Thread: Gear Ratio
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Old 11-10-2009, 04:13 PM
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GregWeld GregWeld is offline
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Swain --

I don't know how accurate this info is - but it's food for thought and some discussion with someone that knows a whole lot more than I do...

I was "told" that the best gear ratio for "street" driven cars is one that puts your RPM at Cruise speeds about 200 RPMS LESS than where your CAM starts to make some torque (not just some torque but where it's going to start getting with it).... as this will allow you to cruise just "off" this area of the cam and by just barely tickling the throttle - you start to hit a nice sweet spot. This is supposed to give good gas milage - but give you great throttle response.

I'm tossing this out - since you said you have a short block - but also that you might change to a BBC... so that CAM selection / torque RPM / Cruise RPM calc would be important and make a huge difference in the feel of the car.

So, as example - you have a Cam that is rated at 2000 - 6500 rpm... I'd figure I'd want to be cruising at 1800/1900 RPMS at ? 65mph? and calculate backwards from there using your tire diameter. Or build the motor - dyno it - and see where it starts making power?
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