Engine block code

[DHAceca]

I have read information about the development of these engines from UMB though CL and CLB until the latest of the engines carrying CLBN. My question is, my Aceca engine also has a "W" suffix and 9/1. My assumption is that the 9/1 relates to the engines compression ratio would this sound correct or plausible? And any ideas what "W" indicates? Many thanks for any information and help

[Klassik Metall]

I seem to remember reading somewhere that the W stands for Wellworthy pistons. The 9/1 would be the compression ratio. I believe that some engines were also stamped with an H standing for high compression.

[tim isles]

Luke, I always believed H for Hepolite? Tim

[Klassik Metall]

Tim, I have to say that never occurred to me but it does make sense. I wonder why they chose to identify what pistons were fitted & if that meant that the piston designs differed, different ring layouts/ thicknesses ect?
   
   Regards Luke.

[B.P.Bird]

This is a topic which has never really been satisfactorily decoded. As we all know there is a logic to A.C. car number prefixes - RS, RSX, CS, FEF, AE and so on, but the equivalent engine prefixes have remained unclear: If we have a UMB and a UMC was there a UMA ? As we then find UBS - the 'S' seemingly for Sports it implies that the basic version of the engine was a 'UM' so what did that stand for ? We then move to a 'CL' which becomes CLB, no CLA ? Then to CLBN, in which instance we know that the 'N' was for Nitride. We know the differences between the UM series and the CL series - white metal and thin wall bearings respectively for instance, but can these differences be made to match the letter codes ?
   Seems strange that such a basic piece of information is unrecorded in the companies paperwork ? Perhaps it is somewhere ?

[mike smith]

quote:Originally posted by DHAceca
   
I have read information about the development of these engines from UMB though CL and CLB until the latest of the engines carrying CLBN. My question is, my Aceca engine also has a "W" suffix and 9/1. My assumption is that the 9/1 relates to the engines compression ratio would this sound correct or plausible? And any ideas what "W" indicates? Many thanks for any information and help
   

   As far as I understand W meant that the engine was fitted with Wellworthy? Pistons