One for the techies.... (This is in no way an advert )

Been thinking about this for a while and havent had a chance to try it myself.

I think I have come up with an idea for a new control algorithm that can be incorporated into an ecu to help reduce turbo spool up and increase throttle response.

This can only be added by an ecu manufacturer as it will require software modifications to the control program.

Normally, ignition is mapped with suitable advance to give maximum power within safe limits.
However, doing this takes energy away from the exhaust turbine as the gas expansion happens sooner and is used mainly to push the piston down.
Mappers will often reduce the ignition advance in the spool up areas of the map to a comfortable average point where the there is a split between gas energy used for both.
I.E. This reduces pushing power on the piston but increases the gas expansion into the exhaust turbine thus spooling up the turbo quicker.

Anyway, at these points in the map, these values are fixed.
I.E. If the revs and boost (load) do not change then the ignition value does not change.
(I exclude closed loop knock advance out of this but you would have disabled this anyway at these points )

So on to my new algorithm idea ...

The method is only enabled when accerating and in the spool up/low boost areas.

The algorithm basically alternates in various sequences a number of different ignition values for 1 mapped ignition point.
Lets say 3 for example.

The first is the normal ignition value originally used. (I.E. the compromised value)
The second is an advanced value optimised for maximum piston pushing !
The third is retarded value for maximum gas flow out the exhaust port.

You cant normally use the second or third values above as either the turbo will not spool up very fast or as in the latter case, prolonged use will make the exhaust valve melt or cause major detonation issues.

The values outside the normal are could be calculated from the original after some experience.

The alternating ratio used and the duration of it depends on a master calculation and is done very fast and perhaps changed every ignition in some circumstances.

This calculation takes time, previous history, current load demand, BSFC to determine the heat load passed through to the turbo and in the cylinder.
EGT and knock sensor could be used to trim this.
This isnt a pure calculation based on current events.

FYI, I have done work like this before on controlling 3 phase motors and knowing how hard you can drive them by back calculating heat load and estimated time to failure/overload for variable speed drives (VSD's).

My basic idea relies on the fact that an engine can actually tolerate DET and intermittent ignition advance/retards outside normal limits for short durations.
E.G.If you heat up the exhaust valve you must allow it to cool
But all this happens very quickly !
Once you can quantify this in real terms as a heat/energy load history I think there are gains to have.
This would need to be done for both the cylinder and turbo.

I hear people screaming that DET is bad for an engine....Not always true.
Nearly all modern cars deliberately run on and over the detonation limit in order for closed loop ignition advance to work !!

Now add to all that fuel control too, it gets comlicated.

I have written a C program modelling a YB engine based on all my mapping experiences and my conclusion are that there are gains to be made.

Unfortunately, there is only one one to find out for sure and how much

The heat load calculation is way too complex for a L8 (sorry Karl/Stu )

Something to think about.....My head hurts now.