Are the RB25 turbo and non turbo heads the same ?

Quote: Originally Posted by DJ Mitzi Let me get this straight Now... Your running a Stock NA RB30 bottem end with stock pistons, a rb25det head.. and your compression ratio is between 8.5 and 9:1.. And the bottom end is still good??? Yes if you do it, you should use the non-turbo bottom end, unless you plan on changing the pistons, as the turbo bottom end doesn't provide a good compression ratio. The rest of the internals are exactly the same. Quote: Originally Posted by Dansedgli Are the RB25 turbo and non turbo heads the same ? Nope they aren't - the n/a non-VCT heads are easier to use though. If you do use a VCT head, you need to tap in an external oil feed and modify the head a little. The turbo heads also have better valve springs, etc afaik.

Are the only differences the valve springs and cams or is the compression chamber different as well? I dont mind using a VCT engine if I do it. It seems easy enough. The Non turbo motors are stacks cheaper as well. What does a set of valve springs go for for the twin cam heads?

Theres a few other differences, but overall the turbo head is slightly better (depending which way you look at it ) but slightly harder to fit. The VCT is really easy, just tap a feed into the oil pressure sender, and tap that into the top of the head where the VCT oil chamber thing is. It's best to do this apparently, regardless of if you have it connected or not. If you use after market cams, you can't use VCT, although there are some quite expensive cams (tomie?) I beleive that work with it. Some original photos have not been recovered yet.

Cool, thanks mate. I didnt realise that VCT was useless with aftermarket cams. Ill look into getting a Non VCT head. Ive got a copy of that instructional PDF file too if someone wants to host it.