Sundance 6g72 "3.0 turbo build thread"(N/A DYNO SHEET pics inside)

[bond_bbs]

Not sure when you're planning on boosting, but if it's soon - why push the for serious timing tunage? You're just going to have to pull it back drastically for tuning in boost, and what you get in the way of timing now is no indication of the timing you'll run in boost.

[Sundance 6g72]

thats a good point. Once my heads are rebuilt (waiting on valve spring compressor from a friend) ill throw the turbo setup on

i plan on pulling the motor, swapping my rebuilt heads on, doing the timing belt, water pump, new clutch, turbo, crossover, downpipe, injectors and anything else that is required for the turbo. i have "all" that parts (i saw that cuz im sure i missed something)

so i guess i should be asking what the max timing is that i should run for 8psi. i know 8psi on one turbo might be different for another but there has to be a starting point?

[Force Fed Mopar]

If it pulls harder and doesn't knock, then it isn't too much Play around with it, bump it up some more if it likes it, but keep an eye out for knock.

[Sundance 6g72]

im not sure what i need to look for though.. never heard a car knock from too much timing advance.. but as stated above, whats the point when im going to be force feeding 8psi into it

[Ondonti]

Practice messing with it before the consequences = boom boom motor.

87, I am pretty sure he used your format for timing but used base timing plus indicate timing because he told me he went crazy high timing.

[Force Fed Mopar]

Practice messing with it before the consequences = boom boom motor.

I concur

[Ondonti]

Mopar3.0 doesn't remember what the base timing was but that he did have an expletive load of timing.

[Sundance 6g72]

Practice messing with it before the consequences = boom boom motor.

87, I am pretty sure he used your format for timing but used base timing plus indicate timing because he told me he went crazy high timing.

tuner studio was set for 50 degrees timing at 5000rpms and higher. last night i went even further but didnt feel much power increase so i backed it down a bunch but im just going to import EDs table again (alot less timing up top but very aggressive during low load situations)

i did what ed said for setting the timing.. its the only thing that made sense in my head.

-set fixed timing of 10 in tunerstudio
-shoot the timing light and it gave me a reading of bellow 10degrees
-lower trigger angle until timing light reads 10* on the degree scales
-ended up with 74.4 trigger angle.

is 50* really that crazy of a number for NA?? ED did have it set at 31 for a reason i guess.


im not sure what you mean by base timing. When MS was sending only 10*, i read 10 with the timing light. when i switched back to the table it gave a super weird reading because my idle was at like 22* or something and thats obviously not going to register on the timing light

i guess im missing something here.

[Force Fed Mopar]

Base timing is essentially how much timing you set by turning the distributor, w/o any other advance from anything.

I don't think 50 is that odd for an NA. Every engine design is different, so I dunno what the norm is for a 3.0. I do know that the old Slant 6's like to cruise w/ around 54* total. I think the V8's are like that also, I know at WOT on old small/big block Mopar you want around 34-36*, and since the vacuum advance typically adds around 15-20*...

On my 2.2 Daytona, cruising at 50mph I see about 33 degrees on the scanner (total). So really you just play with it till you find what works for your engine. Ported heads like different timing than stock, different compressions like different timing etc.

[c2xejk]

is 50* really that crazy of a number for NA?? ED did have it set at 31 for a reason i guess.

I am just starting my dyno testing so anything I say right now, I can reverse on...

I was having problems getting the RPM signal to the dyno computer. Fiddled with it for a while before I gave up and collected some data without RPM info (and thus torque.) I did a pull with the table I gave you (31 or 32 degrees during WOT) and then did a pull with timing at 38 degrees for WOT. Maybe a 0.6 hp increase in peak hp. There was a gain in post peak hp hp. So there is gain in more advance, but not till very high RPM. (>6200 RPM based on looking at the MS log file and making an educated guess.)

Being clear, this is what happened on my engine and increasing spark advance on a different configuration could well yield different results... Some of the differences include: stage 2 heads, ported runners, custom plenum, different spark plugs, etc.

Ed Kelly - www.kmperformance.com

---------- Post added at 12:53 PM ---------- Previous post was at 12:45 PM ----------

Base timing is essentially how much timing you set by turning the distributor, w/o any other advance from anything.

I don't think 50 is that odd for an NA. Every engine design is different, so I dunno what the norm is for a 3.0. I do know that the old Slant 6's like to cruise w/ around 54* total.

Worth noting for those that are not aware, that at part throttle you often need more advance because the mixture is leaner and thus the flame front propgates slower...

Monday night I was talking to a friend that has done spark calibrations professionally (for an OEM) and he refreshed my memory on several details...

Ed Kelly

[87turbodance]

..

Monday night I was talking to a friend that has done spark calibrations professionally (for an OEM) and he refreshed my memory on several details...

Ed Kelly

Is this info that you wish to keep private or would you be willing to share some of your discussion?

[c2xejk]

I can share most of it. Hopefully I can do what he said justice.

Probably the most important thing was his analogy of spark advance to riding a bike.

On a bike there is an optimal angle to push on the pedal the hardest. Likewise in an engine there is an ideal crank angle for the in cylinder pressure to peak. The exact angle depends on engine geometry and can be calculated. Generally it is 5-15 degrees ATDC (After Top Dead Center.)

Too early is like pressing on the bike pedal when it is straight up. Too late and you are chasing the pedal down... With the idea in mind there is a "ideal" angle the goal is then to figure out when to light off the AF mixture so cylinder pressure peaks at that angle. Unfortunately the light off angle (Spark Advance) changes depending on a variety of factors (engine speed, A/F ratio, air in the cylinder, etc.)

So the "easiest" way to determine spark advance is by experimentation. OEMs do it by running spark hooks. This is where you hold the engine at fixed operating point (MAP and RPM) and vary the spark advance and record the torque (this is done with non-knocking fuel.) When the spark advance is graphed on the x axis and torque on the y axis it forms a hook shape. ie. there is a spark advance that generates maximum torque for that specific operating point.

If you took all those peak points you would have an "ideal" spark advance table. However, most engines are "knock limited." That means running real world fuel the "ideal" table would have too much advance. So then you have to determine the knock limits of the engine on real fuel under all conditions... Engineers usually throw in a safety margin. That is why you can generally advance timing a few degrees, not have knock and make more power.

He also said some of the same things I have mentioned before.

-More advance is needed at part throttle and lean mixtures.
-Changing a camshaft can throw off you spark hooks and your "safe" spark advance table.
-You want to run the minimum spark advance that achieves max torque.

That covers most of the relavent stuff. We spent some time discussing how I might be able to check spark advance for the non-WOT table points, but didn't come to anything that I have much confidence in yet. Best answer would be to start with the stock table...

For those that are curious I plan on upping the octane level of the fuel I am running for the remainder of the spark advance testing. Then I plan on running a "knock detector" to see if I can hear any issues on the 87 Octane fuel I have been running.

I have a little more work to do on the VE tables. I just re-cal'd my wide-band and noticed that there are a few "lean" spots that I need to address.

Feel free to ask any questions you have. If I can't answer them, I will try and pass them along to get a more definitive answer.

Ed Kelly

[Sundance 6g72]

Awesome postIs there a point where you can run to much advance causing a loss in power even though the engine is not knocking?

[RoadWarrior222]

Yes! .... and the important point, ignition advance does not equal power, peak cylinder pressure at the exact right time equals power.... so if you hear people saying "Ima fill with premium so I can run more advance" .. just nod, smile, back away...

[Sundance 6g72]

So how should I do it for a stock block with stock heads?Does Anyone have the exact numbers for wot spark advance for the stock computer? I like using eds table but the wot portion could prolly be more aggressive than 31 degrees. I wonder if the 50 I ran was to much

[RoadWarrior222]

I think Shelgame had the ignition table figured out. All I know about the stock one is it works a lot better with 15* base timing

[Sundance 6g72]

Isn't base timing just idle timingI idle at 22degrees. Ed has a reason behind it. But with ms it obviously dosnt throw the whOle ignition table off

[RoadWarrior222]

Erm, yes and no, it's open loop cold idle timing. To check/set it on a stock 'pooter you have to unhook the CTS... otherwise it might read at something like 22.

[Sundance 6g72]

but with megasquirt would that matter? i guess im not getting what base timing is..

unless i look at it like this

-base timing, the timing your car runs when the computer does not intervene
-normal timing, timing that the computer sets + base timing?

idk.. im to tired to think.

[Ondonti]

With megasquirt its effectively offsetting the distributor from zero.

It seems to be necessary because of the strange way they have designed the firmware. Also, not all motors can change timing. Like I mentioned before. Some versions of firmware have NO timing advance when starting unless you have base timing. Makes no freakin sense but its probably just the programmer being lazy.
If you have noticed, Megasquirt doesn't do so well with firmware support. The manual never seems to match up with any firmware I have ever used. They make changes to things that make no sense. Thats what you get with something that is a hobby for its creators.