TheSamba.com :: View topic - The official thread about: 2-piece 356 engines

Fri Nov 09, 2012 3:56 am

I hope we can gather some information about the early 2-piece engines in the Porsche 356 here in one thread.

I am restoring a June-1951 Coupe and with regards to the engine, I am doing a fair bit of investigations...

My car had a Typ 506 1300ccm engine originally, and the original was destroyed during ice racing on some Finish lakes in the 50ies.. I am building a new engine for my car now.

All 2-piece cases for the 356 was cast and supplied by VW. VW switched from aluminum to magnesium on January 19th 1951. Many claim that Porsche bought a load of the "rigid" alu-cases in fear of the lighter Mg-cases being to weak for the sportscar. The same rumor states that all 356 2-piece engines (up to 54) were all based on "old" alu-cases from VW. This can not be true - I have seen and pictured many 53-54 2-piece 356 engines which are all based on Magnesium-cases.

So...to my main question: When did Porsche switch from alu to magnesium in their engine cases?

...the same time as VW (jan 1951)?....or at the end of the 1100-engine? ....or is it true that they "hamstered" alu-cases during the winter of '51 and used them as long as they could?

I guess the most correct answer would be if Pre-A owners chime in here with their knowledge of original non-restamped 356 cases from 1951-54....are they alu or magnesium?

Thank you in forehand...feel free to chime in with other 2-piece knowledge as well...

Fri Nov 09, 2012 5:00 am

For the record: I am only publishing pictures that anyone can find on the net - not publishing anything I have photographed myself.

Here is one very interesting car to support the first post:

Coupe no 11237 - Early February 1952
1300ccm Typ 506 engine no P-20905

Totally untouched original car...the close up of the engine give some very interesting hints:

1. Magnesium case (judging from the picture)
2. Hole for oil filter is there and machined, but plugged and not used (many say oil filters were optional from 51, but std from 53)
3. Casting-area around engine number is of "VW 30hp"-style", not "VW 25hp-style"...and this I find very strange...

Fri Nov 09, 2012 5:06 am

To illustrate my engine-number casting-area difference - here are two pictures of some VW blocks I have:

May-1952 VW 25hp Magnesium-case:

January-1955 VW 30hp Mg-case:

.....very very strange that a Feb-1952 Porsche case has the "post-Dec-53" VW type engine casting....this is a mystery to me.

Can anyone shed light on this?

Fri Nov 09, 2012 6:47 am

I sold a '51 (without engine) to Dr. Brett Johnson, which he raced for a while with vintage groups here in the US. Have you corresponded with him?

I believe he used VW engine basics.

I can send his email address to you if you wish, please let me know.

My own experience with very early 356s did not begin until I had three 1953 models, 2 Coupes and a Cabriolet. I would like to participate here in this thread, but I will just politely read and learn, as I have no 2-piece case engine experience at all.

Fri Nov 09, 2012 10:14 am

The question interested me sufficiently enough to do a little searching. Samba classifieds have a recently sold Jan-51 25hp witha serial # just post 1/19 cutoff. Case appears to be electron/mag. Square sserial # area. I searched the classifieds and gallery section - no 25hp had the rounded/curved style area surrounding the serial #. No 36hp engines had a squared serial number area. My 6-54 was the earliest I could find (after searching duh) and its curved.

So onto Porsche. I looked at Joe Ruiz' (aka Mr. Okrasa) http://www.prea356.com/ and he has photos of pre-A engine build with a serial # just above the P20905 provided above. Square serial number area.

I am NOT a 356 person, but all this leads me to believe the following - Porsche likely did NOT stockpile large numbers of aluminum engines as they were really still in the startup phase of production at the beginning of 1951 and being that I see no VW electron/magnesium 25 hp engines with the rounded area, the photo provided above leaves me with a big :?:

So for the purposes of the original poster, my thinking is a electron/magnesium case would be in order for a June 51 car and it should have a square serial number area.

If proved otherwise, I'll gladly stand corrected.

Fri Nov 09, 2012 10:50 am

Thanks a lot for your inputs - all appreciated!

Would you mind posting the pictures of the Ruiz block? I can not seem to find it.

Fri Nov 09, 2012 11:19 am

# appears to be 322xx so above the one originally posted is this an A or pre A irrespective, still square. Paying closer attention - interesting that the 2's on each case are stamped differently, but that is possible. You might want to PM Mr. Okrasa and ask about this issue.

Fri Nov 09, 2012 12:29 pm

Thanks!

This block above is a 1954 number for a 1500 engine.... Very odd that it is a "angle type" number area...it would be really interesting if Ruiz could post the date code of this block on here.

Fri Nov 09, 2012 12:37 pm

More...

So - two key questions we are trying to adress in this thread so far:

- When did the VW casting change from "angle type" to "curved type" in the area around the engine number?
- When did Porsche change from alu case to magnesium case?

Just to show what an aluminum case looks like..in the area we are discussing, here is a picture of a June-1950 engine:

Fri Nov 09, 2012 12:55 pm

OK...I went through some engines in the barn here..

The change in the casting in this area must occur sometime during 1953...and we need more pictures of original VW engines from this era..

No doubt, the "curved type" was introduced during the last year of 25hp production, so there is both styles on a 25hp.

December-1952 Type 1 Zwitter engine;

December-1953 Type 2 engine (last 25hp T2 engine was no: 20-0695356):

Fri Nov 09, 2012 12:58 pm

I found 356 forum user Jack Stenner's (hope he doesn't mind) pre-purchase photo album. Here's a shot from his photo album.

http://visuals.jigglingwhisker.com/gallery2/automobiles/porsche/pre-purchase/IMG_0469.jpg.html

As you can see just slightly above the serial # I provided earlier. So, my question would be when did Porsche stop buying VW engines and start casting their own? Was it after the transition to the A?

As to VW - My guess is that the curve was most likely started with the introduction of the 36hp at the end of 53. I'd have to look for engine photos from that time period to see the tail end of 25 hp production and the start of 36 hp. Again, I I have no 25 hp with the curved area. Could be wrong.

Fri Nov 09, 2012 9:06 pm

replacement 25hp cases after 1953 were essentially 36hp castings with the smaller 25hp cylinder bores, I have seen many NOS "replacement" 25hp cases with the 36hp style serial number casting, I would suspect that the "totally untouched original car" has a restamped original engine number on a replacement case, in many places prior to the standard VIN number system cars were titled and registered to the engine number which would require a replacement engine to be stamped with the old number,
pluralitas non est ponenda sine necessitate: William of Ockham

Sat Nov 10, 2012 10:08 am

52 1300 case

Sat Nov 10, 2012 1:07 pm

Quote: replacement 25hp cases after 1953 were essentially 36hp castings with the smaller 25hp cylinder bores, I have seen many NOS "replacement" 25hp cases with the 36hp style serial number casting, I would suspect that the "totally untouched original car" has a restamped original engine number on a replacement case, in many places prior to the standard VIN number system cars were titled and registered to the engine number which would require a replacement engine to be stamped with the old number

Makes sense. Would a Porsche engine have been subsequently rebuilt wth a VW case?

Sun Nov 11, 2012 11:47 am

All Porsche 2-piece cases are modified Volkswagen cases.

Mon Nov 12, 2012 10:48 am

I have Porsche crankcase P 10053, which is a 1100 block. This was originally from a model 50 car.

I can confirm it is Electron/Mag.

Personally, I think Porsches' use of material in there cases ran concurrently with VW, so only Gmunds and early model 50's got the Aluminium case.

Mon Nov 12, 2012 11:09 am

So I did a little cleanup and tagging of my images of early engines. Here is a set of '53 engines sorted by serial number. You can see that the earlier engines have the "angle type" casting and later you begin to see the "curved type" casting. The last two images are of an early 1500S, so the casting is consistent with the earlier form.

Of course, this is a small sample, so you can't really say anything definitive. But it looks like the casting changed during '53 model year production. All of my '54 images are "curved type" castings.

Would be nice to have a larger set to compare!

Mon Nov 12, 2012 5:12 pm

I typically wouldn't post in this forum but since I picked up this motor today I am!! Short block only so can't answer too many questions but if anyone needs any case specific info let me know.

Motor# comes up as a January 51.

Tue Nov 13, 2012 1:31 pm

Wow - thanks for a lot of valuable inputs!

A couple of points/conclusions:

- The change from "angle style" casting to "curved casting" on the 25HP blocks occured sometime mid-53, as opposed to "believed knowledge" of this happening together with the 25-to-30/36 change at the end of 53. Very interesting! - I guess we need to get a thread going over in the Oval-forum in order to picture and define exactly when this change happened...

billmetric;
Yes indeed - you point to a very good point/conclusion. I support it and believe it is a valid conclusion....this early 52 car has had its block replaced and restamped at some point.

splitvws:
Wow - nice block...not too far from my own car....do you want to sell that block?

52 deelux:
Extremely important info!!! If what you are posting is true....we (you) have just answered one of my key questions... Your engine is from around 10th of March 1951...7 weeks after VW swapped from alu to mag...and if your engine is authentic...then it prooves that Porsche did not stockpile alu-cases and indeed did the change when VW did it.... It even shows that 4-digit cars made after Jan 51 has mag cases...I believe "everybody" thought all 4-digit cars had alu cases....WOW...thanks for the info. One important thing: Could you give us the casting date for your block on the side of the generator stand??? Thanks a lot in forehand!!

jjjjack:
Thanks for all the hard work and good info....again - goes to show that VW changed the casting in mid-53, with the last half year of 25hp blocks having "curved style"-casting.

turkis-deluxe;
You have a very early VW mag case...the change occured with engine number -1-0272061 on 19th Jan 1951.

Tue Nov 13, 2012 1:45 pm

52deelux:
I got so excited by this info... could you post a picture of your engine block please?

Or pm/mail... Very interesting!