ignition timing after full header back exhaust installation.

[rmoltis]

So I've never actually adjusted ignition timing before.

I understand the steps laid out in the service manuals on how to "adjust" the timing withing spec.

But what I don't know is how to find the perfect timing setting for my specific application.

How will I know if I set the degrees of advance to its optimum setting?

I have dickmeyers long tube header with 2" piping all the way back and 2" everything else in/out.

And the intake is the stock airbox with the drop in k&n.

And adjustable fuel pressure regulator set at 42psi.

Premium wires and ngk iridium plugs.

Brand new upstream and downstream o2 sensors.

And new cat.

So everything is new and should be ready for an optimal "tune"

Also I always run premium gas which is 93 octane.

And I know these variables won't dictate an exact number.

But it let's you guys know that it probably needs adjusting.

I can use my scanguage to see exact ignition timing reported by the ecu.
To see where the timing is set to before and after.
Maybe even during.

Right now it sits at 10 Btdc at idle
And can reach into the 35+btdc range at higher rpms.

I can also read engine load which may or may not help with the timing adjustments.
I'm not sure if ignition timing affects cylinder filling or intake vacuum.

I currently don't have a timing light so I can't do this now.
As well as I haven't installed the upstream o2 sensor yet.

But once its ready to be driven again.

How will I know I have the optimum setting without using a dyno?

Also would it not be smart to time without a timing light?
Even if my scanguage shows me ignition advance?

And after timing is set will my intake vacuum increase or stay the same?

I'd like to take on this task by myself because the actual adjusting of timing is simple.
It's just the finding the optimum timing that I'm unsure if I will know/understand when I am there.

[FestYboy]

purchace a vacuum gauge. with engine warm, take a reading of intake vacuum pressure. shut down or disable ignition advance control and increase mechanical timing. take another reading. continue process untill engine vacuum reaches a maximum (no vacuum increase with subsiquent timing increase). NOTE: base idle must be reset each time the timing is adjusted (use 700rpm as a constant). once maximum vacuum is reached, enable advance control, testdrive and listen for ping or knock. if any is heard, decrease mechanical advance by 2* and re-test.

given your current setup, i'd start with 14* base timing and go from there. that should get you close to the limit anyway, then it's just fine tuning ans using your ear and vacuum gauge.

[rmoltis]

So when you say disable ignition advance.

That's where I use the paperclip as a jumper to ground the self test input terminal at the data link connector
To defeat the computers automatic advance?

And the mechanical advance is where I adjust the distributor back and forth for the base timing correct?


On a side note adjusting the timing should also help me gain some mpgs back as well won't it?

I guess now I just need to get a vacuum gauge.

[FestYboy]

yes, yes, yes, and yes, in that order

[rmoltis]

The last question is.
The manual says idle should be 650-750.

Other than idle fuel consumption.

Would there be a reason to have this lower or higher?

Or is 700 just a good middle ground between the two.

And thx again for all your answers.

[FestYboy]

if the engine is in better than average condition, a 400 idle rpm can be used, but such a low rpm can cause lack of sufficient coolent flow and low charging voltage.

700 is a good middle ground and is easy to maintain. also the fuel consumption is neglagable as there is little load on the engine at idle.

[rmoltis]

Sounds good ill just stick with 700.

Thx again for all the responses.

They were helpful in building my confidence to complete this task.

[rmoltis]

It's been a while, forgot I had this thread floating around.

Just wanted to put out some updates in here.

I initially started with increased fp and some advance.
But after a while I realised that even with 40psi pressure at the afpr.
The car still needed more fuel.

It was running on the lean side of the afr with an advanced timing to compensate.
Has been running good for the longest time now.

But today I went out and put in another .5-1psi of fuel and pinging started up.

What this means is
A.) Fuel is entering the stoich and rich side heading towards fastest burn and max power at wot.
&
B.) That it is to advanced, it was perfect for lean burn.


But now that its getting closer to max power and efficiency, I had to start pulling out timing slowly as fp rises,
Until I find the point that it burns at the fastest rate at wot.

Once I get to this point I shouldn't have to add or remove any more ignition timing.
Because since the fuel burns faster retarding it puts the entire event closer tdc.
Where it can create peak pressure without having to fight the piston on the upstroke from being advanced.

This places strain on the engine, pistons, connecting rods etc for a reduced amount of time compared to an advanced ignition timing. That starts expanding much before Tdc as the piston fights the increasing pressure on its upstroke.

So the goal is to have the fastest burning flame front possible with the smallest amount of ignition timing possible for engine efficiency.

That way peak pressures occur at the correct time, where the piston has the most leverage on its downstroke.
And reducing the time the cylinders are exposed to those pressures and high heat.

I am very very close to finding the sweet spot with my at home tune :-)
Just tiny incremental changes over time will show me the direction to go.

also on a side note i only do my tuning on sunny warm/hot days.
that way i can see exactly when pinging can occur at max operating temp and high outside temps.
i feel as though if i can tune to have no pinging on hot days at full temp,
then on colder days my car should be just fine

[rmoltis]

went out for another whole day dedicated to timing/fp/idle air mixture adjusting.

ive finally done it.
i have everything spot on for efficiency and power.

the main vision in my head to get right first was adjusting the fp to the point where engine load is highest at torque peak(which is 4000rpms) while slowly tapering off after that as hp increases to the 5000-5500rpm range. this is based off of dickmeyers powerband specs associated with the header

this was done by dialing in the fuel pressure.
so the first thing i aimed for was getting the engine load dialed in for peak torque.
this required me using the real time data from my scanguage for engine loading.
i would go for a drive and go wot a few times and watch at which rpm peak load occured for each setting.

as the fp increased the torque peak moved downward in the powerband.
but as a result of too much fp bringing the torque peak below 3000rpm for example on one occasion,
as rpm increased the af mixture became too rich and power drops off above torque peak.

so i started at base fp and started going up in small increments until the scanguage showed peak torque occuring at 4000rpm.
now at this point i went out for a drive to feel how things were. and that includes taking it past torque peak into peak power and feeling/seeing where it occurs.
my goal was for the power to hit around 5k like spec'd.
but at 4k tuned for peak torque it put my hp in the 4800 range.
every header dickmeyer made couldnt be exactly the same there has to be + or - some airflow.
so i found that my exhaust seems to perform best with peak torque occuring at 4200rpm and peak power in the 5000-5500rpm range..
i also have id say a cone filter but it is more of a cylindrically shaped filter with a built in velocity stack/radiused edge where it meets the maf,
the velocity stack also has a stepped edge so it buts up against the tube creating a smooth transition into the maf from the stack.

now once the fp was in the correct area the engine loading occured at the same ranges regardless of timing advance/retard.
timing advance would just hold onto the pressure for longer, not neccessarily change where torque peak occurs.
and retarding some degrees just holds onto pressures for a shorter period of time.

but aside from all that the data showed that where torque peak occured stayed constant once fp was set (it seemed to like a hair over 40psi best.)
the point at which the flame front travels the fastest, for gas it is 11:1 but for e10 im not sure exactly what it is i cant seem to find it, but e10 tends to have about %4 different fuel ratio. so doing a simple conversion comparing the other gas to e10 afr's. i came up with 10:56.
now the number isnt important since i cant just go type in the value somewere and have everything magically perfect.

now this fastest flame front needs to be positioned for peak hp.
and once it is in the correct location, the torque peak might shift slightly but torque peak will be more towards the stoich + or - zone.
once these two values are realized. as rpm rises and fuel enriches from between stoich and max flame front speed/max power afr.
the flame front speed increases as well. its like advancing your timing automagically but with varying flame burn rates instead.
and this allows you to remove some timing to bring this whole event closer to tdc.

now as you come down in rpms from torque peak ve also starts slowly dropping from reduced airflow from modifications,
as well as the afr becomes leaner becoming harder to burn. so the engine is less efficient down there.
but still runs great driving in the city.

with the open exhaust and intake there is reduced ve at low rpms.
what this means is, if i go wot at a low rpm in gear, the throttle opens up
the air rushes in all at once filling the cylinder and stalling the airflow into the engine.
which presents itself like a bog down.

but if im light throttling it keeping the throttle opening small during the first 1500-2000rpms.
it helps keep air velocity high and moving and it gets up and goes great in the city.
and if i decide to get on it next to someone, i just need to either drop down a gear or get into the 2500-3000rpm range, then step on it and the power is available.

now for the timing, once i had the fp set it was onto timing.
i noticed the other day that removing some timing was bringing my power up.
i didnt have much, but i basically put it back to the stock setting or around 9 degrees. im leaning a little towards 9.
but once i removed the timing there was a sweet spot and it moved up and down with advance/retard.
now since flame front speed was optimised.

when the engine timing was advanced the mixture would ignite and expand as the piston was on its upward stroke,
which reduced power because the engine had to fight this, you would feel the power but part of it wasnt being applied to the ground
simply because it was being eaten up by you could say pumping "losses"?


since the flame front speed was optimised and works like advancing the timing as rpm increases,
it makes removing timing more feasible without losing power.
to bring some of that lower rpm performance back.
once retarded it brought the whole event closer to tdc.
which reduced the force imparted on the pistons on their upward stroke as the gas expanded more towards the end of the cycle.
but increased the leverage on the piston on its downward stroke due to building optimal cylinder pressure at the correct degree to which the piston has the most leverage.
i could tell when it was at this point because when you would accellerate it would accelerate as if nothing was holding the pistons back (advanced timing felt like the pistons were being held back when accellerating) probably because it was just advanced outside the correct range
also reduced my chances of knock or ping because the engine c.c. will be running cooler being exposed to cylinder heat/pressures that are lower from removing timing.
this should help light off the cat faster since more of the combustion heat now goes into the exhaust.
also can help draw gasses out of the crevices in the combustion chamber between the piston and cylinder walls,rings,etc during scavenging.


i think thats pretty much it.
its been a long time finding the perfect spot.
now im here, i can just set it and forget it :-P.

i will say it though, my car has quite the kick to it now once it in the powerband.
its really hard to stay off the gas sometimes.
fuel mileage has also increased. not over stock but since the changes were made.
i was getting around 22mpg right after installation, my last tank i was sitting at 30mpg from city driving which is a nice increase.
and now that everything is dialed in ill have to run another tank of fuel through the engine before i can get you guys some more accurate mpg readings.
im assuming now that the e10 im running has enough fuel added to bring it into its own stoich zone it is what helps bring my fuel economy back up.
and btw i always use premium shell gasoline from the station right at the end of our street so that the fuel blends remain fairly constant.
it is nice to finally see the advantage to using premium fuel now that it is all dialed in.

kinda makes me contemplate what e85 would feel like.

mmooaahh ppoowweerr!!

[TorqueEffect]

POWEEERR!!!!!!!

https://www.youtube.com/watch?v=ygBP7MtT3Ac

[rmoltis]

POWEEERR!!!!!!!

https://www.youtube.com/watch?v=ygBP7MtT3Ac

This^ :-D

[bravekozak]

rmoltis, What does your engine sound like? Can you post a wav or mp3?

[rmoltis]

In descriptive form:

The engine at idle and under light load driving is very quiet and low profile almost un-noticeable.

But once under load and past the resonant point (4200 rpms) it gains a whole new tone and feel.
the sound literally changes at 4200 rpms and you can hear the power kick in.
It is quite the sound from a little b3.

I will try to get a good sound clip up here as soon as I can figure out how.

But I need a way to record it from the outside while moving for best sound.

Inside my car it is too sound deadened and doesn't record much.

And I never thought the parking lot Rev was good enough.
to guage what it would sound like while under load driving.

If I had a gopro I could do it easily.

Any ideas anyone?

[bravekozak]

Tape a Sony Walkman to your rear hatch and record or have a passenger hold it out the window while you shift.

[rmoltis]

Won't the wind blowing over the microphone cause the sound to be distorted and full of noise?.

I need to use a mic with a little poof ball on the end to reduce wind noise I think.
I currently have a mic with a long cord. But it has no poof ball on the end.