What is boost creep?

[WS6]

I've been reading posts with references to it and have yet to get a real explanation.

What is it?
What are the mechanics of this problem?
and how do people solve it?

I know it seems to be a dumb question to the more experienced turbo owners but allow me to catch up over the winter please. It's spoken about as though everyone knows it, but I don't have enough seat time to have experienced it yet.DontKnow:

 

[TurboJoe89TTA]

I believe if you get a external wastegate you could virtually eliminate boost creep. I think boost creep is basically when the boost continues to rise and your wastegate is not open completely. Another definition I have heard is boost creep is due to too much exhaust gas flow through the turbine section.

 

[Quiky One]

Boost creep is where you set your boost to 20PSI and the longer you are floored the more boost it makes. It is mainly predominant in higher gears where your car has the most load. IE-3rd gear and converter locked. It can happen in other situations.

I would not go external wastegate to fix the issue. Many manual boost controllers rid of it. I have an RJC boost controller on top of my HD wastegate and see no boost creep with the converter unlocked. I have yet to test it locked as that is racetrack material. Kinda fast to do on a city street....

You can solve it in a few ways. Either by buying a manual boost controller (or electric I guess) or by porting out the wastegate hole on the turbo. I would never do this as it is permanent but it suits some. This just creates bigger hole to bleed off the boost which can have negatives effects the day you want to crank down on the screws.

Jason

 

[RatFink]

I believe if you get a external wastegate you could virtually eliminate boost creep. I think boost creep is basically when the boost continues to rise and your wastegate is not open completely. Another definition I have heard is boost creep is due to too much exhaust gas flow through the turbine section.

+1,

If you run an open cutout in overdrive with a slightly loose converter, you'll see boost creep with a stock wastegate, I do, even with an 18lbs wastegate. I have to close my elec dump if I try to do a top end run or race at top end, just too much exhaust flow with that much load (4th gear), motor will knock instantly a 80mph roll if the car is 4th with the exhaust open. It's almost like it needs back pressure in 4th to keep things in check.

 

[WS6]

So, if I'm reading this correctly, the puck is not able to bleed off enough exhaust gas in the drive side of the turbo, causing the driven side(compressor) to continue to build pressure (boost) till it's maximum output capacity of that particular turbo correct?

I mean the puck is off the hole, in theory, but not enough to keep the exhaust gas from overdriving the compressor wheel. And this maybe because of a modified exhaust sysytem that flows better than stock, right??


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[RatFink]

So, if I'm reading this correctly, the puck is not able to bleed off enough exhaust gas in the drive side of the turbo, causing the driven side(compressor) to continue to build pressure (boost) till it's maximum output capacity of that particular turbo correct?

I mean the puck is off the hole, in theory, but not enough to keep the exhaust gas from overdriving the compressor wheel. And this maybe because of a modified exhaust sysytem that flows better than stock, right??


...


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Sounds right to me. There is probably a whole section of threads discussing boost creep, waste gates internal and external deltagate and tial type on turbobuick.com

 

[WS6]

Sounds right to me. There is probably a whole section of threads discussing boost creep, waste gates internal and external deltagate and tial type on turbobuick.com

I did a search for "boost creep" and then "creep" and got a few pages of threads, but as with what I was mentioning it is written about as though everyone knows what it is and is not detailed.

Which is probably more the fault of the search function and not TB or here. You can't just ask a question like google...hey...that's a thought!

Thanks for the input!

 

[echostatic]

+1,

If you run an open cutout in overdrive with a slightly loose converter, you'll see boost creep with a stock wastegate, I do, even with an 18lbs wastegate. I have to close my elec dump if I try to do a top end run or race at top end, just too much exhaust flow with that much load (4th gear), motor will knock instantly a 80mph roll if the car is 4th with the exhaust open. It's almost like it needs back pressure in 4th to keep things in check.

jeez, what kind of boost are you running? i usually have more knock problems in lower gears than in higher and thats with ~23lbs of boost on 93+alky. WOT at highway speeds is usually pretty smooth sailing.

 

[RatFink]

jeez, what kind of boost are you running? i usually have more knock problems in lower gears than in higher and thats with ~23lbs of boost on 93+alky. WOT at highway speeds is usually pretty smooth sailing.

18 -19 on pump gas no alcy
23 on pump gas and alcy
25 on unleaded race gas and alcy
20 on unleaded race gas no alcy

if your in 4th gear with a cutout open and you load the motor by going wot, not easing into it but flooring it will momentarily go 25psi, it's so fast that IMO the fuel isn't there, so I get some knock, also the alcy comes on at 20psi (non-progressive) This is totally my experience, I've never ridden in another TTA, well it was totally stock in 1990, but this is my experience. I don't have any knock problems in lower gears. IMO opinion there is more load on the motor in higher gear.