-----Original Message-----
From: Dave Dahlgren [mailto:ddahlgren@snet.net]
Sent: Monday, June 28, 2004 3:36 PM
To: Freiburger, David
Subject: RE: An interesting study of bore and stroke
I will bite on this just to have some fun but you have to send back what you
found and why you think it worked that way as well..
I would intuitively guess that the shorter stroke bigger bore engine needs a
little more timing yet is more sensitive to it.
Has a flatter torque curve that is slightly lower in peak and is willing to
rev a little higher though not much..depending on how good the identical
heads are.. or what size the headers are or the manifold for that matter
might favor one over the other from the start. IE. 2 1/4 header vs a 1 7/8..
tunnel ram with 2 dominators vs a dual plane and a 750 DP
If it has a carb it is probably more sensitive to minimum usable rpm due to
the lower peak air speed to get it on the mains, if EFI not an issue.
The cam is pretty short if a race engine so it might favor the street use of
the long stroke engine. personally for a race engine i would have picked
something more along the lines of a 276/282 on a 112 with rectangular port
heads and a 268/260 if old oval ports and a 272/276 114 in a good ported
head and they are N/A engines
So what did you find on the dyno??
DD
> -----Original Message-----
> From: owner-land-speed@autox.team.net
> [mailto:owner-land-speed@autox.team.net]On Behalf Of Freiburger, David
> Sent: Monday, June 28, 2004 2:18 PM
> To: 'land-speed@autox.team.net'
> 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
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