Loss of 22.5% HP

RCZ

guys, different dynos read lower and higher on the same exact car. Im sorry to say but this thread was doomed before it started.

It depends on the dyno, most low low reading dynos like a mustandyne or a dyno dynamics will read around 260 for a stock Z. A normal reading dyno like a dynojet will run around 270 and a high reader like the dynapaks will run 280 stock.

This is not a rule, its just ranges. There are ringers out there.

m4a1mustang

+1. I'm going to get a baseline on a dyno-dynamics tomorrow. Yeah, it sucks that I'm not going to see DynoJet numbers, but I just want to track the improvements my intake and exhaust will provide... so no big deal. If I want some big numbers to advertise in my sig I will go all the way out to Altered and run on their DynoJet.

Anyhow, this serves as another The370Z.com Learning Lesson (TM) that when we try to compare dyno numbers we should disclose the type of dyno used.

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wstar

^ +1. theDreamer just did a DD baseline at 243rwhp on a 6MT car. I know that sounds low, but (a) this is DD, which reads lower than most, and (b) even among the same mfg, every Dyno is set up a little different, and runs in different conditions, etc. Apparently EngineLogics is our local super-heartbreaker. It's kinda nice knowing that your numbers can't possibly be interpreted as inflated though

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lando76

So basically most of you agree that not one dyno is accurate. One thread said " A normal dyno" which to me sounds a little broad. How about this I will go to three different dyno shops and pay three times what I want to pay and take the average. I do believe that most dyno shops have to have their machines calibrated by the state of some sort to charge customers money and be considered a business.

Ryan@IP

All dynos are accurate on their own scale, as long as they are well maintained (ours is). Even car manufacturers can't always agree on what to accurately rate engine power at. What you also have to consider is the formulas behind each dyno and how the numbers are determined. It is a fairly complicated process that takes in a scary amount of values to determine what numbers to output on the screen. As a previous poster pointed out, some dynos are load bearing; others are not. Some, like a Dynapack, measure from the hubs rather than the mounted wheels and tires.

There is no such thing as a "normal" dyno or a right vs. wrong dyno. We have our reasons for choosing a Dyno Dynamics over the other choices, but that does not mean that we feel DynoJet numbers are irrelevant. They are simply using a different scale than ours. The important thing is that you remain consistent on the brand of dyno that you go to. A DD's numbers will be comparable to just about any other DD's numbers, but directly comparing a DD result to a DynoJet gets a little more fuzzy. The only *true* way to measure horsepower output is through an engine dyno, not a chassis dyno. All we can realistically do is measure gains from our baseline on X dyno to the results on the same type of dyno.

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wstar

Well, in *theory*, the value of a a ft/lb of torque is based on international standards. Therefore any machine reading ft/lbs of torque from the spinning wheels of a car under the same loading conditions (meaning, some standardized approximate simulation of the weight of the car and aerodynamic load), with the same (hopefully minimal) wheel-slip error on the rollers, should read the same value.

I understand, to some degree, why the situation is as it is, but I think there is a "right answer" as to how much rwhp is actually being put out of the car, and I think the dyno mfgs could be doing a better job than they are of getting their results in line.

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tbss370z

What gear should be used when dyno testing? Is there a formula that you can use to adjust for weather conditions such as temperature, humidity & atmosphere pressure?

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theDreamer

Some allow for things like these, but the best thing to do is either a) do the dyno tests on the same day b) try to recreate the weather conditions as best as possible.

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wstar

For your 6MT, do it in 5th, as this is the 1:1 ratio and it's what others have been using. 7AT guys have to do it 4th at the highest, as we hit the stock speed limiter before we hit redline in 5th and higher, even though 5 is also our 1:1 ratio (we have a different rear end ratio, that's what makes the difference).

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tbss370z

I believe I was told the dyno was done on 3rd or 4th gear. How does that affect the results?

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m4a1mustang

If that's the case, the operator probably ran it in 4th, possibly under the assumption that it was a 5 speed. If it was run in 4th, you can probably add 5whp or so.

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2theextreme

That sounds familiar.......

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tbss370z

Thanks. Is that the rule of thumb on 6MT or does it depend on the car?

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