FAQ For Twin Cam Cylinder Head

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Revised 2/23/20

This is not now nor will never be an open box, install head affair. The head casting is just the staring point for a competent engine builder to put their “mark” on the head. I feel this is the best way forward so that you are not tied into purchasing parts that are not appropriate for your build. The prices I’m throwing out there are based on what I believe the production heads will take to machine as well as estimates on having the additional automotive specific machining done. As more heads are produced more accurate estimates will be made.

I’m constantly updating this list.

1)What’s the price and when can I buy one?

Pricing

The head will come without valve seats and valve guides. The best thing to do if you are truly interested in a head is to start a dialog with whomever will be building the head and work outward from there.

Prototyping phase is over and I’m in constant (but slow) production on the heads.

Currently there are two running 240Z’s with KN20 heads being daily driven. Mine and SN/005. SN/004 was built by Rebello along with a 3.5L engine. It produced at the crank 492 hp at 8000RPMs and 360lbs of torq at 6000 RPMs.

2) Will it have VCT and variable valve lift?    It won’t have variable valve lift but it can have VVT. I have it running on my head and I seem to have all of the bugs worked out. I personally feel the money would be better spent elsewhere but from a technical standpoint nothing is standing in the way.

3) What alloy is the head.  The head casting is A356 aluminum. After casting it is shipped to a company that does Hot Isostatic Pressing. They heat the head in a pressure vessel to around 900 degrees F and then pressurize it in the 20,000 psi range. This compresses the microporosity in the casting and makes the density close to billet. It is then shipped back to the foundry where they are heat treated to a T6 condition.  After I machine the head castings they are shipped to have them vacuum resin impregnated. This seals up any remaining porosity. At this point the resin impregnation is more of an insurance policy.

I’m in the process of redesigning the casting process on the heads. The HIP method was amazing but I could not control the overall shrinkage and it was causing me a lot of headaches. I’m opting for a more traditional approach by using combustion chamber chills to cool the aluminum. This will result in very strong chambers and make for a much more consistent casting.

4) What will it flow? I had the prototype Flow Tested     This is with minimal porting done. Here are the flow test results on V2 after Rebello did some port work on it. Rebello figures that the ports can easily support 450 HP normally aspirated.

5) Any provisions for coil on plug ignition scenario?  Yes. The valve cover has bosses on the inside so you can point the wires towards the front or towards the rear. It is pre drilled to point the wires to the rear.

6) What are you planning for intake and exhaust manifolds?  I’m casting a single 2 barrel manifold and that will be used 3 times. The inner ports are formed with 3D printed sand so there isn’t a part line to deal with. For now headers are custom for each build and has been handled by the builders.

7) How much horsepower is it putting out? Not sure. Making power wasn’t the purpose of the V1 prototype. It was about testing the valve train and trying out different timing chain configurations. If ultimately power is what you are looking for then the head needs engine displacement to make power. I would think 3.1L minimum.   SN/004 was built by Rebello along with a 3.5L engine. It produced at the crank 492 hp at 8000RPMs and 360lbs of torq at 6000 RPMs.

8) Why didn’t you use the Honda timing chain?  The crank gear was too small to fit over the snout. single chain was my preferred route but there was just no way to make it happen. At least not with off the shelf components.