Originally Posted by Vlad
If your posting refers to UKDM Sti, and the way they compare to JDM engines, please clarify that.
In any case, GDB Type RA and Spec C Type RA are two different cars. There is nothing for me to choose, because they are different timeline wise and engine wise.
Type RA uses a different cams than Spec C in revision A. They should not be confused.
Also, "big port" is a vague designation.
All the JDM Sti are "big port".
If you look in my posting, you will see that, although the Type RA (and NOT the later Spec C Type RA), already had big ports, they did an additional radius smoothing.
Take a look at the technical drawing provided, it will help with ID-ing those engines.
Now, as far as the Type RA and Spec C Type RA having different heads than their contemporary JDM Sti, this is incorrect.
All you have to do is go and look up the part numbers for, by example:
2001 JDM Sti and 2001 JDM Sti Type RA
Same part number.
Now the radius smoothing was a process said to be done after the heads were machined.
If you meant to compare the Spec C with an UKDM Sti, please specify this, otherwise causes confusion.
The LHS and RHS are casting and assembly codes, but not part numbers.
A Subaru Part number has a format as the example above (1139AB370).
Using these instead of part numbers is a good atempt of creating useful information for enthusiasts, if you have more info of this nature please post it.
It's possible that some in UK consider thet the UKDM EJ207 from an UKDM Sti and the same year JDM EJ207 from a JDM Sti, are one and the same engine. They are not.
Agreed all JDM STi heads are Big Port,but you cannot forget on JDM WRX which from V7 using AVCS and are Big port,although they're have different cams(i've run before on our 20k wagon JDM WRX AVCS heads,which has been Big Port)
UKDM STi using small port heads as on USDM,cams are different,although they're interchangeable(you can use JDM STi cams in UKDM)
Agreed GDB STi Type RA and Spec C Type RA are two different cars,Spec C Type RA using VF34 and Type RA has used VF30 as S202 STi,JDM STi v7 I''ve just been confused with the Type RA
In heads compartment would say,Spec C single scroll or Twin scroll heads are different for sure in ports etc.
About the ID drawing,good work
I've at home 3 pair of the JDM Big port heads which suffered as every 2.0L with cracking around the spark plugs,last set is S204 which have clean faces and no cracking
LHS20/RHS20 or RHC20/LHC20 is not part number,but with this is much easier to see difference,if you are going to buy some heads yourself and from this you will know what they're.This is usually stamped on the heads above the ports
No UKDM or any other EJ207 is different from JDM EJ207,heads are not the same as I said they're small port,cams are different etc