Hi guys, I'm currently in the middle of a blob eye WRX engine rebuild. The situation is when I took my heads to the machine shop they found a hairline crack between one of the spark plugs and valve seats, luckily they had a spare LH head laying about and did the work on that for me. I checked both heads over and they looked identical, now that I've put them on the block I can see that the inlet ports are slightly different, can anyone tell me if this difference will only be marginal? Will the flow be too different? :/ I'm not planning on tuning the engine, it's going to be kept relatively standard. Any help or advice will be massively appreciated.



RH - one that came with car





LH - one given to me from machine shop

 

Replacement LH head is from a Version 5~6 WRX/STi without the port divider on the inlet throat.
Using miss matched heads is never ideal from a flow point of view but at least both of the heads you now have are small port.

Are you using the original valves, springs and buckets from the old blob head in the replacement head ?



Mick

 

Hi Mick, thanks for your reply. Yes I have used all the components from the original head. I have asked a few people and they seem to think the flow differences will be minimal between the two heads so I should be fine, although it's not ideal. What do you think? I really hope I can get away with it as I've spent a small fortune on all new parts so far and I'm so close to the end of the rebuild. Again, thanks for getting back to me.

 

I rather put identical heads it funds allow ...as you don't want to built it twice