99 L29 454 build

[Supercharged111]

I always thought the best timing curve was to run it up against the KS then back off 2deg. Let the engine determine how much timing it wants.
Yes,No?

Dyno is the only way. Some engines are knock limited and others are not.

 

[Scooterwrench]

No dyno,just a datalogger and a stretch of back road.

 

[Supercharged111]

No dyno,just a datalogger and a stretch of back road.

Same here. I advance it to the knock threshold then back off some with the assumption that I am knock limited. But like L31 said, they fall off before knocking usually so the Dyno truly is the only way to get it right.

 

[Scooterwrench]

Same here. I advance it to the knock threshold then back off some with the assumption that I am knock limited. But like L31 said, they fall off before knocking usually so the Dyno truly is the only way to get it right.

Gotcha!!

 

[L31MaxExpress]

I always thought the best timing curve was to run it up against the KS then back off 2deg. Let the engine determine how much timing it wants.
Yes,No?

Not necessarily, some combinations are not octane limited. It is thus possible to advance the timing past the point of losing power without running into knock.

In most cases it is benificial to know the engine family you are tuning well. I know the GMs aside from the GenV well enough to put together a timing map that will extract about 95% of the available power without going to the dyno.

 

[Scooterwrench]

Not necessarily, some combinations are not octane limited. It is thus possible to advance the timing past the point of losing power without running into knock.

In most cases it is benificial to know the engine family you are tuning well. I know the GMs aside from the GenV well enough to put together a timing map that will extract about 95% of the available power without going to the dyno.

Guess I'm gonna have to get some kind of accelerometer too. The closest dyno shops around here are either an hour east or an hour southeast from here and I'm guessing passes aren't cheap. How does a dyno compared to real world driving?

 

[L31MaxExpress]

Guess I'm gonna have to get some kind of accelerometer too. The closest dyno shops around here are either an hour east or an hour southeast from here and I'm guessing passes aren't cheap. How does a dyno compared to real world driving?

Depends on the dyno. Inertia dynos can not load the engine the same way an absorber based dyno can.

 

[Scooterwrench]

Absorber based,eddy brake?

 

[L31MaxExpress]

Absorber based,eddy brake?

Correct, Mustang dyno with an Eddy brake would be one way. The dyno I have run on a lot over the years is an AWD unit. It has multiple rollers and an addy brake. To help keep from overworking the Eddy brake all the rollers turn and the front wheels also get spun up. Similar to the way Hypertech did their development and testing runs. They loaded the vehicle as close as possible to real world as they can.

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[Scottm]

I'm on something like the 8th trip back up to the tuner. Besides still pinging at wot, it audibly and steadily pings at hway speed 55-65 climbing slight hills, when rolling into the throttle in 3rd and 4th gear, and at 30-40% throttle accelerating through the gears. So I asked them to reduce wot timing again, and make the cruise timing back off more effectively as map pressure goes up (Vac goes down), like conventional distributors have done pretty well for 80 years now.

This is the reply I got:

"MAP doesn't dictate timing on that platform, it is based on air density largely determined by MAF. The MAPxRPMxIAT calculation is largely just a sanity check against the MAF."

Does that sound right to you guys? Isn't map and manifold density essentially the same thing? I have trouble believing the powerful 0411 can NOT adjust timing based on manifold pressure/vacuum..