nothere

iTrader: (23)

I know this question prolly belongs in the general engine management section but I know all you Utec guys know your stuff, so I will ask it here.

What are you finding as a good timing advance when boosted over 15 lbs?
Are you still able to carry twenty, in the teens or in single digits?
Figure stock turbo. And I guess we had better know what afr you are running there too.

thanks
Bruce

turboback with cat
wi
little known ecu

MalibuJack

iTrader: (5)

This is a pretty general question, the funny part is, if you search, most "Tuners" are unwilling to give away their secrets..

Generally, safe is around 4-5 degrees at peak boost, climbing to 20 degrees at redline..

I have personally gotten 8-10 degrees and 25 degrees toward redline with the stock turbo, but EVERY car seems different, there are other people who can't even approach that.. Also, your AFR's have a bit to do with it, if your running fairly lean, you can't get as aggressive as if your running fairly rich (its still a balance)

It unfortunately varies with every car, so you have to start with a safe baseline (I started my map by logging my car's stock timing for about 2 weeks and built a map) then I smoothed the timing a bit, and set my target AFR's for my boost level.. then I would increase timing a little at a time while watching for knock and EGT's.. if I had a hot spot or a small bit of knock, I'd alter timing/AFR slightly in that region... It took about 6-8 runs to get me to a point where the car felt nice, without being tuned within an inch of its life.. I also have a "Race tune" which I leave nothing on the table, its still a pump-gas tune, but its not the type of tune I'd run unless I know I had at least 1-2 gallons of race gas...

I've seen some tunes on race gas that have an insane amount of timing advance, I'm not so sure I'd attempt to do that, but if you have access to adequate logging/road-dyno tools, or a dyno, you can make multiple runs and really go to town with race gas or WI tuning..

MalibuJack

iTrader: (5)

Let me also add, that boost levels, and RPM will have a definite impact on what timing to run.. since timing is all about... TIMING.. The key to making power is to time your spark event so the combustion process begins building cylinder pressure just at TDC or after.. Basically you balance the amount of fuel, and timing, so the process produces the most complete burn and most cylinder pressure on the power stroke, the better you can time it, and the more air and fuel you can burn in that time, the more torque your going to produce.. If you haven't already noticed, it becomes a slippery slope since there are several factors that can affect how much timing, how much fuel, etc.. you can run at any particular time, since if everything is timed and fueled Perfectly, you leave no room for error (bad gas, hot spot in the combustion chamber, boost spike, etc..) and can very quickly do damage.. Thats where the "Safe guidelines" come in.. 11.0-11.5 AFR's etc..

djh

Here's something interesting, at least to me: at 7200 rpm one degree of crank rotation is 23 microseconds! What does that have to do with ignition timing? Well, the spark fires when the electric field between the plug electrodes (the voltage difference divided by the gap) reaches the breakdown field strength of the mixture. Lots of things can have an effect on exactly when that point is reached, so even a 10 microsecond jitter from a difference in resistance or capacitance of plug wires or a plug gap that's off a bit can put your timing off by half a degree from what you expect.

Dave

USP45

iTrader: (13)

Malibu Jack, how are you checking or listening for knock? Knock Link? And whatever method you are using, where would I find one? Another quick question, do knock sensors go bad, and if so is ther any way to test them? Thanks!

Oh, and djh, pretty cool information. I like obscure information like that, it's interesting.

MalibuJack

iTrader: (5)

Oh yeah! Thats a really good point, you need to have a predictable and healthy ignition system if you want to tune aggressively since variations can do damage.. And even then, there's always risk (abhorrant misfire or anything like that)

MalibuJack

iTrader: (5)

I have my UTEC adjusted to be very sensitive to knock in the midrange and higher RPM, and pretty dulled at low RPM's..

However, I use the TurboXS Tuner Pro which has its own knock sensor and knock threshold settings, I have them set pretty sensitive, and use the headphones and plug into the Tuner Pro.. You can hear a nice little ping over valvetrain noise pretty easily with it... The knocklink actually works very well too, but I think its a visual tool and I prefer to work with both visual and audible cues..

I love that obscure information too, His point is exactly why I chose to upgrade my ignition way before anyone else thought it was worth doing..

Knock sensors CAN go bad, their just Piezo microphones (solid state), and those do sometimes go bad, but its rare on a knock sensor since their designed to be in physical contact with a vibration generating device (The engine).. Most sensors are affected by the attenuation, there are several factors can affect their sensitivity frequency range, in a car engine, even the type of oil your using can actually affect that.

nothere

iTrader: (23)

thanks to all,


I had read that timing might go as low as 22 or 21 degrees (must have been a typo) on boost. That did not jib with what I had seen on my car. With an AFR for water injection I saw timing was being pulled at 5400 rpm. (With the water and a less agressive AFR there was no timing pull.) That event was from about 13 degrees, on the water tune I have since set it much lower.


MJ, what ignition setup do you use?

MalibuJack

iTrader: (5)

I have two systems I have used, the current setup is an AEM C2DI with Honda/Denso stick coils from a CBR950RR motorcycle, Its off the car at the moment waiting on some custom harness connectors that Im using to replace the parts I salvaged off stock coils. I had run the HKS DLI-II which worked well, but I wasn't happy with the output of the stock coils and that unit.