RE: 5ktqw Low End Power

["Lewis, Gary M" <Gary.Lewis@West.Boeing.com>]

Dave said:


> A little input here. The K24 is a smaller turbo than the K26 series. And
> it
> is
> even hard to compare at this level because the ur-q K26 is different from
> the
> MC K26 which is different from the porsche 944 K26.... So I assume you are
> discussing replacing the MC K26 turbos with K24s.
> 
> The K24 is smaller and spins up faster because it has a smaller inertia
> than the K26 series. And because it is smaller, it ultimately will flow
> less/hotter 
> air than the K26 series at elevated boost pressures. The trade off between
> 
> these is that the K24 spools up very quickly and helps at lower rpms, but
> as
> you
> have mentioned, there are K26s which can be modified to spin up quicker.
> 
> >
> >> Absolutely agree on this point.  Great upgrade to a pre Mac-14 Q.
> Should
> >> run nicely on 1.8 Bar.
> >
> >   A k24 with 1.8 bar would be VERY Nice.  
> 
> The K24 was used at 1.8 bar in the 20V engines, that is what it is
> designed
> for.
> 
The Mac-14 89 - 90 10vt q's used a K24.  They also increased the CR.  Why?
I think to improve lowend HP.  And I don't think the car suffered any high
rpm boost problems as a result.  However, did they increase the static CR so
they didn't have to run 1.8 bar on a K26 designed MC intake/boost system?

I am the "K26 is better at higher pressure" protagonist.  I did however make
the above comment about a >>pre-Mac14 MC running better up to 1.8 on a
K24>>.  I agree that the 20vt's system is different (bypass valve, for
example) and gives the K24 the ability to run 1.8 bar better than on a 10vt.
I _assumed_ (fatal word on this list) that a 1.8 bar modded Mac-11 car w/K24
would have more low end boost (i.e., 1.8 bar at <= 2,000 rpm), than same
w/K26.  However, I have no BTDT on this issue.

Not trying to slam, just understand.  I have NO experience in these areas.
I have talked to someone I consider an expert, and have decided to start
with 2.0 bar and a single-pass IC.

> I have prepared a special 1.8
> bar ECU for 
> this car but we haven't had the chance to test it out. 
> 
I am VERY interested in the results.
>  
> 
> One underlying theme is the people who are impressed with the K24 swap,
> are
> installing
> it on the original ur-q WX engine. A number of people have done that and
> think it is
> the cats meow, Glen P, Glen L, RDH, John K, and probably more. So it seems
> that
> the fast spooling K24 helps the 7.0 CR engine get going and elminates the
> 3500 rpm 
> surge of power that the original ur-q was known for.
> 
I'd love to know how this translates to a MAC-11 running at 1.8 - 2.0 bar.
Thanks,

Gary Lewis 
88 5kcstq 1.8 bar 108km Pearl w/Fuchs
86 5Kcst 5sp 1.4 Bar 202km Sapphire
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