Hi,

The engine on my 2002 rally car just expired so I'm now planning to build up a new one. I have the original engine with a 121 head and a later engine out of a 520 with a E21 2.0 head. Which would be the better base to start with?,

Cheers
Craig

to my knowledge the original 2002 have a higher compression therefore it may be producing some more power. now if you have the 520 engine with the e21 head and turbo charge it then that will just totaly rip everything apart.

i would go with the 121 head and build from there with weber dual sidedraught carb's as they are very strong and pretty reliable

someone please correct me if im wrong

I believe if you're going all motor and running stock or mild cams, you can get a bit more compression out of the 121 head. It all depends on what pistons you are going to be running on your block. If going forced induction then e12 would be your best bet imo.

Both motors need a complete overhaul & new pistons so I can basically decide what compression ratio I want, At this stage I think I'll probably use the 121 headed engine and put in the larger inlet valves.