Boost creep

[BenHer]

Ok I need some education here. Seems one of the main issues with internal waste gates is boost creep. I'm assuming this is uncontrolled boost pressure increase on extended boost. My question is - Wouldn't this be countered with a blow off valve? What am I missing?

 

[dadofthree]

PM Richard at RCC or Frank at Powerhouse if you don't get a response.

 

[POWERHOUSE]

Ok I need some education here. Seems one of the main issues with internal waste gates is boost creep. I'm assuming this is uncontrolled boost pressure increase on extended boost. My question is - Wouldn't this be countered with a blow off valve? What am I missing?

It is not the function of a blow off valve (BOV) to regulate or control boost levels; A BOV is designed to relieve pressure in the plenum when the throttle is closed; its signal to "open" and vent the plenum occurs when it sees vacuum. When the engine is positive (on boost), the BOV remains closed and has no effect on boost pressure, if it is functioning properly. Internal "flapper" style wastegates will typically "spike" because they cannot flow enough, even wide open boost is still being made. Porting the turbo will reduce this somewhat, as will running a full exhaust. The best answer is an external gate . . .

 

[OZBooster]

not so much uncontrolled pressure, but an unexpected pressure rise, boost creep is not like a wastegate that has lost its reference hose that would be an uncontrolled sharp rise to very high levels
Boost creep is a few psi more than intended, , for many this is dangerous to the motor as they may already be close to the knock or detonation limit
usually only happens in the low boost areas, once you get more boost happening the back pressures in the turbine and compressor reduce the level of creep
and in some circumstance boost creep can be handy , gives you a bit of a hp increase at the top end without so much mid range torque that may otherwise lift the front or blow off the tire

BUT it is much better to have a wastegate that can control boost properly and if you want to tailor the boost curves, use a good boost controller and get adjustable repeatable results

 

[BenHer]

Thanks That's what I needed to know. Going cross-eyed reading 96 pages of turbo posts but sooner than later I've got to lay some money down and take the plunge. I bought the bike just to build a turbo or I might as well as stayed on my 916!