TheSamba.com :: View topic - Porsche 356 PreA 2-piece case engine heads

Tue Feb 15, 2011 4:13 am

I would like to see some detail pictures and info of the evolution and variants of cylinder heads used on the original 356 Pre-A 2-piece engine cases... Are there any good sites / sources / albums of this?

Thanks.

Tue Feb 22, 2011 2:53 pm

Hello-

You might want to try stefi.g. He seems to work on Pre-A engines.

Paul

Fri Jul 01, 2011 12:48 am

If one were to put a Porsche-head on a VW 30/36HP engine case/cylinders....from what type of 356-engine would this nead need to come from? Only the 2-piece engines, or would a 3-piece head fit onto a 2-piece case?

Fri Jul 22, 2011 2:48 am

Didnt the guy at BBT who built the coachbuilt outlaw use 356 heads on a VW 30hp engine?

Thu May 09, 2024 4:37 pm

SplitPersonality wrote: If one were to put a Porsche-head on a VW 30/36HP engine case/cylinders....from what type of 356-engine would this nead need to come from? Only the 2-piece engines, or would a 3-piece head fit onto a 2-piece case?

Only 2PC engines work: BOTH the head stud locations AND the cylinder spacing are different.

I've built quite a few... If Stefi's still making those heads, that's the way to go!

RT

Mon May 20, 2024 3:09 am

rtroy wrote: SplitPersonality wrote: If one were to put a Porsche-head on a VW 30/36HP engine case/cylinders....from what type of 356-engine would this nead need to come from? Only the 2-piece engines, or would a 3-piece head fit onto a 2-piece case?

Only 2PC engines work: BOTH the head stud locations AND the cylinder spacing are different.

I've built quite a few... If Stefi's still making those heads, that's the way to go!

RT

There are some possibilities based on 356 pre A engines
a) 1100 ccm till 9´54
b) 1300 and 1500 ccm

Its rather easy to built a 356 engine in a VW 24,5 HP-case, when you go 1100 ccm-based. VW crank and rods, 356 Pistons, Zylinders, heads, and valve-train. The VW-case can remain untouched, not machined.
Well, the parts are rare and so some sort of problem.
Pistons were 73,5 mm stock, but i have a used set also in 75,5 mm, not knowing where it really comes from. Getting 75,5 mm Porsche-style-pistons, you can go with used 75,0 mm VW cylinders und machine them up for 75,5 mm.
The Porsche 1100 Zylinders have the same diameters and lengh as VW cylinders, only a bigger wall, matching VW case as well as 24,5 PS heads.

Early 356 gmund-engines used single-port VW-heads.
Then for the new Porsche-designed dual port heads, late 49 onwards, there were at least 3 in details different versions for 1100 ccm heads till 9´54. (lying around in my humid cellar) The first 2 versions had 4 x M6 studs for the intake manifolds, the third version has the common 3 x M 8 studs. All newer 356 manifolds fit the last 3 x M8 version. Sorry, I still don´t know, how long the 4 x M6 heads were originally used, guess late 50 to early 51. Who knows better?

For 1300 or 1500 ccm VW cases, 24,5 or 30 HP must be machined, at least for cylinders. Porsche crank bearings have 60,25 mm outside, VW only 60,0 (standard)
Once, the case is machined, it´s rather easy going, solving some minor further tasks. But going pre A Porsche engine, due to rare and expensive parts, there are lots of $$$ per HP at the end. Porsche is always interesting, mostly good, but never ever cheap!
For 1300 and 1500 ccm Porsche engines, there are some different heads with 8 mm or 10 mm valve shafts and small round or bigger oval intake channels. But all of these (pair) of heads fit the stock 80 mm alu-cylinders with hardchrome surface. (aftermarket in GG and maybe alu/nikasil)

There were aircraft engines with 74 mm Porsche crank, combined with good cooling 80 mm alu cylinders and 80 mm flat pistons, for ex from early 2-piece Porsche industrie engine and machined cheap VW 30 HP heads along with cheap (may be a bit boaring) VW cam and valve-train.
Designed for 1500 ccm, output around 42 HP at 3000 RPM (for airplane-use)
A rather tasty and good invisable combination in single-carb, or period in dual carb-setup for beetles and co.

Sun Sep 15, 2024 10:33 pm

Don't do it just to get more power, though! A good friend of mine did extensive flow testing and found the Okrasa heads made more power. Not to mention the valve gear was simpler!
He used the 1100 displacement and Okrasa heads in a 356 chassis and got a world land speed record in his class about 1969 or so.

Mon Sep 16, 2024 1:48 am

Alan Brase wrote: Don't do it just to get more power, though! A good friend of mine did extensive flow testing and found the Okrasa heads made more power. Not to mention the valve gear was simpler!
He used the 1100 displacement and Okrasa heads in a 356 chassis and got a world land speed record in his class about 1969 or so.

That sounds interesting. Is there more information about engine setup or pics, maybe from Bonneville? Are there documents?
Was the LSR-event in the year 1969, 55 years ago and if so where, or has that number another meaning?

Mon Sep 16, 2024 5:05 am

Google Tom Bruch, Cedar Rapids, Iowa. Might have been 1966? I visited with Tom many times. He got his first record with the Speedster, but I think he garnered several over the years. Last I knew, he was still living, but about 90 years old.
https://www.facebook.com/groups/601238493280887/?h...0553938649

Sun Feb 09, 2025 2:45 am

hi guys, I still produce PreA heads, all they are in stock,you are welcome to contact me.