Quote:
Originally Posted by Packard V8
FWIW, the desktopdynosim programs are fun and will point the way. They can show the crossover points where more cam, more compression drop off. However, they can't show where it will ping. I don't see you getting into any trouble at 10:1 with aluminum heads and a light car.
The one real mistake I see you about to make is thinking you can run "one of the bigger cams I have stored away" with "a 3.00 diff goes in for a little better gas mileage." That will be a miserable combination. Bigger cams need lower gears. With a 3:00 diff, the engine will at cruise way below the sweet spot and fighting the overlap. Choose one - big cam/low gears or short cam/high gears. For a bigger, peakier cam (230@050" and above) I always choose the highest sustained cruise speed I'm ever likely to be holding and gear for the top of the torque curve there. Whichever way you go, stay with a 180-degree intake.
thnx, jack vines
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Agreed on the big cam and high gears.
The 3.00 diff goes into the 32 roadster.
I probably explained it poorly, but the yet-to-be-built 10/1 engine goes into a different roadster.
This one a 31 A on 32 frame rails - a traditional and popular hot rod - with chassis set up for drag racing now and then.
Gearing and tire size will about equal the overall gearing combo of the 32 with its present 3.70 diff and in fact the 31 will be about 5% lower overall.
Weight looks like it will come in at about 2200#.
Part of the reason for building the new roadster is that I had some parts left over from the 32 build and even though they're not quite right for optimum output they're there and I plan to use them.
I can always make changes later....
As an aside, every bracket racer I know is striving for maximum output with their engine, but it seems a modest engine in a light car with gears that won't allow the engine to be overly stressed by high rpms in the traps is the way to go.
Consistency is the key and if the car runs a half second slower or 8-10 mph slower it won't be a problem for me.
I like the aspect of running a hydraulic cam, street type carburetor, change the oil and go to the races far better than a faster machine that requires thrashing on it between rounds....
