Replica engine

[Impi]

I have been giving much thought into modifying a 1600 twin port beetle engine to replicate the feel and running characteristics of a 1600 Porsche engine. Obviously the Porsches internals are much lighter and there is some differences in the heads but I am sure they can be gotten around. The tin ware will be modified to look the part as well
My thoughts: lighter 8 doweled flywheel
counterweighted crankshaft
40mm x 35.5 valves
Port and polish job on the heads
8 to 1 compression ratio
40mm dual carburettors (weber IDF)
electronic ignition
Cam with about 276 degrees duration
Oil pump with filter
Fully balanced
Exhaust which mimics the original.
I am sure 80 hp is possible with this combination for a relatively inexpensive engine. To get to 95 hp maybe 1776 with 90.5 cylinders is the way to go.

Can anybody elaborate on these thoughts please?
Armand

[Tony G]

[JTR70]

Thanks Tony! Very impressive right off the top of your head at work on a break.

[Tony G]

Some thoughts....

A nicely configured 1776cc (69mm stroke x 90,5mm bore) would also yield decenty performance but I like the 74mm stroke over the 69mm and since you will be counterweighing the crank, why not step up? Another option is to use 90.5mm B stroker pistons with the 74mm stroke and use longer rods to get you a better rod ratio and lessening the cylinder shimming.

The main things I would focus on is trying to mimic how Porsche attained the displacement and performance characteristics (i.e. carburetion, head design, camshaft, ignition, exhaust, compression ratio, and combustion chamber, etc..). Some small bore combos will get you near 1600-1750ish cc's. Basically, the Porsche 356/912 engines breathe a lot better thermodynamically due to their overall design configuration. Hard to believe how two physically similar yet different engine configurations with the same displacement perform so differently. Don't be afraid of breaking the 9:1 compression ratio and aim to be between 9-9.4:1.
Good luck.

[Impi]

Hi Tony
Thanks for the valuable inputs. I am in the collecting stage of the parts and will be asking more questions as I progress. I also do an upright conversion on the type four engine which should fit into the 356 with ease but I haven't tried it yet.(installing into the 356 that is) a few of them are running around.
Armand

[roy mawbey]

Wow, some real experience here with engines.Really interesting considering you are not having to modify parts but buy them in.

Thanks for your input.

Roy

[Tony G]

I've done several Type 4 upright conversions and one of my faves is the 1911cc 66mm stroke x 96mm bore. Heads are P&P'd and 42mm x 36mm valves fed by 40 IDF/DRLAs. 280ish cam and full-flowed external cooling/filter system. Easy, cheap, reliable, and peppy!

[JTR70]

Roy, I came to learn several years ago just how highly detailed and sharp Tony is in the world of Air cooled engines. His practical knowledge is impressive. Thanks again for sharing some of it Tony!

[Tony G]

No problem. Working on these cars is my escape from my primary job. Happy New Year everyone!

[Jonesy_356]

This is very awesome advice Tony, thanks for sharing. I am lazily considering putting a beefed up VW donk into my BT5. I haven't split the case yet but have taken the P&C off and I think I will have to replace them. Looking at the comparitive prices between mid range 356 performance gear and VW gear, it's tempting!

Again many thanks, good luck Impi.

Jonesy

[Tony G]

Glad to be of help. Impi, keeps us informed of your choices and progress.

[Meissen540]

Tony,
I have considered changing the stroke length on a 356 engine to move towards a more effective rod ratio, as you said, for better combustion chamber characteristics, I.e., top dwell time. My hesitation is the it seems you can only change it about 5mm without getting really radical, and increasing your investment exponentially.
So my question is: how much "seat of the pants" improvement/ feeling will you get out of it? Do you have any experience with this on a 356 engine?

A couple of comments, just for discussion purpose, not to question your experience/knowledge.

The 356 Carillo rod bolts are scary to me. They are only 1/4" size. Seems small even if they are high strength. I know some of the racers have had them fail. The problem is the cam/crank clearance, there is not enough room to go bigger.

Here in Georgia, everyone has 93 octane gas. I have used 10:1 successfully multiple times. Just pay attention to potential hot spots on the piston (valve pocket edges), and head, and measure the cc CAREFULLY multiple times.

911 swivel valve adjusters.... I like that idea!!!

I find it amazing no vendors are not marketing a billet head for the 356. With all the work on the VW aftermarket heads, I would think the economics would be there, much of that work is portable. Quite a few years ago an individual in Germany wrote a thread on the R site that he was offering billet heads and aluminum nickasil cylinders. He posted pictures of the heads, and engine it was on. Several of the vendors and lackeys jumped on the thread and poopooed what he was doing. He never posted again, and who knows what happened to the product, or if was even real. There is more speed equipment out there for the VW Type 1 than the 356 engine. For years now you can build a higher HP Type 1 than the 356. It's seems development is squashed whenever something new comes out. I recall when when AA Performance started expanding their offering, all the protectionists were out in force making accusations of sorts against their products... Seems they are one of the few that have held on and expanded some of their offering. Good for them. We now have a single vendor controlling everything in the 356 world. It sure would be nice if CB or someone would offer some more improved products. As far as the engine goes, the head could probably offer the 2nd best bang for the buck in performance upgrade for the 356.... 2nd behind displacement increase.

Tom

[Tony G]

Sorry, I have been busy...
Stick with the 74mm stroke in the 356/912 case, it lives there comfortably with the clearances. I suggest you carefully plan out your engine and focus on those things that really matter like the utmost care of balancing all parts and configuring the best combination of parts for a nice peppy, easily tunable, and dependable motor. Going larger is not always the best way to go if it is not done right. All you need is something to be out of whack to effect the overall engine configuration. A nicely put together 1720cc engine can be lots of fun and not to expensive.

Regarding 1/4" rod bolts, the materials nowadays are considerably a lot better that that of that available in the 1960's. Rod bolts nowadays provide 220ksi strength or more and are high tech compared to the ol' school fasteners. I've used a lot of ARP fasteners on my VW Type I and Type 4 engines and have even modified rods to accept Chevy 3/8" ARP bolts and the much better Dodge Clevite rod bearings with great success. Doing mods like these gave me much great confidence that the connecting rod weak link was mitigated with effectively.

It is a shame that some folks bash those who try to do something new and that is why I was originally quiet about modding rods until several eventually contacted me about the details and I even had my mechanic, now retired, do several rod sets for some of my fellow VW Type 4 upright-conversion buddies in the Type 4 realm of yesteryears. There was a time when CB Performance offered much more Type 4 components but sadly, that ceased for reasons unknown.

There are now some good proven 356/912 piston and cylinder kits out there and also conrods, cams, ignition, flywheel, clutches, etc... You just have to first arrive to the decision of what kind of performance you want, your budget, and realistically how you intend to drive your car. Once you figure this out, then you can more clearly and honestly ponder on what type of configuration will meet your needs.

I too am putting together a configuration for my 1964 356 SC and am helping Justin with his engine. My engine will be a 1720-cc with a better than stock cam, Carillo or Pauter rods, AA or JE pistons in biral 86-mm cylinders, stockish valvetrain with minor improvements, Solex carburetion, and all balanced and blueprinted. I intend to stick to the stock Bosch 022 ignition and fuel system. I believe I will be satisfied since I really want to confidently drive this car everywhere.

Break time is over, I have to get back to work. I will try to visit this site a little more frequently. Feel free to post here or contact me with any questions. BTW, sorry for any typos...