Trottle Response
10-20-2006, 03:18 PM
#46
Drifting
Thread Starter
Very thorough response!!
A few points
Are you sure about that, the vacum line is not connected anywhere on the afm, the vacum signal my be transfered to an electric signal, that's possible.
Understood and agreed.
I have not put any oil anywhere but it could help, it was actually extremelly clean in there so dirt is out of the question but oil could help. manually moving the door is fairly easy but I do feel a strong resistance from the spring.
Ya I guess we'll never make those cars rev like a Ferrari, now that's impressive. 
Thanks
A few points
When you open the throttle, you apply a vacuum signal to the barn door
you need to reduce inertia or strengthen the vacuum signal's initial "punch".
Loosening the spring will open the barn door more for a given flow but it will have little effect on how fast it opens.
I am just guessing but I think reducing friction would help response more than reducing spring tension. If the barn door is dragging on carbon deposits, cleaning it may help. Maybe oil the barn door pivots?
Last but not least, the S2 motor is one big, honkin' four pot. The pistons are huge and the stroke is long. It simply can't rev as fast as a shorter stroke motor unless you think crankase ventilation via thrown rod is a good thing. Again, you can't fool mother nature.
Thanks
10-20-2006, 03:40 PM
#47
10-20-2006, 04:15 PM
#48
Instructor
Join Date: Oct 2004
Location: Atlanta
Posts: 225
Likes: 0
Received 0 Likes
on
0 Posts
have you replaced the check valve on the fuel pump...they do go bad...i had one lying around and put it on my car and it made a world of difference in how the car reacted when i applied some throttle...worth a try...it's only a $15 to $20 part...before i changed the check valve my car seemed to hesitate when i applied throttle. now the throttle revs at my command
10-20-2006, 09:12 PM
#49
Advanced
Join Date: May 2005
Posts: 67
Likes: 0
Received 0 Likes
on
0 Posts
Sysgen,
At steady state the "Barn door" is mostly open, it is kept open by the mass of the air hitting the door. However, whenevery you ask for more air and the door is relatively closed, initial motion is due to pressure difference. Since the pressure behind the barn door is momentarily depressed, it meets the definition of vacuum. However, it is not manifold vacuum. I should have chosen a different word.
As flow increases, pressure drop is less important and mass flow dominates. The second flap- the one that swings into the "cubby" next to the intake tract- helps compensate for pressure. However, when a person revs the car from idle with no load, pressure drop probably dominates initial movement. Whether the primary mechanism is pressure or mass, the result is the same. You don't get air until the barn door is open.
Have fun,
Bill
At steady state the "Barn door" is mostly open, it is kept open by the mass of the air hitting the door. However, whenevery you ask for more air and the door is relatively closed, initial motion is due to pressure difference. Since the pressure behind the barn door is momentarily depressed, it meets the definition of vacuum. However, it is not manifold vacuum. I should have chosen a different word.
As flow increases, pressure drop is less important and mass flow dominates. The second flap- the one that swings into the "cubby" next to the intake tract- helps compensate for pressure. However, when a person revs the car from idle with no load, pressure drop probably dominates initial movement. Whether the primary mechanism is pressure or mass, the result is the same. You don't get air until the barn door is open.
Have fun,
Bill