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

QSHIPQ at aol.com QSHIPQ at aol.com
Tue Dec 4 06:33:11 EST 2001

[ Picked text/plain from multipart/alternative ]
I believe that sums it up well Gene.  That said short bursts of 2.4PR is ok,
short bursts of 2.5PR isn't, nor is there any room for leak or hiccup.  Ned
and I discussed this topic a couple times over the years, and we both agreed
that 2.4PR was THE limit for the k24 stocker.  I personally use that as the
"for 6 seconds" you describe below, not as continuous duty.  CD should be
somwhere in the 2.2PR.

All that said, since these turbos heat the charge air and the IC so quickly,
it's the rest of your protection circuits (CAT, engine temp, knock) that
probably save more k24's, regardless of chipset.

My .02

Scott Justusson
In a message dated 12/4/01 4:05:11 AM Central Standard Time,
gene.ghc at verizon.net writes:

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.


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