Fuel Economy and the 20020vtq and cam setup

Bernie Benz b.benz at charter.net
Fri Jan 31 12:46:30 EST 2003

OPPS!  Sorry Phil,

I inadverntly used the cam timing chain sprocket tooth count, rather than
the correct, 52 tooth TB cam sprocket, in my calcs below.  So in correction,
one TB tooth is only worth 6.9 cam degrees, or 13.8 crank degrees, but still
a gross error!


Phil, you may wish to rethink your cam timing expectation.

One TB tooth (25 teeth on the cam sprocket) is 14.4 cam degrees, 28.8 crank
degrees!  While this gross error may or may not cause mechanical
interference, I don't know. an error of this magnitude is way out and beyond
any reasonable tweeking range.  As you may know, retarded cam timing
relative to a neutral, split overlap condition favors top end power at the
expense of low end torque and visa versa for retarded timing.  But normal
tweeking adjustments are in the range of 2 to 4 crank degrees.


on 1/27/03 4:59 PM, Phil Rose at pjrose at frontiernet.net wrote:

> Speaking of retarded timing:
> Ever since I got my Lago car--over 4 yrs ago--I've felt it had distinctly
> less low-end power compared to the '91 200q it replaced. Later, when we
> acquired #3 (Tornado Red) that car also had better low-end performance than
> ol' Lago. So when it comes time to replace the TB (sometime this Spring) my
> expectation is that I'll probably find the cam sprocket has been "off" by
> one tooth all this time. This also might help explain the car's somewhat
> better-than-expected highway fuel economy.
> Phil
> Phil Rose

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