Originally Posted by F-BIRD'88
Accelerate from a stop, starting out in 3rd gear.
Now do it starting in 1st gear, then shift thru 2nd and 3rd gear. Which causes the car to accelerate faster.?
Unless you only criteria is absolute bonneville like top vehicle speed,
it is critical for good acceleration and overall car's performance that the gear ratio and expected engine operating torque rpm range be well matched to the job.
The higher the camshaft duration the higher the engine wants to rev to make its best expected power and torque . The smaller the engine CID relative to the car weight, the more critical the axle gearing selection is going to be.
The short answer is cammed up engines want to rev up to make power and torque and needs gears to do that and get the acceleration you are after.
Otherwise initial acceleration is less than inspiring. A typical car with a big duration cam and no gear or "hiway gears" takes quite a long time to gain rpm from a stop ,,, to get " up on the cam" Then, it runs hard.
A very larger CID engine is much more tolerant of a big cam than a smaller CID of the same engine family, in a said car weight.
It is one thing to have "400 horsepower" or have "500 horsepower". it is quite another to actually apply the power and usefull power range to go fast and or accelerate quick.
this is exactly my point!
not all acceleration contests start from the car being at a dead stop.any car that does cornering has little or no use for a deep first gear(drag racing) The lowest speed I have ever come out of a corner was 40 kph,about 25 mph. At 25 mph I would have zero use for first gear.
If I even just do a simple parking lot event,knocking over pylons,I would constantly be shifting gears instead of just using first gear,that is entirely rediculous.
I do use a 3.50 gear,not the original 2.73 gear because 2.73 gear ratio is wrong for my application.
If I raced my car in the 1/4 mile, the difference between 3.50 gears and 4.30 gears " might" be 2/10s.
my cam is not huge but is big 256/264º @.050,it makes peak power @ 6500 rpm. power band is 35-68,if it was drag car then a 4,000-4500 stall for an auto would be correct. As a standard I would launch at 6500,as a road race care I would just slip the clutch and go,same for hill climb.
the 4.30 gears would be useless for road racing/hill climb/parking lot gymkhana,and highway driving.
gears match the cars application