Cylinder head differences, What head fits what block
 

Does anyone know the differences between cylinder heads for the RN motors? This would be valuable information for many Volvo Enthusiasts. My 2004.5 S40 has a B5254T3 and is currently in need of a head gasket replacement, at the very least, and I would like to know which heads will work (just in case it needs a new head). Are all the Dual CVVT heads interchangeable? Is there a difference in thickness on certain heads? Do certain heads flow better? Any other information that could be of importance? Please share, Thanks.

https://en.wikipedia.org/wiki/Volvo_...engine#B5234T3

most of the T number variants are for different tunes - bolt ons like the size of the turbo, intake/downpipe design, not so much the head design (which would be very expensive to change tooling). Google around for more info. T3 heads should be easy enough to find. Check out car-parts.com to get a sense of used head prices.

I have done much research on this topic, especially the B5254T3, and the head is not the same. Because the compact design of the S40/V50/C30/Focus RS and other models, the head was shortened. The CVVT solenoids and oil filler are in a different location than on other 5 cylinder engines. The spark plug has 1" of threads, same as R models, instead of .75". If anyone has a comprehensive list please post it. I believe the B5254T7, B5254T12 and many others may be similar.

ALL Volvo I-4, I-5, I-6 RNC cylinder heads will fit on RNC blocks. The main differences between the engine code designation numbers are in tuning, camshafts, throttle bodies, or manifolds, especially the integrated turbo/exhaust manifolds. I am still trying to find any other differences. The RN white block and RNC white block