I currently have four d16a6 motors in the garage (one of them in an 89 CRX Si; the 2nd one in a 91 CRX Si; and the third I bought from someone; and the fourth is seized up). The third "new" motor has a head code cast in it that says "PM9-3". All other head codes start with PM3-x. I learned from (a little) research that the "x" is the assembly line that the head was cast at. But what is the relevance of the prefix of the head code?

Supposedly, the PM9 was pulled from a 91 Civic Si, which was manufactured in Canada, while the PM3s were all from CRX Si's, which of course were Made in Japan.


For reference, please see the related threads:

https://honda-tech.com/zerothread?id=786093

In the above thread, there is a PM9-3 head listed for the 91 Civic Std! This kind of makes me wonder if the same head used in the Civic Std is the same head as the Civic Si?!?

and

https://honda-tech.com/zero...age=1 - specifically this post:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Superhatch &raquo;</TD></TR><TR><TD CLASS="quote">Head codes....

Some info from this thread https://honda-tech.com/zerothread?id=786093

Shows that a 1991 Std D15B1 4sp has the head code PM9-3, which is the same as my A6 head code. My other A6 head has a code of PM3-7, and the other D series I have a D15b2 has the code PM3-23.

Are head codes irrelevent? What exactally do they mean? </TD></TR></TABLE>


Thanks for reading and I appreciate any input/opinions.

 

bump...

 

my 88 d16a6 rex is pm3-11 ???

 

MODS: please move this to "All Motor" - it seems that maybe nobody here knows? (or cares )

 

i have seen em with pm6,pm3 and pm9 stamped only...but thats just the few that i have seen...