how much timing?

[93sr20240]

just installed and started tunning my aem ems series1 and cant seem to get a good idea of how much timing i should start out with under load on pump gas... my setup is redtop sr with freddy intake 740cc inj top mount gt3071r bb z32mafs bc 272 cams ret and springs goin to run about 20lbs boost would like to get an idea of how much timing everyone runs thanks

[Kingtal0n]

You should use an EGT to dial it in more exact,

but for the sake of argument, around peak torque you expect something like 9* of total advance, with around 12* around peak horsepower, assuming 18psi which is about the max that I would use

[Croustibat]

The timing map is somewhat U shaped, the lowest timing being at peak VE efficiency.

As for getting a good timing value, that is a matter of trial - error.

You need an EGT sensor and gauge and a dyno, or use a virtual dyno software (like virtualdyn). The value given by a virtual dyno may be off, but you dont need accurate absolute values, you need to compare relative values from a run to another.

Set your timing so your EGT does not go higher than 950° after multiple runs, you get no knock and you still get power. Start conservative, make a "dyno run" or 2, add 2°, make another batch of runs. Then compare your data. Theres more power on the second run ? Add 2° again. No more power ? pull 2°. Or 4. You want some safety margin, dont forget this is winter. Less power ? quite unlikely to happen before det occurs... And if det occurs, pull 4° and leave it at that, this is the limit of that fuel. If there is room for more power, get higher octane fuel and try upping timing again.

Any higher temp than 950 will damage your turbo. And if you stay under 750 your turbo will spool slower. Think about that too.

That is for WOT and max power. You also need to dial correct timing at spool time and part throttle... less than ideal timing will decrease spooling time but decrease power a bit. Theres a trade off here. Also, remember fuel burns at a different pace when lean or rich. If you change AFR, you may need to change timing. And by changing timing, you might also need to change fueling.

You really should not seek other people numbers, as it really is fuel and setup dependent. Compression ratio, AACs. On e85 fuel, you could be running 20°. On pump fuel, it will det much before that and wont give power. BTW dont even try running 20°, it will surely kill your engine in a matter of seconds.

[rcdad123]

if you are trying to get a base map to get your car running, i would set total timing to about 32-34 degrees at about 3,200 rpm with NO BOOST. that is probably around 12-14 degrees at 1,000 rpm. i would go up about 2 degrees per 250 rpm. that is only on rpm. as far as map goes, i would retard it about 1 degree per pound of boost. that is a basic ignition map. final tuning should be done with the recommended methods by the previous posters.