1500cc versus 1600cc

[Jay Laifman]

I have a new inquiry for anyone who cares to play. This is in connection with our Elva 356 Porsche race car we are building. The factory records show the original build was for a 1500 cc 356 engine, but I think I can show the original owner actually raced it with a 1600cc engine. So we are trying to decide which way to go.

Thus, my question is, what is the difference between a 1500 cc 356 engine and a 1600 cc engine? Yes, I know 100cc, and that the 1600 will have more torque. But what about other characteristics? Will one be more "sweet" to run? Yes, this is strictly for the race car, where "sweet" really shouldn't matter. But, I'm trying to understand the subjective differences - because we want to enjoy the ride, not just hammer down for the win. Otherwise we wouldn't even be doing this kind of racing.

For example, let's go the other way. There is something really special (perhaps "sweet") about a well set up 1600 cc 356 engine compared to a big bore 356 engine - which goes another 120cc or more in the other direction.

Also, I don't know if the 1600 is considered square or over square. But, whatever it is, it's more that direction than the 1500. So that plays a part in it.

Finally, I know from another marque, the smaller cc engine in the same car is claimed to rev more freely at high rpm. Would that be a factor here? (but admittedly there could be other difference for that car that case the difference).

Thanks for any thoughts.

Jay

[Vic Skirmants]

I will only discuss the over-square issue. Even the 1300 was 74.5mm bore and 74mm stroke, so even it was over-square. Of course the really early 1300 was 80mm bore and 64mm stroke; REALLY over-square.

[C J Murray]

Jay, where are you and what are the rules you run under and what size engines are you running against?

Do you intend to cheat?

You should build the largest legal engine you can build.

A serious 356 race engine requires a special close ratio gearbox. If you aren't going with a proper gearbox then you need to build a very mild engine and not expect to run with the top runners.

Sweetness should not be a consideration when building a race engine. Street engines, yes that is nice.

[Tom Coughlin]

Jay: Is there an engine number stamped on that case? When Porsche introduced the three piece case it was 1500 cc through model year 1955 and changed to 1600 with the advent of the 356A (which I believe agreed with a change in race group engine sizes).
The engine number should allow you to determine what it was originally. My guess is that most 1500 cc engine (excluding show cars) are now 1600 or bigger. We can all guess that the first time that your engine was rebuilt it went to the max allowed in class at the time.

[Neil Bardsley]

Jay, where are you and what are the rules you run under and what size engines are you running against?

Do you intend to cheat?

You should build the largest legal engine you can build.

A serious 356 race engine requires a special close ratio gearbox. If you aren't going with a proper gearbox then you need to build a very mild engine and not expect to run with the top runners.

Sweetness should not be a consideration when building a race engine. Street engines, yes that is nice.

Where some raced with 1.8 4 cams? I would, with zero experience, agree with Cliff. Run the largest engine you can. 2l if you can get it homologated! Why be at the back being lapped when you have have fun nearer the front.

[Al Zim]

It seems to me that preserving your race car is the most realistic avenue to follow. There are members of this forum that race their cars and over the years accidents and mistakes happen that cause the cars to deteriorate. At some point in time they will not longer be able to be correctly restored for what the car is worth.. We are now looking at street cars that are approaching this situation. It i my suggestion that you acquire a set of Cast iron Porsche 1600 cylinders and have a 4 ring set of pistons made that have the oil control ring located below the piston pin. Use a relatively mild camshaft c/SC heads are nice but a set of Super heads will be more than adequate. Have the machine work done by someone that can read and has measuring tools. Always drive conservatively and the value of your car will increase and you will have fun without continually fixing things when no spare parts exist. al zim 2018/12/13