rockjeep

What are corrections. I ran the dyno this weekend and asked the tech what corrections where. he said for people who don't know what they are doing. But I keep seeing people post there dyno numbers here and the keep saying corrections. Please school me in proper dyno usage.
Kory

JCLeary

It's a way of keeping dyno readings consistent with varying weather conditions.

They Dynojet is the most consistent. No matter what, a 5000# roller is a 5000# roller.

If it takes 550hp to spin it up in X seconds on a 50 degree day, it will take 550 hp on a 100 degree day. But it takes a lot more air on a hot day to make 550 hp.

The correction factor equalizes those numbers. My truck did 555/960 on an overcast, cold day. Corrected at .95 (favorable conditions) it was 526 and change.

Same truck on the same dyno would probably read at or near 500 on a 100 degree day. The correction factor would be 1.XX to bring the number up to 526, as it's harder to make HP on a warm day. The air is not as dense.

There is a specific way to calculate correction factors depending on temp, humidity, altitude, etc.

But, because of the static weight of the rollers, geographically and also from day to day, Dynojet numbers will be the most consistent.

Load dynos, however, are a different story. Setup is important, and comparing numbers dyno to dyno are is more difficult. Load dynos can, however, be beneficial. They can properly load down a truck to spool big turbos, getting big numbers. But, load dynos usually show lower (read more realistic) horsepower/torque numbers. My 550 "uncorrected" hp truck was more like 500-ish on three different load dynos. One of them was really humbling, I think around 450-ish. Lots of guys were complaining that day, though, except a certain 12v that did 777hp. No problem there.

I do love to claim uncorrected dynojet numbers, though. Your truck made what it made right then and there, no question about it.

On edit:

I'm no expert...