graemebc wrote:Best thing to do if you wanted to run quads would be to source the manifold etc from japan.
The difference with a turbo would probably not be great as you say, but that would also depend on the plenum shape.
I intend to go quads with a 99 head on my 1.8 with some mild cams. 140 rwh is quite doable with decent headers and exhaust. Those levels will keep me very happy with not much loss of drivability. After I fiddle with runner lengths to try and keep as much as low end torque as possible.
Why Japan? I've had 3 different styles custom made here - around $600 per piece or companies like EFI Hardware will take a stock manifold, remove the mounting flange and make you a manifold for a similar price. Buy local if you can - especially in these times.
Cam choice is quite important with quads as is air speed into the head. For a road car, smaller butterflies and runners help airspeed to stay up maintaining torque and power in a usable range. Talk to guys that do it all the time but for a pretty stock roady, 40-42mm throttles would be sensible. I used to have 48mm in the racer with 120+rwkw to give you an idea. There are websites around with the calcs for helping you to work out ideal butterfly size and CFM requirements - worth a google.
