Cad files 5.3 V12 HE

(Kevin Van Uem) #1


I am looking for cad files of the V12 block, heads or headgaskets. I tried making them from some images but I don’t have anny accurate refrence to the size or accurate images.

Contruction drawing will also be helpfull.

So if you can provide me with one of these it wil be highly appreciated!

(Philip Lochner) #2


Just wondering what you intend doing with the cad files… Might be interesting.

(PeterCrespin) #3

Dag Kevin

Ik ken iemand die misschien zoiets heeft. However, since it cost him a lot of time to develop the files I’m not sure he would supply them for free. Drop me a PM with exactly what (and what format) you need and I’ll see what he says.

(Kevin Van Uem) #4

Hi Philip,

I wan to desing and build some quad cam heads, with vvt and maybe vvl. I have made a mock-up but the demensions i acquired from a photo of a head gasket aren’t really accurate. I don’t have anny heads laying arround so I am not able to digitalize them.

Best regards,


(David Jauch) #5

If you really want to pull this through I would just gat a used head from somewhere, cheap, maybe broken. Then you have all the measurements for CAD as I am quite sure that unless you find some blueprints you will not find all the information you need.
If you want to completely redo the design then why not buy a gasket set for 200 quid or so and take the measurements. If you want to machine two heads you better spend that money on gaskets you might want to have later on should you eventually have the heads.

Apart from that you have bore diameter, piston spacing and you could draw something up and later adjust to the actual measurements.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #6


I dunno why anyone would bother with DOHC on an engine this large. Go with SOHC with rockers instead. Greatly simplifies the cam drive, greatly simplifies valve lash adjustment, and by using rockers with a gain you can attain much greater lift without huge base circles. And you can put rollers on the rockers rather than dealing with flat tappets. And I, personally, would go with a 3-valve layout, two small intakes and one big exhaust, primarily because it makes the rocker layout simple. I believe some Ford Modular engines had a 3-valve layout a few years back.

(Philip Lochner) #7

I agree with Kirby. All this development effort, time and money! Its simply not worth it IMHO. BTW, did the original XJ13 (the reason the Jag V12 engine exists) not have dual overhead cam heads? Reverse engineer those?

Presuming you have serious CAD skills, rather slap on a small pair of low pressure turbo’s (avoiding intercoolers). You’ll then get a more driveable engine that will deliver serious torque at low rpms rather than having another screamer that only really starts out performing the standard engine above 4500rpm (or whatever).

Much, much cheaper, quicker, lighter.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #8

Or go with nitrous. Much, much cheaper, quicker, lighter yet. It might help to rebuild the bottom end for more strength first, though.

(Kevin Van Uem) #9

I do have a design for the combustion chamber and inlet- & outlet ports. The valve angle is 15° that allows me to go with an inlet valve diameter of 38.5mm and an outler size of 30mm. They will probertly end up smaller as 38.5mm isn’t a standert size. Only the CFD simulations will tell me if I want to spend the money on custom valves.

I intent to use hydraulic roller rockers in combination with composite cams. The goals is to design a driveable engine arround 500 bhp. Cam phasing will make the compromise less, if you want better performance at low rpm you need smaller valves or less lift and the other way arround fot high rpm. If I can aslo incorporate variable lift I can have both.

I don’t really want to make a lot of power, I like the purity of a n/a engine and adding turbos feels like cheating when you want make power. I just want to build one because I think I can. To me it is a procces part of my hobby.

(David Jauch) #10


(Neville Swales) #11

I already have …

Please contact me by email or by my website. I can help with CAD for the V12 head faces.

The new heads are being machined as we speak.

(Paul Wigton) #12

One needs no better a reason! Ill be interested in your results.

@V12_Racer has done this recently: you might confer with him.

EDIT: might help if I actually read ALLL THE WAY to the bottom of the thread!!!


(Kevin Van Uem) #13

This is what I have right now based on a tracing of a photo of a headgasket.

The cams need to be wider appart to acomodate the cam phasers and thus be larger, this will also make the cams stiffer. Variable lift will be the same as vtec from honda, that is why there are hydraulic tapped instead of hydraulic lash adjusters altho there might be room for them. In that case it will also be easier to go to a 3 stage VVL, the only downside is that the head will have to be a few millimeters higher.

I also ran into a bit of a problem with the outher studs and I am not sure on how to solve this. The most easy way would be to divert the in- and ouletports but this will create a difrence in lenght from the inlet to the valve or the ports al will be on an angle. The later is performance wise better but will make it harder to fabricate in-and outlet manifolds, altho I am thinking of 3d printing the inletmanifold.

The volumes of the combustionchambers are just a roughly calculated without the thickness of a headgasket. I have chosen a compression ratio of 12,5:1 for now. I just wanted to see what i can fit in the chamber and schape it a litle bit.

Let me hear what you think of it, I am always open to improvements/sugestions.

(Paul Wigton) #14

Who will fab up all the components, once you’re through the design phase?

(Kevin Van Uem) #15

I am trying to use existing component when possible. I can make some small things like the rocker arms myself but there only a few custom parts that are to big or to complex for me to make, these will be outsourced. Think of the head itself which consist out of multiple parts mainly to be able to make the water jackets and oil journals. Most oil journals are in the cam and rocker towers. The inlet manifold will probably be 3D printed and the exhaust manifold can be welded from stainless steel.

The collectors are a bit to close to the block but it is possible to extend the exhaust ports with a nice curve and keep the runners equal length while it still fits in the car.


Trynader, a very interesting project. Is this for a 5.3l or an enlarged jag with 96mm bores? What material do you use to 3D print the inlet manifold?

Done right you would have some demand for these heads. People spend big bucks on their V12s.

(Paul Wigton) #17

Panel heat defectors would minimize the radiant effect on the block.

(Kevin Van Uem) #18

It’s for the standard 5.3, but recessed pistons will be needed to clear the valves right now. The material for the manifold will probably be ULTEM 9085. There will be big pressure differences in the manifolds so it might not be strong enough in which case I will resort to cnc milled 7075 aluminium or print a plug to make a mold for a carbon manifold wich will be the cheapest option.

Because the inlet ports are quite big now I resorted to an oval mid section in the inlet manifold so the runners can pass each other. They aren’t faired, so yea I know there is a funky kink. The sectional area is the same as the port so flow should almost be the same as the round sections. Again it is just a mock-up so I used some parts of an old desing for the 2 valve engine I made a few years back and scaled them a bit. I don’t think itb’s will be practical so i’ll just slap a pair of throttle bodies on the ends. I won’t make anything precises until I get the sizes of the cam phasers.

Rotating the ports won’t do anything good. If I use the same trick as with the inlet manifolds it would create a complex exhaust manifold which cannot be printed. Maybe a rectangular shape with rounded edges will be the best compromise.


Trynader you have some serious skills. Did you see the Jenvey intake?