Login



03242010, 11:39 PM  #89 
Major
25
Rep 1,002
Posts
Drives: 135i TS
Join Date: Jul 2009
Location: Brisbane, Queensland

Good looking graph Adrian. One question though  why the plateau between 48005500?
__________________
2009 BMW 135i  Titan Silver
2005 Subaru WRX Club Spec 8  Crystal Grey Metallic  Fiddled with a bit  SOLD 
Appreciate
0

03252010, 12:10 AM  #90 
Captain
13
Rep 672
Posts 
That was my fault.... I had not driven the dyno in a while, and the car ran up the rollers as the torque increased so I backed off just a little and with V4 this drops the boost a little, and I then got back on it as the car settled. I was annoyed at myself for doing this, as this was the best run. I think it would have filled out that area if I had not done this and peaked a little higher. Previous runs were around 250255kW, but then I let the car idle for 10 minutes with dyno fan on and than this run. I did not have time to cool the engine down again to go for a smoother run. Typical power output of a warm engine would be 250255kW. You get another 510kW if you let the FMIC cool right down by idling with the fan on.
This was on map 2 which runs a bit more boost up top, and I was impressed that with the decat pipes, it holds the power right to peak at 6500. This is atleast a 70kW gain on standard... I expect flywheel power is around 300kW Adrian 
Appreciate
0

03252010, 12:46 AM  #92 
Banned
51
Rep 3,076
Posts
Drives: A boring one...
Join Date: Oct 2008
Location: Australia

Standard run was only 90kw?!
Very nice though, more than I expected! Well done 
Appreciate
0

03252010, 12:46 AM  #93 
Captain
13
Rep 672
Posts 
All default settings so 100%. I wanted a baseline that would represent what can be achieved with no custom tuning.
I think with a standard FMIC, reducing the ignition would actually decrease power... temps get hot pretty quick on a dyno... it is a balancing act on a dyno... you won;t get full boost until about 8090C oil temp, so you need to bring oil temps up to atleast that, but try and keep FMIC temps down... best way for a good run is just let the engine idle for 10 minutes with fan on, and then do a run... always 510kW better than the following run. Adrian 
Appreciate
0

03252010, 12:55 AM  #94 
Captain
13
Rep 672
Posts 

Appreciate
0

03252010, 01:04 AM  #95 
Major General
135
Rep 7,326
Posts 

Appreciate
0

03252010, 01:14 AM  #96 
Captain
13
Rep 672
Posts 
No... Autotech (Granville). I believe that the ALS dyno would read 510kW lower... only because most standard cars on that dyno got less than the 190 mine got standard. This surprised me though, because I also have done alot of work on WRXs, and the Autotech dyno is one of the lowest reading DD dynos for WRXs. Much lower than a hub dyno (around 30kW). I believe the ALS dyno reads faily low. My guess is that my car would have been around 180 standard and 250 modified on ALS.
For reference... with stage 1 mods (stock except procede) I got 239kW ATW, so from stock, tune added 50kW, and dump pipes and DCI added another 20kW. Adrian 
Appreciate
0

03252010, 01:26 AM  #97  
Major General
135
Rep 7,326
Posts 
Quote:
Three of us dynoed our 135's at Als back in 08, when my car had 850km's on the clock.. The other two 1er's had identical figures at 178kW at the wheels where mine had 182kW.. Then after installing the JB3/1.3 and running map 5 with the custom mid pipes exhaust (NO centre cats or resonator ) I got 258kw on a hub dyno.. This was about 12 months ago and have since changed the mapping.. 

Appreciate
0

03252010, 01:56 AM  #98 
Captain
13
Rep 672
Posts 
Yep... go back to ALS... I reckon you would be 230kW ATW compared to the hub dyno figure of 258kW ATH.
You cannot compare hub to roller dyno. Most of the losses on a roller dyno are in the tyres. These losses do not exist on a hub dyno... Only losses in transmission which are quite low. I know Jim at tunehouse will try and tell you otherwise, but he is wrong. I think the reason ALS may read lower is because he does not run shootout mode. Depending on what settings he runs on the dyno (ramp rate etc.) the figure could be lower or higher than shootout mode. Shootout mode locks these settings so you can come closer to comparing one shootout mode dyno run to another. Hub dynos are great dynos... they are just inconvenient to do a quick dyno run, and not very common. Dyno dynamics is the most common so if you want to compare to others get a run on a DD dyno in shootout mode. Notice mine in the graph at the bottom, mine says SHOOT_6F which is shootout mode for a 6 cyclinder forced induction which is the correct mode for our cars. Notice also I was reading 28C in the workshop. Also, I leave the ambient temp sensor in atmo air. It would read higher power if it was in the intake, as it would read hotter and then the correction would knock the number up, but I believe this is unfair... if your setup gets hot air it is a problem with the setup. It should not be given more power because it has a poor intake!! I would have picked up another 510kW if I put the sensor in the DCI as they would suck fairly hot air. Adrian 
Appreciate
0

03252010, 05:18 AM  #99  
Major General
135
Rep 7,326
Posts 
Quote:


Appreciate
0

03252010, 07:03 AM  #100 
70
Rep 1,513
Posts 
Adrian,
Why did you run Map 2? Why not run a map 3+ if you were looking at showing the peak number or if you want some big numbers run one of the SouthernBM maps to smash a big one. I'm Glad you like the power increase of the downpipes 
Appreciate
0

03252010, 07:23 PM  #102 
Captain
14
Rep 900
Posts 
Yah plonker . That'd be the torque curves you're reading. And you're using the wrong yaxis too. The torque scale is on the righthand side of the graph (in Newtons rather than Newton.metres).

Appreciate
0

03252010, 11:24 PM  #103 
Banned
51
Rep 3,076
Posts
Drives: A boring one...
Join Date: Oct 2008
Location: Australia

Hahaha yeah I realised this after... so used to seeing the torque curve near the power curve!

Appreciate
0

03262010, 12:38 AM  #106  
Captain
13
Rep 672
Posts 
Quote:
Now I have been working with cars on dynos for a long time. I am an engineer and trained in physics. I just want to say that the vast majority of people including workshops owning dynos do not understand how dynos work. I am going to give you some info here in an attempt to help you to understand. Firstly... a dyno only measures one thing (plus roller speed). It does not seperately measure power and torque. It measures tractive effort and the speed of the rollers. Tractive effort is the amount of force pushed on the outer circumference of the roller. This is what is displayed on the graph above in Newtons (N). So naturally, car will have more force in 1st gear than 6th even if it makes the same power. Therefore the tractive effort measurement is next to useless for comparing cars unless they have identical gearing including diff ratio and tyre size. The software in the dyno can convert the tractive effort to torque of the rollers (which is totally different to torque of the engine). Torque = Force * radius. The software knows the radius of the rollers, so it calculates torque at the rollers. Once it knows Torque of the rollers, it can then calculate power at the rollers. Power = Torque * RPM. Therefore if you have a constant Torque with RPM, the power graph will be rising linearly in a straight line, as power will increase with increaseing RPM. Notice how in my graph the tractive effort is almost constant between 3000 and 4500 on the blue line, and the resulting power is straight increasing in a straight line. When tractive effort starts to drop, the power flattens. So basically torque is the slope of the power graph. Torque and power are connected... so at a given RPM point, a certain power implies a certain torque. it is impossible (at a given RPM point) for a car to make more torque than another car if they have the same power, as power = torque * RPM, so if power and RPM are the same, torque is also the same. Now, torque is multiplied by gearboxes, but power is not. If a gearbox has no losses, then the power in equals the power out, but the same cannot be said for torque (which is related to radius of gears as torque = force * radius). Therefore unless you know the radius of the rollers, and every gear ratio in the system, you cannot calculate torque using just the tractive effort chart. The tractive effort graph shape will be the same as the torque graph shape (since Torque = tractive effort * radius), but the actualy units are meaningless without the other data. Another observation is that you can 1000Nm of torque with 0 power... it is possible for say an electric car to be pushing with heaps of tractive effort but if the retarders on the dyno stop the rollers from moving (so RPM is zero), power is 0!!. Anyway, I will now tell you the most accurate way to determine the peak torque that I am aware of using the info we have available. Firstly, the graph shape for tractive effort is the same as torque. So when the tractive effort is at a max, so will torque be at a max. This occurs at approx 4500RPM. So we know peak torque is 4500 (although it is pretty flat 30004500). At 4500, the car is making approx 220kW ATW. Now we need to estimate the power at the flywheel (engine). A standard car has 225 kW and dynos 190kW ATW, which is 35kW loss in the drivetrain. So lets add the 35kW to the 220. So at the flywheel at 4500RPM, we are making around 220+35=255kW. Now power = torque * RPM, so torque = power / RPM. Now there is actually a constant in this calculation that is a result of the units change (2pi radians per revolution and 60 seconds per minute etc.), so the exact formula is torque = power * 9549 / RPM. So torque is 255 * 9549 / 4500 = 541Nm. Now there are some assumptions made to get to this calculation (like losses from flywheel to wheels), but I can assure you this is pretty close. For instance, the engine makes similar tractive effort at 3300, where is makes about 160kWATW. So that is 195kw at engine. Torque = 195 * 9549 / 3300 = 564Nm. Now this is 20Nm higher (but still close), and I will tell you why... the drive train losses are actually lower at lower speed of the wheels (as tyres are spinning slower and they are the main source of losses). So losses are probably closer to 25kW instead of 35kW. If you recalculate for that, you get Torque is 185 * 9549 /3300 = 535Nm. Anyway, I would say the torque is in the 520 to 550Nm range. So that is a long rambling, but it is a pet hate of mine the way people ramble on the internet about dyno curves. Especially how people who do not make the power figure they hoped for tend to rave on about how its OK, because they have heaps of torque. Moral of my post... Power and torque are directly related via RPM. You can't magiacally have heaps of torque but poor power at a certain RPM. What can happen however is that an engine has poor flow, which mainly hits at high RPM, so an engine may have good torque at low RPM, but poor torque at high RPM which results in low power since power = torque * RPM. So I hope you guys can better analyse and compare dyno graphs now!! Adrian 

Appreciate
0

03262010, 12:41 AM  #107  
Captain
13
Rep 672
Posts 
Quote:
Realistically, DMS is a fair way behind the other tuning options (Procede, JB and GIAC) in terms of dyno power. Adrian 

Appreciate
0

Post Reply 
Bookmarks 
Tags 
procede, vishnu 
Thread Tools  Search this Thread 

