Red top in the ae86

[Nismo]

(04-27-2022 09:12 PM)banpei Wrote:  

(04-26-2022 11:27 PM)Nismo Wrote:  Your engine maybe a redtop with an adaptor plate to fit the TVIS?

To be honest I wouldn't know a sane reason why you would try to fit a TVIS on a smallport. The whole purpose of the TVIS is to have the ability to block off one of the two intake runners per cylinder, which increases the airspeed. This allows the engine to be more fuel efficient in low revs. The idea of the smallport is that the engine will have more torque in the lower revs (at the cost of fuel efficiency) while having a higher airspeed at higher revs compared to the bigport. The drawback is that due to the smaller ports the head is now more restricted in the amount of air/fuel mixture you can get into the engine (at high revs). Those two heads are basically meant for very different purposes.
So the idea of fitting a TVIS to a smallport makes as much sense as fitting a TVIS to a 20 valve VTT head.

When my car came over from Japan, this is the setup I had, which I found strange.