RE: 5ktqw Low End Power

["Lawson, Dave" <dlawson@ball.com>]

>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?

Right, a K24 is used, with increased CR, but still only 1.4 bar. I 
believe it is like you state, the CR was increased so that they didn't 
need to run 1.8 bar. In stock form this engine is a nice driver and
does what it was designed to do very well. It also lends itself to 1.8 bar
upgrades very well. 

>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 not yet driven a K24 with a 1.8-2.0bar setup, but as I said before,
on the MAC-11 MC/k24 engine with tweeks, I was underwelmed with the drive
at the stock 1.4bar setting.

>I'd love to know how this translates to a MAC-11 running at 1.8 - 2.0 bar.

My instinct says that the mac-11/K24 1.8 setup should be pretty favorable.
The ur-q WX engine runs 1.8-1.9 bar as stock, so from the data collected
the K24 likes to operate in the 1.8bar range.

-
Dave Lawson