The guys at Circle Track magazine did a pretty thorough test of this a few
years ago. Basically a longer rod will broaden the power band because the
piston sits at TDC longer and the angularity of rod and crank improves the
leverage slightly. In a 350 ci Chevy at 9000 rpm, it makes a difference, but
you probably won't be able to tell the difference on a street motor.
Basic truths for the technically-inclined:
With a longer rod, the piston will remain near TDC and BDC longer. At TDC on
the Power stroke, this allows cylinder pressures to build a bit higher.
Since the piston has to traverse the whole cylinder during each cycle, and
since the maximum piston speed at the middle of the cycle will be the same
regardless of rod length, this means that piston ACCELERATION will be
somewhat greater with a longer rod. Again, this may be a factor at 9000 rpm
with super-light pistons, but not in a street motor.
A longer rod will also weigh more than a shorter rod, while the piston
weight will change very little (if at all). This may reduce the ability of
the engine to rev, partly offsetting the gains from the first factor.
Gordon Glasgow
-----Original Message-----
From: datsun-roadsters-bounces@autox.team.net
[mailto:datsun-roadsters-bounces@autox.team.net] On Behalf Of Daryl Smith
Sent: Wednesday, April 08, 2009 4:21 PM
To: Tim Waltz; datsun-roadsters@autox.team.net
Subject: Re: [Roadsters] long rod (r16) stroker
I keep hearing about it, but haven't heard any definitive information on the
correct pistons to use.
The rod angles will be slightly smaller, but from my reading this will
minimally affect power and torque.
The 280/300z pistons may however be cheaper than U20 pistons which may make
it a more attractive option to some.......
Read this thread for a detailed discussion:
http://www.gofastnews.com/board/engine-technology/85-rod-ratio-vers-eng-acce
leration.html
Daryl
From: "Tim Waltz" <printner@att.net>
> Another stroker option I've heard of is using the longer (R16) rods, and
> later Nissan (280Z, 300Z?) pistons.
>
> Has anyone ever heard of this, done this, or have any insight on this?
> I've heard it has more torque and lower rod angles. Sounds like a great
> option, but I need more info.
>
> TIA
>
> Tim
> 67.5 1600 waiting to be stroked
> (that doesn't sound right)
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