Louis

iTrader: (7)

There has been a lot of discussion lately about how much ignition timing is worth.

The test car is a 2013 ZL1 Auto, 8" lower, 2.6 upper, headers only, injectors, CAI, pump gas, TR8 plugs, boost is 200-206 KPA (14-15 psi)

We had to flash a stock cal file in it, so naturally, we progressed our way into the tuneup.

There are 3 pulls here, 12*, 14*, 16*. AFR is a pretty flat 11.5:1.


These are back to back to back, only down time is the time it took to make a cal change, and the 30 seconds to reflash. The ONLY change to the cal during these pulls was timing. AFR was rich, and I chose to leave it alone.





Louis

Somebody09

god damn that's a lot of gain!

Grr

iTrader: (2)

I agree on this, another thing I noticed was below 11* the car started losing power FAST, like 25-30whp per degree.
starting at 11*, I gained 14-17whp and about 1mph per degree of timing up to 18* when the gains started to diminish. This was at 12-13# of boost

9sectruck

iTrader: (9)

Great info,

SMOKNSS

iTrader: (3)

That's a pretty cool test. Nice to know... never seen a back to back comparison before.

9sectruck

iTrader: (9)

Usually when the timing gets to its limit torque will start to drop before the end of the pull.
Looks like its still climbing. Did you look at plugs through the pulls?

Louis

iTrader: (7)

Yes, I always pull plugs. I have done enough of these cars, that I know where the limit is before I even start within a few degrees. 16* is childs play, considering Ill run almost double that on C16. I ended up with almost 20* on pump gas with an 8 plug and stock cam with 9:1 compression.

Timing has its limits, like anything else. Always check plugs, always keep good fuel in it if youre pushing the limits, and just be aware. You can melt **** easily if you do not pay attention!!

As for reaching MBT, we will see spark knock before we see MBT, unfortunately, with this setup. Stock, its the opposite, we will see MBT before we see spark knock.

ajrothm

Nice test info!

Thanks for posting.

My last time on the Dyno I was seeing about 15rwhp gain for every 1 degree of timing increase... Up to 17* anyway.. That's where I stopped.. I was seeing similar gains with leaning the AFR every .3 also..(in the high 10 AFR range.)

71 chevy

iTrader: (18)

great information. thanks for posting.

malarlar

When ignition timing was advanced , it also leaned out the a/f ratio if it liked the timing change. You are seeing gains from fuel and timing.

Blackpanther99

iTrader: (8)

Great info and a great increase!

Louis

iTrader: (7)

Not true. The same amount of Air and fuel enters the chamber. Timing only dictates at which point that charge is lit. Air fuel stays the same. The crank angle at which the plug sparks, doesnt add or remove air or fuel.

If you are REALLY off base timing wise, you could have an incomplete burn, which may affect AFR, but not in this case.

All of the runs ( about 10 total) were all the same. You cant tell which ones were which because they lay on top of each other.

typhoon1015

iTrader: (5)

Very nice to see consistent data, it doesn't happen much anymore. Thanks for taking the time to share with us.

did the HP start tapering off enough to end the pull at 6k ish? due to stock cam?

the torque curve seems like this would be crazy on the street, but somewhat predictable since its a broad curve.

71 chevy

iTrader: (18)

Louis, doing some rough math,

for the 12 deg setup to match the power of the 16 deg setup, 3.5-4 psi more boost will need to be added.

which is harder on the engine in your opinion

16 degs and 15 psi, or
12 degrees and 19 psi

The Alchemist

iTrader: (19)

This is very interesting data. I'm running around the same amount of boost and only using 13-14 degrees of timing. I guess a few degrees more wouldn't hurt.

ajrothm

I see NO difference in AFR when playing with timing... unless its a BIG swing....Say going down to 12* from 17*....and even thing its barely measureable...


I also see no real distinguishable difference in AFR from the dyno to the street pulls....My AFR is around 10.9-11.0 on the dyno, and on the street pulls...and the same on race gas (103)+meth vs. 93+meth.... AFR is always pretty constant.... Despite what the internet tells me.

rotary1307cc

iTrader: (5)

I went 2mph faster in the 1/8 going from 19* to 22*

123 to 125/126

Louis

iTrader: (7)

Be careful! This LSA is a 9:1 compression engine, so you can reach MBT easier before spark knock. Just pull your plugs and keep an eye on everything

If this was a or 11:1CR setup, Id be lucky to get 12* in it!

Louis

iTrader: (7)

I would run 19 and 14* timing

Boost and timing can both be detrimental. Its hard to say with such little increases. I would have to say that less boost and more timing would be safer, but more boost, depending on the efficiency of the setup, it may make more power with more boost.

denmah

iTrader: (2)

i typically see 25rwhp per degree thru a th400 on the turbo LSX cars i tune.

i lock em out at like 10deg at 8psi and up and push for like 16-18 wherever we wanna stop and then bring it up a degree or two at a shot (depends on where we are)

and it looks just like that, i push for 20+rhwp per degree, then when it makes 5-10 i quit there or go back down a degree.