prewar 6C2500 engines - what differentiated the various types?

[6ccorsa]

I have got the impression that the engine differences between the 4 types (excepting the Corsa)are limited to piston changes (to alter CR) and the number of carbs fitted.
Fusi gives these figures:
6C2500 Turismo CV 87@4600 CR 7.0:1 Carbs 1
6C2500 Sport CV 95@4600 CR 7.5:1 Carbs 1
6C2500 Supersport CV 110@4800 CR 8.0:1 Carbs 3
6C2500 SS Corsa CV 125@4800 CR 8.0:1 Carbs 3
and slightly anomalous:
6C2500 Coloniale CV 90@4500 CR 7.0:1 Carbs 1 (con correttore di quota) - maybe a better carb?
Does anyone know of further changes? Pistons and carb variations would seem to account for the quoted power differences again excepting the Corsa. These probably had different cams but according to Fusi kept the same valve sizes as all the other types.

I have engine no S923911 which fits into Fusi's range of engines grouped together as Sport or Super Sport. I am interested to note that in John's list (see his post in the Ala Spessa thread) some engines prefixed by S rather than SS were fitted in cars with the SS conversion. I would like to know if mine was one of them and it has occurred to me that I can check the CR when I get the engine back from the machine shop. I obtained it dismantled and it came with a single piston (maybe not original to the engine?). This is marked 'R7-6,75. 12/45 G 275'.
12/45 could be piston manufacture date I suppose, although the engine is listed as 1940 by Fusi.
Of course if it wasn't original to the engine this won't prove anything either...

[gtv2000]

Quote:

Originally Posted by 6ccorsa 6C2500 Coloniale CV 90@4500 CR 7.0:1 Carbs 1 (con correttore di quota) - maybe a better carb? Does anyone know of further changes?

[6ccorsa]

Quote:

Originally Posted by gtv2000 Dry sump? Or do I get confused with the Matta 1900 engine?

[dretceterini]

I think the horsepower figures quoted are for post-war cars. The pre-war cars may have had less horsepower model for model. If I remember correctly, didn't the pre-war 6c2500 engines still have babbit (poured) main bearings (meaning less revs available; and therefore less horsepower)?

[6ccorsa]

Quote:

Originally Posted by dretceterini I think the horsepower figures quoted are for post-war cars. The pre-war cars may have had less horsepower model for model. If I remember correctly, didn't the pre-war 6c2500 engines still have babbit (poured) main bearings (meaning less revs available; and therefore less horsepower)?