Alright, I always see people posting Dyno charts, and I ain't gonna lie, I dont' get most of it. Can someone break it down and what all the terms mean? Some parts are obvious, but I'd like to get a better understanding of all this. I know alot of other people would like to know this too.

 

The left and right scales are HP and Torque, the bottom is RPM

Normally there is two plots on the same graph.
The first plot starts at about 2500 RPM and angles up at about 45 degrees
that is the HP plot. The other is Torque.
You can see what HP or Torque is being created at what RPM by looking at
the intersection of the X and Y axsis.

Does that make any sense?

 

Torque literally is the twisting force the engine creates at the crank. All that gets pushed through the gearbox, drivetrain, etc. (where you have some friction losses) to the wheels, and ultimately translates to acceleration.

If you look at the torque trace, the bottom of the chart will show RPM (revs per minute, or engine speed if you're not familiar) to show you how much force the engine creates at every given engine speed.

Horsepower is the translation of torque to a measure of work. Let's set that aside for a moment.

Hopefully the dyno chart you're looking at will show before and after lines, for both torque and HP, or four lines total.

The torque line will usually look like a pretty balanced curve, and for the MINI have a high point around 4,000 RPM, where maximum acceleration happens.

So for *me*, when I look at a graph, I go through the following mental process:

1.) I know that I like the acceleration I'm getting out of the MINI at 4,000 RPM. I just wish it hit that hard at 2,000 RPM as well. Now I know that (seat of the pants) about 130 lbs-ft of torque is a good mark for torque for the MINI.

2.) Compare this to the AFTER picture and you can get an idea of the impact of the mods that the owner has done. Look at things like the % it's gone up, where in the range you're getting the most benefit, and how this relates to how you drive. I know what the MINI feels like at 2k, 3k and 4k RPM, and now I have some numbers that I can correspond to the seat-of-the-pants acceleration.

Look at Sleepless' dyno as an example (nice work, btw.) Simplistically speaking you could expect acceleration just about everywhere in the range that's better than what you had at peak, and about a 20% boost in acceleration at peak.

And more to the point, you're seeing good increases in the low and midrange, where you're normally spending most of your time (well, for some!)

Key for me is to take what you're seeing on paper and think about what that really means seat of the pants. Big gains at redline don't impress me. It's fun winding it out occasionally but I'm not doing it every shift, every day.

HTH, Jeff