95ron 99ron difference in Ignition Advance on boost
Discussion
Hi Herman,
I map ECU's on a daily basis, its my job. you cant judge how much ignition advance to add or remove by guessing, ideally the car needs to be on a dyno to gauge increase in power as you advance knock until you reach MBT (minumum best timing) if you were to advance ignitrion, how do you know wether you have gained anything without testing it? how do you know wether the timing was correct initially?
sometimes I will spend hours testing an engine on a dyno to work out ignition advance vs fuel type/intake temps and no 2 engines are ever the same.
hope that helps
I map ECU's on a daily basis, its my job. you cant judge how much ignition advance to add or remove by guessing, ideally the car needs to be on a dyno to gauge increase in power as you advance knock until you reach MBT (minumum best timing) if you were to advance ignitrion, how do you know wether you have gained anything without testing it? how do you know wether the timing was correct initially?
sometimes I will spend hours testing an engine on a dyno to work out ignition advance vs fuel type/intake temps and no 2 engines are ever the same.
hope that helps
davea said:
Hi Herman,
I map ECU's on a daily basis, its my job. you cant judge how much ignition advance to add or remove by guessing, ideally the car needs to be on a dyno to gauge increase in power as you advance knock until you reach MBT (minumum best timing) if you were to advance ignitrion, how do you know wether you have gained anything without testing it? how do you know wether the timing was correct initially?
sometimes I will spend hours testing an engine on a dyno to work out ignition advance vs fuel type/intake temps and no 2 engines are ever the same.
hope that helps
As close to knock as you can get will give best torque & power, 2 degrees off knock is regarded normally as optimal for a road car due to fuel/ weather variations so i'm told very reliabily (Dave Rowe). You don't make power by finding the minimum advance, you make most power by finding the maximum before det sets in, if you pull too much timing you'll increase EGT's and reduce power. Ignitions more important than fueling when it comes to power at a defined boost level, better to run a bit rich 11:1 and get as much advance in as you can than sticking to 11.5/7 and fitting ignition round the fueling. Dynos are good for getting to high load cells and giving a customer a power figure, but road mapping will give better results.I map ECU's on a daily basis, its my job. you cant judge how much ignition advance to add or remove by guessing, ideally the car needs to be on a dyno to gauge increase in power as you advance knock until you reach MBT (minumum best timing) if you were to advance ignitrion, how do you know wether you have gained anything without testing it? how do you know wether the timing was correct initially?
sometimes I will spend hours testing an engine on a dyno to work out ignition advance vs fuel type/intake temps and no 2 engines are ever the same.
hope that helps
I've twin maps on my ECU, at a flick of a switch it swaps to a new fuel map, new Ignition map & new boost map. The car is mapped well on 99ron fuel, initial map by professional mapper, remapped by another to tidy it more & touched up again by me to be A1 all perfect at cruise (for 99ron). I copied these maps to other switch position, lowered boost as its more a "commuting" map, went for spin with knockbox hooked up, bit of knock at 4500rpm 150kpa 100% throttle, so I backed it off 2 degrees in that area and added a touch more fuel as AFR was 11.6 so took it down to 11.2, I maybe able to squeeze a bit of ignition back in. Now i'm wondering how close to knock the rest of the map is, it wasn't knocking but it could be very close, so to save me doing a load of logging and listening is it worth me backing the rest of the map off 1 degree?
What do you think?
Cheers
Steve
Edited by Herman Toothrot on Tuesday 15th January 12:44
so when you are fine tuning it on the road, what method are you using to find where its knocking without going into knock?
MBT is the best method IMO as theres no need to get anywhere near knock, just see where the advance stops an increase in power, this can often be as much as 8 degrees before knock sometimes 2 degrees, every engine is different. so by finding the point at which it knocks then pulling 2 degrees isnt often the best way as you may be able to pull a further 5 degrees and see no deteriation in the power the engine produces but a much faster burn with lower egt's. this method can only be used on a dyno though. on the road you cant measure this as there is no way of measuring the realtime power.
MBT is the best method IMO as theres no need to get anywhere near knock, just see where the advance stops an increase in power, this can often be as much as 8 degrees before knock sometimes 2 degrees, every engine is different. so by finding the point at which it knocks then pulling 2 degrees isnt often the best way as you may be able to pull a further 5 degrees and see no deteriation in the power the engine produces but a much faster burn with lower egt's. this method can only be used on a dyno though. on the road you cant measure this as there is no way of measuring the realtime power.
dave.a said:
so when you are fine tuning it on the road, what method are you using to find where its knocking without going into knock?
MBT is the best method IMO as theres no need to get anywhere near knock, just see where the advance stops an increase in power, this can often be as much as 8 degrees before knock sometimes 2 degrees, every engine is different. so by finding the point at which it knocks then pulling 2 degrees isnt often the best way as you may be able to pull a further 5 degrees and see no deteriation in the power the engine produces but a much faster burn with lower egt's. this method can only be used on a dyno though. on the road you cant measure this as there is no way of measuring the realtime power.
Knockbox to hear for the onset of knock (when I say onset, where you'll hear one maybe 2 "spat, ...spat" noises, before it turns into knock proper "spat,spat,spa"t all at once, not cheap but supposed to be the best :-MBT is the best method IMO as theres no need to get anywhere near knock, just see where the advance stops an increase in power, this can often be as much as 8 degrees before knock sometimes 2 degrees, every engine is different. so by finding the point at which it knocks then pulling 2 degrees isnt often the best way as you may be able to pull a further 5 degrees and see no deteriation in the power the engine produces but a much faster burn with lower egt's. this method can only be used on a dyno though. on the road you cant measure this as there is no way of measuring the realtime power.
http://www.theknockbox.com.au/content/view/2/2/
Its a bit odd what your saying about EGT's, I've only ever read the furthur you take ignition back from the point of knock the hotter your EGT's get?
Edited by Herman Toothrot on Tuesday 15th January 16:01
Vixpy1 said:
Some engines make max power before knock, which needs to be taken into account.
I see, i've not read or been told some do, I'm just going by what Ryan & Dave Rowe have told me & a few books.My cars been tuned purely by taking it to onset of knock and pulling back 2 degrees & WB obvuiously. Your familiar with it Charlie, the black mx5 that turned up last at a dyno day at yours and pulled the best figure of the day 250bhp/217lbs, not bad for the clunky old 1.8
Edited by Herman Toothrot on Tuesday 15th January 16:08
Herman Toothrot said:
Vixpy1 said:
Some engines make max power before knock, which needs to be taken into account.
I see, i've not read or been told some do, I'm just going by what Ryan & Dave Rowe have told me & a few books.My cars been tuned purely by taking it to onset of knock and pulling back 2 degrees & WB obvuiously. Your familiar with it Charlie, the black mx5 that turned up last at a dyno day at yours and pulled the best figure of the day 250bhp/217lbs, not bad for the clunky old 1.8
, He knows what he is doing 
I have never used a knockbox but have been informed that they are a greta bit of kit.
the old method of taking it to knock and then retarding a few degrees is mostly phased out and often frowned upon in modern ecu tuning as dynos have got more and more advanced and now bhp/torque increases can be measured in 0.1 bhp/lb/ft incraments (I use a dyno dynamic dyno, steady state tuning is fantastic!)
and there really is no need to take a vehicle into knock, you will see power start to flatten off as you add more ign advance until it flatlines as you continue to add ignition and then power drops off at the onset of any knock. so you know long before the point of knock (when it flattens off and stops gaining bhp) that you have reached optimum timing. this can occur anywhere from 10 degrees to 2 degrees before the point of knock.
the old method of taking it to knock and then retarding a few degrees is mostly phased out and often frowned upon in modern ecu tuning as dynos have got more and more advanced and now bhp/torque increases can be measured in 0.1 bhp/lb/ft incraments (I use a dyno dynamic dyno, steady state tuning is fantastic!)
and there really is no need to take a vehicle into knock, you will see power start to flatten off as you add more ign advance until it flatlines as you continue to add ignition and then power drops off at the onset of any knock. so you know long before the point of knock (when it flattens off and stops gaining bhp) that you have reached optimum timing. this can occur anywhere from 10 degrees to 2 degrees before the point of knock.
I see, good to learn these things. All the info on tuning i've been trying to gather has not mentioned this for example, always good to learn something new. I'm still wondering about the EGT's though as thats something all the sources of information i've seen agree on, retarding timing = higher EGT's, I suppose it doesn't matter if they don't get to temps that are dangerous for valves. My manifold has a threaded hole, funny Gas US gas thread though, maybe worth getting a pyrometer in there to see.
Interesting, 
so I have nothing really to loose pulling say 1 degree across the board out of the 95ron map, may loose me nothing or could even gain me a little thinking the maps basically a 99ron map taken to 2 degrees off knock. Really so for safety running 95ron pulling maybe even 1.5 deg's maybe sensible when taking into account minor knock was present just on the change of fuel, so the 2 degrees of safety for 99ron was taken running 95ron.
so I have nothing really to loose pulling say 1 degree across the board out of the 95ron map, may loose me nothing or could even gain me a little thinking the maps basically a 99ron map taken to 2 degrees off knock. Really so for safety running 95ron pulling maybe even 1.5 deg's maybe sensible when taking into account minor knock was present just on the change of fuel, so the 2 degrees of safety for 99ron was taken running 95ron.MBT is indeed where its at. General rules for x amount of retard etc are just that, general rules.
Only real way is dyno. I had zero knock on my lsx v8 and in some places up to 10* was taken out to get max power. Other places only a couple of degrees.
It varies hugely depending on where peak cylinder pressure is based on engine volumetric efficiency, rpm etc.
Less timing is often better, afterall advanced timing just means you are creating a counterforce to the motion of the piston for longer. Cant be good.
Keene Bell of Supercharger fame state leaner fuel gives more power. Dousing the flame front with shedloads of non combustable fuel just slows the burn forcing you to use more timing and often results in less power.
Also take a read of this http://www.innovatemotorsports.com/resources/rich....
Only real way is dyno. I had zero knock on my lsx v8 and in some places up to 10* was taken out to get max power. Other places only a couple of degrees.
It varies hugely depending on where peak cylinder pressure is based on engine volumetric efficiency, rpm etc.
Less timing is often better, afterall advanced timing just means you are creating a counterforce to the motion of the piston for longer. Cant be good.
Keene Bell of Supercharger fame state leaner fuel gives more power. Dousing the flame front with shedloads of non combustable fuel just slows the burn forcing you to use more timing and often results in less power.
Also take a read of this http://www.innovatemotorsports.com/resources/rich....
Very interesting, so basically thats saying almost the opposite of what Dave Rowe & Ryan have been saying, i.e. squeeze in as much ignition as you can and then back off 2 degrees. Also saying tune at AFR on power of 11.5 dropping to 11.1 if at 11.5 your finding you have to back ignition off too much.
I maybe better off, getting a stead AFR of say 11.7 on boost and then loosing a bit of timing?
I maybe better off, getting a stead AFR of say 11.7 on boost and then loosing a bit of timing?
there are no concrete rules as to what will and wont work, there are basic guidlines but often while tuning engines they can throw up results which go against these basics, no 2 tuning sessions are ever the same.
some engines conform to the gudelines, some dont. I have had some engines that make better power with an AFR I would normally class as lean and try and richen it up a bit, but lose power. others have done the oppsosite. Without the dyno I would never have known this and just guessed the AFR i thought would give the best results. Hence why dyno tuning is a far more accurate method that street tuning which is effectively just a 'good guess' as the power that the engine is making cannot be measured on the road.
some engines conform to the gudelines, some dont. I have had some engines that make better power with an AFR I would normally class as lean and try and richen it up a bit, but lose power. others have done the oppsosite. Without the dyno I would never have known this and just guessed the AFR i thought would give the best results. Hence why dyno tuning is a far more accurate method that street tuning which is effectively just a 'good guess' as the power that the engine is making cannot be measured on the road.
Yes a lot depends on the combustion chamber, piston crown etc. Newer heads and chambers use quench and turbulance to minimise timing requirements. And of course if you can get the same or more power with less fuel why wouldnt you? Emissions will be lower and so will the number of trips to the petrol station.
Good stuff, so really the way forward for me could really be tweak the maps make some changes save a few variations. Book a dyno for an hour or two, do a run on each map, best map then fine tweak on the dyno? Thing with the dyno, will it ever give me AIT temps like the car gets on the road i.e. the night I posted this thread the logging sesion I did my AIT's were 17deg C with 8psi boost, I think ambient was 9 deg C. On a dyno without 70mph air flow through the IC I'll never get as good AITs?
AFR does indeed change. Most ECU's use EQ or Lambda, EQ being the more modern eqivalent. EQ less than 1 is lean, more is rich. Basically opposite of Lambda.
Mr Motec is generalising, if you are tuning without a Dyno then you could use that rule, with a dyno Id take it with a grain of salt.
Mr Motec is generalising, if you are tuning without a Dyno then you could use that rule, with a dyno Id take it with a grain of salt.
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