I'm getting ready to build a high compression turbo engine using 6port side housings. I'm curious to know what approaches others have taken. Two goals are 1) up to 400hp and 2) remain streetable for daily driving. My thought was to leave the end housings relatively untouched but open up the primary ports in the center housing.

Appreciate any help...

 

I'm curious about this as well, how would it react if you ported the end plates 2 ports into one large port? I know it would make power very high in the rpm range but wouldnt the turbo change that?

 

have done more than half a dozen of these since the 90's

for the FC 6 port engines-
i use the G coded jap/oz t2 centre plate and port it taller for late close

i keep the 6p secondaries and aux porting stock

i do some cross porting at the secondary/aux runner /manifold face
cause i use t2 modded LIM and this port matches the entry

exhaust porting varies across whichever example engine from stock to wild

PS
search out the early s4 turbo TB,, or at least an auto s5 unit
these have vac cans used to hold out the vac delay secondaries while the engine warms
the trick here is to use them to control the secondary operation until load or mild boost is seen in the TB
this will boost low down TQ radically
to do this you delete the one way valve and hook the vac can to a vac source on the primary side of the TB
the delays will open when zero vac or boost begins to build in the primary runner

the s4 unit works in both directions,, the s5 unit is slotted and can only pull shut

the s4 unit works better actively self adjusting the secondary delay in either direction for maximum TQ
, but is more fickle to setup with a nasty habit of being too sensitive and working as crusie control when in 4 th or 5th

the s5 turbo auto TB works only to hold out the delays till there is zero vacuum and then the delay will follow throttle as normal
- not quite as good at maximising airspeed and gaining low down TQ as the s4,, but lots better than the fully mech delay TB's

 

bumpstart - could you post or PM some pictures of your setup? I'd like to get a visual on how you are actuating the aux ports.




I would not grind out the separation from the secondary ports and the aux ports. Rotarygod (i think) has a writeup on why not to do that.

 

no aux valves

i use modded t2 manifolds , several casting reliefs are welded up along the face and the 6 port gasket pattern is transposed with a die grinder into the inlet manifold, the manifold is refaced for flat
some attention with die grinder is paid to the radius of the turn in the manifold
and the engine plates are port matched between the aux and secondary runners
to make the opposite to the manifold for an egg shapped passage formed to feed the aux runner

some very old pics -








more pics ( different manifolds , same principle )