Bought Stilo 2.4 head recently as i'm preparing 20VT engine for my mid-engined Alfa 156, and it's great, easy mod IMO.
Intake plate will be from Stilo as well, but as gift i received exhaust manifold.
It will be less less hassle for me using Stilo's exhaust manifold and just make new flange for the GT28RS - it's just cutting and welding and i can do it by myself.
Question is - will exh. manifold for N\A Stilo be able to survive - as far as i know cylinder ignition order is same, there will be less weight on the entire manifold because downpipe will be only 1 meter long and will exit in front of the rear wheel(as i said it's mid-engined), so i guess there will be less material stress. And there is no space related concerns as well.
Any thoughts???

Aren't exhaust temps higher on a 20vt than a N/A Stilo? So is the manifold material suitable?

What exhaust valves are you using in the head?

Higher for sure, but i saw many n\a cars running stock ex manifolds in combination with nitro - it becomes red hot after 400m drag, but survive years.
Will use stilo intake and exhaust valves, if 20VT exhaust valve is used on Alfa 145\146 1.4TS, Alfa 147 1.6TS, Bravo 2.0HGT, Marea 20V - well it's not uncommon turbo cars to use n/a engine valves.
Had Flea remap for 1.4 boost and i'm not plan to run more that 1.3 and have water/meth injection as well.
Have more concerns about manifold material and it will be suitable for the turbo - i mean exhaust gasses phase ect....

Why bother? - we know the standard 20VT manifold will flow up to 500bhp with some gentle port-matching

I'd worry that the primaries on the Stilo manifold are too big, which would slow down the gas speed and kill the spool-up time

Have one spare standard 20vt manifold, but it's a bit too heavy and i'm mad about every single kg i add around the car. Plus it's cheap try, already have one, i do all of the labor.....


Good point, visually i did not notice any difference compared with my present manifold, i'll measure exhaust head exits and both manifolds ID.......
Anyway i'll try this for sure, have plan B if something wrong.

Definitely measure the ID, as the wall thickness on the Stilo manifold will be much thinner than the OE cast manifold

I know its difficult to tell from the photos, but the OD of the Stilo manifold looks quite large, which means the ID could easily be too big for the 2 litre 20VT