Software etc

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>I'm still using that old DOS version -- in dosbox on a unix

>machine. How cheap am I? :-)

 

DOS on UNIX?? I wouldn’t call that cheap I’d call that SMART !!!

 

>Where are the errors in these sorts of programs? I always thought

>they were meant for comparison purposes more than calculating

>exact horsepower; like, will a bigger valve help here? Watching

>cam changes move the torque peak, etc. That seems more important

>to me than whether it's 250 HP or 200hp.

 

>Does desktop dyno simply get the numbers wrong, or are peaks in

>the wrong place, etc?

 

Basically Desktop Dyno relies on “models” to get it’s answers. One of the
car mags  did a comparison test on a couple of the programs a while back and
found them to be surprisingly close for the inputs they have. You are right
they were not originally meant to accurately measure horsepower but to
compare changes. But as the programs mature they keep getting better and
better. 

I left the shop with the dyno before these programs came out so I can’t
comment on comparisons in real life. However I recently did some searching
for any results users have had from the cam I’m putting in the 390 I’m
building now (240’@.050 solid Crower). I found 2 guys who HAD run 401’s
built very similar to my engine and who HAD compared Desktop Dyno to their
actual dyno results!! BOTH said although the HP results were optimistic (a
good 30HP to high) the torque was VERY accurate, within about 10 ft lbs.

That’s one of the main differences in the programs, the INPUT. The more
expensive programs require actual flow readings at different lift points.
These programs get the results more accurate than DD,,, but they also cost
more.

Take a look at “Engine Analyzer” from performance trends and you’ll see what
I mean. DD is a good program and easy to use.

But hey,,, that’s just ME!!!

Bruce Hevner

 


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