Hey guys, I was feeling gitty after buying a manual boost controller. Normally my s5 t2 with to4 hybrid boosts around 7-9psi around 6K rpm wot without wastegate. I put the mbc and got way faster spoolup and it started knocking around 5K rpm wot. That konck was loud! So I let off gas and popped the clutch.


I'm pretty scared my engine might have minor damage and isnt showing signs of fatigue yet. How bad is knocking like that? Im not hearing any missfires or anyting out of the ordinary yet. Im hoping all 3 corners of both rotors are ok.

 

is it pulling good vaccum still? is the boost gauge going up and down while idling? one quick way is to do a compression test. you would be surprised at what these motors can withstand... what sucks tho is that like you said "right now" it's ok. it's possible a seal could be slightly cracked and work it's way apart as you keep driving it.


just be easy on it for a few good miles and see what happens.

 

I spiked 20psi on my stock turbo and heard an audible thunk. No problems after that (although I freaked out for a little while) and I killed and STi the week afterward

 

Vacuum is probably the best diagnosis. The car should pull the same vacuum before and after this incident.

Detonation is bad, but in most cases will not damage the engine unless you do something monumentally stupid (like crank the boost on a stock fuel system...).

 

That is waht I am afraid of, the seal being slightly cracked and finally going out in the next few miles.

What is good vaccum for a street ported s5 t2 engine?

Everything seems ok from driving 50 miles today, but I'm still paranoid and scared something bad might happen.

 

Is it running normally? Most likely if you put 50 miles on it, its okay. You probably took a few thousand miles off the life of that motor though.

 

If it's running fine, it's okay.
Even if the apex seal is "slightly" cracked, it's going to idle like ****.
I've detonated heavily on my freshly built motor, and it's still running.
Brand new apex seals does wonders! :P


-Ted

 

what you have to worry about with more boost is cracking irons not popping the seals, if it aint leaking oil or idling like a paint can shaker then i doubt you harmed anything much.

the inaudible detonation is the apex seal killer! (lean AFRs)