In my sig for sure!

Seriously though... The masses appreciate the information that you give. Please don't let a few idiots ruin it for everyone.

 

I'm going to be completely honest here, I just don't understand them/know how to read them. When explaining something to me, you have to explain it to me like you would a retard, or else I won't get it lol.

 

Scott, I couldn't have said it better.

 

I enjoy the data too GrocMax. Keep it coming.

What I would *love* to see is on/off throttle boost response.

 

That was some funny sh*t. You have to remember though, by definition, half of the people in the world are below average intelligence.

Seriously, though...there are some people who understand the data and could make great use of it. For those people, information like this is priceless and I would take data like this over 10000000 dyno graphs. Give me compressor/turbine maps, inlet and outlet temps, shaft speeds, mass airflow rates, etc...screw the hp/tq curves that some car put down on some dyno. Don't get me wrong...a dyno is a great tuning tool for comparison sake, but give me the hard data behind the turbo, IC, and mods, and I can apply it from there to my own car and goals.


Eric

 

***in a'. Thank you, Grocmax!

 

Looks like I'm the only idiot in here that's "below average intelligence" to understand it .

 

Mass flow on a turbo engine is a slippery yardstick to measure what power it ultimately makes for each possible scenario. There has to be a certain amount, but what you GET out of it in terms of WHP per lb/min flow can be very different from car to car.

For turbo testing I set the car up to operate as an efficient hot gas generator, not an efficient power generator, and it is a total DOG to drive in comparison. It makes and consumes LOTS of flow and produces coitus-all for WHP. Just like a really bad tune or combo.

Dyno graphs and MPH/ET are certainly relevant points of data to discuss, but how you get there is another story. Very frequently in the competitive racing world the engine that makes LESS peak HP runs circles around the monster motor all other things being equal, focusing on a peak HP number alone is an exercise in futility to all except those who race dynos.

 

Dyno testing and ET testing are VERY relevant for an individual car, but peak HP numbers alone do not guarantee improvement. Dyno is just another tool and sometimes they measure things in the wrong way for what you are trying to achieve.

In drag racing only two things count- ET, and what happens between the green light and the front tire tripping the start beam. Get both of those things as low as possible and you win even if it takes slightly less HP to do it.

 

Well said.

 

If you need an explanation of something specific just ask, we'll try to translate. Majority of it is rather simple once your mind can visualize it.

Most of this stuff is decades old and is directly related to aerospace, and anyone who thinks all the money spent going to the moon was a waste, yet benefits in their daily lives from the results of the big push in pure R&D, can go jump off a cliff , or go back to living in a sod house with outdoor plumbing where they belong.

I ain't that smart, I just know when I was 3 years old putting my hand back on grandma's wood stove meant it was gonna hurt, again, so I quit doing it.

Visualize the stove. Don't do that again. Check.

Use frog vision- food, or danger?

 

Okay that GrocMax I understand. I don't feel dumb anymore. I reread the graphs and pretty much understand all of them but the Delta T one?

 

Delta T = Outlet compressor temp - IAT?

 

Delta T is the increase in absolute temp from the inlet to the outlet due to compression and losses.

Whenever you compress a gas you increase its temperature. My visualization for this is to imagine a bunch of molecules bouncing around crazy, in a high energy state. When you compress them together, they have less room to move, hit each other, and they go to a lower energy state. In order to go to a lower energy state they must reject or lose some form of energy, in this case that energy is HEAT.

The amount of heat produced from ideal, perfect compression of a certain gas is known to be X amount. The Delta T is part of the formula for efficiency but not all of it. There are several different ways to calculate 'efficiency', all need temperatures and pressures measured in absolute values.
100% efficiency would be to produce the same amount of heat that ideal compression would result in, but nothing is free, there are losses.

True adiabatic efficiency cannot be measured on a car, you have to wait for all the parts to reach thermal equilibrium before measuring the temps. When turbos are run on test stands they are run for HOURS at a time at a single operating point to try to reach thermal equilibrium, everything is kept constant. Every tenth of a deg K error produces error in the actual eff calcs.

Compressor Efficiency is another slippery term that, at times, and looked at out of our context, irrelevant to our goals as boost junkies. Why would you care that one compressor map has an 80% efficiency island and another one that only goes to 74% WHEN YOU ARE NEVER OPERATING THEM ANYWHERE NEAR THERE AT PEAK POWER LEVELS?

Where 'efficiency' becomes relevant to turbo development for performance applications is when you talk about the 'losses' portion of the compressor efficiency.

Compressor Efficiency is another way of saying it takes this much shaft power to move this much air at this PR. If you reduce the shaft power it takes to move an equivalent amount of air at an equivalent PR, the turbine side doesn't have to work as hard. If you look at the white/1580 datalog, at the point where the 1580 starts to have a marked increase in Delta T, also notice the turbine pressure is ALSO increasing- it is taking more and more shaft power to move the same total amount of air compared to the white. They both have the exact same turbine wheel and housing.

How this results in a engine power increase at the same boost is- you can't get it in if you can't get it out. There are two simple ways to restrict an engine's output- restrict intake area, or restrict exhaust area. Sanctioning bodies seldom if ever use exhaust restriction in racing, because all it results in is increased heat and burned up stuff, but the net effect is the same- loss or a limit on power.

And we all know if you turn up the boost we make more power. If you can turn up the boost higher, keep the same or even less exhaust pressure, if you DON'T make significantly more power, something is wrong.

Another thing us boost junkies do that is irrelevant to a proper compressor map is drive it completely off the map and use every last gram/sec that thing will produce.

The end of the map, the 'wall', is the shaft RPM where the compressor stops working. It can be easily calculated. As it gets close to this point, we see shaft RPM continue to rise, it is crossing RPM and efficiency lines like crazy trying to maintain flow, efficiency drops like a rock and its done. You never see this on compressor maps because mfg do not consider this proper operation, but we do it all the time!

At the cursor point in that graph the 1580 is taking in air at 91F and spitting it out at 334F, while the white is taking in air at 133F and spitting it out at 315F while maintaining a nearly flat RPM. The 1580 has begun 'hitting the wall' at the very beginning of the log, the white is just cruising along INSIDE some higher efficiency islands, it is just barely starting to increase RPM.

Doesn't seem much different in temp output does it? But the difference is HUGE on the delta.

Is there any wonder why really good modern IC cores help a ton?

If you compress air to 3 times its pressure it gets really hot even with perfect compressor efficiency.

 

Engine IAT is irrelevant to the turbo performance characteristics we are measuring. It is very relevant to IC performance and engine performance as you can see from the above numbers.