Kingtal0n

This is beautiful. Many people do not realize how discrete matter really is, and most of our tools take, as you mention, averages for our single digit simplicity pleasure. There is much more in this post than anyone realizes, I want to pick a few good un-obvious points out though right away;

As you mentioned, the air fuel is jumping in your example because the engine is accelerating too quickly to determine exactly what load cell is what air/fuel and everything is a jumbled up mess. Typical of single wide open throttle runs, right? There are many tools to combat this mess, such as a transient delay wideband data-logging session, and common sense. I know the air/fuel that was picked up in my cell .020 seconds after the cell was being read is behind about .150 seconds because the fuel injected from that cell at 2,000 rpm has to be burnt and read by the O2 sensor. Thats transient delay. The common sense part comes from reading the log and noting that from one cell to the next the number simply change: That is, specifically, If you put the same exact fueling number into every single load cell, then technically, the air fuel ratio should be the exact same for every single load cell also, right? WRONG! Internal combustion engines are generally NOT LINEAR. The air fuel is fluctuating for MANY Reasons, but generally, it fluctuates because volumetric efficiency changes, and with it, so does the mass of air being burnt and the required amount of fuel being injected. But we are skipping the plethora of other changing variables such as; air temperature (as compressor efficiency changes) which affects air mass (you can increase VE and decrease air MASS and make less power because of this and thus require less fuel even though the engine is more efficient... think of a T-25 turned up past 10psi on a 3L engine at almost any RPM), engine flow characteristics (pretend our example engine has a long 28" runner manifold and the VE spikes around 4400rpm drastically then falls off quickly afterwards, like a chevy tuned port injection from 1992).

These things affect engine breathing capability and they require more than just a "line of numbers that makes sense". A good tuner should be able to recognize a 28" runner and should know about the acoustic effects of Helmholtz (thanks scott!). A good tuner should recognize that not every cell in a straight line should have the same fuel and timing value. This is now common sense; but therein lies the ultimate definition of tuning: Technically, I never need to start the engine. Technically, I never need to drive the car. Technically, I can calculate the amount of fuel required by the engine at ALL load spots without even seeing it. If I account for everything; that is, all of the fluctuation of airflow, all of the changes in air temp, all of the rotating mass requirement even the viscosity of the oil and the pumping action of the lifters and the shape of the intake ports and the lengths of the runners and the size of the exhaust inlets and the shape of the turbine and the location of the wastegate and the symmetry of the exhaust manifold and the expected path of the incoming column of air through the calculated velocity of that air at the expected flow rate of the engine at any RPM, even calculate the speed of the injectors at the voltage supplied with math can determine pretty damn close how much fuel is going to be injected and there are some things we MUST assume such as the tightness of the cylinder (we must assume the engine is properly assembled) if EVERYTHING is accounted for with good math then we technically never need to start it to "tune" it.

Which brings me back to the common sense aspect of tuning and the reason air fuel ratio numbers "jump seemingly randomly" as an engine makes a pass through it's fuel map; If the jumping around does not make sense then either you lack the tuning common sense ability, or, there is something wrong with one or more of the components. The Air/Fuel ratio on a Honda S2000 engine will be consistant with the same fuel value in every maximum N/A load box because the volumetric efficiency and atmospheric pressure do not change much as it accelerates during a wide open throttle run (thanks to honda design of course) my point here is simply this common sense aspect; should the tune "jump around" that is, as you mentioned, should the air fuel fluctuate for any reason, we know there is a problem with one or more of the components... because common sense tells me that the VE and therefore torque on this N/A engine should/is flat and so should the fuel requirement be assuming a steady A/F is desirable. We wont even need a wideband if I calculated the injector on-time required at every rpm for the desired A/F ratio.

Kingtal0n

Well you are out of context here. I said the "ultimate tool..." with regards to my original comparison: "We are assuming daily driver, pump gas, etc..." Keep in mind everything I write is from this aspect (since that is most of our goals, a daily driver performance vehicle with good fuel economy)... In Which Case... The street is the ultimate "tool" simply by virtue of being the place that the vehicle will spend most of its time. If we are talking a strict drag vehicle then a TRACK is the "ultimate tool" because the numbers that appear on the big screen is our "dyno"- its how we know if the car is faster or slower, which is all that matters to a strict drag vehicle.

rocknrollkat

No context problems here.
The street gives its own numbers, like fuel economy, if that's what you're set up for. "J" curves, anyone ??
Also, racing is not just drag racing. Yes, the 'clock' at the end of the strip is the "tell-all", but lap times anre the determining factor in road racing.
I agree that the final result is the real world, the dyno is just another tool among many.
More to follow....

Kingtal0n

Engine dyno tuning is useful and it has a place but it is not the end-all of engine tuning. The main IMPORTANT thing to keep in mind is resistance- just like resistance on a muscle during strength training, the force of gravity on the mass of a vehicle m, combines to form a vehicle weight, which by the physics of friction and a given tire compound, will exert an opposing force on the drivetrain (and thus the crankshaft/connecting rod/piston) and this opposing force is the MAJOR DIFFERENCE that everyone seems to be missing when comparing engine dyno / chassis dyno / street application tuning.

To illustrate this important let me think up an example:

I have a 6L engine at idle. If I snap open the throttle, it free revs easily to 6000rpm- very fast right? Because there is no load right? Well, actually the rotating assembly represents the load- the weight of the components that are turning and require "work" to move, those components represent an opposing force on our engine, just like a load from the road. Its just significantly LESS than a road would provide.

So enough energy is produced to accelerate the internals. Some energy is used to simply keep the components moving, and the leftover is available to accelerate them as fast as we want- until we run out of energy or until the whole thing flies apart in pieces. Either way, the concept here is whats important: The goal of Free revving an engine is identical to the goal of revving an engine under load- Increase engine RPM, thereby increasing the rotating speed of the components, and in a vehicle, the speed of the tires right?

Now we can hit the nail directly: Think of my 6L Engine free revving and how quickly and easily it does... THEN think of my 6L engine in a VERY HEAVY TRUCK. Now put the truck in fifth gear (at zero MPH) and dump the clutch and go wide open throttle. Clearly, instead of a clean free rev, we get a dead engine or a seriously ruined clutch. THIS IS THE CRITICAL DIFFERENCE! The "WEIGHT" of our rotating assembly increases dramatically when we connect it to the drivetrain of the truck. Suddenly the engine not only has to accelerate its own internals; NOW it has to also accelerate an enormous mass of metals also.

So lets draw a line between the two situations: Lets start to lighten up our truck. As I take weight from the truck, more and more weight, until finally the truck is completely gone all together and we are left with only our engine alone again; AS I REMOVE WEIGHT from both the truck and its rotating components until they are GONE... At some point, at some critical point, our engine becomes "capable" of actually moving the truck, even in fifth gear. This can lead to a tech talk about gearing and torque but lets move past that into the real central idea I want to bring to the table: The resistance experienced by the rotating assembly of the engine directly affects its fuel and timing requirements. . As we lighten up the truck, during a full throttle (0 vacuum) run, it will generally require more and more ignition timing (for the sake economy and burning the most of our dollars) and less and less fuel (as fuel only serves two purposes: burn for energy and prevent engine damage). Same engine, different loads, totally different fueling/timing requirements. To see why you must visualize the piston being forced down by the expanding soon to be exhaust gas. The gas expansion represents the ability to transmit energy to the rotating assembly. If the gas expansion happens TOO QUICKLY engine damage will result. If the expansion happens too SLOWLY we will lose fuel to the exhaust plumbing (EGT should go up!). The same thing applies to the ignition timing; as the load increases we want less and less ignition advance, or engine damage will result (because the burn begins too soon!). So lets jump back to our engine dyno for a minute; Does the load exerted on the flywheel by the engine dyno exactly mimic the load experienced by that engine when it is installed in a vehicle of given mass m? NO. Not unless we set it up to do exactly that job! Therefore, an engine dyno can generally not represent a way to "tune an engine" before it goes into a vehicle, since depending upon the vehicles various components masses (m), the required amount of fuel and the required amount of timing will change. You can get close, but fine tuning will always be required, and nothing is ever perfect. Imagine I want to tow a trailer one day... Did I account for this in my fuel and timing map? I Mean 0psi is 0psi, whether I have a trailer on the back or not, so my truck was fine for years until I decided to pull a trailer one day and my "perfect map" blew my engine because my ignition timing was "perfect" for the truck's exact mass all these years and I had no headroom for the trailer.

4x4le

I tend to disagree about the road forces and weight changing (such as towing a trailer) changing what is needed from a tune although when I tune a car on a dyno dynamics I do change the load all the way, even to a point that the engine cannot overcome the load at all.

In theory the max power is going to come from the flame front being extinguished 15* after tdc. So, I do tend to bring some safty margin into my tunes by trying to come close to finding this. If I add 1* of timing across the map and gain 15hp everywhere great, time to add another 1*. Cool, made another 15hp. Add another 1* in 2 different cells (or at certain rpms) I only gained 10hp but gained 15hp in the others. Im going to watch the areas that only gained 10. If I only gain 5 the next time in those areas I have the decision to make to either leave their values there, retard it back 1 in those areas or whatever. Since it was still making gains Ill typically leave it there because if it was still making more power than before it wasnt detenating yet (im listening for that as well). I can then load the dyno up to a higher value and 99% of the time It will make the exact same power as it did on the previous pull, still be entering the same cells too if were still at the same boost or vac level, were just causing the engine to rev slower. The engine will still consume the same air at that rpm per cycle regardless of load and if your igniting the mixture at the same time too ( * btdc) and the piston is moving at the same speed, the flame front will go at at the same time too.

kingtalon, you seem really smart and I cant help but think a dyno dynamics would change your entire outlook on everything and make you a dangerous weapon when it comes to tuning.

rocknrollkat

Kingtalon said ---"Engine dyno tuning is useful and it has a place but it is not the end-all of engine tuning.", which is pretty much what I said, which was --- "It makes the most sense to develop the engine on the test bed, get all your settings correct, then place it in the chassis, track test, etc. to establish a baseline."
It may seem simplistic, as you point out, to set up an engine on the dyno, since the engine has no idea where it is.
In a vacuum, that's correct, as an abstract assumption.
However....
As far back as the early 1960s, when Ford was developing the four cam Indianapolis V8, the engineers set the engine dyno to simulate the track conditions at Indy. The automation ran the engine lap after lap and the engine had no idea that it was on an engine dyno, it thought it was in a racecar at Indy.
Here's some info on the engine, enjoy !!
Development of the Quad Cam Ford engine

4x4le

Here is a t25 ka-t i tuned. It was street tuned by a local tuner, blew up, rebuilt, retuned on the street again. The lower numbers was the tune it came to me with. I didnt advance the timing ANYWHERE i retarded it. Some areas need more fuel, some needed less. Im sure it would have blown up again if I wouldnt have dyno tuned it.
Ill stick to my opinion and ill encourage anyone that likes street tuning an engine to try out a dyno dynamics.

sent from my rooted thunderbolt

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rocknrollkat

This is too funny !!
Let's see, an engine that you didn't tune blows itself up, and you all but guarantee that if you 'tuned' it, it would be blowup proof !!
Let me fill you in on something that should be obvious.
Drivers blow up engines.
If this driver over-revs his engine with your 'tune', it'll blow up just like it did before, only sooner, because now it's got more power !!

4x4le

Do you realize how fucking retarded your making your self sound grandpa? I would never promise someone a bullit proof engine. What i was saying that he wouldnt have even had to do anything stupid at all with that engine and it would blow. Its detenation was so audiable it was sickning. I didnt add 1* of timing in its map anywhere, i pulled at least 5* from everywhere and as much as 15* in some areas. Also the air fuel ratios were wack.

And your not filling me in on a god damn thing either, i know all engines are doomed at some point. Do you think i havent blown my fair share of engines at the track? Never fault of a tune, some got a little hot, some lost oil pressure, my fault for not noticing but not my fault for the tune.
You know, i bet if he drains his oil and goes racing it would probably blow up too huh? Or if he runs out of gas he probably wont be able to get it started.
Usually its the 16 year olds stating stupid things on here, not olds that have but 16 years left to live.


sent from my rooted thunderbolt

rocknrollkat

You sound angry.
Let's see, you said --- "Im sure it would have blown up again if I wouldnt have dyno tuned it."
You're pretty much coming in the side door by saying that without your wizardry, the engine was doomed to fail again. in effect, you're saying that you deliver blowup proof engines.
I like the 'grandpa' touch.
I was setting up racecars before you AND your father were born, sonny.
Oh, and by the way, you also mentioned --- "Also the air fuel ratios were wack."
Just what does "wack" mean ??
I couldn't find it in any reference book.
It's not a Japanese word either, in case you're trying to pawn yourself off as "JDM".
Settle down, you'll live longer, trust me.

rocknrollkat

Yes, I'm 63, and dynos were around LONG before the early 1960s, when I first got involved with cars.
"You guess ??"
From what I can see, you guess quite a bit.
Instead of guessing, here's a link that will introduce you to dynamometers, from the earliest "Prony Brake" to the latest innovations.
Dynamometer History - A Timeline of Innovation

4x4le

All you have done since your stay on zilvia has started is beat around the bush and make yourself look like a douche.
You have impressed me with none of your own knowlege and it seems you have learned how to google stuff and copy and paste links. Look up troll, your picture will be listed.

rocknrollkat

Luckily, I don't exist on this planet to impress you. Obviously your ego gets in the way of any coherent responses, and your 'knowledge' of the topic is pathetic. It's useless to attempt any meaningful dialogue with someone who immediately covers his (her ??) ignorance with foul language, childish attempts at put downs, and name calling.
Engine 'tuning' ?? It's all plug 'n' play to you. Without your laptop you'd be lost. And poking fun at my age ?? Now THAT'S childish !!
My knowledge would be lost on you.
First, you can't shut up long enough to hear anything, and if you did, you haven't shown me enough background knowledge to be able to comprehend anythig I could tell you.
Battery's dead on your laptop ??
'Tuning' session's over !!

4x4le

honestly what are you talking about? Yes, tuning efi systems is plug and play. Were not jetting carbs and setting mechanical advance on distributors.

Were not changing chips in 7al's.
Tuning ecu's is very precise work and I have become very good at doing this. I have a good reputation for doing this and I have customers come from all over to have their engines calibrated by me. No horror stories, and plenty of return customers when they change cars or the setups on their cars.

Yea I poked at your age, reason being, you havent brought anything but old school ideas to the table. Should I have kept going with it, no your right.
Do you know about cars? Quite possibly, no one would know though by reading what little you have posted on here. Im 4x4le on every forum im on. Feel free to look me up if you wish, I have helped many many people out.

What keeps me wondering about you is how you dont seem to think that it was a big deal that pulling 15* of timing out of a ka-t and making more power as a result wasnt alarming. That engine WOULD have blow its self to pieces. You also seem to think it will be more likely to blow up now because it makes more power? No, its cyl pressures are now lower but they are just being pressurized at the right times. Im sure you already knew that though.

rocknrollkat

Actually, we never got to the point of discussing timing, or anything else relevant for that matter. Now that you seem to be addressing specific topics besides my age (no offense taken), 'timing' is a discussion that gets involved pretty quickly. Fifteen degrees (15) is an arbirary number until we put it in context. If you can hear detonantion from across the street, then obviously there's a problem, and the ignition key is the first step to a solution. Turn the engine OFF !!
If the driver kept 'pushing' the engine with that kind of racket coming from under the hood, then take your pick, 'holed' piston, bent rod, shattered valve ?? It's up to fate at that point. What did the driver think was happening ??
I'd check several things, including timing. Don't forget 'bad' gas. Picking up a bad batch at the pump has happened, and don't overlook that possibility.
Of course you know that timing that is TOO advanced leads to a very quick falloff in power, even if detonantion is not present.
I've seen power increase by RETARDING the timing to a more realistic number (still advanced, but not past the max pwr. point)
That's where a dyno makes life easier, but it sure helps to listen for "engine knock" !! (an 'old school' term for you.).
Regards,
Bill

mr_eh

skipped everyones reply.

431whp srt4 tuned on the street most of it's life - it did see some dyno tunes but it was always finalized and checked on the street.

315whp break in tune on my built sr 35r full race kit was on the dyno, and will get it's full tune on the dyno...

I'd prefer all of the dyno tuning be done on the street but it's not always viable, depends on the tuner.

__________________
My 96 S14 | 501whp SOLD

rocknrollkat

I agree. that's what started this discussion in the first place. I've been doing it this way since 1963, and yes, we had dynos back then. The time slip or the triple stopwatch lap timing board was the end game, not the dyno chart.

Bill