Diff between theory and practice

[jon hanson]

At 11:42 23/11/96 +1000, you wrote:
>The difference on this motor could be due to the motor involved. With
>these 4AG toyota motors the inlet tract length is changed by the TVIS
>system. Removing these butterflies will change the torque point. Toyoto
>use this system to spread the tourque curve. It is a common racing
>change in australia to remove the butterflies which then gives you more
>torque at higher revs than before. With this modified motor the torque
>peak could well be occuring at 6000 rpm as the injector duty cycle
>implies.
>
>Regards 
>
>David Chambers
>
>
David,
I've got some doubts on this one. On a TVIS 4age each of the 8 intake valves
draws its air thru a separate tuned length intake runner. one of the 2 runners
to each cylinder is throttled with a a butterfly which opens at 4350 rpm (on 
the 112 hp usa spec motor anyway).This maintains a high gas velocity and
turbulence which peps up the torque curve at lower revs. When open all
8 runners provide the airflow needed at higher rpm's. The length of the inlet
tract which would move the peak torque point is not changed and the butterflies
are fully open at > 4350 rpm so I dont think it would move peak torque up 
from 4800 rpm. Any thoughts on this one, anyone

Regards Jon Hanson
Johannesburg
South Africa