Area Under the Curve
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I am obsessed with wringing every once I can out of this setup while maintaining good street-ability.
Thanks for feeding my illness! LOL!
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I admit to having read only about half of this thread.
This board has quite a few cars that are truly optimized for dyno numbers and 60-130 times. As we all know most dynos are run in 4th gear, punching it at about 2,000 RPM an letting the tallish gear give the turbos time to build boost (TQ and HP). This is also the best way to run a 60-130 and if you can brake boost, the best way to run a freeway roll on race. Especially with larger turbos, since the shift is probably not conducive in that re-spoolin the turbos (no matter how fast one shifts) takes time and speed.
I think that has a place and I certainly don't knock people for having different goals. Build and test your car for what you built it to do!
I do have an honest question and that is how do these larger turbo cars drive in day to day driving? I know you can launch hard, especially if your car has a a laucnh control algorith. But I'm talking about caning it in the lower gears 1-3rd mostly... Is the turbo boost so laggy that it takes away from the fun of zipping around?
This board has quite a few cars that are truly optimized for dyno numbers and 60-130 times. As we all know most dynos are run in 4th gear, punching it at about 2,000 RPM an letting the tallish gear give the turbos time to build boost (TQ and HP). This is also the best way to run a 60-130 and if you can brake boost, the best way to run a freeway roll on race. Especially with larger turbos, since the shift is probably not conducive in that re-spoolin the turbos (no matter how fast one shifts) takes time and speed.
I think that has a place and I certainly don't knock people for having different goals. Build and test your car for what you built it to do!
I do have an honest question and that is how do these larger turbo cars drive in day to day driving? I know you can launch hard, especially if your car has a a laucnh control algorith. But I'm talking about caning it in the lower gears 1-3rd mostly... Is the turbo boost so laggy that it takes away from the fun of zipping around?
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A very good question Ari, and one that I wondered about too. I'm looking forward to Dave's driving impressions b/c he went from stock to modded vtgs to mega-uber-superfantastic turbo setup. He will be able to provide the subjective answer.
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This kinda what I'm getting at. Unlike a NA engine, load and time make a big deference on turbo spool. You just can't load the engine in gears 1-3 like you can in 4-6+
I think the VTG's are too slow to react. In lower gears - 2,3,4 there is still appreciable lag and no outside dyno has ever recreated the plot shown by Porsche with 500 ft lbs hitting at 2100 rpm. Most dynos are run in 3rd or 4th and I have never seen one with a sheer torque wall - all are a slope that rolls on at 3500-4000 rpms.
Now take the car in 6th gear, start at 1000 rpms and jam the pedal - the torque will hit at 2100 rpms. This is not seen in the other gears so Porsche did not lie, but the skyscraper of torque is not there for 90% of driving situations. The only ones getting their money's worth on the VTG's are the autobahn heroes dragging from 200-300 kph...
Now take the car in 6th gear, start at 1000 rpms and jam the pedal - the torque will hit at 2100 rpms. This is not seen in the other gears so Porsche did not lie, but the skyscraper of torque is not there for 90% of driving situations. The only ones getting their money's worth on the VTG's are the autobahn heroes dragging from 200-300 kph...
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Finally got around to calculating my AUC. The data was obtained on a Dynapack dyno which was done in rwd.
The thin black line is the simulated curve for the integration. It's a good fit so the AUC is pretty accurate.
For comparison, the highest AUC for VTGs is Champion's 68mm with an impressive AUC =1938 (on gas) for the same 3000-6800 range although that data was obtained on a Mustang awd dyno so interpret the comparison as you will. I have no idea.
The thin black line is the simulated curve for the integration. It's a good fit so the AUC is pretty accurate.
For comparison, the highest AUC for VTGs is Champion's 68mm with an impressive AUC =1938 (on gas) for the same 3000-6800 range although that data was obtained on a Mustang awd dyno so interpret the comparison as you will. I have no idea.
Last edited by TTdude; Nov 17, 2013 at 11:46 AM.
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The definite integral can be used to find the area between a graph curve and the ‘x’ axis, between two given ‘x’ values. This area is called the ‘area under the curve’ regardless of whether it is above or below the ‘x’ axis.
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AWE GT2RS Exhaust Produces ~5.3% increase over stock.
https://www.6speedonline.com/forums/...-rs-build.html
AUC Graph
https://www.6speedonline.com/forums/...-rs-build.html
AUC Graph
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Hi Scott, Looks like an awesome dyno. When I was simulating the dyno, however, the tq/hp crossing came out to be 5308, not 5252 where it should be. I think you can see this also on your original dyno sheet. The line falls more than half-way between 5000 and 5500. Do you think you can have Neil send me the raw data rather than me taking it off the graph? I can still do the graph/calcs but it won't as accurate as I would like to see.
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