Ok, so.. what issues will I have with timing when I tune for 27lbs of boost? Will I need to start figuring out the MSD box and retard the timing? Im simply unsure of what is going to happen at high boost. What exactly happens to cause the timing to advance?

Thanks for your time.

James

http://auto.howstuffworks.com/ignition-system1.htm

I understand how an ignition system works. However, when you force a motor and electrical system to do something its not designed to do what will happen? My question was more specific towards the 420a motor and my current setup. Not a generalization of all motors and how they are built to work. Thanx for the link though.

Theres really nothing to figure out w/ the msd. Its as easy as plotting it out and telling it to retard x degrees at x rpm or x psi. Its cut and dry.

You kind of need to see whats going on w/ some dyno time and taylor you timing to whats going on. What type of fuel do you plan on running? Our ecu just goes to 17 degrees advance at wot so its not really a situational occurance like it is w/ cars whos ecu make the decisions based on air flow/injector pw and things of that nature. You also have aftermarket cams if i'm not mistaken right?

400whp or bust.

He is right, I'm sure if you do a few dyno passes and post the sheets there are some people here who can give you an idea of what type of adjustments to make.

You'll need to retard a couple degrees up top. I can do ~24 PSI on the 20G using 93 octane unleaded without pulling any back. When I push it past 24 PSI, I use leaded C16 and pull just a couple degrees. Make sure you watch your EGTs *very closely* at those boost levels. It'll get real hot with too much or too little timing advance.

Also, I'd recommend tuning your A/F ratio in the low 11:1-11.3 on the dyno (11:5-11.7 on street) range at points above 20 PSI. The extra fuel helps prevent detonation.

That's great and all... but I'm telling you not to boost that high with 93 octane, weather you retard the ignition or not.

You'll also need about 28-29 PSI of 20G boost on your current setup to make more than 400 WHP.

Ill throw in some higher octane gas for the dyno just to be certain that everything will be fine. HRC made 382whp at 27lbs of boost on the 20g with the portfueler system. I wonder what octane they were running.

edit: err. with the 20g i mean

Also that was with stock everything else except for the ignition system so all the extra goodies have to amount for something.

One last thing on the subject of my dyno numbers.. Im really starting to wonder if the dyno ive been using is acurate. Maybe I should go somewhere else for tuning the portfueler. Ive used the same dyno the entire life of the car.

check out this post.

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=38&topic_id=157780&mesg_id=157780#157780

I would def not run more than 20 psi on 93 octane..Pump gas tuning is one big balance act when you start running high boost. I would use at least 110, or some C16. From the tuning I've done, I've come to the conclusion that the biggest problem is the timing advance during peak torque. Knock is more prone to happen during this time, and I get slight amounts of knock at 15 psi on a 5th to 4th downshift, but only for a second, then its fine.

I would start off at lower boost, and get your target A/F ratio set. Doug has great advice here, with a 11.1-11.5 or so for 20+ psi. Maybe start out at 10 psi, then go up in 2 psi increments trying to keep your target A/F. Once you are up to 20 psi, and your A/F is set, up the boost a few psi, and keep close tabs on your EGT and A/F. I would pull out at least 2-4 degrees during peak torque(stock cammed 420 is between 3500-4500), and then put that few degrees back in after peak torque. I would also put in a little bit more fuel during peak torque also.

It's going to be very difficult to use a ignition retard box and get good power results, mostly becuase retarding by rpm is not going to be very efficient in producing max output power. We don't need that so much, but we need to be able to retard X amount of degrees, at X amount of boost, at X amount of retard. No CD box that I know of can do that. This is where a stand alone of some sort is really needed.

Having complete control and tunability of the fuel and timing is KEY to pump gas power. You will find out rather quickly that not having complete control of the timing is one of the boosted 420A's downfalls when it comes to making big power. Just my thoughts..

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