I gave you two examples of smaller engines being quicker and faster even at the same horsepower.
Think about this. I have to make the math easy because I don’t feel like doing a bunch of math today.
Lets say you have 1320 feet to get the job done. But it doesn’t matter because any length of course will work. Or even on the street. That’s why God gave man the brains to make transmissions. Never overlook that fact.
You’ve got 1320 feet. And your car does 10 flat. At let’s say…6000 RPM. That means you have 100 RPM per second. You divide that by two (because the crank has to turn twice to make one cycle) and you get 50 firing cycles per second. You following this?
You make power by firing the cylinder. Even at the same horsepower.
In the above example for a 10 second run you get 500 firing cycles during the run. That’s it. In fact, the crank only turns 1000 times!!!!!! That’s not many times is it.
Now let’s say that we change the engine up so that it makes the exact same HP but it does it at 7500 RPM. That’s 125 RPM/Sec. That’s 25% more RPM/Sec that at 6000 RPM.
That means you have the crank turning 1250 times during a 10 second run. Which is 650 firing cycles during the same run. You have 150 MORE times that the cylinder is making power.
And you say so what? It’s still running 10 flat. Maybe, but the car should go quicker IF you tune the chassis and converter for the higher RPM and more firing cycles.
Thats at the same HP. You can’t take gearing and converter out of it because it matters.
Thats why I can say I could have built the same engine as above with LESS stroke and MORE RPM and gone quicker and faster with less displacement.
Of course, this is somewhat simplified because the RPM used is peak and not the average RPM a going down the track.
Obviously you launch at an RPM lower than 6000 or 7500 RPM, and you have RPM fall back at the gear change. But the fact remains that RPM will INCREASE displacement!!! It sure does.
Every time you fire the cylinder you are displacing 1/8 of your total CID. If you fire the cylinder more times you are effectively increasing the displacement.
It‘s amazing how so many discount or even ignore gearing and gear ratios. It’s a simple concept.
Just like a longer wrench will give you more leverage than a shorter wrench, lower gearing gives you more leverage than a longer stroke will.
