Travis, thanks for the heads up. Every once in a while, these mags
produces some very good articles, that take the myths out of a lot of
automotive lore.
Larry
Travis Hall wrote:
> This months Hot Rod magazine is one of the best I've seen in a long time.
>
> There is a large article debunking the myths of Bore vs. Stroke. Even
> if you choose not to believe their results, it's a worthy read.
>
> They basically take two blocks, same heads, cam, manifold, carb. One
> they give a large stroke with a small bore, the other a large bore
> with a small stroke. They wind up with the same displacement. Next
> they put them on the dyno and compare the results.
>
> Are strokers better at low-end torque? Are short stroke, big bore
> engines better at high rpm. Amazingly, there is only a negligible
> difference throughout the rpm band (like 3hp).
>
> It's a very informative article.
>
> Next is pit stop (letters about tech stuff).
>
> A reader writes in that he wants to improve his stock 289 heads with
> larger Chevy valves. I did this 15 years ago and found the results
> amazing. This confirmed it. They did say that it is important to not
> just add the valves, but to port the heads. I was lucky at the time
> and was able to borrow a cylinder head off of a Shelby GT350 and match
> the porting to the work Shelby had done. The oversized valves and port
> matching just added to the improvements. Their answer is quite lengthy
> and informative, but not quite correct as I remember it. I did not
> modify the valves at all, they advise you to buy custom ones. In the
> end they flow test the heads and post the results. Here's the high
> and low from the chart:
>
> at .100 lift on the cam (all flow numbers are in cfm)
> Intake stock 44.3
> Intake ported 81.0
> Exhaust stock 26.5
> Exhaust ported 49.0
>
> at .500 lift
> Intake stock 184.5
> Intake ported 211.4
> Exhaust stock 92.5
> Exhaust ported 144.3
>
> Again, worth the read.
>
>
> Travis
> B9472584
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