[Chris Mureen]

So I lowered my compression from 9.85:1 to 8.5:1. I want to improve my fuel economy and low end torque for just driving around.

How much timing can I add to make up for the lower compression when NOT at WOT. There is no way I can hear pinging because it is a bit noisy.

Any ideas?

Chris

[Dale McPeters]

Chris,
A mechanics stethoscope works very well
when there is to much noise in the engine
compartment.

[Chris Mureen]

Chris,
A mechanics stethoscope works very well
when there is to much noise in the engine
compartment.

That is pretty tough to do while driving down the road. :)

My question is pretty simple but I haven't found ANYONE who can give much of an answer. Most agree that more timing is likely but no one can give any general guidelines or experience?

Sure would love to hear from someone who has been there.

Chris

[pthornton]

This may be off the wall, but adding boost effectively increases compression ratio. Adding boost to my 9.2 engine results in about 14.2 ratio. The general rule of thumb is to reduct timing one degree for every two pounds of boost. So that about 1.25 degrees per unit of compression. Now does this apply to just reducing compression? ;) Told you it was off the wall.

[Dale McPeters]

That is pretty tough to do while driving down the road. :)

I thought you were doing it on the dyno.

My question is pretty simple but I haven't found ANYONE who can give much of an answer. Most agree that more timing is likely but no one can give any general guidelines or experience?

Sure would love to hear from someone who has been there.

Chris

Possibly since you have a 4 valve engine.
I would drop Joe Lynch an email as he has been
doing a lot of tuning lately on the newer cars with the
SCT software. He will probably have the answer that you seek.

[boss96]

Like everyone else, can't give a definitive answer but about the car being noisy..My car had 3" dumps which makes it quite loud inside the car but if I roll up the windows I can hear detonation pretty easy. Would that work for you?
Otherwise I would try adding 5 degrees overall except at wot and see how it works.
Bob