Awadd9

<center><img src="http://pictureposter.audiworld.com/68627/graph_stages.1.jpg"></center><p>Almost complete. I am pleased with the results..
I will post a brief follow up of my calculations..

All my runs are done warm and we remove any Hail Mary runs. So numbers are consistent and can be repeated over and over again. I use a Dyno Dynamics AWD load bearing Dynomometer..

Awadd9

<center><img src="http://pictureposter.audiworld.com/68627/numbers1.jpg"></center><p>I think Audi rates the torque at 166 at the crank so my correction for torque may be off.

Using a claimed 166 of torque I think it comes to like 267 and not 274.

Also new GIAC injectors can provide plenty of fuel to run a Hybrid KO4. First launch is for the stock KO3 set-up, then KO4-15 software will follow, after that software will be available for the KO3 and KO4 hybrids. With a few other things in the pipeline. The initial set-up will cost considerably less than the APR 1+ and will be a totally turnkey product.

I am Beta2 guy.

paul_858

First off a using % coefficient of loss is generally wrong. That percent may be accurate for 170chp but it drops significantly when you increase the power. Your car will lose approximately the same amount of HP (in the same gear) regardless of how much more HP you make.

So in your example your car lost ~60hp due to drivetrain/tires/alignment/dyno load so take your whp of 154.9 and add 60, that's a more accurate reading of how much power you are making crank. Just because you make more power doesn't mean you're losing that much more power, it may be measurable but it isn't significant.

By your calculations if your car was now making say 500whp, with your correction you're losing ~175hp(rough not using calculator so bite me). Where did the extra 115hp loss come from? The parts are spinning at the same speeds, albeit getting there a bit faster.

Another point to note, loss increases as wheel speed increases so it's not a linear 60hp across the RPM band. obviously at lower speeds the drivetrain is generating less heat, so less energy is lost that way. The faster the parts move, the more energy you lose.

paul_858

btw still very good numbers

Yippers®

I think the link is informative as is this post and the (germane)surrounding posts in the discussion.
https://forums.audiworld.com/performance/msgs/48357.phtml<ul><li><a href="http://www.pumaracing.co.uk/trans.htm">http://www.pumaracing.co.uk/trans.htm</a</li></ul>

paul_858

more power being produced, would the loss be that simply grow because of the added power? The drivetrain would spin up faster due to added power, but is it going to remain at the same % rate? This loss also will vary depending on when peak power arrives. My argument is primarily that DT losses aren't linear, they aren't a fixed % value.

Why would the same car making significantly more power, lose THAT much more power to the drivetrain so that it's the same proportional rate as stock? I don't believe it does.

Awadd9

<center><img src="http://pictureposter.audiworld.com/68627/04wrx.jpg"></center><p>I am really not an expert on this and more education from you guys would be appreciated. I often wondered if loss was a constant or if it varied as power increased and wheel speed increased.

Also I am not sure if the Dyno Dynamics Machine puts a constant load on the wheels, so however fast the wheels are spinning it is still putting the same amount of load on them. I am not even sure if that makes a difference.

Yippers, honestly the article was a touch over my head, and I did not see AWD referenced. Can you give me more insight? It would be appreciated..

Finally this is a stock WRX with a claimed 227 crank hp from the factory. Now I know we could argue efficiency of the drivetrains and such but if I take paul_858's advice and do the 154.9+60, I come to 214.9. Now is it even feasible to compare the Subaru claim off 227 with 156 lets say at the wheels to my 155 at the wheels.

I know they are two different cars but I am interested in hearing peoples thoughts..

Thanks guys and I look forward to hearing more..

Andrew

Awadd9

So if this is the case you would have to address the torque number before the HP number, right?

Also how applicable is the constant load from the dyno?

Yippers®

On the main page there is also a link to another site that also has a wealth of info http://www.sdsefi.com/tech.html

I think John's formula addresses how losses are proportional to the power being applied. Transmission losses are routinely expressed in percents by transmission engineers. IIRC there is a transmission engineer that posted to this effect in either the thread I referenced or another Performance Forum discussion (around the same time frame) on this subject.
Think of the impact on your cars acceleration by heavy 19" wheels as opposed a set of lightweight 17's. In this case your power level remains constant and the rotational mass increases but the net effect is that the loss to inertia far outweighs the power loss one would expect from the change in weight alone. Another way to think of it is that with the car in the air I can spin the driveline slowly but I can't spin it rapidly as I lack the power to overcome its inertia. The stock engine can only accelerate it at a finite rate determined by the amount of available power. A chipped engine generates more power and can therefore accelerate it still more rapidly. A 300 CHP engine can spin it still more rapidly, 500 chp more rapidly still, etc.

"4wd cars will have higher losses because of the extra differentials and other power transmission components. The tyre and main gearbox losses will be the same though. Correlating the performance of vehicles with the both 4wd and 2wd options (Audi's and the Sierra Cosworth are examples) shows 4wd transmission losses to be about 5% higher than rwd. 22% seems to be a good average"
Quote is from:
http://www.pumaracing.co.uk/power3.htm

Interestingly this ~22% is a recognizable value from empirical evidence we've seen from baseline to chipped to Stg3 car's dynos. In turn, those 'calculated/estimated' crank power levels seem to be equally supported by 1/4 mile time/speeds for the stock, chipped and Stg3'd cars. While there is, of course, a measure of driver skill influencing track results, that is pretty good test of engine power levels to accelerate a known mass to a known speed in a known time.<ul><li><a href="http://www.sdsefi.com/tech.html">Edited to provide a link</a></li></ul>

Awadd9

Excellent article...