Timing a custom supercharged engine
 

Hey gents. I been eyeballing those Daytona Sensors style ignition boxes. I really like the features on them. You can pretty much set up a timing curve, like an EFI engine.

Lets say on my engines, where I have been running 34* timing, locked. By using the programming feature, I'd be able to set the timing to say 10* while cranking, which is easier on the starters/batteries. Then, as soon as the RPM hits 500, the timing can be set to whatever I like. I know my style engines love advance at idle, and really helps give a much stronger idle. Maybe, I could set them at say 36, or even 38*, between 500RPM and 1000RPM??

Then, as far as cruising, esp in the peak torque area, I can pull some timing out, maybe say run 30* between 4000-5000RPM. Then, after peak torque, start bringing timing back in. Possibly even be able to run say 36*, at say 6000RPM?

I guess what I am asking, what kind of timing map are some of the EFI supercharged guys running? I'd imagine when you're buying a Eddie Young, Alex Haxby, supercharged EFI monster, the timing isnt simply "locked". The start retard, higher idle lead, ability to add/pull timing in different areas, etc, is much cooler than locking it out. Im bored and want to do something to the engines this winter.

Take this with a grain of salt as it is from timing a turbo engine in a car, but we would use lots of timing at idle, and then almost have an inverse of the torque curve.

I think you are leaving a lot on the table as far as manners, safety margin, and performance running locked timing. I would be interested to see if you could actually run more boost safer with an optimized curve.

Knock retard would be the bees knees for ultimate safety but setting up the noise table can be a bit finicky.

I am considering adding a knock/timing retard system as one of my winter projects. I think this will be a simple add on and may work well. I am running an MSD Pro Billet distributor with an MSD6M box, locked timing, dominator carb. No electronics at all. Just as a point.... I run a secondary ignition coil that will fire without the MSD box, just in case I have a problem. I can isolate the primary system within a minutes worth of unplugging the primary and plugging in the secondary. Kind of like Nascar does.

http://www.jandssafeguard.com/NewUni...alVersion.html

Turbo cars get real fun when you activate a timing retard on the brake to get the egt's way up and spool the turbos ;) makes some funny noises lol

Antilagging a big turbo is fuking awesome. Try doing it at a stoplight when a Prius is behind you. :evilb:

Joe, my experience mostly comes from small blocks with blow thru's and big heads. That being said, since these engines typically lack velocity, I usually run 38* of lead / locked timing. Others around here are running more and taking out more per pound of boost and having success. A theory I've started to adapt to also.

Since the game plan is to get as close to knock as possible without running into it under heavy load, a knock sensor makes sense. But the big question is which one??? And how reliable will it be over 4000 RPM's??? My understanding to be accurate, is to have the sensor in the head. Toyota maybe the only one using these in mass productions at this point. I have to imagine big Chevy's EFI's factory knock sensor should be "tuned" to ignore noise. Though these are probably heavy knock conditions only since any change in factory bore size or piston type could change things. I wouldn't be surprised if the ecm is programmed to ignore the knock over 4k, that is if it's a high sensitive setup.

If i were to have my engine on the dyno. I'd research a system that meets my budget, give's me programmable spectrum / frequency flexibility and has ear muffs. This way I would have control. If your close to your dyno guy maybe he'll let you experiment on dyno pulls.

Good luck, this stuff is addicting.
Andy

Yep anti lag on the supra is good times!

Joe. Sometimes if it ain't broke don't fix it. You have a strong reliable combo. Hard to mess with that until something happens. Lol.

But then if it breaks ill be forced to build some bigger mills :-)

on the mefi4b's that I tune,,the knock retard is working all the way up.I use the data record func of the mefi hud display and mod tables to run it perfectly.no dyno,,just real world running tune.on my chit I run my engines lean enough to just tickle the knock sensor.