Spark retardation and turbo spool - Miata Turbo Forum - Turbo Kitten is watching you test compression.

rider384 · **Spark retardation and turbo spool**

I have always tuned spark so that it shrinks as the RPMs rise. I have been looking at a couple of other people's maps and I noticed they do the opposite of mine.

It got me wondering, does retarded spark at lower RPMs and ambient (and slightly above) air pressure help the turbo spool?

My line of reasoning
1. Retarded spark = less energy used in engine, later gas burning
2. Less energy in engine = more energy goes to exhaust
3. More energy goes to exhaust = more energy goes to turbo
4. More energy to turbo = faster spool.

I will post my map when I get home. Is this line of thought correct or am I way off?

18psi · 03-09-2011, 01:27 PM

Most tuners dip the timing and fuel right before boost onset using the same logic. It helps the turbo spool a little quicker and hit a little harder.

At peak boost/load is where you wanna be careful with timing.

Up top when boost/torque starts tapering most start tapering timing up to provide a more flat/linear torque/power curve and get a good looking curve.

Jeff_Ciesielski · 03-09-2011, 01:29 PM

Quote:
	Originally Posted by rider384 I have always tuned spark so that it shrinks as the RPMs rise. I have been looking at a couple of other people's maps and I noticed they do the opposite of mine. It got me wondering, does retarded spark at lower RPMs and ambient (and slightly above) air pressure help the turbo spool? My line of reasoning 1. Retarded spark = less energy used in engine, later gas burning 2. Less energy in engine = more energy goes to exhaust 3. More energy goes to exhaust = more energy goes to turbo 4. More energy to turbo = faster spool. I will post my map when I get home. Is this line of thought correct or am I way off?

This is a long and hotly debated topic amongst tuners with no clear outcome that I'm aware of. There is plenty of reading material out there on this.

djp0623 · 03-09-2011, 01:38 PM

How much timing are you pulling on the onset of boost? I can see this making sense from the perspective that if you are tuning for 20psi. Who cares if you retard the spark as you are passing through ...15,16,17...psi because you are only there for a fraction of a second.

What is the consensus on this? Should we be running uber conservative up to target? From a detonation perspective.....Don't you have to pull more timing to get rid of det once it has started than you do to keep it from happening to begin with???

shlammed · 03-09-2011, 01:41 PM

if you have a powerful ecu with multiple spark mod factors you can tune it to help out there.

couple this with an electronic boost control solinoid connected directly to this ecu and you can mess with PWM to allow you to spool the turbo as soon as your specific setup will allow.

i gained 400rpm of spool with timing and EBC going from what my car was tuned for off the WG. Fairly substantial if you ask me.

i ended up pulling about 3.4 degrees at the maximum cell. this was with smoothing into the adjacent cells as well... never have walls of timing jump in your timing map or your car will drive like ****.

djp0623 · 03-09-2011, 01:50 PM

I pulled quite a bit of timing on my way to target, but it never felt like I lost power. Obviously only a dyno can tell.

shlammed · 03-09-2011, 02:15 PM

That doesnt look terribly retarded.... looks like a smooth transition into boost besides your cells between 55 and 75kpa all the way across the board.

This is where MS3 or a nice ECU would make sense with their ability to have more load breakpoints to better define cruise vs load cells as well as TPS varibles.

***Braineack*** · 03-09-2011, 02:31 PM

doesn't look like a smooth transition at all...

as soon as you hit boost you're dropping around 10° timing, just like that for no good reason.

IMHO, timing retard should be gradual as the load and rpms increase.

djp0623 · 03-09-2011, 02:49 PM

Quote:
	Originally Posted by Braineack doesn't look like a smooth transition at all... as soon as you hit boost you're dropping around 10° timing, just like that for no good reason. IMHO, timing retard should be gradual as the load and rpms increase.

I started another thread about my 100kpa row. Would you increase the 130 row, or decrease the 100kpa row? I'm inclined to lower the 100kpa row.

***Braineack*** · 03-09-2011, 02:49 PM

look at the map i posted in the other thread.

This is how my path of timing looks when I drive around and get on boost. As the load increase, I start retarding the timing. At peak torque I have retarded to my in boost target.

I haven't found any benefit with retarding spool the way you have shown in your map, or by adding/subtracting fuel in the same area. Although I haven't gone crazy with the timing retard...but I'm not drag racing the car, so I don't care.

**hustler** · 03-09-2011, 02:52 PM

I sway a direct relationship between spark angle and output/MAP. I assume a smaller turbine might benefit from this, but I'm no engineer.

djp0623 · 03-09-2011, 02:56 PM

Quote:
	Originally Posted by Braineack look at the map i posted in the other thread.

Gotcha, thanks. Look at all that spark resolution. ahhhhhhhhh

I'll look at my spark table. Maybe that's why mine spools so slow unless I start at 3800 rpm. Then it is almost a vertical climb through the spark table.

While I have you here Brain: do you use an idle valve delay?

***Braineack*** · 03-09-2011, 02:58 PM

As in the "close valve when not idling delay"? the min. I can use.

djp0623 · 03-09-2011, 03:20 PM

Quote:
	Originally Posted by Braineack As in the "close valve when not idling delay"? the min. I can use.

***Braineack*** · 03-09-2011, 03:27 PM

yeah I use 1 sec.

rider384 · 03-09-2011, 07:10 PM

Here is my map