Hi all,

Sorry for the dumb question but as a non native English speaker I don't understand well what's behind boost spike and boost creep.

Well in fact I figure quite well what spike is: a sudden boost raise above the normal pattern that drops immediately right? or does it hold at the too high level?

For creep I have no freaking idea what's behind that word... some good soul would explain me please?

Thanks guys

 

That's what happens when you're a lazy guy, sorry guys right after posting this I found that, which is quite explanatory:

http://www.allpar.com/mopar/boost-creep.html

Anyway, if you guys have further inputs, you're welcome

 

Boost spike is just what you said. It's a spike of boost above the set level that then drops to the correct amount. For example, if you have your boost set at 12psi. Basically it's caused by the pressure increasing so quickly it spikes past the set boost point before dropping back to the desired level.

Boost creep is caused by entirely different issues. It is due to the wastegate, which is why a lot of people replace the wastegates or port them, though I'm unfamiliar with the porting method myself. It is caused because the wastegate cannot release pressure fast enough under boost, so rather than being released they add to the pressure on the turbo, causing the boost levels to slowly increase.

Easy example:
Boost Spike: Boost set for 12psi. When you floor the accelerator, it jumps to 13 then goes down to 12psi.
Boost Creep: Boost set for 12psi. As you stay under load with the turbo spooled, the psi will increase gradually, such as slowly raising from 12, to 13, to 14, depending on how long you have the turbo spooled up.

If anyone has any more to add to this feel free. I don't know everything about these two things by any means, as I just started working on my first turbo car 1 year ago, so please correct anything that I said that may be wrong.

 

Question: Can boost creeping be relieved by lifting off the accelerator?

For example, if my car is creeping to 10psi at 6000rpm, can I lift off a bit to drop back into vacuum, then get back into boost and not hit 10psi again? Or will it immediately jump back to 10 after i floor it?

 

if you give it less than full throttle, you can compensate the creep by giving it less exhaust flow. so if you want 10 and it goes to 12, ease off.

 

Thanks for the inputs mates, I think I get it now.