For Tuners That Don't Understand MBT & Ignition Timing

Why does tuning the ignition timing correctly for your specific engine make you more power? Ignition tuning is often misunderstood by those new to tuning, and it can have serious consequences when we get it wrong in a high load/high boost area of our tuning table/calibration map.

Using a low-load area of the map and a Haltech ECU-equipped Mitsubishi EVO 9 with a turbocharged 4g63, let's examine what advancing or reducing our ignition timing angle does via a torque optimisation test on a Mainline dyno.

We'll examine why we want to have our ignition angle spot on and where that place is in our compression stroke, as well as what happens when we stray too far on either side. We'll also consider some things that might prevent us from finding our MBT value, including knock/pinging/detonation/pinking, which is not to be mistaken for the commonly incorrectly used term pre-ignition.

Key Terms:
TDC = Top Dead Center
BTDC = Before Top Dead Center
MBT = Maximum Brake Torque or Miminum Best Torque
RPM - Revolutions Per Minute
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TIME STAMPS:
0:00 - Common Issue
0:13 - Getting It Wrong
0:22 - The Plan
0:37 - What Is Ignition Timing
0:51 - Combustion Misconception
1:13 - What Is Actually Happening
1:35 - TDC - Top Dead Center
1:53 - BTDC - Before TDC
2:10 - Load Vs RPM
2:24 - Combustion Pressure Graph
3:10 - Compression Begins
3:53 - Peak Cylinder Pressure
4:08 - What Happens When Timing Is Wrong
4:42 - Overly Retarded Ignition Timing
5:23 - Overly Advanced Ignition Timing
6:08 - The Goal Of Ignition Tuning
6:26 - Cylinder Pressure Data
6:44 - Torque Feedback
7:00 - Torque Optimisation/MBT
7:30 - Sweep Test
7:53 - Base Ignition Timing 3D Table
8:19 - Test Cell
8:56 - Dyno Demonstration
10:06 - Results
10:49 - MBT - Maximum Brake Tourque
11:21 - IMPORTANT TO NOTE!
11:38 - Knock/Detonation/Pinging/Pinking
11:57 - Just ONE Cell Optimised Here
12:11 - 1st Ignition Tuning Table Trend
13:04 - 2nd Ignition Tuning Table Trend
13:34 - Low Load
13:50 - High Load
14:02 - Final Notes
14:25 - BUILD.TUNE.DRIVE
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LINKS:
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TAGS:
#highperformanceacademy #buildtunedrive #ignitiontiming #tuning #torque #learndriveoptimise #learntotune #enginebuilding101 #dontletthesmokeout #wiring101 #dieseltuning #datanerd #racecraft #cars #motorsport #racing #boost

[hpa]

Key Terms:
TDC = Top Dead Center
BTDC = Before Top Dead Center
MBT = Maximum Brake Torque or Miminum Best Torque
RPM - Revolutions Per Minute

TIME STAMPS:
0:00 - Common Issue
0:13 - Getting It Wrong
0:22 - The Plan
0:37 - What Is Ignition Timing
0:51 - Combustion Misconception
1:13 - What Is Actually Happening
1:35 - TDC - Top Dead Center
1:53 - BTDC - Before TDC
2:10 - Load Vs RPM
2:24 - Combustion Pressure Graph
3:10 - Compression Begins
3:53 - Peak Cylinder Pressure
4:08 - What Happens When Timing Is Wrong
4:42 - Overly Retarded Ignition Timing
5:23 - Overly Advanced Ignition Timing
6:08 - The Goal Of Ignition Tuning
6:26 - Cylinder Pressure Data
6:44 - Torque Feedback
7:00 - Torque Optimisation/MBT
7:30 - Sweep Test
7:53 - Base Ignition Timing 3D Table
8:19 - Test Cell
8:56 - Dyno Demonstration
10:06 - Results
10:49 - MBT - Maximum Brake Tourque
11:21 - IMPORTANT TO NOTE!
11:38 -
11:57 - Just ONE Cell Optimised Here
12:11 - 1st Ignition Tuning Table Trend
13:04 - 2nd Ignition Tuning Table Trend
13:34 - Low Load
13:50 - High Load
14:02 - Final Notes
14:25 - BUILD.TUNE.DRIVE

[FutureProofPerformance]

Thank you for making this, It's worrying how many people in our profession don't fully grasp some of the underlying physics.

[Anotherboost]

Great video.
It’s always good to leave some room for error.
Old story on how a “pro tuner “ kept adding timing on an Acura v6.
Then it broke in front of everyone. Guy just walked off.

[stevesloan]

At 4:33mins I was thinking of how you push someone effectively on a swing, via timing the push precisely.
Great video.. I’ll be watching this one a few times.
🇦🇺🤜🏼🤛🏼🍀☮️😎

[deancrawford]

When tuning for best torque with standalone ecu on NA engines should be fairly straight forward, however when other aspects are thrown into the mix it gets a bit more time consuming, a variable loop type resonance inlet manifold with cvvt cams and compression ratios of 12, 5:1 on pump fuel whilst still trying to reach emissions targets.
You got to hand it to OEM's in that regard.

[russelloppenheimer]

So well explained. Max mechanical advantage at 16-18 degrees after TDC.

Easy to imagine pressing down hard on pedals of bicycle. If pedal at top of stroke, or even just after, most of your force is just wasted into bike frame. Push hard too late, you don't get much bang for your foot. We can just imagine that magic spot when pedaling we should press hardest. About 17 degrees past pedal TDC!

Then knowing flame propagation for a given fuel density is same at all rpm, clear you need more advance at higher rpm, as well as more advance for less density (light throttle).

[JethroRose]

excellent description of what is going on and how timing actually generates more power if correct! first time i’ve seen someone ever explain the concept of getting the maximum cylinder pressure to happen at the point of maximum mechanical advantage on the rod/crank. cheers!

[Danger_mouse]

13:40 Great info as always.
What this part of the video serves to reinforce is the brilliantly clever old centrifugal and vacuum controlled distributor system.
Properly set up and adjusted it did all this with no computer using physics 🙂

[XX-nwxg]

This was really great, I didn’t know we could test for MBT that way

[kylemilligan]

Observing Best timing for a turbo engine with low turbine inlet pressure differential is very different than street combinations operating at 2.5 to 3:1 intake /exhaust differential. High backpressure combinations love more ignition timing because of the egr effect of exhaust residuals left in the cylinder, but will spark knock in a heartbeat because of the retained heat in the combustion chamber. Making it clear, high turbine inlet pressure will love more timing because of retained inert exhaust gases, but will melt pistons under sustained load

[jesseyoung]

Your presentation was very clear and cincise, and with the visual aids, it helped me visualize what's going on, and how the variables interplay...

[teagreen]

All different engine configurations will require different timing for maximum power, including the fuel that is used. With the absence of a dyno to test with, I use the amount of airflow through the engine which is scanned while driving. It is important to have an acceleration load on the engine while finding optimal timing for power. Fuel must be spot on during testing and as you get closer you should adjust the fueling. Find highest airflow for each rpm section, such as per each 500 rpm range, throughout the entire usable rpm range by adjusting the timing. When no more airflow is gained you are at best timing for the rpm. You can finally back the timing off a little based on expected fuel and temperature variation. Love your videos!

[BEYTEK]

As a tuner i never recommend tuning right up to MBT, Less margin for error if loads or batches of fuel are diffrent to the dyno.

[StreetDreamzTT]

Really great explanation. Best I've seen.

[johnconnor]

Awesome video! Easy to understand. Keep them coming

[MRworldEtIkA]

pro tip yall, never use universal race coils. It'll fried your ECU. had one installed on my own last month, night ride my bike stall i recon it was the fuel pump again (a day ago its socket was burnt), not a minute later it started like normal (i didnt bother checkingit out), 3 weeks after that it stalled again, brought it to my cousin's workshop and found a small portion of the ECU is burnt, the silicone part that is.

my guess is that my ECU relying on the OEM coil's resistances, since race coils has lower electrical resistances it doesn't limit how much electricity can be sucked by the coil, so the ECU gave it all and bust a circuit.

it was an NA so idk why i bought a race coil

[owl]

Can you automate the dyno timing sweep if you have a DBW pedal?

[RonaldReed-uldu]

As I understand it, an efficient operating Chiller would change everything stated here, or am I missing something?

[owl]

could you put a load cell under the electrode of a spark plug and measure cylinder pressure that way?

[bobbyd]

Are rotaries any different? Obviously there are no knock sensors and premix must play a part.