The Cal-look Lounge

Hey there,

my name is Jerry. I live in the south-western part of Germany and drive a 55 swing axle bug with Porsche 356 drums and 1830 ccm type 4 engine. I am a casting engineer and I love designing things.

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When I did my last quarter mile pass in 2016 in Bitburg with a 14,8s ET I got somehow bored after shifting in 2nd gear and waiting till finally approaching the finish line. I thought I needed more bang for the bug.
It was no option for me just to increase the displacement which would have been a quiet easy idea to gain a higher power output. I definitely wanted to keep the original and very durable 94 mm x 66 mm concept of the engine because it features the super stable original VW crankshaft with the 55 mm crankpin and a relatively small bore which keeps the load of the bulkhead low. So how to increase power and keep or even improve the durability?

At that time I definitely decided to go for an old idea: I wanted to have my own, self designed cylinder head for my car.

Three items where on top of my personal requirement sheet

- efficiency
- durability
- some extra horses of course

It’s 2020 now and I made some progress I would like to show you.

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The head shall be cast in 2021 from the alloy AlSi7MgCu0,5.

I don't know if the pictures are properly displayed, if not you can find more information here: https://www.instagram.com/p/B4AjGiFomuo/?igshid=4jalzevmlj2h

Interesting initiative! It is going to be done by gravity casting but what type are you going to implement?

Gravity casting is possible, but the thin and long fins require a very careful process layout. The current plan is to cast the heads by low pressure casting in printed sand molds.

Marvelous, please document the process! Do you plan to simulate the casting beforehand?

This are Heads of
 Rolf Klaus !

I think they know each other:

https://youtu.be/LseCa1kDzGA

@ Morgan: There will be definitely a casting simulation, otherwise it could be a quite expensive experience. I don't know yet who will do it, but I will give some updates on the project.

@ malec 300: You are a good observer. The heads contain a lot of Rolf Klaus' ideas.

@ Arnoud: You are right. The cylinder head is a kind of father and son project. I started the whole thing on my private base to bring the type IV air cooled history into the future with a current alloy and apply everything wich is technical feasible from casting point of view.

Have you flow tested the intake side
And above all the exhaust side of the 3D sample

/// Micke

Hi Micke,

I did not test the current resin prototype. The intake and exhaust geometry featured a very basic design. I just ordered a new cylinder head resin protoype with the more elaborated geometry of the latest stage you can see on the pictures with a manifold belonging to that design. The parts should arrive within the next two weeks and I am really excited for that moment I can hold the new parts in my hands.

The next steps will be mounting trials again and flow bench testing in 2021.

A maximum flow is quiet important for a good power output, but especially for a street driven engine I took care not to overdo with the intake and exhaust channels size, because I want to maintain good conditions to build up a resonating system for an improved cylinder filling.

It would be very interesting to have some more comprehensive flow bench values with testing conditions to compare with. I found a nice source in the VW TECH L'atelier magazine issue 12, having some more material would be interesting. Maybe you or somebody else somebody in the lounge has some material?

J

That with flow can be tricky to think it works
The air can go strange ways that did not think worked
Important things are the combustion chamber design for it to flow well
Angles on valves can also cause it to flow better or worse
The important thing is that the flow increases with the lifting height (where combustion chamber design is important)
That with the size of the channel on a street car can be small but if it flows poorly it can be devastating(Ps surface finish should be rough if you want more flow and gas velocity
Not blank or fine
  But if the flow is good, it can be very bare driveable with a lot of power
I am adding a link from a Swedish site So Can you build your own flow bench on a weekend(and a few days It works great with vacuuming engines)
http://www.topplocksverkstan.se/flodesbanken.html
tonight's testing of my racing head
/// Micke
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Hello Micke,

thanks for your reply! How did the testing of your race head work out?

I fully agree - the combustion chamber and valve angle play a very important role concerning the flow of the head. I carefully revised the valve angle and finally kept it stock type 4 and I am happy with it. I still have the original valve train geometry which keeps everything simple and works pretty well since the 1960ies.

I modified the position of the exhaust port which enables for a better flow and better cooling between combustion chamber and exhaust port.

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Love this!  Thanks for doing what you do and for sharing.

How about to just consider in the casting additional material for us who run 103-108 large bore cylinders, prepared for 5-6 stud?

Yes, it got better than I expected  :D
That few degree angle change can do so much
+15 cfm @ 25 "water column of 14 mm on a 44 mm valve
/// Micke

Hello Frallan,

I like the cal look lounge and follow the forum since the early 2000s if I remember right. The whole thing lives from sharing and now I have something I can share :-)

The layout of the head is rock solid up to 103 mm, a bigger bore might be possible but was not intended. I revised the original design and put more material where needed to go up for a durable 103 mm bore engine but not above in order to let the air pass properly through all sections I created. I also added new very stable load path for the lower cylinder head bolts as this is a weak point of the original heads. I enabled for a proper airflow around these load path to keep the whole head cool, especially around the exhaust port.

All areas of the head which do not face high loads are designed to a nominal wall thickness below 4,0 mm. So the head is very light.

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I stayed with the original four bolts which can handle 250 horses or more (with a 2,6l with 103 mm bore) which is enough to kill the crankcase after a few 10.000 circuit kilometers. I don't know when the clamp load of the original bolts does not hold the head to the cylinders anymore, maybe you have some experience as a turbo guy. However it's still on my list to calculate the bolting condition. The whole combustion chamber of my new head design is very stable and can easily handle some assumed 90 bars peak firing pressure for a normally aspirated engine. I want to do a simulation to find out where the limit is reached for a turbo application (there are so many things on my list but time is rare). For my application the big boost is not relevant. I created that thing to endure till my retirement and above.

It's always a great feeling when something works out like intended and even better :-) I am a little away from that point and I am looking so much forward to that moment

Very nice, going to follow this closely.

I see you have the ' klaus air funnel ' at the bottom of the head. what does this do?

Regards Eddie

THANKS!  I do like your answer. Excellent strategy and good engineering.

Hello Eddi,

one root cause for leaking cylinder heads is like following:

- the engine gets hot during operation and the cylinder head expands
- the clamp load of the head bolts holds the expanding head to the cylinder
- the aluminum of the cylinder head wants to escape from that pressure and creeps locally sideways or where it can go (the creep is higher on the positions where it is locally hotter)
- when the engine is cold after shutdown the aluminium which has creeped away is missing in the area of the sealing line and the head leaks...

So the solution to overcome that issue is to have a homogenous temperature distribution on the whole sealing area of the cylinder head and to keep it as cold as it is possible!

The air funnel is one part of the solution. It ducts cool air from the fan shroud to the lower side of the head where it cools the combustion chamber. It is a kind of 3D cooling because it cools the vertical fins oriented in direction to the street and the horizontal fins oriented sideways. The horizontal fins have furthermore a stiffening function and are directly attached to the sealing line of the cylinder which ensures good material properties, a high hardness and a low heat expansion of the aluminum in that area. The air cools very effectively because it hasn't been heated up by cooling other areas of the cylinder head before and because it has a high velocity since it goes the straight way from the shroud without being redirected before by sharp edges or by any tight sections in the head.

More cool and fresh air is directed between the intake manifolds to the lower side of the head. The vertical fins below the intake manifolds have a cooling and and stiffening function of the head.

For every fin of the head the condition of a highly forced convection is true which enables for a very efficient cooling.

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Hello Frallan, thanks a lot! I am looking forward to the moment when that thing is running for the first time!

Thanks for that info, sounds very good to me.

I would make them with smaller ports too , for street use and for the head porters to do their own work .   I thought only Rolf Klaus would sell them ...

Hello Udo,

thanks for your feedback, I appreciate it a much and like your super quick car, it's always fun to see it blasting down the 1/4 mile!

I started the project on my private base in order to touch borders in all concerns like durability and efficiency combined with a satisfying power output. So the ports are adequate for my personal goal of exceeding 75 kW/l. The port layout complies with established layout formulae. Maybe it just looks a bit bigger on the pictures than it is in reality. The free cross section at the intake flange equals a round port of 43 mm diameter, the whole design of the ports is very harmonic which enables for a good filling and cylinder charging.

BTW, there are several engines running with a similar port layout, all of them have a pretty good low end torque and an excellent power output. I think one car is well known: https://www.youtube.com/watch?v=BRu_duooFbo (https://www.youtube.com/watch?v=BRu_duooFbo)

I have been asked why the ports are square shaped, there is only one reason: The square port leaves about 8% more cooling air (in the area between the intake ports) to the lower side of the head than a round port with the same intake cross section.

And let's talk about selling and purchasing in the future, I will let you know when the time has come! The head shall run and be carefully validated before. My personal motivation and the reason why I started the project was to have a cylinder head for my engine which reflects all my wishes, ideas, experiences and learnings concerning air cooled engines, material science and foundry technology. In fact I started about 20 (yes 20 ...) years ago about with researching literature, reading numerous papers and books and browsing the web for countless hours. I started the project in hardware about three years ago and did everything from scratch following the standards of automotive industries as far it is possible with such an old engine concept and the available time and resources. And I never stopped asking my father Rolf Klaus about his thoughts and ideas to transfer them into my project.

BTW, there are several engines running with a similar port layout, all of them have a pretty good low end torque and an excellent power output. I think one car is well known: https://www.youtube.com/watch?v=BRu_duooFbo (https://www.youtube.com/watch?v=BRu_duooFbo)
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Thanks for that link and entertainment. No, the car on the track is not known to me and it would be fun/interesting in knowing a bit more about engine, transmission and maybe brakes.
A link to a site with that car or similar?
A wild ride on Hockenheim which is well frequented by me, but only so far when the show is Drag Racing.

Thanks for that link and entertainment. No, the car on the track is not known to me and it would be fun/interesting in knowing a bit more about engine, transmission and maybe brakes.
A link to a site with that car or similar?
A wild ride on Hockenheim which is well frequented by me, but only so far when the show is Drag Racing.
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Hello Frallan,

the car has a 2,6l with 46/40 valves with modified cylinder heads and a 78,4 Oettinger crankshaft. The gear box is a Porsche 5 speed, the breaks in the front feature Porsche 996 calipers and Kerscher in the rear.

I made some progress on my project and received a new toy last week ... the 3D printed mock-up of my head arrived. :-) I did some first evaluation concerning assembly and cooling air flow and I am extremely happy with it!

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Very nice!!!

Super

Will you be flow testing the 3D printed model? 

Have you done any CFD analysis on the port flow? 

I love where you are going with these, and it will be great to see a cast option come to market. 

I have ported lots of heads, and I agree... Leave the ports small as possible, and preferably round all the way through.  I would think and ideal shaped intake port would take precedence over the 8% larger cooling area, especially between the intake runners.  If you were closer I would put them on my flow bench for you and see how they do.  It would be interesting to see the average airspeed, and the E/I flow ratio. 

Brian

.   Thanks for the info / I talked to your father about it and waiting for selling them

Hello Brian,

thanks for your kind words and your comments!

I am going to flow test the heads, this was one purpose of the 3D printed parts. I didn't do a CFD analyzes. A comprehensive CFD simulation would be a very mighty project if done properly. Maybe I will do something similar to a flow bench test in virtual reality.

Do you have numbers on flow bench results and average air speed? I found this interesting thread on the samba https://www.thesamba.com/vw/forum/viewtopic.php?t=573099&postdays=0&postorder=asc&start=100 (https://www.thesamba.com/vw/forum/viewtopic.php?t=573099&postdays=0&postorder=asc&start=100), I am always interested in more material.

I agree, a round port is usually better than a square shaped one. I calculated the hydraulic diameter of the port before I went into CAD in order to have a rough indication concerning the flow of the square shaped versus a round one. As I mentioned the free cross section of the port equals a round port of 43 mm diameter, the same is true for the hydraulic diameter which is close to the 43 mm round port. I am very confident that my ports will deliver really good results due to the very harmonic shape and carefully designed radii which shall effectively avoid stagnation areas.

The proper cooling of the head is #1 priority for me. We have the Autobahn in Germany ... here you find out what is poor, just good and what is the best concerning constant and reliable power output. Charging the cylinders with cold air means to maintain a high power output during hard operation. Therefore I have a lot of cold air around the intake ports. The Dodge Viper has a composite material intake manifold in order to keep the intake air cold in the hot engine compartment (https://www.springerprofessional.de/the-evolution-of-a-performance-powertrain-the-dodge-viper-8-4-l-/12070668 (https://www.springerprofessional.de/the-evolution-of-a-performance-powertrain-the-dodge-viper-8-4-l-/12070668)). VW claimed in the early 1950s that a 10 degree Celsius cooler cylinder gave a 2% higher charging of the engine. (Versuche an einem luftgekühlten Ottomotor, R. Poppinga, MTZ, Jahrgang 14, Nr. 5, Mai 1953).

I need to correct myself that there is only one reason for the square shaped port - it is not only the free cross section for the cooling air to the lower side of the head, it is also a design feature. The square shaped port is in integral component of the structure of the head which significantly adds stiffness to the whole cylinder head. The combustion chamber is supported by the rocker arm housing and the intake ports and ribs connect them with each other.

I am going to do the first preliminary trials on the cooling air flow in the next weeks, finish the functional description and FMEA analyses. 2021 will start with flow and assembly testing (when Corona and my available time allows for it), casting and machining is going to follow after successfully completing the tasks.

Have a nice x-mas time and new year's eve!

Most important is the direction of the port - most cut material where it is needed. Best is experience on size and how it must look like.  I also like material around the guides on exhaust and intake.    We have the most power with square ports but also up to 270 on a 42 round with billet heads . 

Any progress here  ;)

Hi there!

Yes, there is defintely some progress! At the moment I unfortunatelly have only little time to share and to work on the project. Give me a while to report the details. I have the first flow bench results, I am very happy with the port efficiency, the intake channel is choking a little bit at higher valve lifts, I think I identified the reason and will do some modifications and retest.