Lower plenum butterfly valve removal?+ -

What are the pros and cons of removing the lower plenum butterfly valves on the DE-K? (Super charge application,2.87)

Gas milage?
Low end?
Top end?

 

I think you know the answer.

 

Is there really a benefit though? I took the ones out of my 99 cali spec and didnt notice too much difference

 

With your FI application it would definitely benefit you to keep your VI opperating correctly.

... I guess it's good N/A as well, but the gains are only compounded with boost.

 

He's not talking about the VI. He's talking about the swirl valves in the intake manifold.

 

Sure fooled me. I thought he was talking about the VI as well.

 

"lower plenum"

 

Since when do '99 cali-spec's have a VI.

 

I would take them out. Ive heard of a huge difference when the engine is cold, they are supposidly closed completly. As the motor warms up, they begin to open. There is still restriction there even when their open.

I vote to take them out for sure

-matt

 

My 99 cali spec motor had the "swirl valves" in it. I swapped the lower plenum with a 96 lower plenum.

One would think it would be better not to have the swirl valves but has anyone proven this theory?

 

I know exactly what you mean(t). I was just showing sonicrunch that one could deduce that you were referring to the swirl valves based on what you had previously posted.

 

No one needs to prove it is better to have less turbulence/restriction.

Are the gains worth the work to remove them is a better question.

 

DOH!

 

FSM description on their purpose makes it pretty clear....

This system has a swirl control valve in the intake passage of each
cylinder. While idling and during low engine speed operation, the swirl control
valve closes. Thus the velocity of the air in the intake passage
increases, promoting the vaporization of the fuel and producing a
swirl in the combustion chamber. Because of this operation, this system tends to increase the burning speed of the gas mixture, improve fuel consumption, and increase the stability in running conditions.
Also, except when idling and during low engine speed operation,
this system opens the swirl control valve. In this condition, this
system tends to increase power by improving intake efficiency via
reduction of intake flow resistance, intake flow. The solenoid valve controls swirl control valve’s shut/open condition. This solenoid valve is operated by the ECM.