[200q20v] intercooler (or: IA3+ & K24 turbo limits)

[Gene Caldwell]

Brian Link wrote:
>
> Thanks Bernie,
>
> Or...
> Has anyone done some datalogging and read either the inlet air temp sensor
> or the mass air sensor.  I'm just trying to run some numbers on 1.  how
> hard im pushing the k-24, and 2. what are the other turbo options.  Scott J
> made a comment on the S-car list that there is 100% failure rate on the
> k-24 above 2.4PR (Is this True?).  I calculate that I'm at 2.6-2.7PR up
> here in Colorado, sea level folks with chips are at 2.4PR.  Could anyone
> that has had a k-24 fail chime in of the how's and whys of the failure?
>
> Thanks in advance
> Brian Link
>


Disclaimer: If I get any of this wrong I hope Ned will correct me.

I believe some comments from Ned Ritchie while I was getting a 3+ ECU
mod done for my 3B motor might be relevant.  Hopefully my memory serves
me correctly.  The context of the discussion was whether or not the IA3+
ECU mod would put my K24 turbo in danger.

Ned told me that the stock K24 turbo rated upper limit is 265hp
(continuous duty, I think).  That's just another way of stating how
much air the turbine is designed to move.

His 3+ software will spin the turbo beyond its designed max speed to
achieve higher boost levels for short periods of time..much like the
'overboost' mode in UrS4/S6 motors.  The only real drawback to this is
that if your turbo impeller is near or beyond the limit for being in
balance, or the shaft is not really true; the shaft will begin flexing
at elevated speeds (read: beyond spec rpm) with a potential for impeller
to contact the housing (ouch!).  Ned says we are OK (according to KKK)
as long as we limit the period of 'overspin' to about 6 seconds.

He went on to say this wouldn't be an issue except that the K24 has
a small diameter shaft.  Almost any other turbo you might consider as
a replacment for the K24 will have a larger shaft diameter.

-Gene