2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
Sponsored by:

heard bad knock, minor engine damage?

Thread Tools
 
Search this Thread
 
Old 08-23-07, 02:03 AM
  #1  
Rotary Enthusiast
Thread Starter
 
initial D is REAL!'s Avatar
 
Join Date: Mar 2007
Location: Pasadena
Posts: 1,485
Likes: 0
Received 0 Likes on 0 Posts
heard bad knock, minor engine damage?

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.
Old 08-23-07, 02:08 AM
  #2  
Just turn up the boost!
iTrader: (1)
 
ZAN_TUNING's Avatar
 
Join Date: Jul 2007
Location: HELL
Posts: 662
Likes: 0
Received 0 Likes on 0 Posts
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.
Old 08-23-07, 09:17 AM
  #3  
rotorhead

iTrader: (3)
 
arghx's Avatar
 
Join Date: Aug 2004
Location: cold
Posts: 16,182
Received 429 Likes on 263 Posts
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
Old 08-23-07, 10:19 AM
  #4  
Engine, Not Motor

iTrader: (1)
 
Aaron Cake's Avatar
 
Join Date: Feb 2001
Location: London, Ontario, Canada
Posts: 29,789
Likes: 0
Received 108 Likes on 91 Posts
Originally Posted by initial D is REAL!
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.
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...).
Old 08-23-07, 08:37 PM
  #5  
Rotary Enthusiast
Thread Starter
 
initial D is REAL!'s Avatar
 
Join Date: Mar 2007
Location: Pasadena
Posts: 1,485
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Intense_Motorsports
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.
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.
Old 08-23-07, 09:17 PM
  #6  
Alcohol Fueled!

iTrader: (2)
 
J-Rat's Avatar
 
Join Date: Jan 2002
Location: Hood River oregon
Posts: 11,093
Likes: 0
Received 2 Likes on 2 Posts
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.
Old 08-23-07, 10:03 PM
  #7  
Lives on the Forum

 
RETed's Avatar
 
Join Date: Feb 2001
Location: n
Posts: 26,664
Likes: 0
Received 16 Likes on 15 Posts
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
Old 08-24-07, 01:25 AM
  #8  
Sharp Claws

iTrader: (30)
 
RotaryEvolution's Avatar
 
Join Date: Oct 2003
Location: Central Florida
Posts: 5,107
Likes: 0
Received 41 Likes on 40 Posts
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)
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
gtcd
1st Generation Specific (1979-1985)
30
08-19-15 02:44 AM
Marty RE
New Member RX-7 Technical
0
08-13-15 11:19 AM



Quick Reply: heard bad knock, minor engine damage?



All times are GMT -5. The time now is 04:13 PM.