n incomplete bare) DOHC L28 head previously sold on eBay for 10k.

Well, Mike made his swap-meet buy pay off. And you guys thought buying parts for cars in the 90's and hoarding them for two decades wouldn't pay off!

 

It will be interesting to see what is revealed as to original intent of that head and what the ports flow, compared to modern designs.

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Considering the high-lobe cam is what this is set up to run, at 300+ degrees seat duration, more aggressive cams won't be needed for quite a bit. Granted the durations at 0.050" lift are not super-aggressive, it IS a long duration cam for a streeter. Will make much good noise.

The rollers will allow for that indeed. There are a lot of Honda guys running exhaust rockers on the VTEC Cam full time to good effect. With two more cylinders, I think it will work out fine.

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Actually if there was a market I would make one but I think there are simpler cheaper options for 4 bangers. I could be wrong though as I've never researched it. It seems like the KA swap is pretty straight forward and affordable.

Exactly, most guys with fours run the Nissan KA head conversion. Far cheaper and practical than a custom casting with mixed heritage components. From what I understand the KA bottom ends come apart often enough, the head is usually not in short supply! LOL

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Wow, that's some powerful reverse-engineering software right there! Keep up the fantastic work, Derek. It's very exciting to see a project of this magnitude come to fruition, especially in the detail that you're documenting it in. Very impressive!

Thanks Leon. 

I think it's important for people to realize just how much effort goes int producing things like this.

 

iVTEC would be awesome on this head. The lift portion would make for more expensive cam design among other things, but what about the continuously adjustable cam timing? Is there room for a tuna can on the end of at least the intake cam? It's amazing how much broader a torque curve you can achieve with even one cam being adjustable on the fly!

 

I am not able to offer another solution, but the cam profiles (presumably low cam) of the K20A2 cams were arrived at assuming that the cam timing would be variable. I wonder if the "ideal" cam profiles would be different in a fixed cam timing scenario. Maybe more aggressive?

 

In theory there is nothing going on with my head casting that would stop someone implementing iVTEC.  But it would take a bit of engineering. I hope someone buys a casting and makes it happen as that would really be the best of both worlds.

 

The way I beat...er...drive my car it would probably just be engaged all the time anyway:)

Edited by Derek
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