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Derek

Twin cam head for the L6 from Derek at Datsunworks

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I forget the stock C Chamber size, it was fairly low given what most modify them to accomplish for N/A.

The 47cc chamber is right there for a 500CC swept volume 3.0 turbo. Most of the HOMO guys are running 10:1 on their turbos, and N/A is easily run 12:1 on pump gas.

 

Even from that perspective, an L28 with a bigdome would have better torque characteristics from the high static CR.

 

The nice thing is the flow is achieved at relatively low lift, meaning  stability at higher rpms and long valve spring life.

 

Looks to be coming along well.

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Is that a Honda O-Ring, or a generic A-XXX O-Ring going in there?

Might try to see if there is an A-Series O-Ring that fits that groove acceptably, it will allow you to buy a bag for a couple of bucks and not have to buy two Four-Cylinder Kits and have two sitting around forever...

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Is that a Honda O-Ring, or a generic A-XXX O-Ring going in there?

Might try to see if there is an A-Series O-Ring that fits that groove acceptably, it will allow you to buy a bag for a couple of bucks and not have to buy two Four-Cylinder Kits and have two sitting around forever...

 

Standard dash 138 o-ring pack of 50 $6.12 Mcmaster Carr:)

 

Edit: Make that $12.00 for 20 in Viton not Buna-N

 

Amazing talent to put all this together. Thanks again for documenting all this for us wishers. I feel an extravagant expenditure in my future. Megasquirt is already in place.

 

Thanks, I think putting it all out there shows people just how much work it is to pull a project like this together. The toughest part for me right now is having to work with all of the minor design flaws that you get when you do things at this low budget level. It's really hard (for me) to think of every single item all the way through during the design phase. Plus since nobody is paying me to do this the starting and stopping is a real pain.  My modification list for the final casting design is pretty long at this point. A lot of it it making the machining process easier. Working with castings is always tough. Until you get a few of any particular item under your belt you're not really sure how things are going to work. 3D printed sand helps but it's a long way from being affordable by the likes of us. That's why I'm only printing the cores. 

Edited by Derek

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Buy 2 he says.....

I have a LS with a Maguson supercharger build that I am wrapping up.  ( I still have a laundry list of things remianing).

This build with your head will be a very slow one. I will have to really think things out because I refuse to do things twice.  I am throwing around the idea of a FULL FRP shell and exterior....

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Started working on cam tower mods and oil distribution. The plan is to pull oil from the oil pressure switch bung and Tee it to the front and the back. The front was pretty easy because I had incorporated material in the casting. The rear...Meh not somuch.

 

Production heads will most likely use the #1 cam tower at the back to supply oil but that was proving to be impractical on the prototype so I opted for a different path. I took an extra #2 tower and made a manifold plate to bring the oil in.

 

20170707040425-16df6034-me.jpg

 

 

I doweled both pieces to maintain alignment. I tapped the tower and it's held together with three screws sandwich style.

 

20170707040433-7950cfa7-me.jpg

 

 

Oil is fed in the bottom. and it's cross drilled and plugged to supply the shafts

 

20170707040445-329583b1-me.jpg

 

 

Tight fit but it will work.

20170707040448-dffc67e0-me.jpg

Edited by Derek

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This happened last night:

 

20170707040501-a91d91ad-me.jpg

 

 

And then this happened:)

 

20170707040503-7990f53b-me.jpg

 

So I took the head down to Scott's Racing engines to get it Flow tested. I'm sure TonyD will pop on here at some point and have something to say. 

 

The before column is a raw port with only the machine work for the port matching done. The after has been cleaned up really quickly with a double cut round burr and then I hit it with a cartridge roll on a mandrel. All I did was remove the sand casting texture, blend the steps between the seats and ports, and remove the additional material from the halve guide bosses. 

The clear acrylic manifold Had a 3.5" bore.

They applied modeling clay to the intake ports to smooth the air entry and they held a tube against the exhaust port to simulate a header.

Here is the before port. You can see the steps between the valve seats and the ports are still there and the valve stem bosses are too long. 

 

 

 

20170707040516-5d18d904-me.jpg

 

Here is my piss poor after port. You can see there is plenty of room for improvement with my porting abilities:)

 

20170707040518-0048c4a6-me.jpg

 

 

 

I'm presenting this data with a few caveats. 

 

Number one. This is the kind of thing that can turn ugly in a hurry as people get their panties in a wad about how accurate or inaccurate the numbers are. Try and keep it civil. 

They are just initial numbers but they do follow what I hoped to see based on my port volumes. When I was designing it I looked up the kind of volumes the K20 head gurus were running and I tried to hit those marks. Especially on the intake. The exhaust is fairly close to the stock K20 in shape but the intake is mine from scratch. I started with the stock entry and exits and made it look pretty in between. 

I don't need to be reminded how bad I am at porting.

I'm happy with the flow results and that's all that matters anyway:)

Edited by Derek

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Almost as good as a KA head  :)

 

Stock or after you work your magic? There is still .1875" minimum wall thickness left for you to work with:) I would hope you could bump those numbers a bit.

 

Edit: Grammer:)

 

Keep up the GREAT work Derek! Will you be having a sale on Black Friday? LOL, I can dream right

 

Yes you can dream:)

Edited by Derek

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Well there was a change in plans and they are being done by Crane. 


Most likely Cranes custom grind numbers RHON 240/410INT and RHON 232/360EXH. 


Keep in mind I'm running stock springs and retainers and a low compression motor so I'm really limited on cam choices at the bottom end of the spectrum.


Edited by Derek

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Didn't I recommend crane months ago......  Did you talk to Chase?  Isky is terrible to deal with, and I will never again.  I  had crane do a billet cam grind for me on a billet I built, and they got it done in two weeks.  With heat treat and copper plate......

 

 

Yea, fairly mild cam grind.

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Didn't I recommend crane months ago......  Did you talk to Chase?  Isky is terrible to deal with, and I will never again.  I  had crane do a billet cam grind for me on a billet I built, and they got it done in two weeks.  With heat treat and copper plate......

 

 

Yea, fairly mild cam grind.

Yes to all that....and I'll leave it at that:)

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