So I have become very interested in the VVT intake manifold but I cant find a shred of info on it. I found maybe 3 pics total for an hour of google searching. The design is just awsome and it seems like there would be very little if anything that could be improved.
Does anyone have some pics that show both the top and bottom sides of the upper/lower manifold? Also, I couldn't help but notice how close the design mimics an LSx manifold.
vvti 1uz rated 290hp @ 6000rpm and 300tq @ 4000rpm for the LS400 and SC400 but I feel the SC400 was more likely 280hp with the terrible exhaust manifolds.
GS400 vvti 1uz rated 300hp @ 6000rpm and 310tq @ 4000rpm
GS430 vvti 1uz rated 300hp @ 5400rpm and 325tq @ 3400rpm
The larger engine makes more low end power and hits peak torque earlier with same cams and compression but IIRK had a reduction in the range the vvti could move the intake. The single tube exhaust manifolds heat the catalysts more quickly but also choke off the motor earlier with no peak power improvement. Seems like GS400s and GS430s have very similar 0-60 and 1/4 mile performance.
The vvti engine intakes utilize dual length runners. The runners come straight up from the port (unlike earlier manifolds) curve over the top and back down the other side with an opening to the bottom of the common center plenum area on the opposite side of the engine. The two halves of the intake create the common center plenum area that is fed by the front mounted throttle body.
Separated the runners to the ports are on the outside edge and slightly smaller than the runner to plenum area. The runners appear to slightly taper down from plenum to the head. Reversion is still a problem as you can see the carbon build up near the heads on each port. But less of a problem the earlier 1uzfe engines.
There is a set of 8 butterfly valves on the plenum ceiling that when opened effectively shorten the runner length by about 40%. Shorter runners tune better for high RPM power and longer are better for low RPM. IIRK they open around 4000rpm if the throttle is over 60% or something like that. They actually look "Ferrari" like.
The intake seems pretty pinched as it goes around the injector. This will increase velocity and reduce reversion but probably costs peak power. Some porting and testing on intake and heads could be VERY interesting especially seeing what RMS got with the old heads with ITB.
Below pictures show:
Bottom half of intake rear view.
Top half of intake front view showing half the TB mounting surface.
Butterflys open.
Butterflys closed.
Downward on port to head.
Upward on port from head.
