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Stock ignition timing on Apex

mbarryracing

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Does anyone have an idea what the stock ignition timing is at idle on an Apex? Anyone have a timing curve?

Thanks
 

The book says 5 degrees at idle. The timing curves are crazy on the stock sleds you wouldn't believe how much timing they run at times.
 
H&H, thanks for looking that up. I'll try it but I don't think mine will even run with timing that retarded.

Yeah, I hear ya on the timing. I think it's so advanced because of the higher RPM the genesis engine runs? Time to get things under combustion...

Thanks again... :Rockon:

Mauri
 
Put a degree wheel on it and check the timing at 1500 rpm. We don't run ours at 5 degrees there either, but its mostly race fuel so a little more timing doesn't hurt.

As far as stock flat out (10,500 RPM) under a load its 34 degrees, but the in between stuff is where the crazy stuff happens. The higher the rpm's are away from the TQ peak the less threat of detonation.

Standalone's are a whole lot of fun, but remember everything is programmed to what Motec feels is the best set-up and with infinite settings there is always room for improvement on each individual sled.

Playing with an Autronics EMU right now, not sure if I care for it yet but we'll give it some time I guess as they all have there good and bad points.

We might be trying a plug in and play Doo Motec here this year for project pump gas lol! Need some freaking ice & snow!
 
My timing is a little hotter then that, more towards 39 but also have a decompressed engine so all things considered... and might be able to get a few more degrees more yet. But she's not pushing oil out the breather yet with the pump gas I've fed her, might leave well enough alone and not get greedy... LOL!
Just trying to get the best idle quality right now, it likes 20 degrees at idle with under 12.5:1 AFR.
 
OK need to clarify things. My base ignition timing map (unboosted) has timing upwards of 39 degrees at WOT, which is very misleading because my ECU also has an ignition comp for boosted MAP so the overall timing ends up being more realistic when under boost...
Thanks to someone who made me think about this a little more to realize this.
I love this site... :Rockon:
 
Mauri,
Just to clarify my message to you, When I said I never run anything over 32, I meant at wide open throttle. My timing maps have timing up to 48 degree's in cruise and generally vacuum, pressures below 100 KPA absolute, manifold pressures or on decell to prevent the sled from feeling like you hit the brakes.
At boost on pump gas, I would caution everyone to be carefull with timing or you can send me your engine for a rebuild, that would be OK by me. LOL
 
Greg,
Yup, that was totally clear and hence my comment about overall timing when under boost. Very true that part throttle and decelerating the cylinder pressures are not very high as they are at WOT at peak torque RPM, etc.
That is a great point that everyone should hone in on, due to the variation we see with pump gas it's really not wise to run on the ragged edge...
Reason I'm staying with max 30 and not sending my engine to you, atleast not yet... LOL!
 
Mauri,

Your idle timing is really up to you, anywhere from 8*btdc to 18*btdc. The right way to build a timing curve to hold a steady& clean idle is to build a compensation table that will get the engine to stay at a preset & desired idle speed. For example, if your desired idle speed is 1700rpm when hot, then your compensation table has 0 compensation at 1700rpm and you include 2 sectors 250rpm apart, one lower at 1450rpm and one higher at 1950rpm. The sector at 1450rpm should have a timing compensation of +5 degrees and the one at 1950rpm should have a timing compensation of -5 degrees. This forces the engine to always go back to a steady 1700rpm. Principle is simple, if TP = 0% and idle creeps above 1700rpm, then negative timing comp brings back the engine speed to the aim idle rpm. Same goes if the engine slows down, positive timing compensation will accelerate the engine back to the aim idle speed.

Many people run the idle without enough air and increase timing to get the engine to idle properly. This is not the right method. It is always better to be slightly higher on the air idle circuit and reduce timing to get to the desired speed.

Regarding WOT timing, yes 32* is an ok figure for people who run the oem ECU with piggybacks and who want to have a safety margin because of the inability of the oem engine management system to properly manage a forced induction application. The MoTeC M400 factors in air temp as a crucial input for overall WOT timing and allows individual cylinder timing and fueling calibration. Without air temperature compensation, one is totally in the dark for overall timing figure. The difference between a 85F degree air charge temp and a 125F degree is easily up to 4* degrees of retard. If this can't be managed or understood, then it is indeed better to stick with conservative and recreational timing figures below 31*btdc on a low compression application running pump gas.

In closed loop knock control mode, I have run engines with stock compression to 180kpa on pump gas at 33*btdc (don't try this at home... :)) This is the absolute edge and this leaves no room for error. It needs to be used with a MoTeC SKM (Standaloone Knock Module) which will manage knock events at speeds up to 200hz, and will automatically retard timing on any individual cylinder that exceed a peak cylinder pressure threshold defined by the tuner. FYI.... 6 degrees retard from absolute peak cylinder pressure before knock pings costs 30hp at 180kpa........

BTW... sorry I did not get back to you earlier on this... swamped!
 
10 years later, and still great info. Used this to fix my timing map in the Motec today. Probably saved me a engine! I had 38 degrees of timing at 23 psi of boost set up! Had it not been for someone pointing me to this thread I would have sent it! I am at 29 degrees now until I get to a dyno and we can dial it up and see what the power level is doing.
 


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