Optimal Timing for EA82T

[TheSubaruJunkie]

Was going to do a tune-up on my RX real soon. What are you performance guys using for the ignition timing? Im not sure what stock timing is, but trying to get alittle more power out of the RX the cheap and easy way.

 

-Brian

[Snowman]

My rule of thumb is to advance it 2 degrees at a time until it starts to ping under load, then back off until it stops. Rather than just going with a setting that somebody has found works for their car, this optimizes the timing for your car, your fuel, and your climate, all of which can affect where the timing should be set.

[hooziewhatsit]

does changing elevation affect this at all?

 

ie, it works at sealevel, then when I go to the mountains, will it start pinging (or vice versa)?

[TheSubaruJunkie]

With a turbocharged car it shouldnt be effected much.

 

I think i'll go bump my current timing up 2 degree's and try it then keep bumping until it pings.

 

-Brian

[Snowman]

does changing elevation affect this at all?

 

ie, it works at sealevel, then when I go to the mountains, will it start pinging (or vice versa)?

 

 

Air density. Less cylinder pressure and less oxygen to burn at higher altitudes.

 

In the case of an F.I. and turbo car, it shouldn't make much difference since the air density is compensated for very well. It's much more of an issue on vehicles with carburetors and mechanical/vacuum advance.

[WJM]

Careful!!!!

[NorthWet]

My rule of thumb is to advance it 2 degrees at a time until it starts to ping under load, then back off until it stops.

Ummm... if the knock sensor and controller are working OK, you should not notice any real pinging.

 

Anybody know for sure what the knock sensor controller's strategy is? As in, does it retard the spark in big hunks or little hunks, frequently or infrequently ("wait a moment and see").

 

BTW, it is actually possible to advance the timing beyond where the engine will ping. Accidently did that to a car once.

[WJM]

Timing is SO critical.

 

big ping will destroy pistons. Little ping will fatige rods. We've had several cars thrwo rods due to other shiops turning DOWN knock sensitivity so it posts good numbers....but 5k miles later...POP...new engine.

[archemitis]

with some cars, and water cooling, somtimes pinging is hard to distinguis from engine noise... carefull with the turbo engines!

 

carb... crank it all the way

[hooziewhatsit]

so I assume in an SPFI you could adjust until it pinged, then back it off? It doesn't have the knock sensor, so the computer shouldn't be adjusting it.

 

btw, I do know that mine will ping... from back before I knew what it was or how to correctly fix it (or that it could cause damage).

[calebz]

Since it hasn't been answered yet, stock timing is 20BTDC

[NorthWet]

I have mentioned it elsewhere, but will do so again for tuning neophytes:

 

Advancing the timing does not necessarily increase power. Given any combination of static conditions (engine design) and dynamic conditions (temp, A/F ratio, RPM, fuel quality, etc) there is an optimal ignition timing, and advancing the ignition beyond this point will reduce developed power.

 

As a corollary, the better the engine design, the less ignition advance is required. The more advance you need to add, the less potential the engine has for making power.

[archemitis]

I have mentioned it elsewhere, but will do so again for tuning neophytes:

 

Advancing the timing does not necessarily increase power. Given any combination of static conditions (engine design) and dynamic conditions (temp, A/F ratio, RPM, fuel quality, etc) there is an optimal ignition timing, and advancing the ignition beyond this point will reduce developed power.

 

As a corollary, the better the engine design, the less ignition advance is required. The more advance you need to add, the less potential the engine has for making power.

 

that almost sounds like your advocating stock recommended ignition timing.

[MorganM]

I read the nifty little sticker that came with my new fancy red turbo hood. Under the EGR section it talks about timing. For the turbo engine it states 25 degrees BTDC. You heard it right, straight from FHI... 25 degrees.

 

Rage it !_!

[NorthWet]

that almost sounds like your advocating stock recommended ignition timing.

Stock timing is usually a compromise on the conservative side. So, no, I am not really advocating it, just think that people should think about why they are doing it instead of assuming that more is better.

 

A carburetor with a single 10"...er, 254mm, barrel wouldn't work well on an EA-series engine, and neither will 120deg of ignition advance. There is a balance,a sweet-spot, somewheres. More is not always better.

[TheSubaruJunkie]

big ping will destroy pistons. Little ping will fatige rods.

 

Thats what I'm affraid of. So when I check it, since I know what is stock (thanks Caleb) I will just set it to stock. Then maybe bump it up 2 or 4 degree's to compare. This is all for a EA82T, MPFI. I hadn't even thought of the knock sensor, I'm glad you brought that up.

 

I can see this isnt like tuning my EA81 The EA81 runs best at like 10-12 degree's even tho stock is 7-8.

 

-Brian

[rallyruss]

hey brian

 

been out of the loop so I dont know if you got the IC installed yet. but I will tell you what I found. on my wagon WITH the intercooler. 25 deg. btdc is the max I can run safely. I set it to this because I had a spec that told my 25 out of a chilton book. tried 26 one time. no good. dont make the knock sensor work. it really does a poor job of controling knock.

with out an IC keep it at 20 deg.

[TheSubaruJunkie]

No IC yet. Thanks Russ.

 

-Brian

[oddcomp]

at 10 psi before i went dis i ran about 1.5 -2 deg below's the stock timing setup non intercooled cheap 87 gas

and got almost no ping that i could hear

[NorthWet]

at 10 psi before i went dis i ran about 1.5 -2 deg below's the stock timing setup non intercooled cheap 87 gas

and got almost no ping that i could hear

With or without APC? And if with, controlling boost or timing or both?

[oddcomp]

both before and after

and apc does not control timing

just boost based on knock

[NorthWet]

both before and after

and apc does not control timing

just boost based on knock

I understand that stock APC doesn't control timing, but knowing the way you like to hack things (and your kids, too, from what I hear!) I thought you might have done something there.

[oddcomp]

nope i just let teh knock indicator tell teh ms the motor is pinging and the ms takes it from there

 

kinda like a double fail safe detonation setup