I'm trying to get a better understanding of the proper way to shift for max acceleration on a four stroke. Also I am trying to understand the benefit of RPMs past the Max horsepower curve. Are they only effective for top speed?

It is my understanding that the best shifting technique for max acceleration is to shift at the point of max HP or just after. As an example, I will use 7500 RPM for the generic quad at max HP. If the generic quad's engine will rev to 10,000 RPMs, isn't it still better to shift at the 7500 mark in this example? In the first four gears, what would be the benefit of rapping the motor past the max HP point at 7500 RPMs?

With that said, I'm guessing the max RPMs of 10K would be most effective in fifth gear going for top speed.

Thanks In Advance.

 

To get max speed over time (drag race), you want to shift just after peak HP *and* have your gearing set up so the next gear doesn't put you too far out of the powerband. If you can get your engine to breathe at higher RPM, you'll be able to build more HP since you are burning more fuel/air over time. Does that help?

 

you always want to be in the highest gear posible that your engines torque can support at the speed it is going, so the faster you can run through the gears the better your drag time will be, but if u go too fast through the gears, then you will lug and it will not be benifitial.

 

So where do the RPMs that are past the PEAK HP shift point come in handy? Where and how are the additional RPMs beneficial?

 

They may come in handy on a closed course when it's not always convenient to shift exactly when you want to. In a drag race, I have seen many times short shifting (under redline a bit) produces better ET's. Not that it isn't useful information, but acceleration is WAY more complicate than a dyno chart. You have to take into account gearing and traction and God knows how many other variables. A stopwatch is the best way to find out for sure.

 

Thanks for the info. From what I've read thus far it can be very confusing, especially to a guy just learning about motors, HP, Torque, RPMs, etc. [img]i/expressions/face-icon-small-smile.gif[/img]

 

it's ok YOUR ONE OF US NOW [img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-blush.gif[/img]

 

We're all learning, it's a process not an event:-)