[Shotimes] New +20 cam dyno results

[Leigh Smith]

Alan;
A recommended procedure would be to adjust the overlap / lobe center on a
dyno to get the best peak torque, probably wider than stock w/ a +.020 cam.
Then the overall advance / retard could be done on the street / drags / race
track under actual conditions. Some type of tuning tool like chrondikes,
stopwatch, or g-meter is needed. In most cases you will find advanced cams,
to be actaully faster, regardless of the actual dyno curve / peak HP, cause
they shift the hump in the torque curve lower. Maybe in Marks case where he
is above 5k all the time, retarded cams would be faster. I had gotten some
cam recommendations from one of the best cam tuners at Cam Dynamics (for
another application), and he recommended a lot of duration, with a wider
lobe center, for a higher & wider hp/torque curve. In his words it would run
harder and rev higher for the best of both worlds. Very streetable and very
fast. Drag racing currently favors just the opposite, with tight lobe
centers, cause it does make the peak slightly higher, but it also makes the
power band very narrow, which is OK on a drag car, but not a street car, or
a low cubic inch car like ours. Chevy numbers say maybe a 6 hp difference at
peak out of 400, tight vs wide LC.
..
I'm not sure what the SHO cam specs are, but with adjustable sprockets, on
the +.020, I'd test it first by opening the lobe center up 4 degrees, then
advancing everything 4 degrees. At that point point it should idle more like
stock.
FWIW
Lee
(My Z28 street cam had 255 duration at .050, with a custom wide 116 degree
lobe center. 20-30 degrees more than a stock street cam, and 4-8 more lobe
center, but that 350 reved to 7300 rpm vs 6000. And it still ran faster
retarded 4-6).
I'd even be interested in working with somebody to tame the +.040 cams for
the street! Anybody interested? Ian? I could see a 7000-7300 power peak with
an 8000 redline! And we should be able to tune the torque back in.

----- Original Message ----- 
From: "Alan Fanning" <Awfanning@earthlink.net>
To: "SHOtimes" <shotimes@autox.team.net>
Sent: Sunday, May 29, 2005 3:19 PM
Subject: Re: [Shotimes] New +20 cam dyno results


> I've always wondered how you go about optimizing power output with the
> adjustable cam sprockets. Without expert knowledge, it seems like there
are
> way too many combinations (and not enough cash to finance the dyno time
that
> would be required to do a complete parametric survey). How do you approach
> this?
>
>     Alan
>
>
> Adam wrote:
>
> > If it were me, I would consider purchasing and
> > utilizing the adjustable sprockets in tandem with an EEC tuning tool so
as
> > to utilize the maximum benefit from your new cam setup.  One without the
> > other, in this case, will only get you so far "down the path".
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