z6 vs y8 IM

[Ej9Is]

hi.

i have d14a4 engine and i want to swap the intake manifold but i dont know what is better to my engine.
my engine is stock with no catalytic converters no resonator with remus oval exhaust and pipercross inbox filter.
i'm high rpm driver and want to know what is better intake manifold for that style z6 or y8?
i search a lot and some say the z6 and some y8.....

[saxophonias]

Hi there!
Have a look at this topic -->viewtopic.php?f=31&t=117
In short if you don't do extreme mods any of these inlets will do the job

[Ej9Is]

now the max hp at 6,300RPM and the torque 4,500RPM.
what the z6 manifold do to the powerband?
the z6 and y8 intake manifold cost the same to me so i want the best for money.
i what the best high rpm intake manifold to my d14a4.

[archyman]

Depends on setup, but in general the z6 will make power higher than stock. Mine is at its best from 6800 - 7500, but after that the power fades quick.
If you go turbo you may use the bigger plenum of the y8, other than that i don't see any benefit.
BR

[richy]

I would use the d16z6 inlet manifold, the 1.4 doesn't want too large a plenum when standard ish, you will loose some throttle response, The main reason though is the y8 manifold is designed to work with the swirl ports of the y8 head. As said before the z6 manifold was good for power up to 7500 or so rpm and i'm not sure you will gain much by revving a d14 any higher if your using a standard camshaft. I ported a z6 manifold on my old eg esi which made a reasonable mid range difference (3000-5500 rpm) but without cutting and shutting the runners to make them shorter it didn't let it hold power any higher. there are several write ups on the American d series forums to show the porting process.