Where can i learn how to map my own car.
Discussion
Max_Torque said:
Be careful of "correcting" driveability issues that are actually chassis rolls artifacts! ie, the power curve often takes a dip after turbo spool up on chassis rolls because the the speed control loop on the rolls taking torque off after it's applied a big wodge (<< technical term!) of retardation to try to keep to it's pre-programmed accelerate rate during the sudden torque ramp on.
Get some proper on track logs of the boost control data, in various gears, and with various different tip in conditions before jumping to conclusions!
If you do have significant boost overshoot (which of course does make the car faster / feel fast, unless it results in wheelspin) then you'll almost certainly have to develop a better open loop boost control valve feed forward table BEFORE you re-tune the PIDs (the closer to target the open loop parameters are, the less work the closed loop terms will have to do, and the smaller the error, and the less likely the system will suffer from phase lag or oscillation etc)
Remember also that there is no point doing the boost control mapping before you have optimised and validated the ignition timing (as exhaust energy is inversely proportional to ignition angle. ie. you retard the ignition, the fuel air charge burns later, so more heat (and hence energy) goes out the exhaust port) For perfect control under all operating conditions, your feed forward boost control tables will need to have an ignition angle trim.
What is PID?Get some proper on track logs of the boost control data, in various gears, and with various different tip in conditions before jumping to conclusions!
If you do have significant boost overshoot (which of course does make the car faster / feel fast, unless it results in wheelspin) then you'll almost certainly have to develop a better open loop boost control valve feed forward table BEFORE you re-tune the PIDs (the closer to target the open loop parameters are, the less work the closed loop terms will have to do, and the smaller the error, and the less likely the system will suffer from phase lag or oscillation etc)
Remember also that there is no point doing the boost control mapping before you have optimised and validated the ignition timing (as exhaust energy is inversely proportional to ignition angle. ie. you retard the ignition, the fuel air charge burns later, so more heat (and hence energy) goes out the exhaust port) For perfect control under all operating conditions, your feed forward boost control tables will need to have an ignition angle trim.
Edited by Max_Torque on Monday 26th October 22:47
Yes I think you're right about the dip being the fault of the dyno, some dynos must smooth the curves then? Or can you make most dynos operate differently to smooth the curves?
I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
The amount of believable or useful information you get on a dyno sheet just gets less and less the more you learn....
Edited by Evoluzione on Tuesday 27th October 08:46
Evoluzione said:
What is PID?
Yes I think you're right about the dip being the fault of the dyno, some dynos must smooth the curves then? Or can you make most dynos operate differently to smooth the curves?
I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
The amount of believable or useful information you get on a dyno sheet just gets less and less the more you learn....
As was already mentioned in your idle control...Yes I think you're right about the dip being the fault of the dyno, some dynos must smooth the curves then? Or can you make most dynos operate differently to smooth the curves?
I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
The amount of believable or useful information you get on a dyno sheet just gets less and less the more you learn....
Edited by Evoluzione on Tuesday 27th October 08:46
http://www.csimn.com/CSI_pages/PIDforDummies.html
https://en.wikipedia.org/wiki/PID_controller
It's how some closed loop control systems work.
Evoluzione said:
Yes I think you're right about the dip being the fault of the dyno, some dynos must smooth the curves then? Or can you make most dynos operate differently to smooth the curves?
I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
Dyno software has smoothing algorithms built in and you can choose the level of smoothing for how the graphs are displayed. Unsmoothed curves are up and down like a tart's knickers which is how engines actually behave. I fail to see the point in smoothing all the dips out as it obscures the areas that need mapping attention. If you go back and look at any of the graphs Peter Burgess posts on here you can see this at its extreme with every glitch removed and curves that are completely unrealistic.I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
Dave is quite right. We display our finished sessions on level 4 out of 5 for smoothing. He is quite wrong about all the ups and downs though as they include tyre inconsistencies, vibrations and all sorts of untoward occurrences, you need to play on these dynos and rolling roads for years to see all the ins and outs involved. We do use lower levels of smoothing to check for vibrational problems and run in different gears to see if the problems are rpm or speed related or both. When we have helped people map cars we do dip in and out of and around levels of smoothing to see for effects of timing and fuelling. The rolling road also imparts a smoothness on the power delivery. It is of interest and maybe not a coincidence that many tuners prefer the smoothness of rolling roads to engine dynos even when they have both.
Peter
Peter
By way of demonstration I attach two curves for a 1500 GT Cortina. Curve 1 shows 91.6 bhp max and 104.1 lbs/ft torque and is at level 1 smoothing. The second curve shows the same power test displayed with level 4 smoothing. max bhp 90.2 and max torque 102.8. We are smoothing out peaks and troughs whether due to power delivery and/or vibrational effects of tyres and transmission. The software stores all the info so customers can see what they like when they like. So far customers are happy with the presented smooth curves.
Peter
Peter
Pumaracing said:
Evoluzione said:
Yes I think you're right about the dip being the fault of the dyno, some dynos must smooth the curves then? Or can you make most dynos operate differently to smooth the curves?
I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
Dyno software has smoothing algorithms built in and you can choose the level of smoothing for how the graphs are displayed. Unsmoothed curves are up and down like a tart's knickers which is how engines actually behave. I fail to see the point in smoothing all the dips out as it obscures the areas that need mapping attention. If you go back and look at any of the graphs Peter Burgess posts on here you can see this at its extreme with every glitch removed and curves that are completely unrealistic.I'm looking at a Dastek curve (just a random graph, turbo car), which just shows two perfect curves.
Max_Torque said:
Be careful of "correcting" driveability issues that are actually chassis rolls artifacts! ie, the power curve often takes a dip after turbo spool up on chassis rolls because the the speed control loop on the rolls taking torque off after it's applied a big wodge (<< technical term!) of retardation to try to keep to it's pre-programmed accelerate rate during the sudden torque ramp on.
I'm agreeing with him for more than the reason that I think a dip in the power deliver like that would be felt on the road, yet it isn't. What might be interesting is me recording the point at which traction is overcome, although that is thrown somewhat off course by (as he rightly points out) the fact that the engine spins up quicker in 1st and 2nd than the actual turbo can. I think it will spin the wheels in the wet in third, so maybe look at doing that too....I believe there is a lot more going on in an N/A than a turbo that causes genuine peaks and troughs, i'm thinking of the pressure waves in the intake for instance. Here is a gap in my engine knowledge and it's hard to find much written on the subject - that is of intake runner length and if pressure waves are present in there on a turbo engine (when it is under pressure). Finding info on that subject regarding N/A is much easier.
The problem (as I see it) is that we have an engine which is running in two states, 'off boost' it acts like an N/A, but then changes as it uses the compressed denser air so what do we do for intake runner length?
Short, good for high rpm
Long, good for low rpm
Adjustable, best of both worlds.
Do these rules still apply to a turbo engine? I'm wondering if long pipes which allow for better low down power will be unaffected by the compressed charge once the turbo is up to speed, but the trends of OE components tend to point to the direction of shorter fixed manifolds being better, or maybe even individual TBs close to the head would be better.
It's not all that simple as there are of course cams to take into consideration, but a program which takes everything from bell mouth entry to end of ex manifold and everything in between into consideration is readily available, I don't believe it's of much use once you put a turbo on, but could be wrong.
And that's before we start to consider plenum volume....
Sorry for the ramble, as you can see lots of thoughts and questions, but no answers!
Evoluzione said:
But as MT points out, the dyno is warping the curve, the dip after initial TQ peak probably isn't there or as bad:
MT is talking about fairly rare situations where turbo boost comes in hard and leads to large changes in torque over a short rpm band. Any dyno worth its salt should at least display proper curves for all N/A vehicles and most turbo ones.If you study unsmoothed engine dyno power curves and compare those to the same engines in the car on chassis dynos you see the same dips and peaks as pulse tuning affects the power delivery. Knowing where those are is key to getting inlet and exhaust manifold lengths correct. Smoothing them out just obscures the data you need to work with.
And to PB, as far as customers go and what they want to see, most of them, 99 out of a 100 or 999 out of a 1000, haven't the faintest bloody clue what the graphs are showing them anyway and most don't even know what torque is or that it's even related to power via rpm. Of course you can happily give the fwits smoothed curves with every glitch removed. They don't know it should or could be any different.
It's a bit like claiming your wife who's never slept with anyone else is quite happy with your four inches because she has nothing to compare it with.
Oh, and as far as drivers not being able to detect on the road power curve glitches that show up on the dyno, the average Mk1 human arsebone struggles to even notice a 10% change in overall power output never mind a brief glitch in a torque curve that is obscured by gradients, gear changes and the fraction of a second the car takes to pull through it.
Pumaracing said:
MT is talking about fairly rare situations
Hardly rare. Any dyno, chassis or engine version, if it has a speed control loop does it! The only way to avoid it is to ensure the primary control frequency is several decades faster than the fundamental system frequency response, or to know what the output torque is BEFORE you run the curve (and of course, if you knew that, you wouldn't need to run the curve.....)As a dyno is a brake, and has an inertia, the torque it measures is reactive static torque, and that is NOT the same as input torque for a dynamic condition.
Evoluzione said:
I believe there is a lot more going on in an N/A than a turbo that causes genuine peaks and troughs,
There is no fundamental difference between what an NA engine experiences and that for a Turbo engine.All a turbo does is to increase the maximum possible intake manifold air density. it DOES NOT "blow air into the engine" in fact, quite the opposite (because exhaust back pressure is (except for a very very few odd cases) higher than boost pressure. As such, manifold volumetric efficiency is REDUCED by a turbo. However, that reduction in the engines ability to swallow air, is more than offset by the increased air charge density.
The reason an N/A curve looks different is generally because the scale is larger! Volumetric effects from intake and exhaust tuning on an N/A engine are worth perhaps 20% and hence are significantly smaller than the airflow changes from often doubling intake manifold density.
Meh! I can't really agree with much of what Max says but what's new? The differences in the shape of the torque and power curves between turbo and N/A engines are due to a number of things.
In general turbo engines are in a low state of tune but with high inlet manifold air density. That means short duration cams, plenum inlet manifolds, low CR and not much in the way of inlet and exhaust manifold pulse tuning. If you took the turbo off they'd produce fairly low bhp per litre. As a result, at a given boost level, they produce fairly smooth power curves.
Getting high specific power outputs by N/A tuning means highly pulse tuned inlet and exhaust systems, one butterfly per cylinder and long duration cams with high CR. The pulse tuning resonances and cam dynamics mean that different parts of the rpm band show peaks and troughs in the power output. Generally there's a sharp dip in torque at about 2/3 of peak power rpm for race and rally engines.
As a general rule high levels of pulse tuning add to volumetric efficiency at some places in the rpm band and reduce it in others. It's swings and roundabouts. OE manufacturers try to reduce these torque swings in road engines by using unequal length manifold runners to spread the pulse tuning effects over a wider rpm range and reduce the peaks and troughs.
In competition engines you want maximum peak power and as much pulse tuning as possible to enhance this part of the rev band and you put up with the adverse side effects at lower rpm which are hopefully outside the main operating range.
In general turbo engines are in a low state of tune but with high inlet manifold air density. That means short duration cams, plenum inlet manifolds, low CR and not much in the way of inlet and exhaust manifold pulse tuning. If you took the turbo off they'd produce fairly low bhp per litre. As a result, at a given boost level, they produce fairly smooth power curves.
Getting high specific power outputs by N/A tuning means highly pulse tuned inlet and exhaust systems, one butterfly per cylinder and long duration cams with high CR. The pulse tuning resonances and cam dynamics mean that different parts of the rpm band show peaks and troughs in the power output. Generally there's a sharp dip in torque at about 2/3 of peak power rpm for race and rally engines.
As a general rule high levels of pulse tuning add to volumetric efficiency at some places in the rpm band and reduce it in others. It's swings and roundabouts. OE manufacturers try to reduce these torque swings in road engines by using unequal length manifold runners to spread the pulse tuning effects over a wider rpm range and reduce the peaks and troughs.
In competition engines you want maximum peak power and as much pulse tuning as possible to enhance this part of the rev band and you put up with the adverse side effects at lower rpm which are hopefully outside the main operating range.
Max_Torque said:
There is no fundamental difference between what an NA engine experiences and that for a Turbo engine.
That's a very gross generalisation which is largely incorrect. Max_Torque said:
All a turbo does is to increase the maximum possible intake manifold air density. it DOES NOT "blow air into the engine" in fact, quite the opposite (because exhaust back pressure is (except for a very very few odd cases) higher than boost pressure. As such, manifold volumetric efficiency is REDUCED by a turbo. However, that reduction in the engines ability to swallow air, is more than offset by the increased air charge density.
Yes I'm quite aware of how a basic engine works, but you are quite wrong about back pressure, with a modern turbo (especially a large one on a high performance engine) pressure ratios of 1:1 and better are easily and regularly are achievable.Slight topic deviation. From a complete novice beginning how would one go about "tuning" and fiddling with a car's ecu. I test software all day long, so im not completly in the dark but lets just pretend i am for now.
I registered and had a look around on ecuedit but couldn't see a beginners guide. So three questions.
1. What hardware do you need (in general, like a dcan cable etc)
2. What software do you need?
3. What posts / pdf's / webpages should i read?
Sorry for the dumb questions, but this appears to be the right thread to ask this.
I registered and had a look around on ecuedit but couldn't see a beginners guide. So three questions.
1. What hardware do you need (in general, like a dcan cable etc)
2. What software do you need?
3. What posts / pdf's / webpages should i read?
Sorry for the dumb questions, but this appears to be the right thread to ask this.
Pumaracing said:
Meh! I can't really agree with much of what Max says but what's new? The differences in the shape of the torque and power curves between turbo and N/A engines are due to a number of things.
In general turbo engines are in a low state of tune but with high inlet manifold air density. That means short duration cams, plenum inlet manifolds, low CR and not much in the way of inlet and exhaust manifold pulse tuning. If you took the turbo off they'd produce fairly low bhp per litre. As a result, at a given boost level, they produce fairly smooth power curves.
The gap between N/A and force fed spec has closed up a bit over the years, modern everyday turbo road cars now are using 10:1 CR and 95 ron fuel, 20yrs ago that was N/A territory.In general turbo engines are in a low state of tune but with high inlet manifold air density. That means short duration cams, plenum inlet manifolds, low CR and not much in the way of inlet and exhaust manifold pulse tuning. If you took the turbo off they'd produce fairly low bhp per litre. As a result, at a given boost level, they produce fairly smooth power curves.
Pumaracing said:
Getting high specific power outputs by N/A tuning means highly pulse tuned inlet and exhaust systems, one butterfly per cylinder and long duration cams with high CR. The pulse tuning resonances and cam dynamics mean that different parts of the rpm band show peaks and troughs in the power output. Generally there's a sharp dip in torque at about 2/3 of peak power rpm for race and rally engines.
It's pretty much the same for turbo cars too, with a modern free flowing turbo the high end turbo engines have gradually moved back towards similar specs to N/A with long duration cams and lots of overlap. Whilst those kind of extreme cams in an N/A give all top end, in a turbo car they spool the turbo earlier and give huge mid range and top end at the expense of little btm end and poor idle unless you utilise separate TBs.Pumaracing said:
As a general rule high levels of pulse tuning add to volumetric efficiency at some places in the rpm band and reduce it in others. It's swings and roundabouts. OE manufacturers try to reduce these torque swings in road engines by using unequal length manifold runners to spread the pulse tuning effects over a wider rpm range and reduce the peaks and troughs.
In competition engines you want maximum peak power and as much pulse tuning as possible to enhance this part of the rev band and you put up with the adverse side effects at lower rpm which are hopefully outside the main operating range.
Take this example again:In competition engines you want maximum peak power and as much pulse tuning as possible to enhance this part of the rev band and you put up with the adverse side effects at lower rpm which are hopefully outside the main operating range.
I think we've probably explained the initial dip at 5000 as a dyno issue*, but look at the more gentle one at 6500. This I think is possibly due to pressure waves, but is being lessened in severity somewhat by the increase in air pressure, as you say relatively smooth, but still there. It would be interesting to put the spec of that engine (without turbo, but maybe lift the CR) into some sort of simulation program or pressure wave calculator and see if it dips in the same place.
- I have a few plots of various spec cars from the same dyno which show the same pattern, although it seems that the more extreme the specification, the quicker it recovers.
Lord 
said:
said: Slight topic deviation. From a complete novice beginning how would one go about "tuning" and fiddling with a car's ecu. I test software all day long, so im not completly in the dark but lets just pretend i am for now.
I registered and had a look around on ecuedit but couldn't see a beginners guide. So three questions.
1. What hardware do you need (in general, like a dcan cable etc)
2. What software do you need?
3. What posts / pdf's / webpages should i read?
Sorry for the dumb questions, but this appears to be the right thread to ask this.
Getting back on topic I would have said I registered and had a look around on ecuedit but couldn't see a beginners guide. So three questions.
1. What hardware do you need (in general, like a dcan cable etc)
2. What software do you need?
3. What posts / pdf's / webpages should i read?
Sorry for the dumb questions, but this appears to be the right thread to ask this.
It depends on how much you want to do, do you actually want to touch the fuelling and spark and effectively 'remap' or just play around with other fine tuning parameters such as idle control etc? It depends on your ECU too - whether it's accessible or you need an aftermarket. As has been pointed out earlier EFI101 forum is a good place to browse.
I guess if i am honest i want a remap without paying 300-500 gbp. I dont mind learning and it would be nice to understand all the parameters i am playing with.
From my limited understanding a cheap remap is not unique to the car, but to the engine. A better remap would be modified to suit each individual car. To start off with I’d just like to apply the former to see the results and as i learn more, get into adjusting each individual parameter.
From my limited understanding a cheap remap is not unique to the car, but to the engine. A better remap would be modified to suit each individual car. To start off with I’d just like to apply the former to see the results and as i learn more, get into adjusting each individual parameter.
Lord said:
said: I guess if i am honest i want a remap without paying 300-500 gbp. I dont mind learning and it would be nice to understand all the parameters i am playing with.
From my limited understanding a cheap remap is not unique to the car, but to the engine. A better remap would be modified to suit each individual car. To start off with I’d just like to apply the former to see the results and as i learn more, get into adjusting each individual parameter.
You'll pay that in equipment alone + ECU.From my limited understanding a cheap remap is not unique to the car, but to the engine. A better remap would be modified to suit each individual car. To start off with I’d just like to apply the former to see the results and as i learn more, get into adjusting each individual parameter.
A remap for one modern car is the same as all of its type, it's only when the spec of the engine changes that an individual map is needed.
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