Not getting full boost in first gear

[jhjones]

Hey, got this problem, I'm not getting full boost (18psi) in first gear, only getting 15psi. When I switch it to low boost (15psi) I only get around 12psi in first gear. I can hear the screamer pipe from around 9 psi on the high boost setting.

The wastegate spring is 1 Bar, Ive pressurized the intercooler piping up to 24psi and there are no leaks.

I can't remember if it was like this when I got the car tuned as I don't really drive the car.

Mods:

RB25DET Neo

GTX3071R

Link G4

50mm Turbosmart wastegate

6Boost low mount twinscroll Manifold

Edited October 12, 2016 by jhjones

[KiwiRS4T]

 You know that 1 bar is only 14.5psi?  Have you got a boost controller or is boost controlled by the Link via a Mac Valve? I'm not sure that full boost in 1st gear is all that important. 

[Shoota_77]

I'd be worried if you can hear the wastegate venting at 9 PSI.  Seems to indicate it's bleeding off too early.

You need to get one of these-

Remove the wastegate from the manifold (so you can see when it starts to open) and then disconnect the vacuum/pressure hose at the engine (so you're including all hose between engine and wastegate which may identify a leak somewhere) and then apply pressure (not vacuum) to the wastegate actuator.  In theory it should not crack open AT ALL until you reach what is supposed to be the wastegate spring pressure.  If it's opening before the target pressure then you either have a weak spring, a leaky diaphragm or a leak in the vacuum/pressure hose.  That's my evaluation anyway!!

Good luck.

 

[jhjones]

Boost control is done by the link using a mac valve.

If there was a leaky diaphragm wouldn't i hear it leaking out the port on the mac valve when i pressurized the intercooler pipping. Same with a leak in the vacuum/pressure hose except i would hear it leaking from the hose.

In the high gears boost shoots up the 15psi then slowly creeps to 18psi. Normal?

[89CAL]

You probably wont get full boost in 1st you know.

[R_34]

Right, bigger turbo and getting full boost in 1st gear doesn't come along because of inertia of the CHRA and available energy on the turbine wheel.

I wouldn't be too worried about getting full boost in 1st gear but more by your creeping issue. What size your gate is ? Which manifold do you use ?

[KiwiRS4T]

Not familiar with your wastegate but have another look at how it is plumbed - especially if there are alternatives.

[Dose Pipe Sutututu]

I don't get "full boost" in 1st gear either, in 2nd don't either. Not enough load on the motor.

 

[menthol369]

How old is your wastegate, and does it hit the track often? 

The wastegate springs get weak over time with continued heat cycling, i had 1 bar gate springs that ended up opening around 6psi due to the heat. This was after a couple of years on the track however.

[jhjones]

alrgiht guess its normal.

wastegate is 1 year old btw

[niZmO_Man]

Pull a 1,000 kg load, might get full boost in 1st.

[Dose Pipe Sutututu]

2 hours ago, niZmO_Man said:

Pull a 1,000 kg load, might get full boost in 1st.

Up a 45 degree hill

[admS15]

With -45°, hectic antilags on. Bang bang pop. Full boost uleh[emoji106]

[Dose Pipe Sutututu]

Wallah 30psi in neutral 

[kingtube69]

I had the same drama, not reaching full boost in lower gears. Thought it was an issue till I started looking into it. Same deal, not enough load in lower gears.