3-valve OHC type 4 (Apfelbeck) cylinderhead project

[Beetspeed]

Hi Guys,

Very exited to let you all know I have taken it upon me to breath new life into the 'Apfelbeck project' my mates have already put so much time and effort into!

In short: I have 3 old (non-usable) castings, a set of digitalised CAD-CAM files of heads and casting molds and most parts for the cam-drive.
So, to get an idea what it looks like, I mocked it up:

One of the original castings (yes, its a large head volume!):

The heads on one bank will be rigidly connected by a thick plate:

Pictured with individual TB's, but I noticed the inlet bore spacing is _very_ close to that of 48IDA's, so I might have a manifold fab up for IDA's since good quality IDA TB's are also available these days from several companies.

To sum up why I am so exited:
- OHC makes for low spring pressure high rev stability;
- 2 inlet valves canted make for great flow (old casting did 270-ish cfm on the 'smaller' 2x36mm valves at just 0,50"lift);
- large cooling fins with ample space between fins
- roller cam profile (with roller ratio rockers) like Ludwig Apfelbeck described in his tuning book.
- twin spark as standard;
- pentroof 3V design with still some squish locations should bring better mixture quality then the Porsche 911 half-sferical combustion chamber;
- equal length head studs makes for a more even clamping force;
- its a piece of history! The pictured castings were made with wooden models in the early seventies, late sixties already specifically for the VW type 4 engine!
- 230hp from a 2 liter engine was expected to be possible (from the tuning book), but on engine analyser-pro with our initial flow data imported, it seemed that 260hp was very possible!

Of course everything still has to be 'proven' in reality and I am a long way from being able to build a complete engine.
The casting models are being developed at the moment though, so things have been set in motion to make this a reality.

I am keeping a more detailled diary on FB on the project:
https://www.facebook.com/ApfelbeckOHC

Of course I'll keep you guys updated on the progress here with more major updates if there is still some type 4 love on here .
Walter
_________________
'75 Superbeetle 1303: 400hp at 1.0 bar boost
'69 notch 1500N - 1641cc

[nogoodwithusernames]

Very cool! I remember reading through the website and thread over on STF years ago and thinking this would be super awesome when complete.
_________________
71 Squareback, T4 conversion
(Conversion thread https://shoptalkforums.com/viewtopic.php?f=1&t=151375&sid=f0542d44a322d290c29d6609fac7f215)
74 914, 2.0L D-Jet

-Derek

[mark tucker]

sweet! those are nice!! I would change ( as I do everything) the chamber shape some at the ex valve sides so it flows better and has more quench area,get rid of the flat floor in the chamber around the seats. .that ex valve looks a bit big,as does the port. I would fill about 1/4 of the floor on the ex port too,possiably make it smaller rectangle so the flow has directional walls to keep it going the right way...or go 4 valve. all the hard work is done. Ive thought may times about going over head cam with my 910 heads, but Ive got too much into what I have already. Get to work and getter done!!

[Beetspeed]

Thanks for the pointers Mark! I never looked at it that way, but I think I see what you mean.
BTW, exhaust valve in this first set-up is 42mm.
_________________
'75 Superbeetle 1303: 400hp at 1.0 bar boost
'69 notch 1500N - 1641cc

[Alstrup]

They are very cool a d can support a lot of power.
I do not know if they still race, but there were a coupme of Austrian guys if memory serves, that raced with Apfelbaeck e gines in rallycross and short course hill climb. Those two engines pulled arou d 230 hp and didnt even rev that high. Around 7 grand.
Put those on a 2275 and Im sure 260hp is almost a walk in the park.

[Ebel]

I remember these from a long time ago. I always wondered what happened with it. I hope you get it finished. Must be a lot of time and money in that project by now.

[Wreck]

would a slight redesign and use a cam box like a 911 be worth the effort. I Just wonder how hard it will be to get and maintain the cam/bearing tolerance with the 2 seperate heads ,even with the stiffing plate/rocker cover .

Will it end up boosted .

[Bad bug]

Good to see that this is back. I am wondering if these heads could be fitted to a 101mm or 103mm bore engine and what would be the total power output running a 80mm crank.

[Beetspeed]

[Beetspeed]

[Chickensoup]

I’m in love

[Chickensoup]

I’m in love

[Alstrup]

[Bad bug]