Caldina GTT Dyno - Comment

[Dell'Orto]

No, they're a tuning tool, nothing more nothing less. An engine dyno is the only way you'll know what its actually making.

[Rych]

wow learn something new everyday. So everyone who claims "my car makes this much hp" means nothing. All the XXXKW ATW in magazines is just a rough estimate?

I don't mean at the engine, but a dyno measuring power at the wheel still can't measure power at the wheels properly?

[strx7]

wow learn something new everyday. So everyone who claims "my car makes this much hp" means nothing. All the XXXKW ATW in magazines is just a rough estimate?

I don't mean at the engine, but a dyno measuring power at the wheel still can't measure power at the wheels properly?

no, you can only comapre before and after power/torque readings on the SAME dyno. it isn't that they are inaccurate it is that they all measure the power differently. The only way you can accurately say that you are making X HP at the wheels is to attach an engine dyno to your wheels

[sergei]

I didn't realize how inaccurate dyno's are. So you mean to say you can't just go take your car to get dyno'd and see how much power it's making because most likely it could be way out and won't mean anything?

Surely there are accurate ones around???

But how do you know which one is accurate?
Unless you have an electric car and 99% sure if its power.....

[Akane]

Funny how I keep hearing people allowing crazy % of "drivetrain loss".

If it's true, after a bit of track time, your gearbox will turn into an ingot.

[sergei]

Funny how I keep hearing people allowing crazy % of "drivetrain loss".

If it's true, after a bit of track time, your gearbox will turn into an ingot.

It is not % anyway. It is non-linear.

[Akane]

Funny how I keep hearing people allowing crazy % of "drivetrain loss".

If it's true, after a bit of track time, your gearbox will turn into an ingot.

It is not % anyway. It is non-linear.

Probably. Only way to find out is to make multiple runs on engine dyno and then road dyno, and plot it out.

I made 218kw @ wheels, I probably guesstimate it to be 225kw at crank at most.

If anything, it's the inertia dyno that'll be affected, since that's what it relies on to get a reading, and your drivetrain have inertia (wheels etc).

but to lose 70kW+ (about 35 heaters on MAX POWER), you got tungstun gearbox or something?

[strx7]

they aren't loosing 70kw, just the dyno they happen to be using reads 70kw less at that kinda power level.

[blindnz]

but to lose 70kW+ (about 35 heaters on MAX POWER), you got tungstun gearbox or something?

The weight or density of the material isnt going to change your loss. In the same way a lightened flywheel wont change your drive train loss all your doing is changing your inertia, not your efficency.

How do the different dyno systems vary in measurement? like does dynometer overcompensate for somethings?

[matt dunn]

The only way you can accurately say that you are making X HP at the wheels is to attach an engine dyno to your wheels

How is that any different to any other dyno attached to your wheels?

Why is an engine dyno more accurate to any other?

What happens if you attach a wheel dyno to your flywheel?

[blindnz]

im not exactly clued up on dynos but isnt a engine dyno measured from the crank or flywheel? as apposed to a chassis dyno being measured essentally from a rolling road.

[Jingle Balls]

best dyno is quarter mile trap speed vs weight. i've had the same car on a couple of different dynos with varying result. dynapac typically read higher than rolling road, but i've been on one rolling road that reads 10-15kw higher than another rolling road

back on topic, power seems right for the boost to me. looks like the gain on the boost controller is set wrong though with that boost spike. should gain about 10kw for every psi of boost you raise it if you want to get more power

[strx7]

best dyno is quarter mile trap speed vs weight. i'

Only if wheels, tyres, diff ratio, gear ratios etc are all exactly the same. Otherwise there is too many variable just different types of rolling road dyno's

ie. 1000kg car with 200hp and a 5:1 diff is going to eat the same car but running a 3:1 diff.

[strx7]

The only way you can accurately say that you are making X HP at the wheels is to attach an engine dyno to your wheels

How is that any different to any other dyno attached to your wheels?

Why is an engine dyno more accurate to any other?

What happens if you attach a wheel dyno to your flywheel?

Are you saying Matt, that there is the same kind of power reading differences/discrepencies between different engine dyno's? If so then who really know how much true power one is making. Or does it just prove that at the end of the day, True HP and True Torque dont mean jack all, it's all to do with how they are used and what the rest of the set up is.

[blindnz]

best dyno is quarter mile trap speed vs weight. i'

Only if wheels, tyres, diff ratio, gear ratios etc are all exactly the same. Otherwise there is too many variable just different types of rolling road dyno's

Not to mention environmental conditions track temp, air temp, air density etc..

[matt dunn]

Any form of measuring anything, is just comparing one thing to another.

Measuring a piece of stirng with a ruler etc,
who says the ruler is accurate?

Dyno's just compare turning force against what it is programed to belive what a specific turning force is.
Two identical dyno's with the same car on them may read different,

and when the dyno guy tells you it has just been calibrated,
calibrated against what?
Did they apply 400hp to the dyno and calibrate it to that?

Or did they just plug in a laptop to it and adjust it's brain a bit?

IMO there is no such thing as an accurate dyno,
as something like that is just not capable of being accurate.


And IMO engine dyno would be the same.

Two different brands of engine dyno would probably read different too.

[fivebob]

best dyno is quarter mile trap speed vs weight.

That would be the worst method for accurate comparision of HP, there are too may variables like tyres, track condition, driver ability etc etc etc.

and when the dyno guy tells you it has just been calibrated,
calibrated against what?
Did they apply 400hp to the dyno and calibrate it to that?

Or did they just plug in a laptop to it and adjust it's brain a bit?

Dynos measure torque, so the easiest way to calibrate them is using a known weight at at known distance eg 1kg weight attached 1m from the point of rotation, then let gravity do it's thing. This only really works with non-inertial type dynos like most engine dynos, and hub dynos like DynaPac/Rototest. Not sure how you'd calibrate a rolling road dyno, or indeed if it's possible to calibrate it accurately.

IMO there is no such thing as an accurate dyno,
as something like that is just not capable of being accurate.

It depends on the degree of accuracy you want, it would be possible to calibrate an engine or hub dyno to within 0.1kw of actual but then you apply fudge factors for atmospheric conditions which, while theoretically correct may not replicate real world conditions, especially in a forced induction engine.

Rolling roads will never be accurate because there are too many other factors involved. e.g. tyres, roller grip etc. (try doing back to back runs on a rolling road just altering type pressure and you'll get different results)

And IMO engine dyno would be the same.

Two different brands of engine dyno would probably read different too.

Dynos will vary because of differences in their setup, differing measurement techniques, e.g. eddy current, water brake etc.

In the end it's only a tuning tool, and a rough comparison tool between engines if using the same dyno under the same conditions.

[Flannelman]

Ive been talking to a tuner with 30 years experince and he said that the guys selling the dynos want to sell "upgrades". All this is changing how they calculate power so that the dyno gives a higher power reading than your competitor and makes you out to be the man at tuning.

This whole thread is about kW. Id be far more interested in the torque given in said gear as it shows what the engine is doing with the boost

[fivebob]

This whole thread is about kW. Id be far more interested in the torque given in said gear as it shows what the engine is doing with the boost

Rough appoximation of the torque/HP curves.

[strx7]

the drop in the torque curve is a head flow thing aye, pretty much every 3rd/4th gen dyno sheet i've seen has a drop in that region, longer duration cams shallow it up a bit but its always there