-
Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.
Your Ignition setting in AEM EMS
- Thread starter menfou
- Start date
These are just my thoughts so please use the advice at your own risk. I also want to add that my thoughts are only given to help create an initial curve that will need modification during the tuning process.
a good starting point is to focus on your off boost timing curve. You can search the web to see how a typical mechanical type distributor ramps in timing from idle through redline. Here is an example I found with a quick search. I am not saying this curve is right for you, but it gives you a general trend. I typically ramp in full timing by 2500rpm, but that is dependent on many variables. I would also look to run more timing than is seen below and on my old TT Z I would run about 40deg off boost cruise. Again, cylinder head design will play a roll in how much timing a motor likes to see. Also remember, we tune our cars in several days wereas OEM spends months developing these curves so don't expect perfection from any tuner.
A typical rule of thumb if you are running 20psi is to ramp out 2/3 of the total timing by the time you hit half of your desired boost and in this case that would be 10psi. So if you cruise at 40deg and you want to see 20deg at 20psi then you should be running around 27deg at 10psi and then taper down to 20deg once you hit 20psi.
I would also highly recommend that you try to use the knock sensor during this process to detect pinging and/or detonation. In my experience another crucial area of concern is when you transition from off-boost to boost. I would typically ramp out 5deg from cruise to 0psi, which it appears your curve does this.
Another critical factor during the transition from cruise to boost is your AFR. It is easy to tune 14.7:1 at idle, 14.2:1 cruise and 12:1 full boost, but what do you do at 0psi or 5psi? This is where you will need to vary both timing and AFR to make sure the motor doesn't ping.
My general comment about your curve are as follows:
This is an old curve when I was running a T64 back in 2000 (pump gas)
This is a timing curve from an SR20DET that we swapped into a 93FD and was featured in Modified Magazine. Obviously this was on race gas, but the car ran around 10.4@140 with a 65shot. This is back before I ramped in timing after peak torque.
a good starting point is to focus on your off boost timing curve. You can search the web to see how a typical mechanical type distributor ramps in timing from idle through redline. Here is an example I found with a quick search. I am not saying this curve is right for you, but it gives you a general trend. I typically ramp in full timing by 2500rpm, but that is dependent on many variables. I would also look to run more timing than is seen below and on my old TT Z I would run about 40deg off boost cruise. Again, cylinder head design will play a roll in how much timing a motor likes to see. Also remember, we tune our cars in several days wereas OEM spends months developing these curves so don't expect perfection from any tuner.
A typical rule of thumb if you are running 20psi is to ramp out 2/3 of the total timing by the time you hit half of your desired boost and in this case that would be 10psi. So if you cruise at 40deg and you want to see 20deg at 20psi then you should be running around 27deg at 10psi and then taper down to 20deg once you hit 20psi.
I would also highly recommend that you try to use the knock sensor during this process to detect pinging and/or detonation. In my experience another crucial area of concern is when you transition from off-boost to boost. I would typically ramp out 5deg from cruise to 0psi, which it appears your curve does this.
Another critical factor during the transition from cruise to boost is your AFR. It is easy to tune 14.7:1 at idle, 14.2:1 cruise and 12:1 full boost, but what do you do at 0psi or 5psi? This is where you will need to vary both timing and AFR to make sure the motor doesn't ping.
My general comment about your curve are as follows:
- Idle looks good
- You ramped in full timing by 2500rpm, which looks good
- You ramped out 4deg of timing from cruise to 0psi, which looks good
- I would play around with cruise to see if the car will take a bit more timing, but perhaps the Honda heads don't benefit????
- I assume 160kpa is around 9psi. On my old z and pump gas I ran around 28deg at 10psi and on other setups more than 30deg with pump, but that is dependent on several factors. The key to running more timing is having a highly efficient intercooler as well as turbo. I was also using the electromotive so it had a very strong ignition system. If you an get charges temps within 20deg of ambient you are doing well. The knock sensor will give you a clue and I would also recommend an EGT located 2" off the hottest port. If EGT's are excessive this can mean you are running too little timing. I believe my EGT's were usually around 1550-1600F at 20psi.
- The only thing that I see is a potential lack of timing at lower boost levels.
- I would also ramp in a few deg of timing linearly from peak torque to redline. If dyno shows torque remains flat then don't ramp in timing, but if torque falls you can ramp in timing.
This is an old curve when I was running a T64 back in 2000 (pump gas)
This is a timing curve from an SR20DET that we swapped into a 93FD and was featured in Modified Magazine. Obviously this was on race gas, but the car ran around 10.4@140 with a 65shot. This is back before I ramped in timing after peak torque.
Last edited:
Similar threads
- Locked
