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Vacuum in intake manifold

Vacuum in intake manifold

phaebo
Senior Member
285
18-03-2021, 11:13 AM
#1
hi

does anyone know exactly what the little vacuum controlled valve does in the intake manifold?
i read something about shorter and longer intake.

I experience some difference in intake pressure during the rpms.

when i am just past 4500 rpm the intake air pressure goes from 0,5 bar to 0,6 bar and then goes back to 0,5 till i get above 5500 rpm then i get 0,6 bar again.

has this something to do with the little valve in the intake manifold?
would it be good to tie the valve to always open? or closed?
phaebo
18-03-2021, 11:13 AM #1

hi

does anyone know exactly what the little vacuum controlled valve does in the intake manifold?
i read something about shorter and longer intake.

I experience some difference in intake pressure during the rpms.

when i am just past 4500 rpm the intake air pressure goes from 0,5 bar to 0,6 bar and then goes back to 0,5 till i get above 5500 rpm then i get 0,6 bar again.

has this something to do with the little valve in the intake manifold?
would it be good to tie the valve to always open? or closed?

Dark Samurai
Posting Freak
4,957
18-03-2021, 01:40 PM
#2
That's your ACIS (acoustic control induction system) which means there's a little valve which will make your inlet manifold runners longer under low rpms, but when you get above, the ACIS valve opens and makes the runners vert short which is better for higher power, whereas having them longer at low revs gives better low end torque. It's called ACIS because the sound changes a fair bit as you know...

Lexus IS300 Sportcross in Platinum Ice.
Click here for garage.

PSN ID: O3107 
Dark Samurai
18-03-2021, 01:40 PM #2

That's your ACIS (acoustic control induction system) which means there's a little valve which will make your inlet manifold runners longer under low rpms, but when you get above, the ACIS valve opens and makes the runners vert short which is better for higher power, whereas having them longer at low revs gives better low end torque. It's called ACIS because the sound changes a fair bit as you know...


Lexus IS300 Sportcross in Platinum Ice.
Click here for garage.

PSN ID: O3107 

phaebo
Senior Member
285
18-03-2021, 11:01 PM
#3
Thanks for the explenation! It does also explain why the boost changes a little bit during the rpms. Its all clear now.
Do you think that the acis is effective with the supercharger installed? Or is this only good with n/a setup?
phaebo
18-03-2021, 11:01 PM #3

Thanks for the explenation! It does also explain why the boost changes a little bit during the rpms. Its all clear now.
Do you think that the acis is effective with the supercharger installed? Or is this only good with n/a setup?

Dark Samurai
Posting Freak
4,957
20-03-2021, 09:07 AM
#4
I really don't know mate. Sorry. I'd assume it'd still be as effective though

Lexus IS300 Sportcross in Platinum Ice.
Click here for garage.

PSN ID: O3107 
Dark Samurai
20-03-2021, 09:07 AM #4

I really don't know mate. Sorry. I'd assume it'd still be as effective though


Lexus IS300 Sportcross in Platinum Ice.
Click here for garage.

PSN ID: O3107 

rob
Senior Member
720
20-03-2021, 10:31 PM
#5
You still get the little kick at 4500rpm with the sc

Sent from my GT-I9505 using Tapatalk 2
rob
20-03-2021, 10:31 PM #5

You still get the little kick at 4500rpm with the sc

Sent from my GT-I9505 using Tapatalk 2

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