Hi
I ran this information thru the Desktop Dyno computer program. I got the
following information, which should be regarded as Desktop Dyno's Opinion.
The Long Stroke (LS) version made slightly more torque from 2000-3500 RPM,
then the Short Stroke (SS) version takes over and makes more power from
3500 thru the rest of the rpm range.
A few comparison points are
SS torque peak 524 @ 5000
LS torque peak 504 @ 4500
SS HP peak 567 @ 6500
LS HP peak 520 @ 6000
I don't intend this as an endorsement of Desktop Dyno Software, it is just
one way of looking at this comparison. This computer program makes many
assumptions in order to simplify the task. Those assumptions reduce it's
effectiveness and accuracy, but it does offer some useful information,
particularly in direct comparison of a single part change. More
information on the heads and cam would be helpful.
If anyone would like a copy of these files to fool with in Desktop Dyno,
email me off list and I would be glad to email them.
Dan
>>Subject: An interesting study of bore and stroke
>>
>>Let's assume you've got two big-block Chevys, both with 11.0:1, both with
>>the same solid-roller cam (253/260 at 0.050 on a 111), and both with the
>>same heads, intake, carb, oil pan, and headers. Both engines are 489ci.
>>However, one uses a bore and stroke of 4.55x3.766, and the other is
>>4.28x4.250. The rod-ratios are similar: the long-stroke is 1.53:1
>>(6.535-inch rods), and the short-stroke is 1.63:1 (6.135-inch rods).
>>
>>
>>What's the difference in the power curves and the required tuneup of these
>>two engines and why?
>>
>>
>>DF
Dan Wright
It's amazing what you can do if you don't know it can't be done.
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