MalcolmV8

Hey guys, is there a rule of thumb for adding timing to the motor when dropping compression? Not so much WOT as that's easy to figure out. I'm more concerned with light throttle street driving.

I have a D16Y8 that went from stock 9.7:1 to 9.0:1 and the drop in gas mileage is quite noticeable in daily cruising around to work etc. I wanted to add some timing in but looking for guidelines before I start playing around. I know timing won't bring back all the mpg but it will help some.

Something like 1 degree of timing for every half point CR lost? or what's something good to start with? It's much harder to detect detonation in very light part throttle driving so trying to educate myself on this as much as possible before tinkering.

rich7777

There isn't... the only way to tune part throttle timing properly is on a dyno. You need to work out MBT for every cell (along with setting the fueling properly against the power output).

MalcolmV8

My understanding of setting up MBT at part throttle on a dyno though is to use a load bearing dyno which can lock you at various low rpm conditions. Say lock me in at 2000 RPMs and then I lay into the gas pedal and off and watch dyno numbers and then add some timing and removing timing etc. till I find the sweet spot. However when I call around nobody in kansas city appears to have a load bearing dyno that I can find.
I don't have enough tuning experience or know how to get this done on a standard dyno jet inertia dyno. I know I could just pay a shop to do it but it's my hobby car I like to tinker with and tune myself.

Uncle Dave

What tuning platform are you using ?

MalcolmV8

Hondata S300

La Maestra

General rule of thumb- plus or minus 2 degree's (1 degree isnt high enough and 3 degrees will make you guess whether to increase or retard.