Dyno Results In 3rd Or 4th Gear

[stealth]

Hi Guys,

Read an interesting article by APC regarding the use of 3rd gear when producing a dyno report. My last couple of tunes by Bris Tuning have been done in 3rd gear which is frustrating to say the least. When I asked why they used 3rd gear they said it was too much strain on the car and equipment (bullshit) but the result would be the same!!dyno_difference_in_3rd___4th_gear.pdf

Edited June 26, 2006 by stealth

[MR331307]

Hi Guys,

Read an interesting article by APC regarding the use of 3rd gear when producing a dyno report. My last couple of tunes by Bris Tuning have been done in 3rd gear which is frustrating to say the least. When I asked why they used 3rd gear they said it was too much strain on the car and equipment (bullshit) but the result would be the same!!

Dyno runs should be in any gear closest to 1.1 ratio such as 4th in a skyline.5th Gear is overdrive.

Varying on the dyno,The run should never reach over 240 Kms an hour otherwise on a dyno dynamics dyno it hits the electric break and slows the car down,In this case you will need to do the run in 3rd gear. If you have it on shootout mode the ramp rate is automatically set when you chose Shoot 6F,The Gear and tyre Pressures should be entered as well as temperatures of the day.Inlet air temps will also show to prove that the sensor isnt near the extractor manifold reading hi inlet temps giving hi hp readings.

If you load the car in 3rd instead of 4th there will be a little change in hp as it will ramp quicker but nothing more then 40hp just depending. I tested this on my dyno dynamics dyno and only got 5 hp difference

[stealth]

Dyno runs should be in any gear closest to 1.1 ratio such as 4th in a skyline.5th Gear is overdrive.

Varying on the dyno,The run should never reach over 240 Kms an hour otherwise on a dyno dynamics dyno it hits the electric break and slows the car down,In this case you will need to do the run in 3rd gear. If you have it on shootout mode the ramp rate is automatically set when you chose Shoot 6F,The Gear and tyre Pressures should be entered as well as temperatures of the day.Inlet air temps will also show to prove that the sensor isnt near the extractor manifold reading hi inlet temps giving hi hp readings.

If you load the car in 3rd instead of 4th there will be a little change in hp as it will ramp quicker but nothing more then 40hp just depending. I tested this on my dyno dynamics dyno and only got 5 hp difference

Its good to hear another side of the story.. as always there are so many different solutions for the same result. Its hard for the novice to know who to believe.

Thanks for the input

[mad082]

yeah i thought they did it so that they didn't over speed the dyno.

[R31Nismoid]

Where the power comes on though is the key.

In 3rd there is generally less load, same as less in 2nd and in 1st

[mad082]

In 3rd there is generally less load, same as less in 2nd and in 1st

turbo cars often make more power with a higher load as they can build more boost (there is another thread on here about it). so in 3rd gear on the same ramp rate it wouldn't have as much power difference as it would on the highest ramp rate.

[GTR1993]

what about changing diff gear ratios?

I have tryed this on my car personally and found that there is very little power difference, even when we changed ramp rates from 100 to 150 only a few kW difference.

also the link isnt working for me.

Edited June 26, 2006 by GTR1993

[Cubes]

turbo cars often make more power with a higher load as they can build more boost (there is another thread on here about it). so in 3rd gear on the same ramp rate it wouldn't have as much power difference as it would on the highest ramp rate.

This is exactly what I have experiened, In third it made 4rwkw less and it was consistent, we did 4 power runs alternating.

[stealth]

what about changing diff gear ratios?

I have tryed this on my car personally and found that there is very little power difference, even when we changed ramp rates from 100 to 150 only a few kW difference.

also the link isnt working for me.

Sorry guys, dont know why the link isn't working - scanned an article and it has created apdf file which doesn't seem to open.. any hints?

[Cubes]

works for me..

Those of you using firefox it will save the file with an incorrect extension, simply rename the extension to pdf and off you go.

i.e should have no problems

[WazR32GTSt]

automatics are dynoed in 2nd gear... wonder if that makes much difference? probalby not...

[GTR1993]

ah yes file works just rename the extension.

[dezz]

i had my stock R33 dynoed...i was putting on an exhaust the next day, so i spent the cash to see what it was making in stock form, and planned to re dyno it once the exhaust was fitted to see the gain made.

my bog stock R33 made 182rwkw....the dyno operator proceeded to tell me that "you never know whats under tha heat shield...the dyno doesnt lie"

after explaining that its not possible for a car with a 187kw engine to make 182rwkw, i gave up as "i had no idea what magical turbo was under the heatshield on my bog stock R33"

i posted a thread about it when i realised it was ran in 3rd gear, and had mixed responses...mostly people telling me that im wrong, and that the gear doesnt make a difference.

Seems someone has deleted my thread ...dont know why

[Busky2k]

Well on 1 dyno day i witnessed a car do 2 runs in 3rd and 4th gear. The difference was only a couple of rwkw. So yeah...

[Turbine]

Hi stealth,

Was this a 4WD Dyno or a 2WD Dyno.?

We have the challenge of running a GTS4 AWD RB20DET car on a Dyno shortly this week, but I'd like to know of some differences between the two as well as the selected gear for the run. Car is an automatic.

Seems a grey area to me about the whole procedure.

Cheers

[The Dan]

Dyno run should always be done in 1:1 ratio or 4th gear.

Sometimes the run is done in third if the vehicle has a speed cut and cannot be taken right out.

[BezerkR32]

As already stated the reason for using lower gear is so not to overspeed the dyno, stock to mild cars should have no problems being dynod in top gear, and the same for automatics, if your car does over speed the dyno in top you usually finish top end of tune at the track, which in most cases is what has to be done anyway. usually only get 90% of tune on dyno and clean the rest on the track. as for the power readings, as long as you dyno the car the same way before and after your modifications, you will see an improvement which is what you are looking for.

Dyno run should always be done in 1:1 ratio or 4th gear.

Sometimes the run is done in third if the vehicle has a speed cut and cannot be taken right out.

[Sydneykid]

The 180 kph speed limiter is also a problem in 4th gear for cars with standard ECU's.

cheers

[ebola]

So there is a difference in output between the gears. I'll put this down to load (ramp rate)... same way that full boost in first happens about the same time as the rev limiter. Load is important to turbo cars...

Theoretically, shouldn't the kW be the same, because it will register as more torque and less speed? and also, a lower gear with a higher ramp rate ('magically' matched, or course) should produce the same load on the engine, so the same amount of kW...

[mad082]

Theoretically, shouldn't the kW be the same, because it will register as more torque and less speed?

yes. power is just an equation using torque as the base unit.