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Derek

Twin cam head for the L6 from Derek at Datsunworks

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Derek    46

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/

 

Well now I’m tackling a DOHC head.

 

 Some history:

I get a PM from Tony D in September of 2012 about the Goerz-Paeco DOHC L6 Head coming up for air.http://forums.hybridz.org/index.php/topic/109116-dohc-l6-was-somebody-looking-for-the-goerz-paeco-dohc-l6-head/?&gopid=1020596

Which led to a brief discussion about what would be involved in producing a head. And that was the end of it... Or so you thought. 

Tony and I started trading emails about the feasibility  of producing it and what kind of heads we could use as a donor for the valve train. Tony suggested bringing Jeff P on board because of his work with cooling the L6 head. Tony and I kicked around RB and KA motors for a while and then Tony suggested checking out the Honda K20. Bingo. Removable cam towers, factory roller rockers and a plethora of aftermarket parts. I called one oh my clients that is big in the import drag market and  procured an old K20 head. I did some quick measurements and decided that it was probably workable. And so the journey began.

 

The idea is to use the cam towers and valve train from a K20.

I grabbed a quick scan with my white light scanner of the exterior. It’s dirty because I’m only using it as a reference scan to design against.

 
20170707041258-6c12ca7f.jpg
 

I imported the scan into my solids program and then proceed to replace the mesh with solids.

 
20170707041251-f053632e-me.jpg
 

Jeff provided me with a great CAD drawing of his head gasket to work from. I decided to take a module approach to model the head. I made a single cylinder complete and the copied and offset it for the other cylinders.

 

20170707041258-d1fee155-me.jpg

I then pulled the solids together to create a single model.

 

20170707035552-40f33f0d-me.jpg

At this point I was at a standstill until I could figure out what to do about the timing chain.

 

Jeff and I had a long conversation about pros an cons of various designs. The preference would be a single chain so I ordered up a K20 set to see if it was workable. NOPE.

Lower timing gear is too small to bore out to fit the L6 crank. Back to the drawing board.

I decided to give the KA set a try. I decided the Altima set would be a good choice as it’s only a single row chain up top. With the roller rockers I don’t think you need a double row.

 

I did a rough mockup on a piece of wood mounting all the pieces. 

20170707035603-9ed2bfa4-me.jpg
 

Then I machined a chunk of plastic so I could actually mount it to the block.

You can see I’m trying to incorporate the KA guides and lower tensioner but that won’t happen without a new lower timing cover.

 

20170707041302-dbd95530-me.jpg

Here is the lower section with stock modified L6  components. The only tricky bit is I need to remove one link from the chain. I think this is a workable solution.

 

20170707041250-04bd9c3c-me.jpg

Now I could finish modeling the front and back of the head.

 

20170707041301-d2486a9f-me.jpg

Next the front timing cover. The water outlet exits the head in the front and makes a 90 degree turn through the timing cover where the thermostat housing will mount.

 
20170707041301-4286c6f1-me.jpg
 

Now the valve cover. The K20 cam towers kind of dictated the overall size but I was still able to get the styling I was looking for. I was trying to have the flavor of the S20. I’m still tweaking the design but so far I’m pretty happy. The “NISSAN” and “3000”  will be machined in so they are kind of placeholders for now.

 

20170707041307-b96207ce-me.jpg

 

After talking with Jeff about his testing on coolant flow I decided to get the most out of the 3D sand printing process as I could. I designed a water jacket that would be pretty hard to duplicate traditionally. There is a lot of surface area so hopefully there will be large improvements in cooling.

 

Here is a nice shot of the intake and exhaust cores, water core, and upper tensioner. You can see where the cross drilling will go to supply oil to the head, tensioner and idler gear lube.

There will have to be additional oil supplied to the last three cam towers as the single feed in the front won’t cut it. 

20170707035622-fe89a5f3-me.jpg
 

Here is a cross section of the head. The cut plane is through the center of one of the intake valves so the ports look a bit off. There is machine allowance on the bottom so the combustion chamber is a little larger than it will be after surfacing.

 

20170707035605-03c72abe-me.jpg

 

Well like I said in the original Goerz-Paeco post I think this is a very viable approach to producing DOHC head.  Should make for an interesting conversation.

 

 

Derek

 

 

 

Oh and one more thing.

What good would a thread about casting a head be without.......

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An actual casting.

 

20170707035600-3bc626d8-me.jpg

 

20170707035601-fdcd77df-me.jpg

 

20170707035602-e9eb9089-me.jpg

We poured this Monday and I just got these pics from the foundry today. I haven't seen the head personally but we're pretty sure it is good enough to move forward with. 

 

Still lots to do but you can't imagine how happy I am to get the first one right. 

 

As long as things proceed as planned I will be selling these. There is still a lot to figure out. I have the foundry working up some pricing for me and I'll post that as soon as I can.

 

Thanks for looking

Derek

 

EDIT: I now have a blog about this head on my site. I'm going to continue to post here but the blog is a condensed version of what you see here. There is a FAQ on the left side bar that has a lot of data. If you are new to this build you may want to come up to speed there and then start following it here as there is a lot of great back and forth that isn't on the blog.

http://www.datsunworks.com/Blog/

Edited by Derek
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Derek    46

I would have donated an RB head to you, had I known. I recycled it instead. Why didnt you make the intake and exhaust mirrored like Tony suggested?  

Hi Ray.

Since I'm using the Honda K20 valves and valve train I felt it was best to stay as close to their design as possible. We decided against the RB as a donor because the K20 just had so much stuff easily available. 

 

This build is going to be the budget build. I bought 2 K20A3 heads used. That will give me enough parts to do one head plus some spares. Since I'm not using the Vtech option I needed  4 additional exhaust rockers.

 

Derek 

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Derek    46

Nice work Derek. What are you planning for intake and exhaust manifolds?

 

Thanks.

The intake will be custom and will be flanged to accommodate the DOCE pattern. I think the port spacing on the DOCE pattern will work so I can use 6  individual Jenvy ITBs.

 

My plan for the exhaust is a little more convoluted.  L6 block on engine stand, Mount P90 on block, bolt on header and fixture it to the side of the block. Remove header and p90. Saw flange off of header. Mount new head on block and return header to fixture. Manipulate tubes with heat and fabrication to match new flange and weld.  

 

This build really is about how cheap. Although the Jenvy ITBs are a luxury, I still want them! I could go with OBX stuff and may have to if I bust the budget.

Edited by Derek

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Derek    46

Hey I just noticed that I failed to mention that ALL of the foundry sand for the mold was 3D printed. not just the cores.  There are no patterns except for some exterior gating pieces. This is pretty cutting edge stuff. I've been woking with the process for a few years now and it's really amazing. Any changes I need to make to V2 are done digitally which is nice. 

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rayaapp2    3

So what are you doing for cams then? RB stuff is stupid expensive for no real reason. RB cams are spaced correctly for the L6 though. But there is little support for them. Id love to see where your going with that, cause I cant imagine one off custom cams are any cheaper?

 

As far as cheap, I think building the intake and exhaust using an existing intake(example from the L series, or RB series) would have been easier and cheaper than all your time into a custom unit? Or at least as tony suggested the mirrored ports so one app could have the exhaust on the pass side and another could have it on the driver side, but then your back to custom manifolds.

 

Excuse all the curiosity. I am really interested in watching the progress, but sometimes I like to prod just to figure out what the path of logic was to the result they got, you know?

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Derek    46

This is really amazing.

 

Are the ports more like the Honda or the Goerz-Paeco head?

 

All Honda. At least the intake inlet and the exhaust outlet. What happens in between is  my design.

 

 

HOLY HELL! BRAVO! Can you do a valve cover with "NISSAN VTEC" machined into it? :mrgreen:

I could but in reality it's a Vtech killer. I suppose if someone was inclined they could make it a Vtech but that is a hill I'm not climbing!

 

So what are you doing for cams then? RB stuff is stupid expensive for no real reason. RB cams are spaced correctly for the L6 though. But there is little support for them. Id love to see where your going with that, cause I cant imagine one off custom cams are any cheaper?

 

As far as cheap, I think building the intake and exhaust using an existing intake(example from the L series, or RB series) would have been easier and cheaper than all your time into a custom unit? Or at least as tony suggested the mirrored ports so one app could have the exhaust on the pass side and another could have it on the driver side, but then your back to custom manifolds.

 

Excuse all the curiosity. I am really interested in watching the progress, but sometimes I like to prod just to figure out what the path of logic was to the result they got, you know?

No problem prodding!

 

I'm going with custom Crower cams. This is not as big a deal as is it used to be. Thank you technology:) 

 

Here is the really neat thing about 3D sand printing. If you want intake on the left and exhaust on the right all I need to do is 3 mouse clicks and the entire mold package is mirrored. 

 

Sometimes cost goes beyond the price of the components. The RB has cam saddles that are part of the head. This requires line boring. The K20 has bolt on cam towers. This reduced the cost of machining greatly. That was the tipping point for me. I don't own a line boring machine:)

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Derek    46

Now that is some cool stuff. Loving the simplicity of using the pre made cam towers off the k20.

 

Finding the cheap part hard to believe though

Cheap as compared to the OS Giken:)

 

I think that comes in around $40,000.00.

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Dan_Austin    10

The last couple of times a twin cam 24V L6 head topic has been brought up I thought

to myself 'That Derek fellow might just be the guy on this forum to do this in a reproducible fashion'

 

If this comes in less expensive than a California divorce I'll be all over this...

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Tony D    143

I would have donated an RB head to you, had I known. I recycled it instead. Why didnt you make the intake and exhaust mirrored like Tony suggested?  

I suggested the K20 Head since it replicates the S20 layout, so it will look proper. nobody is really going to need swappable left/right intake exhaust options, and the symmetrical ports are not flow proven. As nice a head as the Paeco-Goertz head was for it's time, the ports may not be optimal. Remember it never ran, and used who knows what for port design. The K20 is a 500CC per cylinder flowmonster compared to the L-Head, and the design is proven, and proven quite well I might add. Look at the numbers for even a stock Honda K20, and then look at the aftermarket support you have available.

 

The idea here was to use something that has tremendous existing aftermarket support, or could be scrounged from a junkyard to complete a bare head and then upgraded later. Really the cams, rocker shafts, and drive were the big imponderables. One of the reasons for suggesting the K20 as Derek said was that we could flycut the head top and bottom on a mill, and simply bolt on the cam towers as is in the Honda. That means I could machine bare castings in the shed at my house (if I ever returned...) The rockers are available aftermarket to remove the odd lobe for the VTEC, and just run the aggressive profile which can be cut on a billet easily enough---remember they are ROLLER rockers, so a lot of that sliding friction goes away as does metallurgical issues. This head would really bring the L-Series into the modern day in terms of oil compatibility as well. 

 

All I can say is "I kept my mouth shut, wasn't me who leaked anything..."

 

But if you search my posts, you will in retrospect see I was literally bursting keeping this under wraps!

 

As for scrapped heads, Derek can attest that I offered up sacrificial L-Heads so we could do a pour and say "This is an L-Head, just recast a bit different" a melding of old and new.

 

I'm happy to see it take shape and now have to turn on my iPad to get a look at the photos that must be residing there now!

Edited by Tony D

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