skewed dyno numbers or not?

[USCG Charger]

I had my car dynoed a few wks back while being tuned and saw my dyno number where a lil lower then before when I had my stock 2.82 gears in. I'm not dyno qween but it's got my lil brain scrambling tryin to figure out if by changing gears (2.82 to a 3.23), it would lower dyno numbers with all things being equal?

[Charger4Life]

Probably not as much as the temperature difference between then and now.

[Hemi31]

It will lower the # a little.

[USCG Charger]

Probably not as much as the temperature difference between then and now.

All things being equal bro...lets just say same dyno, same car , same mods, everything!

[Super T]

Horsepower = Torque * RPM / 5252


Your torque and your RPM will both be changed by the gear, but torque goes down as RPM goes up (with a changing gear ratio)... the resulting horsepower number should not change.

[Hemi31]

Horsepower = Torque * RPM / 5252


Your torque and your RPM will both be changed by the gear, but torque goes down as RPM goes up (with a changing gear ratio)... the resulting horsepower number should not change.

But it does......don't ask why cause I can't tell you....I just know it does.

[USCG Charger]

Horsepower = Torque * RPM / 5252


Your torque and your RPM will both be changed by the gear, but torque goes down as RPM goes up (with a changing gear ratio)... the resulting horsepower number should not change.

So my tq number will be down on the dyno?

[USCG Charger]

I ask this b/c AJ (Hemituner) said that's prolly why I was getting different number then what I previously dynoed at..... I know dynos are different and all the variables so please lets not get into that on here... I was just wondering about the number and the why gears effect them on dynos

[Redfox0099]

I know my #s are down from what they were when I went from 3.06 to 3.55 with no other changes at that time.

Posted via LXFMobile

[USCG Charger]

I know my #s are down from what they were when I went from 3.06 to 3.55 with no other changes at that time.

Posted via LXFMobile

Do u recall how much NAte?

[Super T]

But it does......don't ask why cause I can't tell you....I just know it does.

LOL... I'll take your word for it :-) I didn't get a "before" pull when I did the 3.55's. What kind of numbers do you usually see it drop by? Couple horse, couple percent, ??? I wonder if it's friction - more teeth meshing per revolution?

[done]

How did it run at the track before and after? That should tell you what you need to know unless you are entering a dyno competition.

I can't believe how empty my life has been by never having my car on a dyno in the 4+ years I have owned it.

[hemidup]

How did it run at the track before and after? That should tell you what you need to know unless you are entering a dyno competition.

I can't believe how empty my life has been by never having my car on a dyno in the 4+ years I have owned it.

Thank you.......

[USCG Charger]

How did it run at the track before and after? That should tell you what you need to know unless you are entering a dyno competition.

I can't believe how empty my life has been by never having my car on a dyno in the 4+ years I have owned it.

Thank you.......

IT ran better at the track... but that's not what this convo is about..... I'm wanting to know if by putting gears in a car will it skew dyno numbers from what they would be with stock gears?

[PowerWagon896]

So my tq number will be down on the dyno?

I would think that the TQ #s would be up, while HP would be down.

IT ran better at the track... but that's not what this convo is about..... I'm wanting to know if by putting gears in a car will it skew dyno numbers from what they would be with stock gears?

I would expect to see less TQ, but more HP under those conditions. That's just a guess though.

Next time, do the pull in 4th gear. Now that you have upped the gear reduction by 15% W/the 3.23s, the speed in the top of 4th gear will drop by the same factor.

It should now be practical to do the tune/pull in 4th gear which is 1:1 so there will be slightly less drivetrain loss as well as more MPH on the rollers.

As mentioned, the weather/DA factors can skew #s a bunch if the proper correction factors are not used. If those correction factors are not used, the #s from 1 day to the next are like comparing apples & oranges.

Given some things that have been brought to light, I plan to do any dyno tunes in 4th after my 3.23 swap W/pulls in 3rd to double check the maps. Actually, if I can afford it, pulls in @ least the 1st 4 gears would be a good thing to do.

Ahh, will this money pit ever get full?