Controlling spark for boost control

[grandprix34]

About how many degrees per pound of boost would be required to prevent detonation?

There is an MSD boost timing control unit which has a vacuum input and adjust ign. timing up to 3lbs of boost.

My question is how many degrees would be suited for a boosted DOHC? I know a Wideband O2 sensor would also be required to tune. SO what do you guys that have knowledge in this field think?

[nocutt]

In all honesty, it really depends on a lot of variables Intercooled? Non intercooled, turbo size...etc, etc!!...ideally you would like to "create" an ign. map with a fuel map and the onset of boost...
for your question, it is generally agreed 2 degrees of timing: 1 lb of boost...it is easy to see you will be pulling a lot of timing if you are going to 10psi...
I will also add, the Qu motor has an advantage of cooling better <AL heads> so with good fuel I will only pull timing when the engine is "seeing" more load...around mid RPM and put some back a the top end...if you have good fuel...I will retard only at WOT...that is just me!!

[timg]

I've been running 7 psi with zero retard. I'm going to start out with a 1degree/pound of boost retard + more boost and see where it gets me.

Tim

[Dave]

actually, the MSD will retard the timing 1° - 3° per pound of boost, up to 20° - not up to 3lbs of boost ... the BEST thing you can do is get an aftermarket knock sensor, and monitor the "volume" or ammount of knock, and retard per that - I'd suggest 1° per lb to start. my Mustang needs 1.5° to run properly.

I've got an MSD 6BTM for my Mustang, so I know all 'bout them.

--Dave

[grandprix34]

So how much spark control would I have to run on my speed density DOHC? How much timing does the DOHC run at WOT?

[timg]

Quick warning. The MSD boxes sound good, but it takes over $700 to get one that allows boost based timing retard on a DIS ignition system. It's not nearly as cheap or as easy as it seems. I'm trying something from split sec. I'll post how it works. Perfect Power also has something that should work.

Tim