R-TuneZ

just as a quick reference, what is considered the most accurate dyno?

Hydrazine

iTrader: (53)

Accurate? ...Its a little hard to answer.

In my research I found Dynapack to be the most "repeatable".

davidv

iTrader: (2)

The one that gives the most horsepower of course. Then you can post horsepower in your signature for cool points.

350z2go

iTrader: (9)

+1

go-fast

i can't wait to see the conclusion of this thread.

superchargedg

iTrader: (4)

The turbonaters company dyno is the most accurate.

Sharif@Forged

iTrader: (92)

Big can of worms.

IBTL

Alberto

iTrader: (14)

There is no "most accurate", just like there is no best car, or best anything usually. This is a subjective topic. Many can say a load based is better, a Dynojet is best because it is the "standard", a Dynapack isnt wheel hp its hub hp, etc, etc.

In the end, they are just numbers, and dyno numbers dont mean squat. Have a fast car? Prove it with undeniable MPH down the track, otherwise spew off dyno numbers and impress the people who dont know any better.

Cux350z

iTrader: (162)

Repeatability = precision. If it gives you the same crap for 300 runs, its still crap.

Accuracy = Agreed to be close to the actual value.

Hydrazine

iTrader: (53)

[quote=Chris @ Migliore;6372916]Repeatability = precision. If it gives you the same crap for 300 runs, its still crap.
[quote]

That depends on what your objectives are.

R-TuneZ

[QUOTE=Hydrazine;6373410][quote=Chris @ Migliore;6372916]Repeatability = precision. If it gives you the same crap for 300 runs, its still crap.
i suppose i was talking about repeatability. being that there is no "standard dyno" it is hard to determine what the actual hp of a car is... i need repeatability, so i can see if i am gaining/losing power. i am just looking to do some research as far as getting a baseline run, comparing that with drop-in k&n, and then Nismo CAI. afterwards i want another run with MD 5/16 spacer. and ultimately Bassani exhaust.

Z1 Performance

iTrader: (564)

the answer is, there is no answer

they all work well, they are all tools, and in capable hands, they are useful tools

the best you can do for repeatability is using the same dyno at the same shop, preferably during the same weather conditions - even with that there are variances.

Hydrazine

iTrader: (53)

That's great you want to document and dyno your progression of mods. Its rare for people have that level of curiosity.

When running on the dyno you have to expect that variables will be working against you but there are ways to counteract them.

First and foremost is to dyno everything you can on the same day, same dyno, same tank of gas, etc, etc, in as short a period of time as possible.

You have a lot of things listed there so it is unlikely that you will be able to do it all on the same day.

Be careful about the effects of atmospheric temperature. It can have a very significant effect on the ECU (Even with SAE corrections).

For example:
You could dyno the Z on a warm afternoon. And if dynod the very next morning when its 20'F cooler outside, the power number will be quite a bit higher.

We all know this to be the case. Its common knowledge. But its an example of an easily measured variable.

You would think the SAE corrections built into the dyno software would automatically zero this variable out.... And you can be sure the correction factors have indeed done their work, but still, the dyno plots won't look the same at all.

The dyno done in the morning will be quite a bit higher than the one done in the afternoon.

The reason is not that the dyno made an innacurate measurement. Its not simply because the air is more dense either. The SAE corrections take care of the change in density.

The change of the dyno result is seen because the ECU changed operational parameters of the engine. The ECU changes spark timing, A/F and cam angles based on temperatures.

And there are a lot of other variables too. Way too many to list here.

Just do your best to dyno as much as you can under the same conditions.