normal vacuum presure at idle

[dvs-b4]

hi all

just wounder what the normal vacuum should be for a b4 leagcy twin turbo?

mines siting at -13 and was woundering if thats normal and ok

thanks in advance

[dubbedup]

my wrx sits at -.8 bar, which sounds about right at -13psi (or close enough)

[log1call]

Sounds too low but as long as it's steady it will be right.

The gauge probably isn't accurate.

[Swindog]

Make sure you check it at normal operating temp.

Mine sits a -20 vacuum.

[dvs-b4]

it sat at -20 when i had it plumed to were the wast gate t was (instead of the wastegate) bt have extended the pipe and teed it off from there nd corection lol its -15 i cnt read lol it boosts fine nd is stedy at idle

[Guest]

-475mmHg +25mmHg / -0mmHg

[Swindog]

 Ichi Ban said:

-475mmHg +25mmHg / -0mmHg

Say it again...

Mine does sit at -23 odd sometimes if ive been pushing it hard...noticed this since the new turbo has gone on.

[Guest]

Somewhere around -20, applies to all cars as far as i know (253 v8 commodore only had -8, found the leak and fixed it, went to -20)

My GT wagon sits on -20

Edit - inlet manifold, at idle when motor is warm.

[Guest]

-475mmHg = -19"Hg

-23"Hg = faulty gauge as it is impossible at idle !

[Jord]

Hmm mine sits at 10 In.Hg.... Is that ok? idle fluctuates a bit. Perhaps caused by the HKS BOV?

[dvs-b4]

iv taken my boost gauge off that line nd put on another nd reads fine nw it sits at -18 to -22 but creaps up to -12 when its jst started and its cold bt cmes right within a min nd boosts to 16psi i was suprised

[Jord]

Ah yea sweet. Im a bit suspicious of the boost gauge install in my car.. Ill be taking it out a replacing it with a smoked one so it blends in a bit more. Gauge only shows 10psi when on full boost on the secondary but still hauls a turbo sounds healthy/ no vac leaks so hoping its the gauge

[dvs-b4]

u have a b4 right? where have you got the T intersection for the boost gauge?

yea -9 to-7 sounds about right thats what mine does if i put my foot to the floor i hit 16psi of boost prity quickly but by then im well over the speed limit

[Bazza-NZ]

Mine reads

Cold = -20PSI

Warm = -25PSI

Hot = -30PSI

During idle the vac changes, due to what i believe is an vac leak somewhere (i just can't find it as of yet)

NOTE - Boost guage is T'd at the BOV to manifold pipe

[dvs-b4]

shit mine neva sits over -22 bt does get up to -12 when cold bt corrects its self

[smokn4]

mine sits on 20 to

[dvs-b4]

i think -20 aplies to all cars nd if it does sit on or around -20 u myte have a leak or a bad vacuum line to T of speaking from experance

[Jord]

Here is where mine is plumbed in...

[Jord]

All modifications were done by previous owner... Is it normal to take it the boost gauge line of that vac line? Turbo cars are new to me haha

[dvs-b4]

i used to have mine off the same place bt have moved it couse it wasnt reading right is urs reading about -12 to-14?

[Jord]

Yep sitting at about -11 at idle. Could you post up a pic of where you have it plumbed in now? Cheers

[dvs-b4]

thats where i took it from the 1 line at the botem is for the bov and waste gate the 1 in the midle idk where it goes to nd i jst chose the top 1 lol nd it works for me

[Guest Eastwolf]

Hmmm all this is making me wonder about my B4.

When I rev the primary turbo is gets around 1 bar (is that 14 pounds?).

Then if I am going downhill with engine braking, it goes negative.

With engine off, it returns to zero.

Normal?

[dvs-b4]

sounds prity normal to me its what mine does so i wouldnt wory to much its normal to go to vacuum when engine brakeing becouse the throtle is closed im prity shore i could be rong and yea it should return to 0 when the car is off

[Guest]

my car reads -20 when at idle, but when parked up the top of mt Ruapehu and the engine turned off it reads -5 to -10 lol must be the air pressure.