scathcart

Just for references sake, how many degrees of advance are you running? This could make a good archive thread.
I run 6 degrees on 87 octane on all the N/A's I build.

State degrees and octane used.
I usually don't advance my timing any more than this for emissions purposes, but if you do advance further, state what you advance to.

Please, if you just moved the CAS and made a guess of your timing, don't post.

To accurately measure your advance:
- Hook up an advance timing light to a leading spark plug.
- Set the advance on the timing light to zero.
- Increase the advance on the timing light (via a **** or digital buttons) until the pointer matches up with the yellow mark on the front pulley.
- Read the advance off of the timing light.



(Now if anyone's really adept... you'll see why timing doesn't really need to be retarded for 100 shots of nitrous and lower on N/A's if using the stock timing).

JamesWade2002

I know this thread is old but I really don't want it to die. Does anyone know what the total advance of the stock ECU is and where it occurs at? Is it possible to rev the engine till the ECU stops advancing and then set your max advance there? I am thinking 30 degrees total advance on the lead will work good, but I really don't know how to set that. I would want to make max power on S4 rotors with 87 octane and lots of mods/ ports. anybody?

dbgeek

I have run 0 to 10 degrees advance, and charted 2nd gear 20 to 60 times, and 3rd gear 40 to 70 times. The conclusion I came up with is that more advance = more power earlier (and I need a better timer than my gf w/a stopwatch). For example, with stock timing, I can feel each intake event (5/6 ports opening, and VDI opening) on the butt-o-meter. As I advance the timing, I lose the feel for the 5/6 ports opening at ~4 deg; further advance hides the VDI opening ~7 deg.

I get nervous as I approach 10 degrees, so I've been running approximately 5 degrees with happy results- smooth pull from ~2500 rpm through 5300 where I feel the VDI open and continue to redline. I have delusions of using a G-tech or similar device to verify gain by degree advance, but noone has ponied up and let me borrow one (still restoring the car means that the funds don't go to "extra" toys atm).

I premix at 100:1 with 87 octane. Plugs came out pretty clean considering how long I let let this puppy idle in my driveway.

Pete

pengarufoo

The stock ecu timing will always be a drastic compromise unless you can reprogram the map. Like the last poster observed, you will be moving the sweet spot around, so this is somewhat subjective, it will depend on where the driver wants the sweet spot to be. To really effectively tune the timing you need more than just one global **** (the CAS orientation).

I'm running 31 BTDC peak lead timing on my street port NA @ 87 octane after last time tuning, a significant power difference from my previous 26 BTDC.... it also made my afr's go lean when going from 26 to 31 requiring me to add a bit more fuel where it was advanced more. But this is with a e6k so theres a **** every 500rpm @ WOT...

WAYNE88N/A

Just as a side note- I ran 5 deg advanced for a while, because she seemed to idle better there after the rebuild. Tweaked her back to dead nuts on the timing marks about a month ago. Not really a seat-of-the-pants difference between the two, as far as I could tell, but I did notice that the gas mileage increased by about .5 gal per 200 miles. Or, in other words, I went from about 25.9 mpg at the 5* adv to about 27.4 after she was tweaked back to "normal"...

JamesWade2002

hmmmm.....now that part is interesting. noone is going to believe this and I am not asking anyone too, but the last time I recorded a "good" mileage, from the trip meter, from pump to pump on the side of the interstate, keeping at 70mph as steadily as I could, I got above 30 mpg. I was shocked but I rechecked it and it was right. I went 49 miles on 1.55 gallons of 87 octane with timming set to stock. This is with no 5th and 6th port dividers as it enters the combustion chamber and no sleeves, TII rotor housings and intermediate housing, header, big pipes, open element, ported throttle body and upper to lower manifolds all the way to the block. oh and an MSD box. not possible...yeah I know, but that is what I got for pure interstate. I'll bump and then take another reading

JamesWade2002

Well I have bumped base timing to 10*BTDC and the car has more power down low, I am not really sure about high rpm power though, my butt dyno is kinda jaded at this point. I do notice that when passengers talk to me and then I punch it, at 4000 rpm in first they tend to stop talking until the end of second gear. I will check gas milleage ASAP and post.

Also, does anyone know how much the stock ECU advances timing under high load, high rpm? Meaning, what is max timing for the stock ECU/CA?

dbgeek

Bump

I'm very interested in the ECU advance numbers as well. If i'm motivated, I'll con my gf into holding revs for me while I measure teh advance. The big quetion is whether it changes based on load, rpm, throttle position, etc...

Henrik

Please do. You will see it vary with rpm and load (among other things). Post
the advance measured every 500rpm or so in neutral (don't forget that the
gun needs to be setup for 2 stroke or divide the reading in half).

-Henrik

Tofuball

That information would help a LOT for my aftermarket ECU setup. However, I am very sure it is load (vac) dependant, as most cars have a vac advance for timing.