s4 turbo housings in an s4 NA...
 

has anyone ever tried this? Is it possible? Is it a bad idea? The guy rebuilding my engine wants to do it, but I want a second opinion. (I searched, btw, and found nothing)

they will fit fine but i advise not to cuz the turbo housings has holes on the side of the housings to feed coolant to the turbo. unless of course you block the passage.

I'll assume he'll do that since he said it wouldn't void the warranty. What about timing? I know some housings have the sparkplug holes in different spots to advance or retard timing. And isn't the exhaust port totally different on the turbo? how will these effect my NA engine?

TII and NA housings have the same spark plug placement.

The only real difference between the two are the coolant ports and the exhaust diffusers. There's no real reason to use TII housings in an NA since you can just grind the exhaust diffusers out (though there is some debate as to whether this makes any difference besides noise).

the spark plug holes are the same in turbo and n/a as long as it's for the same model. (swapping fd housing onto a fc engine will affect timing) if he says it doesnt void the warranty then i guess go for it. also since you're not boosting your n/a your timing will be the same as it was before the swap.


*edit* aaron beat me to it.

unless they are Jspec housings, S4 Aspec rotor housings all have the same spark plug timing, S5/S6 Aspec and S4 Jspec housings all have a slightly earlier leading plug timing as well the S5/S6 has a knock sensor boss in the side of the housings. housings are directionally stamped "F" and "R" for front and rear for EGR passage placement.

the coolant passages can be blocked easily so that should not be an issue.

ah ha, thanks guys!

the reason we're using the turbo housings is because my NA housings are junk and I happen to have the turbo ones lying around.

keep in mind your exhaust will be a bit louder with the n/a port sleeves.

actually, they are jspec... how big of a deal is this?

probably unnoticable, many people have run Jspecs on Aspec ECUs for years with little problems, it is once you start upping the boost on a Jspec with a piggy backed Aspec ECU i might think this would become a problem.

*sigh of relief*

Thanks for lending your knowledge, greatly appreciated.