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Not Reaching Full (Stock) Boost

L0Ki

By L0Ki,
in Engines & Forced Induction

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L0Ki Enthusiast

L0Ki

Posted
Posted

Hey Guys,

I realise this is a pretty broad question, but I'm asking anyway. Car is a R32 GTST stock

I notice that when i accerlate hard (full throttle) and watch the boost guage (stock) its only goes to just above the halfway line so about 4-4.5 mmhg when it should be closer to 5.5 to equal 10psi as this is what i believe to be stock boost for the R32 GTST???

Now i know i only have the stock gauge but could a blown headgasket cause this lack of boost? (yea i suspect my car has a blown headgasket - its loosing coolant slowly) Or could it be something else? A blockage? I just want a few things to look for before just going crazy pulling everything apart in the engine bay.

Car has a stock rb20det engine with possible blown headgasket :rolleyes:

Any help would be appreciated. :worship:

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SargeRX8 Grand Master

SargeRX8

Posted
Posted (edited)

Hey Guys,

I realise this is a pretty broad question, but I'm asking anyway. Car is a R32 GTST stock

I notice that when i accerlate hard (full throttle) and watch the boost guage (stock) its only goes to just above the halfway line so about 4-4.5 mmhg when it should be closer to 5.5 to equal 10psi as this is what i believe to be stock boost for the R32 GTST???

Now i know i only have the stock gauge but could a blown headgasket cause this lack of boost? (yea i suspect my car has a blown headgasket - its loosing coolant slowly) Or could it be something else? A blockage? I just want a few things to look for before just going crazy pulling everything apart in the engine bay.

Car has a stock rb20det engine with possible blown headgasket :rolleyes:

Any help would be appreciated. :worship:

Lol and you are still driving it with a blown gasket? You risk overhearing, contaminating the oil and destroying your bottom end, loss of power. A blown gasket could make you lose boost. When the cylinder fires, the pressure exerted from the explosion is lost through the gasket leak acting like an indirect wastegate. Fix that damn head gasket. Just to confirm you have a blown gasket do a compression test. One, maybe two cylinders will have little to no compression.

Edited by SargeRX8
GTSBoy Grand Master

GTSBoy

Posted
Posted

Number 1 - don't trust the stock boost gauge.

Number 2 - don't trust the stock boost gauge.

Number 3 - don't trust the stock boost gauge.

Number 4 - don't trust the stock boost gauge.

Number 5 - don't trust the stock boost gauge.

Number 6 - don't trust the stock boost gauge.

Number 7 - don't trust the stock boost gauge.

You get the idea?

They're not all crook - mine reads pretty accurately, but I've seen plenty that tell lies.

Put a proper boost guage on it just for a test.

sneakey pete Grand Master

sneakey pete

Posted
Posted

I get the impression that if you had a blown headgasket you'd know about it.

Leaky blow off valve maybe? mine was, to the best of my knowledge (in so much that blocking it off seemed to fix things)

L0Ki Enthusiast

L0Ki

Posted
  • Author
Posted

Lol and you are still driving it with a blown gasket? You risk overhearing, contaminating the oil and destroying your bottom end, loss of power. A blown gasket could make you lose boost. When the cylinder fires, the pressure exerted from the explosion is lost through the gasket leak acting like an indirect wastegate. Fix that damn head gasket. Just to confirm you have a blown gasket do a compression test. One, maybe two cylinders will have little to no compression.

Only indication of a blown headgasket is that coolant level is slowly falling in the overflow tank. So it could be a leak somewhere aswell? No milkshake, or oil in radiator.

Oh, and 1 bar or 14.7 psi is actually 760 mmHg, not 7.6mmHg.

Yep, just thought I'd try an keep it simple :nyaanyaa:

I get the impression that if you had a blown headgasket you'd know about it.

Leaky blow off valve maybe? mine was, to the best of my knowledge (in so much that blocking it off seemed to fix things)

Will it hurt the engine to block the BOV off for testing? Ive seen people cut out a soft drink can and user that.

L0Ki Enthusiast

L0Ki

Posted
  • Author
Posted

Blocked the BOV off and no difference. Took the front bumber off to check for any loose intercooler pipes and nothing aswell.

Any other ideas?

Could just be the boost guage i guess but it doesnt feel very 'fast' or maybe I'm just used to the stock power now?

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