Technical data on "flashes"
#1
06-29-2010, 08:02 AM
Technical data on "flashes"
I have posted this in a few places but I guess there may be a few on here who might find it informative:
How Porsche tuning has grown in the last 20 years is an amazing thing, I have watched it from the early days of Motronic when only a handful of people could even access the code to today when people casually talk about a “flash” as if it is something as simple as an air filter.
Those who may have read my ramblings over the years will know that I am very biased towards the tuning done by race engine builders RS Tuning who have a sophisticated, expensive engine dyno set up and many years of ongoing experience of working with that tool to produce the best performing Porsche race engines in the world. Their road engine packages benefit directly from this experience but they are hideously expensive and are only available if you buy the complete “kit” which goes against the “modular” form of tuning which has grown in this industry where for obvious reasons (which are both financial and for the fun factor) people like to bolt bits on and get a “re-flash” to suit.
We did some data logging at the airstrip a few weeks ago with some generous owners allowing me to plug the Durametrics into their cars to see what was actually happening and what exactly the “flash” was doing to their motors……
The results were quite interesting.
The ambient temperature of the day was about 17 degC
Reading the data in the pics below, unfortunately I haven’t lined up all the columns to read in the same order but you can read them if you look:
We have:
Time, this is the first column always and shows the elapsed time of when the reading is taking place, usually there is an updated reading every 10th of a second or thereabouts.
Engine speed is in RPM, sometimes you may notice that a spurious reading creeps in there – that should be considered a “spike” and not actual.
Mass air flow – this is the amount of air the engine is ingesting in kg/hr, basically the more air, the more power all else being good
IAT is intake air temperature, this is the temperature of the boosted air in the inlet tract, these cars (two 997tts and a 997GT2) work well to 55 degC which is said to be the point where timing starts to be retarded. The GT2 IAT is always higher since the GT2 runs much higher boost (1.6bar) in the inlet which is reduced by the action of the expansion intake manifold so the actual air entering the combustion chambers is not boosted so high and is cooler.
Ignition angle – this is the degree of advance which the engine is running at, basically higher advance number the better and a steady number shows a more balanced engine tune.
Vehicle speed is in KPH so for mph divide by 1.6….. so 200kph is 124mph
The lambda banks 1 & 2 are the readings from the lambda sensors and indicate the air fuel ratios. If you multiply the lambda readings by 14.7 it gives the AFR ie a 0.70 lambda is 10.29:1 AFR.
So to the data:
First up is a 997tt with sports exhaust and 200 cell cats and a “flash” from a BIG and well known German internet tuning house.
This car was fast up to 100mph setting IIRC a 3.4s 0-60mph on the way, the problem for this car was that the aggressive boost led very quickly to high IATs at 68DegC, at the gearchange 5th to 6th there is a good amount of timing advance ~14 degrees but varying quite a bit showing the ECU is working hard to keep the numbers good and AFR around 11:1 which is all good. It has a Mass air flow of 1486kg/hr peak at 6860rpm which represents the air it is using at peak power.
After the gear change the revs drop to 5521 and things start to turn nasty, the high IAT forces the ECU to take some action, the ignition advance is held way back and the mixture is richened to 10:1 to protect the motor from knock onset….. EGTs are well controlled.
This car slowed considerably over the 250kph mark in its physical acceleration and the data graphically shows us why.
Next up was a 997tt Cab with just a flash from a well know UK “flasher” who has sold a lot of his product in the UK market.
This car appeared very fast chirping its tyres as it changed 1st to second and with the owner reporting wheelspin changing 3rd to 4th gear !!! The acceleration data again showed it started to slow dramatically over 100mph.
Take a look at the data – it is not at the same speed points as the previous run because the owner was changing gear way before the red line.
So we see he changes gear 4th to 5th at 6093rpm IAT is high at 63DegC but the ECU has already been richening the mixture to cool it down with AFRs at 10:1 at the top of 4th gear.
Now checkout the chaos as 5th gear is engaged, possibly because of too high boost, the timing advance goes to pot and is all over the place even retarding the ignition for a couple of readings and the AFRs get as rich as 9.8:1 to cool things down – it appears the ECU does its job and the IAT starts falling – all this activity results in much slower acceleration.
OK so the last two were $2000 “flashes” from “tuners”. My “flash” was a program written by RS Tuning over 2 days on the engine dyno (most of which was doing part load programming so not relevant to these full load runs) specifically for the bolt on turbos, air pipes and 100 cell cats and expensive intercoolers which my GT2 engine has.
Mine is a 4th to 5th gear change. At 6902rpm you can see the Mass air my engine is ingesting is 1775kg/hr – what this data also shows is the “overboost” which RS program into their software. If you look at the data when 5th gear is engaged the Mass air for the first reading is still 1746kg/hr and then descends over the next few readings, this is the program allowing extra boost and extra torque as the next gear is engaged, this also happens if you stomp on the gas pedal in the mid range and gives extra performance in this area – non of the other flashes did this……
Next up, the IATs at 51 degC, lower than the others but remember the GT2 runs 1.6 bar in the inlet manifold so the IATs are always higher. The timing advance speaks for itself both in high degree of advance and in consistency. The AFRs are immaculately controlled with little variation at around 12.2:1 on this engine the IATs go lower as 300kph is breached and all the other numbers stay similarly constant…
I hope people find this analysis useful and please feel free to correct me on anything I may have said which is incorrect.
The second car really drove it home to me that some people will think they have really fast “tyre shredding” packages – this car was chirping its tyres as I said, but it is all just smoke screen programming to give the illusion of a fast accelerating car.
Just because the numbers are very “pretty” to my eyes below is the data trail of my GT2 up to 190mph, see the dropping IAT, the 22.5 degrees of timing advance and the steady 12.2:1 AFRs – it is poetry – right up until the rods break !
Not sure what this all really means to us enthusiasts ? Certainly modern electronics are awesome and can cope with whatever is thrown at them as long as the safety bits are left in, but to me it makes me even more cynical about "flashes" .....
How Porsche tuning has grown in the last 20 years is an amazing thing, I have watched it from the early days of Motronic when only a handful of people could even access the code to today when people casually talk about a “flash” as if it is something as simple as an air filter.
Those who may have read my ramblings over the years will know that I am very biased towards the tuning done by race engine builders RS Tuning who have a sophisticated, expensive engine dyno set up and many years of ongoing experience of working with that tool to produce the best performing Porsche race engines in the world. Their road engine packages benefit directly from this experience but they are hideously expensive and are only available if you buy the complete “kit” which goes against the “modular” form of tuning which has grown in this industry where for obvious reasons (which are both financial and for the fun factor) people like to bolt bits on and get a “re-flash” to suit.
We did some data logging at the airstrip a few weeks ago with some generous owners allowing me to plug the Durametrics into their cars to see what was actually happening and what exactly the “flash” was doing to their motors……
The results were quite interesting.
The ambient temperature of the day was about 17 degC
Reading the data in the pics below, unfortunately I haven’t lined up all the columns to read in the same order but you can read them if you look:
We have:
Time, this is the first column always and shows the elapsed time of when the reading is taking place, usually there is an updated reading every 10th of a second or thereabouts.
Engine speed is in RPM, sometimes you may notice that a spurious reading creeps in there – that should be considered a “spike” and not actual.
Mass air flow – this is the amount of air the engine is ingesting in kg/hr, basically the more air, the more power all else being good
IAT is intake air temperature, this is the temperature of the boosted air in the inlet tract, these cars (two 997tts and a 997GT2) work well to 55 degC which is said to be the point where timing starts to be retarded. The GT2 IAT is always higher since the GT2 runs much higher boost (1.6bar) in the inlet which is reduced by the action of the expansion intake manifold so the actual air entering the combustion chambers is not boosted so high and is cooler.
Ignition angle – this is the degree of advance which the engine is running at, basically higher advance number the better and a steady number shows a more balanced engine tune.
Vehicle speed is in KPH so for mph divide by 1.6….. so 200kph is 124mph
The lambda banks 1 & 2 are the readings from the lambda sensors and indicate the air fuel ratios. If you multiply the lambda readings by 14.7 it gives the AFR ie a 0.70 lambda is 10.29:1 AFR.
So to the data:
First up is a 997tt with sports exhaust and 200 cell cats and a “flash” from a BIG and well known German internet tuning house.
This car was fast up to 100mph setting IIRC a 3.4s 0-60mph on the way, the problem for this car was that the aggressive boost led very quickly to high IATs at 68DegC, at the gearchange 5th to 6th there is a good amount of timing advance ~14 degrees but varying quite a bit showing the ECU is working hard to keep the numbers good and AFR around 11:1 which is all good. It has a Mass air flow of 1486kg/hr peak at 6860rpm which represents the air it is using at peak power.
After the gear change the revs drop to 5521 and things start to turn nasty, the high IAT forces the ECU to take some action, the ignition advance is held way back and the mixture is richened to 10:1 to protect the motor from knock onset….. EGTs are well controlled.
This car slowed considerably over the 250kph mark in its physical acceleration and the data graphically shows us why.
Next up was a 997tt Cab with just a flash from a well know UK “flasher” who has sold a lot of his product in the UK market.
This car appeared very fast chirping its tyres as it changed 1st to second and with the owner reporting wheelspin changing 3rd to 4th gear !!! The acceleration data again showed it started to slow dramatically over 100mph.
Take a look at the data – it is not at the same speed points as the previous run because the owner was changing gear way before the red line.
So we see he changes gear 4th to 5th at 6093rpm IAT is high at 63DegC but the ECU has already been richening the mixture to cool it down with AFRs at 10:1 at the top of 4th gear.
Now checkout the chaos as 5th gear is engaged, possibly because of too high boost, the timing advance goes to pot and is all over the place even retarding the ignition for a couple of readings and the AFRs get as rich as 9.8:1 to cool things down – it appears the ECU does its job and the IAT starts falling – all this activity results in much slower acceleration.
OK so the last two were $2000 “flashes” from “tuners”. My “flash” was a program written by RS Tuning over 2 days on the engine dyno (most of which was doing part load programming so not relevant to these full load runs) specifically for the bolt on turbos, air pipes and 100 cell cats and expensive intercoolers which my GT2 engine has.
Mine is a 4th to 5th gear change. At 6902rpm you can see the Mass air my engine is ingesting is 1775kg/hr – what this data also shows is the “overboost” which RS program into their software. If you look at the data when 5th gear is engaged the Mass air for the first reading is still 1746kg/hr and then descends over the next few readings, this is the program allowing extra boost and extra torque as the next gear is engaged, this also happens if you stomp on the gas pedal in the mid range and gives extra performance in this area – non of the other flashes did this……
Next up, the IATs at 51 degC, lower than the others but remember the GT2 runs 1.6 bar in the inlet manifold so the IATs are always higher. The timing advance speaks for itself both in high degree of advance and in consistency. The AFRs are immaculately controlled with little variation at around 12.2:1 on this engine the IATs go lower as 300kph is breached and all the other numbers stay similarly constant…
I hope people find this analysis useful and please feel free to correct me on anything I may have said which is incorrect.
The second car really drove it home to me that some people will think they have really fast “tyre shredding” packages – this car was chirping its tyres as I said, but it is all just smoke screen programming to give the illusion of a fast accelerating car.
Just because the numbers are very “pretty” to my eyes below is the data trail of my GT2 up to 190mph, see the dropping IAT, the 22.5 degrees of timing advance and the steady 12.2:1 AFRs – it is poetry – right up until the rods break !
Not sure what this all really means to us enthusiasts ? Certainly modern electronics are awesome and can cope with whatever is thrown at them as long as the safety bits are left in, but to me it makes me even more cynical about "flashes" .....
#2
06-29-2010, 09:34 AM
It's pretty fascinating data. How much of the variation in ignition timing is simply down to excessive IATs? Are we looking at a case study in the importance of intercooling, or is there more detail behind why the IATs are so high on the other cars?
Pardon my ignorance, but this is my first time seeing data like this, so I may be a bit naive on this stuff.
Pardon my ignorance, but this is my first time seeing data like this, so I may be a bit naive on this stuff.
#3
06-29-2010, 10:47 AM
It's pretty fascinating data. How much of the variation in ignition timing is simply down to excessive IATs? Are we looking at a case study in the importance of intercooling, or is there more detail behind why the IATs are so high on the other cars?
Pardon my ignorance, but this is my first time seeing data like this, so I may be a bit naive on this stuff.
Pardon my ignorance, but this is my first time seeing data like this, so I may be a bit naive on this stuff.
My guess is that the IAT is having the biggest effect on that timing and AFR activity but don't forget all these things are connected and controlled by the program so if the new program is done right then all the numbers should be right like in mine. Why would a "tuner" allow an ECU to be flashed with a program (knowing which components are on the car -paryicularly stock intercoolers) which allows 68DegC IAT in 17 DegC ambient ?
The high IATs are a direct result of too high boost which then results in all the other stuff - this is what the chassis dyno "tunes" end up like, its just you don't know its happening and as long as the cars do 0-100mph in 7.5s customers are happy.....
We are hoping to log more cars in a few weeks to include a Proto 800hp monster, a Cargraphic 997tt stage 2 (544PS/800NM) and a stock 997tt
#5
06-29-2010, 01:50 PM
Regards the AFR, I guess it is how it works in conjunction with all the other factors, if everything else (especially the heat management) is A -OK then it makes the power at this level - if the IATs go too high as on the other cars then the ECU richens it up....
#6
06-30-2010, 09:01 PM
Very interesting! Would love to hear some of the tuners on this board chime in on this info. I'm sure your RS tuning wasn't cheap..but it seems you are getting what you paid for.
What does the boost curve look like on your tune?
Look forward to the next update.
What does the boost curve look like on your tune?
Look forward to the next update.
Last edited by L8apex; 06-30-2010 at 09:08 PM.
#7
06-30-2010, 09:09 PM
You need to calculate the value based on ambient atmospheric pressure using Durametric v5 (6.0B variable seems to be labeled differently.)
"Boost pressure of sensor" is an actual value, and it is displayed in mbars. Ambient pressure needs to be recorded as a constant. Under acceleration, the sensor reading needs to b e corrected with the ambient pressure constant.
ie
990 mbar at idle
At 6734 RPM WOT, I will record 2178.75 mbar.
2178.75 - 990 (reading at idle) =1188.75 mbar / 1000 = 1.18 BAR
#9
07-01-2010, 08:41 PM
Great info Toby,
This is exactly what i have experienced with some tuners here,
It looks like they only tune cars for 1/4 mile. Customer doesn't feel any powerloss at 1/4 mile test but when they roll on the highway they are dissappointed with performance after 220km.
This is exactly what i have experienced with some tuners here,
It looks like they only tune cars for 1/4 mile. Customer doesn't feel any powerloss at 1/4 mile test but when they roll on the highway they are dissappointed with performance after 220km.
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