Fw: Broke exhaust valves and 4ktq's (fwd)

[Orin Eman]

As he says, please copy replies to mardkins at email.msn.com

Forwarded message:
> From mardkins at email.msn.com  Sun Mar  4 15:18:12 2001
> Message-ID: <006301c0a502$13579b40$fae00b3f at pattywack>
> From: "mardkins" <mardkins at email.msn.com>
> To: "Orin Eman" <orin at wolfenet.com>
> Subject: Fw: Broke exhaust valves and 4ktq's
> Date: Sun, 4 Mar 2001 15:23:07 -0800
> Organization: Microsoft Corporation
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> 
> Orin, could you forward this to the main list and see if anyone has any
> ideas.  I am not subscribed so they will need to reply direct.
> 
> Thanks
> Pat
> 
> 
>  We finally got Seans car taken apart tonight and yet anouther broken
> exhaust valve.  This time #3.  This makes 3 confirmed valve breakages in
>  4ktq's that I know about.  All seem to happen the same way.  2 of the 3 had
>  good intercoolers 1 even being a stock 5kt intercooler.
> 
>  So it begs the question why?  They were all running less than 15lbs of
> boost
>  which 5kt's dont seem to have a problem with.  The other 2 were in cylinder
>  4.  They all apear to have broke near the base of the stem.  So does
> anybody
>  know if the 10v turbo's in 5kt's have had problems with valve breakage?  If
>  they do I have never heard of it.
> 
>  I do have a couple of theory's though.
> 
>  1:  Fuel volume.  One of the things they all have in common is they are
>  using stock 4k fuel pumps.  Is it possible that these fuel pumps arent
> supplying the volume to keep things cool.  Sean did have an EGT guage but
>  sadly was not watching it when it gave up.  There does not seem to be
>  problems with knocking and it does not show up on a oxy sensor reading as
>  lean.  Orin seems to think that they typically do not show enough detail to
>  be worth much valuable information.
> 
>  2: Transmission.  With the stock 4kq transmission we are spending alot of
>  time right near redline.  This is true on PIR, Bremerton, and SIR.
>  Could this be the problem.  I have honestly not been watching 5ktq's
>  tachometers on the track to see where they are running but I would guess
>  they could run a bit lower in the rev band for 2 reasons.  Longer gearing
>  and better aerodynamics which helps them pull a little better at higher
>  speeds without stressing the engine as hard.
> 
>  So please shoot these theories down if you think they are not valid or let
>  me know any additional theory's you might have.  Are there any solutions
>  that could be had reletively easy.  Sean needs to put his car back together
>  and we both would like to feel better about pushing are cars.
> 
>  Thank you for listening and I cant wait to hear your suggestions/theories.
> 
> Pat Martin
> 86 4000csq turbo, 2 1/2 cat back, H&R-Boge holdin it up, MC and loving it.
> Drilled and stopping it. Yokohama Avs intermediates turning it, K&N and uh..
> 84 4000sq  AKA: The beater.
> 95 subaru legacy
> Bothell, Wa
> 
> 
> 
>