Question on Dyno Run

[titanic]

I did a dyno test recently with three consecutive runs. The test was done in small enclosure with no air circulation. The test showed the highest hp in the first run and lowest in the 3rd run. Which run is more accurate? Shouldn't the proper test be done with a big fan blowing cool air towards the front of the car to simulate real road driving?

 

[shaaz]

Re: Question on Dyno Run

Where was the Dyno done?, the 3rd last run is / should be the most accurate. Most Dyno places i've been to have a big fan infront,

 

[Sting]

Re: Question on Dyno Run

Yes, there should be a fan in the front to simulate airflow through the engine, thereby cooloing it to some extent. Normally, the first run is least accurate.

 

[titanic]

Re: Question on Dyno Run

Where was the Dyno done?, the 3rd last run is / should be the most accurate. Most Dyno places i've been to have a big fan infront,

Did mine at Dyno Technica. I had 20bhp difference between first and 3rd run, on two separate tests. I didn't remember any fan blowing air.

 

[louis]

Re: Question on Dyno Run

Did mine at Dyno Technica. I had 20bhp difference between first and 3rd run, on two separate tests. I didn't remember any fan blowing air.

20bhp difference is too large a difference to attribute to normal variance between individual runs. how long an interval between each run? what was the ambient temperature and humidity for the day? where was this loss in power? in one particular rev range or throughout? did you take AFR readings?

without knowing the specifics, my guess is that you were experiencing some heat soak. was there some ecu tuning done to your car?

if so, from what i understand, some of the adjustments that tuners do include advancing ignition timing and leaning out your stock AFRs to gain some power/torque. while this more aggressive tune can gain you power by maximizing the higher octane fuels available here, it also leaves you more susceptible to the effects of heat soak; this leads to a lower threshold before your ecu begins to retard your ignition timing and a subsequent loss in the power/torque that was available on your first run.

i stand to be corrected by more knowledgeable folks like shaun, yendor, WT etc etc though

 

[shaaz]

Re: Question on Dyno Run

Did mine at Dyno Technica. I had 20bhp difference between first and 3rd run, on two separate tests. I didn't remember any fan blowing air.

Been there b4, i've been there for dyno tuning, if u look towards ur left and right infront of the car.. there's a blower blowing air.. now, i dun take figures frm there.. just to tidy up my AFR.

I prefer ST Powered Dyno anytime.. i till today believe that it's the nearest/most accurate figures for me.

 

[louis]

Re: Question on Dyno Run

oh, as a reference for comparison, i saw a variance of about 2hp/2Nm or roughly 1% (after correction for drivetrain loss, ambient correction and what not) between my dyno runs.

this was with stock bmw tuning and about 1 minute between the runs, a small-ish fan placed in front of my kidney grills and temp of 32.9 degrees celsius.

 

[louis]

Re: Question on Dyno Run

Been there b4, i've been there for dyno tuning, if u look towards ur left and right infront of the car.. there's a blower blowing air.. now, i dun take figures frm there.. just to tidy up my AFR.

I prefer ST Powered Dyno anytime.. i till today believe that it's the nearest/most accurate figures for me.

i think they're a little generous with the correction factor though; i've seen some runs done and there were no inputs to indicate if your car has a manual or auto transmission.

also, when i asked for specifics on how the software corrects for ambient conditions, transmission, RWD, FWD etc and the magnitude of the relevant correction factors, they couldn't really tell me. i then asked to look at the rwhp/tq numbers and i asked if those numbers had been corrected for ambient conditions etc etc or if they were raw, unprocessed numbers before software adjustments and again, they couldn't tell me.

 

[racingaprilia]

Re: Question on Dyno Run

i just did a dyno today at ST Powered.. oh god was i shocked.. my e90 320i could only conjure 132.3 horses at 6200rpm and 178nm at 3385rpm.

my ride has been fitted with light weight AC type V rims, sprint booster, coil booster, ivac amplifier, knn drop-in filter and sebring exhaust.

to be honest im utterly disappointed.

 

[shaaz]

Re: Question on Dyno Run

i think they're a little generous with the correction factor though; i've seen some runs done and there were no inputs to indicate if your car has a manual or auto transmission.

also, when i asked for specifics on how the software corrects for ambient conditions, transmission, RWD, FWD etc and the magnitude of the relevant correction factors, they couldn't really tell me. i then asked to look at the rwhp/tq numbers and i asked if those numbers had been corrected for ambient conditions etc etc or if they were raw, unprocessed numbers before software adjustments and again, they couldn't tell me.

Yup, true dude, thier correction factor pretty generous, the diff btwn figs i dyno'ed at Ubi and ST were a freaking 50bhp and 57nm.. hahaha.. i rem he telling me the correction factor is 15%.

i just did a dyno today at ST Powered.. oh god was i shocked.. my e90 320i could only conjure 132.3 horses at 6200rpm and 178nm at 3385rpm.

my ride has been fitted with light weight AC type V rims, sprint booster, coil booster, ivac amplifier, knn drop-in filter and sebring exhaust.

to be honest im utterly disappointed.

132.3 bhp at wheels or crank??.

To be honest, sprint booster.. not a power gain mod, coil booster and IVAC amp also not a power gain mod ( makes torque and power smoother). Your sebring exhaust is just the back box (muffler) supposedly does give a teeny bit of bhp but mostly just sound.K&N Filter is suppose to give ur power tho u're looking at 2bhp.

Another thing is that, did u do a base run dyno before all these ?, cause if you are taking numbers frm ur specs (paper) then usually most never get the figures on paper.. just sharing ..

 

[hetraa]

Re: Question on Dyno Run

can see your dyno chart? the coil booster and ivac will prob smoothen yr curves..not really add power as what shaaz says..

knn high end increase a bit, low end suffer cos in singapore mah, air so hot here..
sebring, no effect..

u need ecu reflash from bvo ..bernard is moving on to the E90s..

i just did a dyno today at ST Powered.. oh god was i shocked.. my e90 320i could only conjure 132.3 horses at 6200rpm and 178nm at 3385rpm.

my ride has been fitted with light weight AC type V rims, sprint booster, coil booster, ivac amplifier, knn drop-in filter and sebring exhaust.

to be honest im utterly disappointed.

 

[Stevied]

Re: Question on Dyno Run

Bm Hq use a 3' diamature fan to mock airspeed. I,m in Thailand so humidiy is a factor. They really know what they are doing, respect to th Bm boys of Thailand.